Retinoic acid conjugate compounds and uses thereof

Abstract

Provided are compositions including conjugate compounds of a retinoic acid and a covalently linked trisaccharide. Also provided are methods for prevention or treatment of cancer or viral infections.

Description

[0001] RETINOIC ACID CONJUGATE COMPOUNDS AND USES THEREOF

[0002] BACKGROUND

[0003] Technical Field

[0004] The present disclosure relates to a conjugate compound comprising retinoic acid and tri saccharide, and the pharmaceutically acceptable salts thereof. The present disclosure also relates to a pharmaceutical composition comprising the conjugate compound or the pharmaceutically acceptable salts thereof and the pharmaceutically acceptable carrier thereof. The present disclosure further relates to the pharmaceutical composition and the uses thereof.

[0005] Description of Related Art

[0006] Retinoic acid (RA) is a metabolite of vitamin A, a fat-soluble vitamin and an essential nutrient for vertebrates. Hence, RA is responsible for most of the activities of vitamin A in growth and development, supporting cell differentiation, immune response, and reproduction. A key role of RAis to act as an intercellular signaling molecule to help determine position along the embryonic anterior / posterior axis during early embryonic development. All-trans retinoic acid (ATRA), also called tretinoin, is the major occurring retinoic acid; other isomers include isotretinoin (13-cis-retinoic acid) and alitretinoin (9-cis-retinoic acid).

[0007] RA and its isomers have been used for treating a variety of dermatological disorders, such as acne and cancers, because of their specific effects on cell proliferation, differentiation, and apoptosis. For example, it was found that in children with high-risk neuroblastoma, treatment with 13-cis- retinoic acid can reduce the risk of the cancer coming back after high-dose chemotherapy and stem cell transplant. ATRA has been studied in combination with other drugs in various cancers and precancerous lesions. For instance, ATRA with different interferons (IFNs) has been shown to enhance the effects of both drugs and lead to growth inhibition and cell death in tumor cell lines. However, it has been found that the dosage required to treat cancer by current retinoids, including retinoic acids, is toxic to the subject. Furthermore, several side effects such as teratogenicity, hepatotoxicity, and headaches have been observed with the use of retinoids. The medical community therefore is still in search of novel retinoic acid analogs in order to increase therapeutic efficiency and / or reduce toxicity, thereby providing methods and pharmaceutical compositions with better safety and higher efficacy.

[0008] SUMMARY

[0009] The present disclosure provides a conjugate compound comprising a retinoic acid and a tri saccharide, wherein the retinoic acid is covalently linked to the tri saccharide. The present disclosure also provides uses of the conjugate compound or methods for preventing or treating cancer in a subject in need thereof, comprising administering to said subject a therapeutically effective amount of a pharmaceutical composition comprising the conjugate compound or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier thereof. In other embodiments, the present disclosure provides uses of the conjugate compound or methods for preventing or treating a viral infection in a subject in need thereof, comprising administering to said subject a therapeutically effective amount of a pharmaceutical composition comprising the conjugate compound or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier thereof.

[0010] In at least one embodiment, the retinoic acid in the conjugate compound of the present disclosure is an all-trans retinoic acid (ATRA), a 9-cis-retinoic acid, a 13-cis-retinoic acid, a fenretinide, a retinal, a 4-hydroxy -retinoic acid, a 4-oxo-retinoic acid, an 18-hydroxy -retinoic acid, a 5,6-epoxy-retinoic acid, or a mixture thereof.

[0011] In at least one embodiment, the trisaccharide in the conjugate compound of the present disclosure includes at least one monosaccharide. In at least one embodiment, the trisaccharide in the conjugate compound of the present disclosure consists of three monosaccharides. In at least one embodiment of the present disclosure, the three monosaccharides are linked by glycosidic bonds. In other embodiments of the present disclosure, the trisaccharide consists of a monosaccharide and a di saccharide.

[0012] In at least one embodiment of the present disclosure, the monosaccharide is an aldose, a ketose, a deoxy sugar, or an amino sugar. In some embodiments of the present disclosure, the aldose is glyceraldehyde, erythrose, ribose, arabinose, xylose, glucose, galactose, mannose, idose, gulose, talose, allose, or altrose. In some embodiments of the present disclosure, the ketose is dihydroxyacetone, erythrulose, ribulose, xylulose, fructose, psicose, sorbose, or tagatose. In some embodiments of the present disclosure, the deoxy sugar is deoxyribose, 2-deoxyglucose, fucose, rhamnose, or quinovose. In some embodiments of the present disclosure, the amino sugar is glucosamine, galactosamine, mannosamine, or muramic acid.

[0013] In at least one embodiment of the present disclosure, the disaccharide is sucrose, lactose, maltose, cellobiose, trehalose, gentiobiose, melibiose, isomaltose, kojibiose, nigerose, turanose, maltulose, palatinose, lactulose, mannobiose, laminaribiose, rutinose, sophorose, sambubiose, or isolaminaribionose.

[0014] In some embodiments of the present disclosure, the trisaccharide is raffinose, kestose, maltotriose, melezitose, panose, isomaltotriose, manninotriose, acarbose, gentianose, theanderose, umbelliferose, planteose, verbascotetraose, laminaritriose, or nigerotetraose.

[0015] In at least one embodiment, the retinoic acid in the conjugate compound of the present disclosure is covalently linked to the trisaccharide by a linker including a substituted or unsubstituted aliphatic group having 1 to 10 carbon atoms. In some embodiments of the present disclosure, the linker is a straight or branched alkyl group. In some embodiments of the present disclosure, the linker has at least 3 carbon atoms. In some embodiments of the present disclosure, the linker has less than 10 carbon atoms. In some embodiments, the retinoic acid in the conjugate compound of the present disclosure is covalently linked to the trisaccharide by a linker having 1 to 10 carbon atoms, a linker having 2 to 6 carbon atoms, or a linker having 3 to 5 carbon atoms, e.g., a linker having 1 carbon atom, a linker having 2 carbon atoms, a linker having 3 carbon atoms, a linker having 4 carbon atoms, a linker having 5 carbon atoms, a linker having 6 carbon atoms, a linker having 7 carbon atoms, a linker having 8 carbon atoms, a linker having 9 carbon atoms, or a linker having 10 carbon atoms. In some embodiments of the present disclosure, the linker has a propyl group, a butyl group, or a pentyl group. In some embodiments of the present disclosure, the linker further comprises an NH group.

[0016] In at least one embodiment, the conjugate compound of the present disclosure has a structure of Formula I:

[0017] In at least one embodiment, the conjugate compound of the present disclosure has a structure of Formula II:

[0018] (II).

[0019] In at least one embodiment, the present disclosure provides a pharmaceutical composition comprising the conjugate compound described above or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier thereof. In at least one embodiment, the present disclosure provides a method for preventing or treating cancer, comprising administering the conjugate compound of the present disclosure to a subject in need thereof. In some embodiments of the present disclosure, the cancer is pancreatic cancer.

[0020] In at least one embodiment, the present disclosure provides a method for preventing or treating a viral infection, comprising administering the conjugate compound of the present disclosure to a subject in need thereof. In some embodiments of the present disclosure, the viral infection is caused by an RNA virus. In some embodiments of the present disclosure, the RNA virus is respiratory syncytial virus (RSV).

[0021] The present disclosure also provides a use of the conjugate compound as described in the present disclosure in the manufacture of a medicament for preventing or treating cancer or for preventing or treating a viral infection.

[0022] In at least one embodiment, the present disclosure provides a pharmaceutical composition for use in preventing or treating cancer or for preventing or treating a viral infection.

