Process for the preparation of the cutin- based material and biomedical applications thereof

Abstract

The present invention relates to a process for the preparation of a biopolymer obtained from the cutin contained in tomato skin and the applications thereof for the production of biomedical devices and products for personal hygiene.

Description

[0001] "Process for the preparation of a cutin-based material and biomedical applications thereof"

[0002] DESCRIPTION

[0003] The present invention relates to the technical field of biodegradable and biocompatible materials .

[0004] In recent years , awareness has increased towards the protection of the land and sea environment and, therefore , ef forts have focused on those materials which are biodegradable and can replace current plastic materials of fossil origin, so as not to increase the production of waste .

[0005] The search for new biocompatible materials in the field of biomedical products continues with the aim of identi fying and developing a material which can be safe in contact with the skin or mucous membranes of a subj ect .

[0006] At the same time , it has been reali zed that agro-industrial processing waste can be a source of new secondary raw materials for the preparation of new materials also by virtue of the use of appropriate " green" technologies .

[0007] Summary of the invention

[0008] The inventors of the present patent application have surprisingly found how to obtain from a natural source , and normally considered as waste , a biopolymer suitable for biomedical applications by virtue of the biocompatibility and antimicrobial activity thereof .

[0009] Obj ect of the invention

[0010] According to a first obj ect , the present invention describes a process for the preparation of a cutin-based biopolymer . In a first aspect , a " green" method of puri fying the tomato skin is described .

[0011] In a further aspect , a method of depolymeri zing the cutin present in the tomato skin to obtain the monomer thereof is described .

[0012] In a still further obj ect , a method of oligomeri zing a monomer obtained from the depolymeri zation is described .

[0013] In a second obj ect , the present invention describes a process for the preparation of a material comprising the monomer obtained from the depolymeri zation or the oligomer obtained from the oligomeri zation and a copolymer .

[0014] In an aspect of the invention, said copolymer is a biodegradable polymer .

[0015] In an aspect of the invention, such a material i s obtained by electrospinning .

[0016] Items and products made from the described material represent further obj ects of the invention .

[0017] Brief description of the drawings

[0018] Figure 1 shows the SEM analyses of the samples and diameter and porosity data .

[0019] Figure 2 shows the wettability, contact angle and saturation profile analyses .

[0020] Figure 3 shows the results of the analyses on the mechanical properties of the material of the present invention .

[0021] Figure 4 shows the results of the biocompatibility tests of the material of the invention . Figure 5 shows the results of the antimicrobial activity tests of the material of the invention on E. coll.

[0022] Figure 6 shows the results of the antimicrobial activity tests of the material of the invention on S. aureus.

[0023] Figure 7 shows the results of wound healing assays.

[0024] Figure 8 shows the results of the in vitro cell proliferation study .

[0025] Figure 9 shows the results of the water permeability assay (absorbance versus time, 24, 48 and 72 hours) .

[0026] Detailed description of the invention

[0027] In accordance with a first object, a process for the preparation of a biopolymer from a natural substrate is described.

[0028] In particular, said natural substrate is represented by tomato skin .

[0029] For the purposes of the present invention said biopolymer is cutin-based .

[0030] More in particular, the process of the invention comprises the following three steps:

[0031] I) purification of the tomato skin,

[0032] II) depolymerization of the cutin contained in the tomato skin, obtaining the monomer,

[0033] III) oligomerization of the monomer, obtaining an oligomer.

[0034] In an aspect of the invention, step I) of purifying the tomato skin is carried out by using supercritical phase carbon dioxide.

[0035] The supercritical phase carbon dioxide conditions are as follows :

[0036] The extraction is performed by alternating static extraction phases with dynamic extraction phases.

[0037] For example, two cycles can be performed for each step (for a total of 4 cycles) .

[0038] For example, a cycle can last up to 1 hour.

[0039] In an embodiment of the invention, step I) is performed at a temperature of 50-80°C and at a pressure of 200-350 bar.

[0040] For the purposes of the present invention, before the purification step I) , the natural substrate, i.e., the tomato skin separated from the pulp, is subjected to a pre-treatment step 0) .