[0023] DETAILED DESCRIPTION

[0024] The present disclosure relates to a conjugate compound comprising a retinoic acid and a tri saccharide, wherein the retinoic acid is covalently linked to the trisaccharide. The retinoic acid in the conjugate compound of the present disclosure provides therapeutic activity, and the trisaccharide in the conjugate compound of the present disclosure enhances the therapeutic activity.

[0025] For example, the conjugate compound of the present disclosure significantly enhances inhibition of viral replication as compared to the retinoic acid conjugated with monosaccharide. In at least one embodiment, the conjugate compound of the present disclosure provides more than 95%, more than 90%, more than 85%, more than 80%, more than 75%, more than 70%, more than 65%, or more than 60% inhibition of viral replication in a subject as compared to the untreated control. The conjugate compound of the present disclosure inhibits viral replication for at least 24 hours, at least 48 hours, at least 72 hours, at least 96 hours, or at least 112 hours. In other embodiments, the conjugate compound of the present disclosure shows enhanced antitumor effect and reduces the tumor volume in a subject. In at least one embodiment, the conjugate compound of the present disclosure provides more than 10%, more than 15%, more than 20%, more than 25%, more than 30%, more than 35%, more than 40%, more than 45%, or more than 50% tumor volume reduction in a subject as compared to the untreated control.

[0026] In some embodiments of the present disclosure, the concentration of the compound of the retinoic acid conjugated with the trisaccharide in preventing or treating cancer or a viral infection can be, but not limited to, from 0.1 pM to 10 mM, from 0.1 pM to 1 mM, from 0.1 pM to 500 pM, from 0.1 pM to 250 pM, from 0.1 pM to 100 pM, from 0.1 pM to 50 pM, from 1 pM to 10 mM, from 1 pM to 1 mM, from 1 pM to 500 pM, from 1 pM to 250 pM, from 1 pM to 100 pM, from 1 pM to 50 pM, from 10 pM to 10 mM, from 10 pM to 1 mM, from 10 pM to 500 pM, from 10 pM to 250 pM, from 10 pM to 100 pM, or from 10 pM to 50 pM.

[0027] In other embodiments, the present disclosure provides a pharmaceutical composition comprising a conjugate compound or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier thereof, wherein the conjugate compound comprises a retinoic acid covalently linked to a tri saccharide.

[0028] In at least one embodiment of the present disclosure, the conjugate compound is incorporated into any acceptable carrier, including creams, gels, lotions, or other types of suspensions that can stabilize the conjugate compound and deliver it to an affected area by topical applications. In other embodiments of the present disclosure, the pharmaceutical composition can be in a dosage form such as tablets, capsules, granules, fine granules, powders, syrups, suppositories, injectable solutions, patches, or the like. The above pharmaceutical composition can be prepared by conventional methods known to a person skilled in the art.

[0029] In at least one embodiment of the present disclosure, a method of use is provided based on the conjugate compound disclosed herein. The conjugate compound of the present disclosure is useful for treating cancer, such as pancreatic cancer. The method comprises a step of administering to a subject carrying cancer a conjugate compound of the present disclosure, in an amount effective to treat cancer.

[0030] The pharmaceutical composition of the present disclosure can be applied by systemic administration or local administration. Local administration includes topical administration and inhalation. Systemic administration includes oral, parenteral (such as intravenous, intramuscular, intraperitoneal, subcutaneous, or rectal), and other systemic routes of administration. In systemic administration, the active compound first reaches plasma and then distributes into target tissues.

[0031] Dosing of the pharmaceutical composition can vary based on the extent of the cancer and each subject’s individual response and can be determined by a doctor or a practitioner. For systemic administration, plasma concentrations of the active compound delivered can vary but are generally 1 x IO'10moles / liter to 1 x 10'4moles / liter, e.g., 1 x 10'8moles / liter to 1 x IO'5moles / liter. In at least one embodiment of the present disclosure, the pharmaceutical composition is administrated intravenously to the subject. The dosage for intravenous bolus injection or intravenous infusion is generally 0.03 mg / kg / day to 20 mg / kg / day or 0.03 mg / kg / day to 10 mg / kg / day.

[0032] In at least one embodiment of the present disclosure, the pharmaceutical composition is administrated orally to the subject. The dosage for oral administration is generally at least 0.1 mg / kg / day and less than 100 mg / kg / day. For example, the dosage for oral administration is 0.1 mg / kg / day to 100 mg / kg / day or 0.5 mg / kg / day to 50 mg / kg / day for a human subject. For example, the dosage for oral administration is 20 mg / day to 1,000 mg / day or 100 mg / day to 2,000 mg / day, e.g., 20 mg / day to 500 mg / day, 25 mg / day to 200 mg / day, 50 mg / day to 500 mg / day, 50 mg / day to 200 mg / day, 100 mg / day to 800 mg / day, 100 mg / day to 600 mg / day, 100 mg / day to 400 mg / day, 200 mg / day to 800 mg / day, 400 mg / day to 800 mg / day, 400 mg / day to 1,200 mg / day, 500 mg / day to 2,000 mg / day, or 800 mg / day to 2,000 mg / day for a human subject. In at least one embodiment of the present disclosure, the pharmaceutical composition is administrated subcutaneously to the subject. The dosage for subcutaneous administration is generally 0.3 mg / kg / day to 20 mg / kg / day, e.g., 0.3 mg / kg / day to 3 mg / kg / day.

[0033] In at least one embodiment of the present disclosure, the pharmaceutical composition is administered by inhalation. Methods of inhalation include liquid instillation, instillation as a pressurized fluid preparation via metered dose inhaler or equivalent, inhalation of an aerosolized solution via nebulizer, or inhalation of dry powder, and directing soluble or dried material into the air stream during mechanical ventilation. The surface concentrations of the active compound delivered via inhalation can vary but are generally 1 x 1 O'10to 1 x IO’4moles / liter, or 1 x 1 O’8to 1x10'5moles / liter.

[0034] Those of skills in the art will recognize that a wide variety of delivery mechanisms are also suitable for the present disclosure.

[0035] In this disclosure, all terms including descriptive or technical terms which are used herein should be construed as having meanings that are obvious to one of ordinary skill in the art. However, the terms may have different meanings according to an intention of one of ordinary skill in the art, case precedents, or the appearance of new technologies. Also, some terms may be arbitrarily selected by the applicant, and in this case, the meaning of the selected terms will be described in detail in the descriptions of the present disclosure. Thus, the terms used herein are defined based on the meaning of the terms together with the descriptions throughout the specification.

[0036] Numerical ranges recited herein by endpoints include all numbers and fractions subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.90, 4, and 5). It is also to be understood that all numbers and fractions thereof are presumed to be modified by the term “about.” The term “about” means plus or minus 0.1% to 50%, 5% to 50%, 10% to 40%, 10% to 20%, or 10% to 15% of the number to which reference is being made. As used in this disclosure, the singular forms “a,” “an,” and “the” include plural referents unless expressly and unequivocally limited to one referent. The term “or” is used interchangeably with the term “and / or” unless the context clearly indicates otherwise.

[0037] Also, when a part “includes” or “comprises” a component or a step, unless there is a particular description contrary thereto, the part can further include other components or other steps, not excluding the others.

[0038] The phrase “an effective amount” refers to the amount of an active ingredient that is required to result in a reduction, inhibition, or prevention of a disorder or condition, or one or more symptoms of such disorder or condition in a subject. For example, the term “an effective amount” used herein may be the amount effective to treat cancer by ameliorating the pathological condition or reducing the symptoms of cancer. An effective amount will vary, as recognized by those skilled in the art, depending on routes of administration, excipient usage, and the possibility of co-usage with other therapeutic treatment.

[0039] The term “subject” used herein refers to a mammal, for whom diagnosis, prognosis, or therapy is desired. Generally, the mammal is a human or a non-human mammal. In some embodiments, the mammal may refer to a non-human mammal used in, for example, screening, characterizing, and evaluating drugs and therapies, such as non-human primates, cows, horses, goats, sheep, dogs, cats, rabbits, pigs, mice, or rats.

[0040] The term “administration” or “administering” used herein refers to introducing, providing, or delivering a pre-determined active ingredient to a subject by any suitable routes to perform its intended function.

[0041] As used herein, the term “composition” can be prepared according to any method known in the art for the manufacture of pharmaceuticals. Such composition or combination may contain sweetening agents, flavoring agents, coloring agents, and preserving agents. The composition of the present disclosure can be further devised into various formulations. A formulation can be admixed with nontoxic and pharmaceutically acceptable excipients which are suitable for manufacture. Nonlimiting formulations may comprise one or more diluents, emulsifiers, preservatives, buffers, excipients, etc. and may be provided in such forms as liquids, powders, emulsions, lyophilized powders, sprays, creams, lotions, controlled release formulations, tablets, pills, gels, lozenges, packets, troches, elixirs, suspensions, solutions, syrups, soft and hard gelatin capsules, suppositories, sterilized injection fluid, packaged powder, on patches, in implants, etc.

[0042] For example, a tablet formulation or a capsule formulation of the compound may contain other excipients that have no bioactivity and no reaction with the compound. Excipients of a tablet or a capsule may include fillers, binders, lubricants, glidants, disintegrators, wetting agents, and release rate modifiers. Binders promote the adhesion of particles of the formulation. Examples of excipients of a tablet or a capsule include, but are not limited to, carboxymethylcellulose, cellulose, ethylcellulose, hydroxypropylmethylcellulose, methylcellulose, karaya gum, starch, tragacanth gum, gelatin, magnesium stearate, titanium dioxide, poly(acrylic acid), and polyvinylpyrrolidone. For example, a tablet formulation may contain inactive ingredients such as colloidal silicon dioxide, crospovidone, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, sodium starch glycolate, and / or titanium dioxide. A capsule formulation may contain inactive ingredients such as gelatin, magnesium stearate, and / or titanium dioxide.

[0043] For example, a patch formulation of the compound may comprise some inactive ingredients such as 1,3-butylene glycol, dihydroxyaluminum aminoacetate, disodium edetate, D-sorbitol, gelatin, kaolin, methylparaben, polysorbate 80, povidone, propylene glycol, propylparaben, sodium carboxymethyl cellulose, sodium polyacrylate, tartaric acid, titanium dioxide, and purified water. A patch formulation may also contain skin permeability enhancer such as lactate esters or diethylene glycol monoethyl ether. Topical formulations including the compound can be in a form of gel, cream, lotion, liquid, emulsion, ointment, spray, solution, and suspension. The inactive ingredients in the topical formulations include, but are not limited to, diethylene glycol monoethyl ether (emollient / permeation enhancer), DMSO (solubility enhancer), silicone elastomer (rheology / texture modifier), capryl ic / capric triglyceride (emollient), octisalate (emollient / UV filter), silicone fluid (emollient / diluent), squalene (emollient), sunflower oil (emollient), and silicone dioxide (thickening agent). See, e.g., Remington: The Science and Practice of Pharmacy 20thEd. (2000) Lippincott Williams and Wilkins, Ed. K. E. Hoover.

[0044] As used herein, pharmaceutically acceptable carriers, which are inactive ingredients, can be selected by those skilled in the art using conventional criteria. Pharmaceutically acceptable carriers include, but are not limited to, non-aqueous based solutions, suspensions, emulsions, microemulsions, micellar solutions, gels, and ointments. The pharmaceutically acceptable carriers may also contain ingredients that include, but are not limited to, saline and aqueous electrolyte solutions; ionic and nonionic osmotic agents such as sodium chloride, potassium chloride, glycerol, and dextrose; pH adjusters and buffers such as salts of hydroxide, phosphate, citrate, acetate, borate, and trolamine; antioxidants such as salts, acids and / or bases of bisulfite, sulfite, metabisulfite, thiosulfite, ascorbic acid, acetyl cysteine, cysteine, glutathione, butylated hydroxyanisole, butylated hydroxytoluene, tocopherols, and ascorbyl palmitate; surfactants such as lecithin, phospholipids, including but not limited to phosphatidylcholine, phosphatidylethanolamine, and phosphatidyl inositol; poloxamers and poloxamines; polysorbates such as polysorbate 80, polysorbate 60, and polysorbate 20; polyethers such as polyethylene glycols and polypropylene glycols; polyvinyls such as polyvinyl alcohol and povidone; cellulose derivatives such as methylcellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, hydroxypropyl methylcellulose, and their salts; petroleum derivatives such as mineral oil and white petrolatum; fats such as lanolin, peanut oil, palm oil, and soybean oil; mono-, di-, and triglycerides; polymers of acrylic acid such as carboxypolymethylene gel, and hydrophobically modified cross-linked acrylate copolymer; polysaccharides such as dextrans and glycosaminoglycans such as sodium hyaluronate. Other pharmaceutically acceptable carriers include xanthan gum, carrageenan, Avicel RC-591 (a combination of microcrystalline cellulose and carboxymethylcellulose sodium), and polyethylene glycol. Alternately, the active compound may be dissolved or suspended in a pharmaceutically acceptable lipid formulation such as those described by Kalepu et al. (Acta Pharmaceutica Sinica B, 3: 361-372, 2013), for example, vegetable oil, coconut oil, castor oil, etc.

[0045] Such pharmaceutically acceptable carriers may be preserved against bacterial contamination using well-known preservatives, including, but not limited to, benzalkonium chloride, ethylenediaminetetraacetic acid and its salts, benzethonium chloride, chlorhexidine, chlorobutanol, methylparaben, thimerosal, and phenylethyl alcohol, or may be formulated as a non-preserved formulation for either single or multiple use.

[0046] As used herein, the term “treat,” “treating,” or “treatment” refers to the application or administration of one or more active agents to a subject afflicted with a disorder, a symptom or a condition of a disease, or a progression of the disease, with the purpose to cure, heal, relieve, alleviate, alter, remedy, ameliorate, improve, or affect the disorder, the symptom or the condition of the disease, the disabilities induced by the disease, or the progression of the disease.

[0047] As used herein, the term “preventing” or “prevention” refers to preventive or avoidance measures for a disease or symptoms or conditions of a disease, which include but are not limited to applying or administering one or more active agents to a subject who has not yet been diagnosed as a patient suffering from the disease or the symptoms or conditions of the disease but may be susceptible or prone to the disease. The purpose of the preventive measures is to avoid, prevent, or postpone the occurrence of the disease or the symptoms or conditions of the disease. The term “cancer” refers to a malignant neoplasm. The terms “neoplasm” and “tumor” are used herein interchangeably and refer to an abnormal mass of tissue, wherein the growth of the mass surpasses and is not coordinated with the growth of a normal tissue. A “neoplasm” or “tumor” may be “benign” or “malignant,” depending on the following characteristics: degree of cellular differentiation (including morphology and functionality), rate of growth, local invasion, and metastasis. A “malignant neoplasm” is generally poorly differentiated (anaplasia) and has characteristically rapid growth accompanied by progressive infiltration, invasion, and destruction of the surrounding tissue. Furthermore, a malignant neoplasm generally has the capacity to metastasize to distant sites. Malignant neoplasms or cancers treated by the composition of the present disclosure include, but are not limited to, pancreatic cancer.