[0041] In particular, said pre-treatment step comprises:

[0042] 0a) separation of the skin from the seeds,

[0043] Ob) drying,

[0044] 0c) micronization,

[0045] Od) washing with water.

[0046] Step 0a) is performed according to methodologies known in the art, for example by filtration.

[0047] This step is necessary especially in circumstances where the tomato skin is obtained as waste from the food processing of tomatoes, for example to obtain tomato sauce or pulp.

[0048] In an aspect of the invention, the drying step Ob) can be performed in an oven at a temperature of about 50-60°C.

[0049] In an aspect of the invention, the micronization step 0c) can be performed by using a grinder or ball mill. In an aspect of the invention, step Od) is performed by adding deionized water to the micronized tomato skin.

[0050] Preferably, a volume of water is added so that the ratio is about 1:30 (g:mL) .

[0051] The suspension is left under mechanical stirring for about 4 hours .

[0052] The suspension is then filtered and the skin is recovered and left to dry in the oven, for example at a temperature of about 60- 80°C.

[0053] A lycopene-rich oleoresin preparation is recovered from step I) which is collected during the dynamic extraction step and stored at a temperature of about -80°C, which can be suitably exploited in other fields, such as the pharmaceutical, food or nutraceutical field .

[0054] As for the depolymerization step IT) , this allows obtaining the monomer represented by 10, 16-dihydroxypalmitic acid.

[0055] In particular, the depolymerization of step II) comprises the sub-steps of: a) treatment with a base followed by treatment with an acid to a pH of about 3.5, b) extraction and isolation, c) purification.

[0056] As far as step Ila) is concerned, this is performed with NaOH.

[0057] In particular, 1 M NaOH is used.

[0058] More in particular, a solution of 1 M NaOH in alcohol, for example methanol or ethanol or a mixture thereof, is added to the natural substrate of the invention or to the micronized and washed product obtained from the pre-treatment step.

[0059] Preferably, it is a solution of 1 M NaOH in methanol in a 1:10 ratio (g / mL) .

[0060] It is then left under magnetic stirring at room temperature for a period of time of about 12-24 hours.

[0061] Water is added to the suspension thus obtained, preferably by volume from 2 to 4 times, and even more preferably 3 times, with respect to methanol.

[0062] Filtration is then carried out, for example under vacuum.

[0063] A solution is obtained at a pH of about 12-14, and preferably about 13-13.5, to which concentrated HC1 is added until a suspension is obtained at a pH value of about 3.5.

[0064] For the extraction and isolation step lib) , the suspension obtained from sub-step Ila) is subjected to liquid-liquid extraction by means of a suitable solvent so as to obtain a preparation of the monomer 10 , 16-dihydroxypalmitic acid.

[0065] For the purposes of the present invention, dichloromethane is used as the solvent.

[0066] Preferably, dichloromethane is used in a ratio of about 1:1 (v / v) and the operation can be repeated 3 or 4 times.

[0067] The solution thus obtained is dried, filtered and evaporated under reduced pressure, obtaining an orange waxy solid.

[0068] According to an aspect of the present invention, said orange waxy solid is subjected to the purification sub-step lie) .

[0069] Said sub-step lie) is performed by using a suitable solvent. In particular, ethyl acetate in a 1:10 ratio (ml / mg) can be used .

[0070] After the separation of the solvent, the solid is dried to obtain a light yellow waxy solid containing the monomer 10,16- dihydroxypalmitic acid.

[0071] According to an embodiment of the present invention, the depolymerization step II) is performed using supercritical fluids.

[0072] In a preferred aspect, supercritical carbon dioxide is used.

[0073] To this end, 1 M NaOH (lg:10mL) , a solvent, such as a mixture of methanol and ethanol, in water) and supercritical carbon dioxide is added to the tomato skin obtained from step I) .

[0074] The supercritical carbon dioxide is for example at the pressure of 300-600 bar and at the temperature of 40-80°C.

[0075] According to an aspect of the present invention, the purification of the skin of step I) and the depolymerization of step II) can then be performed in a single reactor (one-pot step) .