[0048] The following examples are used for illustrating the present disclosure. A person skilled in the art can easily conceive the other effects of the present disclosure, based on the disclosure of the specification. It will be apparent that one or more embodiments may be practiced without specific details. The present disclosure can also be implemented or applied as described in different examples. It is possible to modify or alter the following examples for carrying out this disclosure without contravening its scope for different applications. Titles or subtitles may be used in this disclosure for the convenience of a reader, which shall have no influence on the scope of the present disclosure.

[0049] EXAMPLES

[0050] Exemplary embodiments of the present disclosure are further described in the following examples, which should not be construed to limit the scope of the present disclosure.

[0051] Preparation Example 1 : Synthesis of a retinoic acid conjugated to a trisaccharide with a linker having 3 carbon atoms.

[0052] Maltotriose-C3-13-cis-RA, a conjugate of maltotriose linked to 13-cis-retinoic acid through a 3-carbon-atom linker (C3) is synthesized through the Scheme I below:

[0053]

[0054] Scheme I.

[0055] Steps of this synthesis scheme are as follows.

[0056] Step 1 : Synthesis of perfluorophenyl (2Z,4E,6E,8E)-3,7-dimethyl-9-(2,6,6-trimethylcyclohex-

[0057] 1-en-l-yl) nona-2,4,6,8-tetraenoate (Compound 10).

[0058] To a solution of 13-cis-retinoic acid (Compound 11, 1.2 g, 4 mmol) in anhydrous dimethylformamide (DMF, 20 mL) were added pentafluorophenyl trifluoroacetate (Compound 12, 1.46 g, 5.2 mmol) and triethylamine (TEA, 0.81 g, 8 mmol) at 0°C. The reaction mixture was stirred at 0°C for 1 hour. The reaction mixture was treated with H2O and extracted with ethyl acetate (EtOAc). The combined organic phases were washed with brine twice, dried over Na2SO4, and concentrated in vacuo to afford the perfluorophenyl (2Z,4E,6E,8E)-3,7-dimethyl-9-(2,6,6-trimethylcyclohex-l-en-l- yl) nona-2,4,6,8-tetraenoate (Compound 10, 1.5 g, 2.3 mmol, 58% yield) as a yellow solid, which was used directly without further purification. MS (ESI): mass calculated for C26H27F5O2 466.19, m / z found 467.20 [M + H]+.

[0059] Step 2: Synthesis of (3R,4S,5R,6R)-6-(acetoxymethyl)-5-(((2R,3R,4S,5R,6R)-3,4-diacetoxy- 6-(acetoxymethyl)-5-(((2R,3R,4S,5R,6R)-3,4,5-triacetoxy-6-(acetoxymethyl)tetrahydro-2H-pyran- 2-yl)oxy)tetrahydro-2H-pyran-2-yl)oxy)tetrahydro-2H-pyran-2,3,4-triyl triacetate (Compound 3).

[0060] To a solution of (3R,4R,5S,6R)-5-(((2R,3R,4R,5S,6R)-3,4-dihydroxy-6-(hydroxymethyl)-5- (((2R,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2-pyran-2-yl)oxy)tetrahydro- 2H-pyran-2-yl)oxy)-6-(hydroxymethyl)tetrahydro-2H-pyran-2,3,4-triol (10 g, 19.8 mmol) in AcOH (120 mL) was added acetyl bromide (Compound 2, 58.43 g, 47.5 mmol) dropwise at 0°C. The reaction mixture was stirred at room temperature (r.t.) for 1 hour. The reaction mixture was concentrated to give Compound 3 (22 g, 18.2 mmol, 92% yield) as a yellow oil, which was used for the next step without further purification.

[0061] Step 3: Synthesis of (2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5- diacetoxy-2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy-2-(acetoxymethyl)-6- bromotetrahy dro-2H-pyran-3 -yl)oxy)tetrahy dro-2H-pyran-3 -yl)oxy)tetrahy dro-2H-pyran-3 ,4, 5 -triyl triacetate (Compound 4).

[0062] To a solution of (3R,4S,5R,6R)-6-(acetoxymethyl)-5-(((2R,3R,4S,5R,6R)-3,4-diacetoxy-6- (acetoxymethyl)-5-(((2R,3R,4S,5R,6R)-3,4,5-triacetoxy-6-(acetoxymethyl)tetrahydro-2H-pyran-2- yl)oxy)tetrahydro-2H-pyran-2-yl)oxy)tetrahydro-2H-pyran-2,3,4-triyl triacetate (Compound 3, 19.2 g, 19.9 mmol) in dichloromethane (DCM, 120 mL) was added HBr in AcOH (33% wt) (9.75 g, 39.8 mmol) dropwise. The reaction mixture was stirred at room temperature for 2 hours. Then, the mixture was extracted with DCM / H2O. The combined organic layers were dried over Na2SC>4, filtered, and concentrated to obtain a residue. The residue was purified by flash chromatography column (eluent with EtOAc in petroleum ether = 0 - 50%) to give Compound 4 (16 g, 13.8 mmol, 68% yield) as a yellow oil. 'H NMR (400 MHz, CDCI3) 8 6.50 (d, J = 4.0 Hz, 1H), 5.61 (t, J = 9.4 Hz, 1H), 5.47 - 5.25 (m, 4H), 5.08 (t, J = 10.0 Hz, 1H), 4.90 - 4.82 (m, 1H), 4.73 (m, 2H), 4.58 - 4.45 (m, 2H), 4.36 - 4.22 (m, 3H), 4.14 (m, 1H), 4.08 - 4.00 (m, 2H), 3.94 (m, 3H), 2.17 (d, J = 12.3 Hz, 6H), 2.11 (s, 3H), 2.07 (d, J = 6.4 Hz, 9H), 2.05 - 2.01 (m, 12H).

[0063] Step 4: Synthesis of (2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5- diacetoxy-2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy-2-(acetoxymethyl)-6-(3- bromopropoxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran- 3,4,5-triyl triacetate (Compound 6). To a mixture of (2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy- 2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy-2-(acetoxymethyl)-6-bromotetrahydro-2H- pyran-3-yl)oxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran-3,4,5-triyl triacetate (Compound 4, 8 g, 8.1 mmol) and 3A Molecular Sieve (MS) powder (8 g) in DCM (80 mL) were added 3- bromopropan-l-ol (Compound 5, 4.5 g, 32.4 mmol) and silver trifluoromethanesulfonate (AgOTf, 4.16 g, 16.2 mmol). The reaction mixture was stirred at room temperature for 16 hours. Then, the reaction mixture was fdtered, and the fdtrate was concentrated in vacuo. The residue was purified by flash chromatography column (eluent with EtOAc in petroleum ether = 0 - 50%) to afford Compound 6 (4 g, 3.4 mmol, 42% yield) as a yellow oil.JH NMR (400 MHz, CDCI3) 8 5.38 (m, 3H), 5.27 (m, 1H), 5.07 (t, J = 10.0 Hz, 1H), 4.90 - 4.69 (m, 3H), 4.57 - 4.42 (m, 3H), 4.35 - 4.15 (m, 3H), 4.06 (m, 1H), 4.02 - 3.89 (m, 4H), 3.76 - 3.64 (m, 2H), 3.51 - 3.40 (m, 4H), 2.16 (d, J = 8.0 Hz, 6H), 2.10 (s, 3H), 2.07 - 1.94 (m, 23H).

[0064] Step 5: Synthesis of (2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5- diacetoxy-2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy-2-(acetoxymethyl)-6-(3- azidopropoxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran- 3,4, 5-triyl triacetate (Compound 7).

[0065] To a solution of (2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy- 2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy-2-(acetoxymethyl)-6-(3- bromopropoxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran-

[0066] 3, 4, 5-triyl triacetate (Compound 6, 3.7 g, 3.5 mmol) in DMF (40 mL) was added NaNa (0.91 g, 14 mmol). The reaction mixture was stirred at 100°C for 16 hours. Then, the reaction mixture was treated with H2O and extracted with EtOAc. The combined organic phases were washed with brine, dried over Na2SO4(s), fdtered, and concentrated in vacuo. The residue was purified by flash chromatography column (eluent with EtOAc in petroleum ether = 0 - 80%) to afford Compound 7 (1.8 g, 1.6 mmol, 46% yield) as a colorless oil. MS (ESI): mass calculated for C41H57N3O26 1007.90, m / z found 1026 [M + NEUJt

[0067] Step 6: Synthesis of (2R,3R,4S,5S,6R)-2-(((2R,3S,4R,5R,6R)-6-(((2R,3S,4R,5R,6R)-6-(3- azidopropoxy)-4,5-dihydroxy-2-(hydroxymethyl)tetrahydro-2H-pyran-3-yl)oxy)-4,5-dihydroxy-2- (hydroxymethyl)tetrahydro-2H-pyran-3-yl)oxy)-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol (Compound 8).

[0068] To a solution of (2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy- 2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy-2-(acetoxymethyl)-6-(3- azidopropoxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran- 3 ,4, 5-triyl triacetate (Compound 7, 1.8 g, 1.8 mmol) in MeOH / DCM = 1 : 1 (30 mL) was added NaOMe (0.97 g, 18 mmol). The reaction mixture was stirred at room temperature for 16 hours. The pH of the reaction mixture was adjusted to 7 by Dowex 50W X8. The mixture was filtered and concentrated in vacuo. The residue was purified by flash chromatography column (eluent with MeOH in DCM = 0 - 80%) to afford Compound 8 (800 mg, 1.2 mmol, 67% yield) as a colorless oil. 'H NMR (400 MHz, MeOD) 8 5.15 (m, 2H), 4.27 (d, J = 7.6 Hz, 1H), 3.96 (m, 1H), 3.82 (m, 7H), 3.69 - 3.58 (m, 5H), 3.52 - 3.42 (m, 6H), 3.27 - 3.18 (m, 3H), 1.86 (m, 2H).

[0069] Step 7: Synthesis of (2R,3R,4S,5S,6R)-2-(((2R,3S,4R,5R,6R)-6-(((2R,3S,4R,5R,6R)-6-(3- aminopropoxy)-4,5-dihydroxy-2-(hydroxymethyl)tetrahydro-2H-pyran-3-yl)oxy)-4,5-dihydroxy-2- (hydroxymethyl)tetrahydro-2H-pyran-3-yl)oxy)-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol

[0070] (Compound 9).

[0071] To a solution of (2R,3R,4S,5S,6R)-2-(((2R,3S,4R,5R,6R)-6-(((2R,3S,4R,5R,6R)-6-(3- azidopropoxy)-4,5-dihydroxy-2-(hydroxymethyl)tetrahydro-2H-pyran-3-yl)oxy)-4,5-dihydroxy-2- (hydroxymethyl)tetrahydro-2H-pyran-3-yl)oxy)-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol (Compound 8, 800 mg, 1.36 mmol) in MeOH (20 mL) was added Pd(OH)2 / C (300 mg). The reaction mixture was stirred at room temperature for 16 hours under H2 atmosphere. The mixture was filtered and concentrated in vacuo to afford Compound 9 (700 mg, 1.05 mmol, 78% yield) as a white solid. ’H NMR (400 MHz, MeOD) 8 5.17 - 5.10 (m, 2H), 4.28 (d, J = 7.6 Hz, 1H), 4.01 - 3.92 (m, 1H), 3.89 - 3.74 (m, 7H), 3.64 (m, 5H), 3.53 - 3.37 (m, 6H), 3.25 - 3.18 (m, 3H), 2.75 (m, 2H), 1.76 (m, 2H).

[0072] Step 8: Synthesis of maltotri ose-C3-13-cis-RA, (2Z,4E,6E,8E)-N-(3-(((2R,3R,4R,5S,6R)-5-

[0073] (((2R,3R,4R,5S,6R)-3,4-dihydroxy-6-(hydroxymethyl)-5-(((2R,3R,4S,5S,6R)-3,4,5-trihydroxy-6-

[0074] (hydroxymethyl)tetrahydro-2H-pyran-2-yl)oxy)tetrahydro-2H-pyran-2-yl)oxy)-3,4-dihydroxy-6-

[0075] (hydroxymethyl)tetrahydro-2H-pyran-2-yl)oxy)propyl)-3,7-dimethyl-9-(2,6,6-trimethylcyclohex-l- en-l-yl) nona-2,4,6,8-tetraenamide (Formula I).

[0076] ormula I)

[0077] Maltotriose-cis-retinoic acid conjugate C3 linker

[0078] To a solution of (2R,3R,4S,5S,6R)-2-(((2R,3S,4R,5R,6R)-6-(((2R,3S,4R,5R,6R)-6-(3- aminopropoxy)-4,5-dihydroxy-2-(hydroxymethyl)tetrahydro-2H-pyran-3-yl)oxy)-4,5-dihydroxy-2- (hydroxymethyl)tetrahydro-2H-pyran-3-yl)oxy)-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol (Compound 9, 150 mg, 0.27 mmol) in DMF (5 mL) were added tri ethylamine (TEA, 81 mg, 0.80 mmol) and perfluorophenyl (2Z,4E,6E,8E)-3,7-dimethyl-9-(2,6,6-trimethylcyclohex-l-en-l-yl) nona-2,4,6,8-tetraenoate (Compound 10, 150 mg, 0.32 mmol). The reaction mixture was stirred at room temperature for 2 hours in dark. The reaction mixture was concentrated in vacuo, and the residue was purified by flash chromatography column (eluent with MeOH in DCM = 0 - 50%) and prep- HPLC (column: Gemini, 5 pm, 150 x 21 mm; flow rate: 20 mL / min; eluent: 45 - 95% MeCN in H2O containing 0.1% NH4OH(aq)) to afford the compound maltotriose-C3-13-cis-RA (Formula I, 30 mg, 0.035 mmol, 14% yield) as a yellow solid. MS (ESI): mass calculated for C41H65NO17 843.43, m / z found 844 [M + H]+. 'H NMR (400 MHz, MeOD) 8 7.76 (d, J = 15.2 Hz, 1H), 6.95 (m, 1H), 6.19 (m, 3H), 5.70 (s, 1H), 5.15 (m, 2H), 4.29 (d, J = 7.6 Hz, 1H), 3.97 - 3.75 (m, 8H), 3.70 - 3.56 (m, 6H), 3.54 - 3.46 (m, 3H), 3.46 - 3.35 (m, 2H), 3.24 (m, 3H), 2.04 (m, 5H), 1.99 (s, 3H), 1.87 - 1.77 (m, 2H), 1.71 (s, 3H), 1.64 (m, 2H), 1.53 - 1.46 (m, 2H), 1.03 (s, 6H).

[0079] Preparation Example 2: Synthesis of a retinoic acid conjugated to a trisaccharide with a linker having 5 carbon atoms.

[0080] Maltotriose-C5-13-cis-RA, a conjugate of maltotriose linked to 13-cis-retinoic acid through a

[0081] 5-carbon-atom linker (C5) is synthesized through the Scheme II below:

[0082] Scheme II.

[0083] Steps of this synthesis scheme are as follows.

[0084] Step 1 : Synthesis of (2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5- diacetoxy-2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy-2-(acetoxymethyl)-6-(3- bromopropoxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran-

[0085] 3,4,5-triyl triacetate (Compound 3).