[0076] After a period of about 60-90 minutes has elapsed, a dynamic extraction is carried out to recover the monomer.

[0077] Advantageously, the depolymerization with supercritical fluids allows reducing the consumption of organic solvents for monomer recovery, maintaining the high degree of purity; moreover, the process is carried out in a single reactor, which also reduces sample manipulations (skin, monomer, etc.) .

[0078] As far as the oligomerization step III) is concerned, this comprises melting the monomer preparation represented by 10,16- hydroxypalmitic acid under suitable conditions. In particular, said melting is performed at a temperature of about 50-90°C and preferably of about 60°C.

[0079] A suitable solvent and an enzyme are then added, and stirring is maintained.

[0080] For the purposes of the present invention, said solvent is represented by toluene, which is added in a ratio of about 10:1 (pl :mg) .

[0081] For the purposes of the present invention, the enzyme is represented by lipase, preferably added in amounts of about 1-20% (w / w)

[0082] The oligomerization is performed for a time period of about 4- 12 hours.

[0083] The enzyme is then removed by filtration and the solution is evaporated under reduced pressure.

[0084] A preparation of a light yellow powdery solid is obtained from the oligomerization.

[0085] In accordance with a second object, a process for the preparation of a material comprising the monomer obtained from depolymerization or the oligomer obtained from oligomerization (the biopolymer) is described.

[0086] In an aspect of the invention, such a material comprises a second polymer (or co-polymer) .

[0087] In another aspect of the invention, said second polymer can be represented by a mixture of two or more polymers (mixture of second polymers) .

[0088] In a preferred aspect, said second polymer or said mixture of second polymers is represented by a biodegradable polymer. Said second polymer or said mixture of second polymers can further be hydrophobic .

[0089] To this end, biodegradable polyesters can, for example , be used .

[0090] For the purposes of the present invention, said biodegradable polyesters can be selected, for example , from : polylactic acid ( PLA) , polylactide-co-glycolide ( PLGA) or polycaprolactone ( PLC ) , and related copolymers .

[0091] According to an aspect of the present invention, the described material can be obtained by electrospinning .

[0092] In particular, said electrospinning is performed starting from a solution comprising the monomer or the oligomer ( the biopolymer ) , and possibly the second polymer or the mixture of second polymers .

[0093] To this end, a solution of the monomer or polymer of the invention having a concentration of about 10-30% (w / w) of the monomer in a suitable solvent can then be prepared, while the second polymer can be present in a concentration of about 15% .

[0094] In an aspect of the invention, ethanol , dimethyl formamide , dichloromethane , acetone can be used as a solvent .

[0095] In an aspect of the invention, a solution of the second polymer or mixture of second polymers in a suitable solvent can be prepared .

[0096] To promote solubili zation, an ice / water bath can be used while maintaining constant stirring .

[0097] In an aspect of the present invention, a solution of polylactic acid ( PLA) and polycaprolactone ( PLC ) in dichloromethane and dimethyl formamide is prepared .

[0098] In particular, said polymers are in a concentration of about 10-20% (w / v) and preferably about 15% (w / v) . To promote solubili zation, an ice / water bath can be used while maintaining constant stirring .

[0099] The solution containing the monomer or oligomer and the solution containing the second polymer or the mixture of second polymers are mixed together and an ice / water bath can possibly be used to promote solubili zation while maintaining constant stirring .

[0100] As described above , the preparation of the material of the invention can be obtained by electrospinning .

[0101] Such a process is performed on the solution containing the monomer or oligomer and possibly the second polymer or the mixture of second polymers .

[0102] For the purposes of the present invention, the solution of the monomer or oligomer of the invention is subj ected to electrospinning according to the following conditions :

[0103] In an aspect of the invention, such a solution is a solution of the monomer or oligomer of the invention of polylactic acid and polycaprolactone .

[0104] In a preferred aspect of the invention, the solution of the monomer or oligomer of the invention, polylactic acid and polycaprolactone is subj ected to electrospinning according to the following conditions :

[0105] In an aspect of the invention, such a solution is a solution of the monomer or oligomer of the invention of polylactic acid and polycaprolactone .