[0086] To a mixture of (2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy-2- (acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy-2-(acetoxymethyl)-6-bromotetrahydro-2H- pyran-3-yl)oxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran-3,4,5-triyl triacetate (Compound 1, 8 g, 8.1 mmol) and 3A MS powder (8 g) in DCM (80 mL) were added 5-bromopentan-l-ol (Compound 2, 5.41 g, 32.4 mmol) and AgOTf (4.16 g, 16.2 mmol). The reaction mixture was stirred at room temperature for 16 hours. Then, the reaction mixture was filtered, and the filtrate was collected and concentrated in vacuo. The residue was purified by flash chromatography column (eluent with EtOAc in petroleum ether = 0 - 50%) to afford Compound 3 (4 g, 3.4 mmol, 42% yield) as a yellow oil. ’H NMR (400 MHz, CDC13) 5 5.45 - 5.21 (m, 5H), 5.07 (t, J = 10.0 Hz, 1H), 4.89 - 4.69 (m, 3H), 4.54 - 4.44 (m, 2H), 4.36 - 4.18 (m, 3H), 4.04 (m, 1H), 3.92 (m, 5H), 3.68 (m, 2H), 3.52 - 3.45 (m, 3H), 2.16 (t, J = 12.4 Hz, 6H), 2.10 (s, 3H), 2.06 - 1.99 (m, 18H), 1.90 (dt, J = 14.0, 6.8 Hz, 9H).

[0087] Step 2: Synthesis of (2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5- diacetoxy-2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy-2-(acetoxymethyl)-6-(3- azidopropoxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran-

[0088] 3,4, 5-triyl triacetate (Compound 4). To a solution of (2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy- 2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy-2-(acetoxymethyl)-6-(3- bromopropoxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran- 3,4,5-triyl triacetate (Compound 3, 4.8 g, 4.5 mmol) in DMF (50 mL) was added NaNs (1.02 g, 15.8 mmol). The reaction mixture was stirred and heated at 100°C for 16 hours. Then, the reaction mixture was treated with H2O and extracted with EtOAc. The combined organic phases were washed with brine, dried over Na2SO4(s), filtered, and concentrated in vacuo. The residue was purified by flash chromatography column (eluent with EtOAc in petroleum ether = 0 - 80%) to afford Compound 4 (1.8 g, 1.7 mmol, 36% yield) as a colorless oil. MS (ESI): mass calculated for C43H61N3O26 1035.96, m / z found 1054 [M + NEU] .

[0089] Step 3: Synthesis of (2R,3R,4S,5S,6R)-2-(((2R,3S,4R,5R,6R)-6-(((2R,3S,4R,5R,6R)-6-(3- azidopropoxy)-4,5-dihydroxy-2-(hydroxymethyl)tetrahydro-2H-pyran-3-yl)oxy)-4,5-dihydroxy-2- (hydroxymethyl)tetrahydro-2H-pyran-3-yl)oxy)-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol (Compound 5).

[0090] To a solution of (2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy- 2-(acetoxymethyl)-6-(((2R,3R,4S,5R,6R)-4,5-diacetoxy-2-(acetoxymethyl)-6-(3- azidopropoxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran-3-yl)oxy)tetrahydro-2H-pyran- 3,4,5-triyl triacetate (Compound 4, 1.8 g, 1.7 mmol) in MeOH / DCM = 1 : 1 (30 mL) was added NaOMe (0.92 g, 17 mmol). The reaction mixture was stirred at room temperature for 16 hours. Then, the pH of the reaction mixture was adjusted to 7 by Dowex 50W X8. The mixture was filtered, and the filtrate was collected and concentrated in vacuo. The residue was purified by flash chromatography column (eluent with MeOH in DCM = 0 - 80%) to afford Compound 5 (800 mg, 1.2 mmol, 71% yield) as a colorless oil. NMR (400 MHz, MeOD) 8 5.15 (m, 2H), 4.27 (d, J = 7.6 Hz, 1H), 3.93 - 3.73 (m, 8H), 3.68 - 3.42 (m, 11H), 3.26 - 3.14 (m, 3H), 1.63 (m, 4H), 1.54 - 1.43 (m, 2H).

[0091] Step 4: Synthesis of (2R,3R,4S,5S,6R)-2-(((2R,3S,4R,5R,6R)-6-(((2R,3S,4R,5R,6R)-6-(3- ami nopropoxy)-4, 5 -di hy droxy-2-(hy droxymethyl )tetrahydro-2H-pyran-3 -yl)oxy)-4, 5 -di hydroxy-2- (hydroxymethyl)tetrahydro-2H-pyran-3-yl)oxy)-6-(hydroxymethyl)tetrahydro-2-pyran-3,4,5-triol (Compound 6).

[0092] To a solution of (2R,3R,4S,5S,6R)-2-(((2R,3S,4R,5R,6R)-6-(((2R,3S,4R,5R,6R)-6-(3- azidopropoxy)-4,5-dihydroxy-2-(hydroxymethyl)tetrahydro-2H-pyran-3-yl)oxy)-4,5-dihydroxy-2- (hydroxymethyl)tetrahydro-2H-pyran-3-yl)oxy)-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol (Compound 5, 800 mg, 1.29 mmol) in MeOH (20 mL) was added Pd(OH)2 / C (300 mg). The reaction mixture was stirred at room temperature for 16 hours under H2 atmosphere. The mixture was filtered and concentrated in vacuo to afford Compound 6 (700 mg, 1 mmol, 78% yield) as a white solid. 'H NMR (400 MHz, MeOD) 8 5.15 (m, 2H), 4.27 (d, J = 7.6 Hz, 1H), 3.94 - 3.77 (m, 8H), 3.71 - 3.42 (m, 11H), 3.27 - 3.18 (m, 3H), 2.66 (t, J = 7.0 Hz, 2H), 1.68 - 1.61 (m, 2H), 1.48 (m, 4H).

[0093] Step 5: Synthesis of maltotriose-C5-13-cis-RA, (2Z,4E,6E,8E)-N-(3-(((2R,3R,4R,5S,6R)-5- (((2R,3R,4R,5S,6R)-3,4-dihydroxy-6-(hydroxymethyl)-5-(((2R,3R,4S,5S,6R)-3,4,5-trihydroxy-6- (hydroxymethyl)tetrahydro-2H-pyran-2-yl)oxy)tetrahydro-2H-pyran-2-yl)oxy)-3,4-dihydroxy-6-

[0094] (hydroxymethyl)tetrahydro-2H-pyran-2-yl)oxy)propyl)-3,7-dimethyl-9-(2,6,6-trimethylcyclohex-l- en-l-yl) nona-2,4,6,8-tetraenamide (Formula II).

[0095] Maltotriose-cis-retinoic acid conjugate C5 linker (Formula II)

[0096] To a solution of (2R,3R,4S,5S,6R)-2-(((2R,3S,4R,5R,6R)-6-(((2R,3S,4R,5R,6R)-6-(3- aminopropoxy)-4,5-dihydroxy-2-(hydroxymethyl)tetrahydro-2H-pyran-3-yl)oxy)-4,5-dihydroxy-2- (hydroxymethyl)tetrahydro-2H-pyran-3-yl)oxy)-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol (Compound 6, 270 mg, 0.46 mmol) in DMF (8 mL) were added triethylamine (TEA, 139 mg, 1.37 mmol) and perfluorophenyl (2Z,4E,6E,8E)-3,7-dimethyl-9-(2,6,6-trimethylcyclohex-l-en-l-yl) nona-2,4,6,8-tetraenoate (Compound 7, 256 mg, 0.55 mmol). The reaction mixture was stirred at room temperature for 2 hours in dark. The reaction mixture was concentrated in vacuo, and the residue was purified by flash chromatography column (eluent with MeOH in DCM = 0 - 50%) and prep-HPLC (column: Gemini, 5 pm, 150 x 21 mm; flow rate: 20 mL / min; eluent: 20 - 95% MeCN in H2O containing 0.1% NFEOHfaq)) to afford the compound maltotriose-C5-13-cis-RA (Formula II, 51.3 mg, 0.054 mmol, 12% yield) as a yellow solid. MS (ESI): mass calculated for C43H69NO17 871.46, m / z found 872.45 [M + H]+. 'l l NMR (400 MHz, MeOD) 5 7.75 (d, J = 15.6 Hz, 1H), 6.95 (m, 1H), 6.19 (m, 3H), 5.69 (s, 1H), 5.15 (m, 2H), 4.26 (d, J = 8.0 Hz, 1H), 3.94 - 3.73 (m, 8H), 3.69 - 3.42 (m, 10H), 3.36 (m, 1H), 3.21 (m, 3H), 2.04 (m, 5H), 1.99 (s, 3H), 1.71 (s, 3H), 1.64 (m, 5H), 1.59 - 1.52 (m, 2H), 1.51 - 1.43 (m, 4H), 1.03 (s, 6H).