[0106] The material obtained with the process of the present invention can be used to make non-woven fabric products using techniques known in the art .

[0107] Such products can be represented, for example , by facial masks , surgical masks , dressings , medical supports for tissue regeneration, medical devices for human or veterinary use , hygiene and personal care products , such as wet wipes , diapers , gauze .

[0108] The material obtained according to the present invention is completely biodegradable and biocompatible .

[0109] Moreover, the material described by the present patent application has surprisingly been shown to possess antibacterial properties .

[0110] The applications of the materials described by the invention, as well as of the products and items obtained therewith, are to be understood not only in the medical field but also in the veterinary field for use in animals.

[0111] The present invention will be further described with reference to the following experimental section.

[0112] EXAMPLE 1

[0113] Preparation of the monomer / oligomer of the invention

[0114] After being carefully separated from the seeds (the pulp was separated at an earlier stage) , the skin is oven-dried at a controlled temperature of about 50-60°C. The skin is then micronized and washed in deionized water (1:30, g:mL) to remove any polar interf erents . The suspension is filtered and the micronized skin is recovered and oven-dried at a controlled temperature of about 50- 60°C.

[0115] The micronized skin is then purified by means of supercritical CO2. The temperature ranges for extraction are between 60-100°C while those for pressure are between 300-500 bar.

[0116] The flow varies in a range of 6-12 mL min-1-

[0117] The extraction is performed by alternating a static extraction (0.5) with a dynamic extraction (0.5 h) for a total of 4 cycles. The oleoresin is collected during the dynamic extraction and at the end of the process is stored at -80°C. The purified skin is then added with a solution of 1 M NaOH in methanol (1:10, g:mL) , and left under magnetic stirring at room temperature overnight. The suspension is added with a volume of water equal to 3 times the volume of solvent used for the reaction and vacuum filtered. The red solution (approximately pH 13.4) is acidified with 37% hydrochloric acid to approximately pH 3.5 to obtain an orange suspension.

[0118] The monomer is isolated by means of liquid-liquid extraction using dichloromethane as organic solvent (1:1, v / v, x 3 / 4) . The solution is then dried, filtered and evaporated under reduced pressure to obtain an orange waxy solid. To eliminate coloring by-products, a purification is carried out by precipitation with solvent (ethyl acetate, 1: 10, mL:mg) . The solvent is withdrawn and the solid subjected to drying. A light yellow waxy solid is obtained. The final product is characterized by GC-MS, FTIR-ATR,3H and13C-NMR.

[0119] The monomer is melted at a temperature of about 60°C, added with toluene (10:1, pL:mg) under magnetic stirring and lipase (10%) . To eliminate the formation of water as a reaction by-product, 4A molecular sieves are added. The reaction is left at a controlled temperature overnight. The enzyme is then removed by filtration and the solution evaporated under reduced pressure. A light yellow powdery solid is obtained.

[0120] Electrospinning

[0121] The electrospinning process is performed with a solvent system consisting of three different organic solvents, specifically ethanol (EtOH 17.9% v / v) , dimethylformamide (DMF 1.6% v / v) ) and dichloromethane (DCM 80.5% v / v) . The preparation of the polymer solution includes first creating two distinct solutions containing, respectively :

[0122] PLA-PCL, solubilized in DCM and DMF (15% w / v) . the monomer or oligomer, solubilized in EtOH (10-30% w / w) . The solutions are kept under stirring in an ice / water bath to promote the solubilization of the polymers. At complete solubilization, the solutions are combined and kept under continuous stirring, keeping them in an ice / water bath.

[0123] The polymer solution was then loaded into a 5 mL plastic syringe and subjected to electrospinning using a Gauge 22 needle, under controlled temperature and relative humidity conditions (30 ± 2°C and a relative humidity of 23 ± 2%) . The process parameters used for the creation of the electrospun prototype are summarized in Table 1.

[0124] Table 1 Process parameters for electrospinning PLA-PCL and cutin: and preferably:

[0125] EXAMPLE 2

[0126] Electrospun sample morphology and wettability

[0127] SEM analysis

[0128] All the samples were morphologically characterized under Zeiss EVO MAIO scanning electron microscope (SEM) (Carl Zeiss, Oberkochen, Germany) . Samples of size 0.5 x 0.5 cm were prepared and then coated with gold in an argon atmosphere to allow observing the features of the fibers, such as orientation, diameter, uniformity of diameter and porosity of the matrix. The images were acquired at certain magnifications at room temperature and under high vacuum conditions. Wettability

[0129] The wettability test was carried out on all the formulations so as to define the hydrophobicity of the formulations themselves as a function of the polymer composition using water, artificial saliva and exudate as a medium to simulate the possible applications. The test was performed at room temperature using the Contact Angle Meter DMe-211 (Kiowa Interface Science Co., Ldt . , Japan) and the data were analyzed by means of the software FAMA. Fig. 1 ImageJ software analysis of diameter and porosity with statistical evaluation (p< 0.0001) . Fig. 2 Wettability analysis on all electrospun samples and on a CTR (filter present in masks currently on the market) ; and Saturation profiles of the samples.

[0130] EXAMPLE 3

[0131] Mechanical properties

[0132] Samples were cut from dog bone using a manual die cutter (Manual Die Cutter, noselab ats) compliant with ASTM D-882. The mechanical analyses were performed by means of the instrument Mark-10 ESM303 instrument (Force Gauge Model MI5-5, G1013, USA) and reworked by the software MESUR gauge Plus. The set analysis parameters were defined following the guidelines indicated by ASTM D-882 using a traction speed of 1.5 mm / second.

[0133] Figure 3 shows the results of the analyses of the mechanical properties of the material of the invention. a) stress-strain curves of the sample SFE_3_10 and the commercial control (CRT) . b) Mpa-expressed Young's modulus of the samples SFE_3_10 and SFE_2_10 compared with the control ; c ) comparison between the UTS , Yield strength and Break point values of the samples SFE_2_10 , SFE_3_10 and of the control ( CRT ) and d) elongation percentage of the samples tested, the analysis was performed following the ASTM D- 882 guidelines .

[0134] In particular, the samples SFE_2_10 and SFE_3_10 are two formulations obtained respectively with : 15% cutin and 10 minutes of electrospinning and 18 % cutin and 10 minutes of electrospinning .

[0135] EXAMPLE 4

[0136] Biocompatibility

[0137] A biocompatibility study was performed to evaluate the possible cytotoxicity of the electrospun samples , always taking SFE_3_10 as a reference sample and only the cells as a positive control . The LIVE-DEAD assay ( Invitrogen, Carlsbad, CA, USA) was carried out on fibroblasts cultured in DMEM with 10% FBS to determine cell viability after treatment .

[0138] Figure 4 shows the results of the analyses of the biocompatibility properties of the material of the invention . a ) Indirect MTT assay, the dotted line indicates the percentage of viability below which the sample is definable as cytotoxic . A 2 -way Anova multiple comparisons stati stical analysis was set up with Pvalue < 0 . 0001 . b ) cell morphology before (BEFORE ) and after (AFTER) the execution of the indirect MTT test 4 and 48 hours , ISO 10993-5 .

[0139] EXAMPLE 5

[0140] Antimicrobial properties

[0141] Assays were performed to provide some preliminary evidence of the antimicrobial activity of cutin-based electrospun samples . Initially, the bacteria ( E. coli ATCC 25922 108 and S . aureus ATCC 25923 ) were inoculated through the agar plate and the samples were positioned on the plate . The samples were incubated at 37 ° C for 24 hours , growth under the sample was determined visually and under the microscope , he electrospun samples were trans ferred into 20 mL of sterile saline and vortexed five times for 5-second cycles to detach the bacterial cells from the sample . The supernatant was serially diluted to 10-7 ; the plated and grown colonies were counted after incubation at 37 ° C / 20 h .