[0097] Example 1: Retinoic acid conjugated to a trisaccharide exhibits enhanced anti-tumor activity

[0098] The anti-tumor efficacy of gal actose-C3- 13-cis-RA and maltotriose-C3-13-cis-RA was tested using BALB / c nude mice as the animal model. Briefly, galactose-C3-13-cis-RA, a 13-cis-RA conjugated with galactose through a 3-carbon linker, and maltotriose-C3-13-cis-RA, as prepared above, were compared for their anti-tumor activities. The concentration of galactose-C3-13-cis-RA and maltotriose-C3-13-cis-RA solutions used was 1 mg / mL in 1% alcohol. Vehicle comprising only 1% alcohol was arranged as the negative control. Dosing volume of gal actose-C3- 13-cis-RA, maltotriose-C3-13-cis-RA, and vehicle were 15 mL / kg.

[0099] Fifteen BALB / c nude female mice aged between 5 to 6 weeks were obtained from Bio-Lasco, Taiwan and used in the assay. Water was provided ad libitum, regardless of administration route. All animals were acclimatized and quarantined in quarantine room of Rosetta animal facility for about 1 week. After quarantine, animals were transferred to feeding room. The humidity and temperature were controlled at 30% to 70% and 19°C to 26°C. The light and dark cycle was set as 12 h: 12 h. Food and drinking water were allowed ad libitum (referring to unrestricted access to food or water for the animals) during housing. Estradiol (4 pg / mL) was added in the daily drinking water for the mice.

[0100] The pancreas tumor cell PANC-1 was implanted in mice to induce tumor. Tumor cells were prepared as 2 x 107 / mL suspension (PBS:Matrigel = 1:1), and 0.1 mL (equivalent to 2 x 106tumor cells) were implanted in the back of mice by subcutaneous inoculation. When the tumors grew to about 45 to 100 mm3, the animals were divided into 3 groups and administrated, respectively, with galactose-C3- 13-cis-RA, maltotriose-C3-13-cis-RA, or vehicle according to dosing regimen below. The dosing frequency was one dose daily (QD) for 14 days, totaling 14 doses (Day 1 to 14).

[0101] Group 1 mice were provided with vehicle through intraperitoneal injection (IP). Group 2 mice were provided with galactose-C3-13-cis-RA (15 mg / kg / day) via intraperitoneal injection (IP). Group 3 mice were provided with maltotriose-C3-13-cis-RA(15 mg / kg / day) via intraperitoneal injection (IP). The assay design and dosing regimens were shown in Table 1 below.

[0102] Table 1 . Anti -turn or activity assay

[0103] N / A: not applicable.

[0104] Tumor volume was measured twice every 7 days with vernier scale for a period of 33 days.

[0105] The tumor volume (in mm3) was calculated using the following formula:

[0106] Tumor volume = % x (Length * Width2)

[0107] Average tumor volume of each mice group was calculated for each group at each measuring day, and the result is shown in Table 2 below. From these results, it is shown that mice in group 3 receiving maltotriose-C3-13-cis-RA have least tumor volume compared to both the vehicle group and the group receiving galactose-C3-13-cis-RA. Treatment with maltotriose-C3-13-cis-RA effectively inhibits tumor growth starting as early as day 4 of treatment, and the inhibition effect lasts for at least another 19 days (day 33) after the 14-day dosing regimen ends. However, treatment with galactose- C3-13-cis-RA only starts to show tumor growth inhibition on day 26 of the study. Furthermore, treatment with maltotriose-C3-13-cis-RA shows 14% tumor volume reduction (Day 4, 70.7 mm3vs. 81 mm3vs. 90.4 mm3) to as much as 55% of tumor volume reduction (Day 33, 122.3 mm3vs. 225.9 mm3vs. 209.4 mm3) when compared to both the vehicle control and the group receiving galactose-

[0108] C3-13-cis-RA.

[0109] Table 2. Average tumor volume (mm3)

[0110] Numbers in brackets are the standard errors of five mice.

[0111] Mortality was observed every day, and body weight was measured on day 1, 4, 8, 11, 18, 21 and 28. Average body weight was calculated and shown in Table 3. Similar body weight across different groups and through the entire study period indicate that the treatment was safe to all the mice and pose no toxic effects.

[0112] Table 3. Average mice weight (g)

[0113] Numbers in bracket are the standard errors of five mice. Example 2: Retinoic acid conjugated to a trisaccharide exhibits anti-viral activity

[0114] The anti-viral efficacy of galactose-C3-13-cis-RA and maltotriose-C3-13-cis-RA was tested against respiratory syncytial virus (RSV), Bl strain, in HEp2 cells.

[0115] Briefly, galactose-C3-13-cis-RA, a 13-cis-RA conjugated with galactose through a 3-carbon linker, and maltotriose-C3-13-cis-RA, as prepared above, were compared fortheir anti-viral activities. The stock solutions of galactose-C3-13-cis-RA and maltotriose-C3-13-cis-RA were prepared with DMSO (Sigma, D2650) at a concentration of 96 mM.

[0116] First, for viral infection, HEp2 cells were seeded into a 12-well plate at a density of 1.5 x 105cells / well. Then, the cells were cultured in an incubator kept at 37°C and 5% CO2 for one day. After a wash with Dulbecco’s Phosphate-Buffered Saline (DPBS), RSV Bl with multiplicities of infection (MOI) = 0.1 along with 50 pM of galactose-C3-13-cis-RA, maltotriose-C3-13-cis-RA, or DMSO (vehicle) was added to the cells. The cells were cultured at 37°C and 5% CO2 incubator for another hour, followed by a wash with DPBS. Then, 1 mL 10% fetal bovine serum (FBS) / Dulbecco’s Modified Eagle Medium (DMEM) was added with 50 pM of gal actose-C3- 13-cis-RA, maltotriose- C3-13-cis-RA, or DMSO (vehicle). The cells were cultured at 37°C and 5% CO2 incubator for 24, 48, and 72 hours. At the end of assay, the culture medium was removed, and the cells were subjected to another DPBS wash. Total RNA of the cultured cells was collected by adding 500 pL RNAzol, and the lysate was collected. The collected lysate was stored at -80°C.

[0117] RSV levels in each group of cells were then evaluated. First, RNA isolation was carried out. Cell lysates containing the total RNA were thawed at room temperature and added with 200 pL diethyl pyrocarbonate (DEPCj-FhO. The mixtures were vortexed and let stand for 15 minutes. Then, the mixtures were centrifuged at 12,000 xg for 15 min at 4°C. Then, 200 pL 75% EtOH were added to a new Eppendorf, and 500 pL of the supernatant were added. The mixture was let stand for 10 min and centrifuged at 12,000 xg for 8 min at 4°C. The supernatant was removed, and the precipitate was washed with 500 pL 75% EtOH twice. Then, the RNA was dissolved in 12 pL of DEPC-H2O, and the RNA was subjected to quantification. Unused RNA was stored at -80°C.

[0118] The isolated RNA was subjected to reverse transcription (RT). First, 4 pg of RNA were diluted to 8 pL with DEPC-H2O and added with 1 pL of lOx RT reaction buffer and 1 pL of DNase I. The reaction mixture was kept at 37°C for 30 min. Then, 1 pL of 50 mM EDTA was added and then kept at 65°C for another 10 minutes. The reaction was added with 1 pL of random hexamer, dNTP, and DEPC-H2O each and kept at 65°C for 5 minutes. Again, 4 pL of 5 / first-strand buffer, 1 pL of dithiothreitol (DTT), and GScript RTase were each added. The reaction mixture was kept at 50°C for 50 minutes, followed by 70°C incubation for 15 minutes. The reverse transcription products were stored at -80°C until further analysis. Finally, RSV levels in each treatment cell group were evaluated by qPCR, following the conventional protocol and SYBR with a QuantStudio 6 Flex Real-Time PCR System, using actin as control. The qPCR program was 95°C for 10 sec, followed by 60°C for 20 sec and elongation at 72°C for 1 sec, and repeating for 45 cycles. Primer sequences used for RSV and actin were shown in Table 4 below.

[0119] Table 4. Primers and sequences used for qPCR

[0120] Results of qPCR with primers for actin and RSV N provide the relative RSV RNA level in different groups of culture cells receiving different treatment. As shown in Table 5 below, cells treated with maltotriose-C3-13-cis-RA in group 3 have least RSV RNA level compared to both the vehicle group and the group receiving galactose-C3-13-cis-RA. Treatment with maltotriose-C3-13-cis-RA effectively inhibits RSV replication, providing a 98% RSV inhibition after treatment, a 90% RSV inhibition after 48 hours of treatment, and a 69% RSV inhibition after 72 hours of treatment. However, treatment with galactose-C3-13-cis-RA only provides 91% RSV inhibition, 75% RSV inhibition, and 6% RSV inhibition after 24 hours, 48 hours, and 72 hours of treatment, respectively. Maltotriose-C3- 13-cis-RA shows unexpectedly higher virus inhibition ability, and the high virus inhibition lasts for an unexpected long period of time. Treatment with maltotriose-C3-13-cis-RA effectively inhibits RSV replication with a 69% RSV inhibition even after 72 hours of treatment, while galactose-C3-13-cis- RA only provides 6% RSV inhibition after 72 hours of treatment.

[0121] Table 5. Relative RSV RNA level in cells

[0122] While some of the embodiments of the present disclosure have been described in detail in the above, it is, however, possible for those of ordinary skill in the art to make various modifications and changes to the embodiments shown without substantially departing from the teaching of the present disclosure. Such modifications and changes are encompassed in the scope of the present disclosure as set forth in the appended claims.

Claims

CLAIMSWhat is claimed is:

1. A conjugate compound comprising a retinoic acid and a tri saccharide, wherein the retinoic acid is covalently linked to the trisaccharide.

2. The conjugate compound of claim 1, wherein the retinoic acid is all-trans retinoic acid (ATRA), 9-cis-retinoic acid, 13-cis-retinoic acid, fenretinide, retinal, 4-hydroxy-retinoic acid, 4-oxo- retinoic acid, 18-hydroxy-retinoic acid, 5,6-epoxy-retinoic acid, or a mixture thereof.

3. The conjugate compound of claim 1, wherein the trisaccharide includes at least one monosaccharide.

4. The conjugate compound of claim 3, wherein the trisaccharide consists of three monosaccharides linked by glycosidic bonds.

5. The conjugate compound of claim 3, wherein the trisaccharide consists of a monosaccharide and a di saccharide.

6. The conjugate compound of claim 3, wherein the monosaccharide is an aldose, a ketose, a deoxy sugar, or an amino sugar.

7. The conjugate compound of claim 6, wherein the aldose is glyceraldehyde, erythrose, ribose, arabinose, xylose, glucose, galactose, mannose, idose, gulose, talose, allose, or altrose.

8. The conjugate compound of claim 6, wherein the ketose is dihydroxyacetone, erythrulose, ribulose, xylulose, fructose, psicose, sorbose, or tagatose.

9. The conjugate compound of claim 6, wherein the deoxy sugar is deoxyribose, 2- deoxyglucose, fucose, rhamnose, or quinovose.

10. The conjugate compound of claim 6, wherein the amino sugar is glucosamine, galactosamine, mannosamine, or muramic acid.

11. The conjugate compound of claim 5, wherein the disaccharide is sucrose, lactose, maltose, cellobiose, trehalose, gentiobiose, melibiose, isomaltose, kojibiose, nigerose, turanose, maltulose, palatinose, lactulose, mannobiose, laminaribiose, rutinose, sophorose, sambubiose, or isolaminaribionose.

12. The conjugate compound of claim 1, wherein the trisaccharide is raffinose, kestose, maltotriose, melezitose, panose, isomaltotriose, manninotriose, acarbose, gentianose, theanderose, umbelliferose, planteose, verbascotetraose, laminaritriose, or nigerotetraose.

13. The conjugate compound of claim 1, wherein the retinoic acid is covalently linked to the trisaccharide by a linker including a substituted or unsubstituted aliphatic group having 1 to 20 carbonatoms.

14. The conjugate compound of claim 13, wherein the linker is a straight or branched alkyl group.

15. The conjugate compound of claim 13, wherein the linker has at least 3 carbon atoms.

16. The conjugate compound of claim 13, wherein the linker has less than 10 carbon atoms.

17. The conjugate compound of claim 13, wherein the linker has 3 to 5 carbon atoms.

18. The conjugate compound of claim 13, wherein the linker has a propyl group, abutyl group, or a pentyl group.

19. The conjugate compound of claim 13, wherein the linker further comprises an NH group.

20. The conjugate compound of claim 1, which has a structure of Formula I:

21. The conjugate compound of claim 1, which has a structure of Formula II:

22. A pharmaceutical composition comprising the conjugate compound of any one of claims 1- 21 or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier thereof.

23. The pharmaceutical composition of claim 22, wherein the pharmaceutically acceptable carrier is a non-aqueous based solution, a suspension, an emulsion, a microemulsion, a micellar solution, a gel, an ointment, or any combination thereof.

24. The pharmaceutical composition of claim 22 or 23 for use in preventing or treating cancer.

25. The pharmaceutical composition for use of claim 24, wherein the cancer is pancreatic cancer.

26. The pharmaceutical composition of claim 22 or 23 for use in preventing or treating a viral infection.

27. The pharmaceutical composition for use of claim 26, wherein the viral infection is caused by an RNA virus.

28. The pharmaceutical composition for use of claim 27, wherein the RNA virus is respiratory syncytial virus (RSV).

29. A method for preventing or treating cancer, comprising administering the conjugate compound of any one of claims 1-21 or a pharmaceutically acceptable salt thereof to a subject in need thereof.

30. The method of claim 29, wherein the cancer is pancreatic cancer.

31. A method for preventing or treating a viral infection, comprising administering the conjugate compound of any one of claims 1-21 or a pharmaceutically acceptable salt thereof to a subject in need thereof.

32. The method of claim 31, wherein the viral infection is caused by an RNA virus.

33. The method of claim 32, wherein the RNA virus is respiratory syncytial virus (RSV).

34. The method of any one of claims 29-33, wherein the conjugate compound or the pharmaceutically acceptable salt thereof is administered to the subject by topical application, inhalation, oral administration, parenteral administration, or intravenous, intramuscular, intraperitoneal, or subcutaneous injection.

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