[0142] Resul ts

[0143] Figure 5A shows the image of the E. coli growth plate after the removal of 20% cutin and the electrospun placebo . After the removal of the samples , the culture plate was incubated for 20 hours at 37 ° C to detect the extent of growth recovery, providing evidence of antimicrobial activity during the contact period .

[0144] The supernatant was also tested by serial dilutions (McFarland standard) . Once plated, the grown colonies were counted after incubation at 37 ° C for 20 hours . Figure 4B shows a visual antimicrobial ef ficacy of the dressing based on 20% cutin with respect to the placebo . The results show a clear reduction of bacterial colonies grown in all the dilutions treated with the material of the invention with respect to the placebo .

[0145] S . aureus grown after the removal of 20% cutin and the placebo samples are shown in Figures 6A and 5B .

[0146] The results reported a visual antimicrobial ef ficacy of 20% Cutin vs Placebo with the reduction of bacteria grown in the colonies in all the samples considered . EXAMPLE 6

[0147] Application to wound healing

[0148] The ability to modulate wound healing to promote physiological wound closure and the inhibition of the formation of aberrant structures was assessed by evaluating: wound closure (A) , cell migration speed (B) , at different experimental times (0-27h) .

[0149] The wound healing scratch results are shown in Figures 7 A and B. The results show the modulation of wound closure in the cells treated with dressings based on the material of the invention with respect to the placebo (PLA-PCL based dressing) . Moreover, a regulation of wound closure due to a slower proliferation and migration of cells was observed.

[0150] EXAMPLE 7

[0151] Tissue engineering

[0152] The biocompatibility of cutin-based polymer scaffolds was analyzed after 3 / 6 days of incubation (37°C / 24 h) on NHDF. A PLA-PCL scaffold was used as a positive control (CTR+) and cells treated with liquefied phenol (> 89.0%) as a negative control (CTR-) . The viability threshold was set at 70% (red line) according to ISO 10993- 12.

[0153] The cytoskeleton, orientation and interaction were detected by DAPI cell nucleus and cytoskeleton phalloidin staining, at 3 / 6 days of growth on cutin-based polymer scaffold.

[0154] The results showed good cell viability, above 70%. A low percentage, measured on day 3, could be due to stress during the seeding procedure (Figure 8 A and B) . At 6 days, NHDF interconnected with the cutin-based scaffold and a consistent level of junctions, with a solid conformation of the cytoskeleton, were highlighted. The extent of the junctions was greater for the cutin-based 3D scaffold with respect to the placebo.

[0155] EXAMPLE 8

[0156] Water permeability

[0157] The prototypes of electrospun fabric based on monomer / oligomers from the process described in the invention (Example 1) , were subjected to an incubation period of 72 hours in a physiological liquid, inside an incubator maintained at a temperature of 37 °C (corresponding to body temperature) . The amount of liquid retained by the electrospun fabric was then measured gravimetrically after the removal of excess fluid. The results obtained were expressed as a percentage, reporting the average of the values together with the standard deviation, based on three separate samples.

[0158] Results - The electrospun fabric showed a remarkable absorption potential, with a measured absorbance of 482.16 ± 35.90% after 24 hours and a remarkable ability to retain fluids, registering a value of 624.41 ± 81.01% after 72 hours. These results testify a marked ability of the fabric to handle liquids, making it particularly suitable for the treatment of lesions with mild to moderate exudate.

[0159] EXAMPLE 9

[0160] Fluid handling capacity

[0161] The moisture vapor transmission rate (MVTR) of the prototypes and the related controls (diameter of 2 cm) was measured in a laboratory stove for 24 hours at 34°C and 11% relative humidity (Body FBI brand, VWR International Sri, Milan, Italy) . Differ 24 hours of conditioning, all the samples were weighed (dry sample) and immersed for 30 minutes in an excessive volume of simulated fluid (2 mL) . After 30 minutes, the samples were removed from the liquid and drained to remove any excess fluid. They were then weighed again and dehydrated in a laboratory stove (37°C, 30% relative humidity) for 24 hours to determine the dehydration rate. The experiments were performed in triplicate (n = 3) and the results expressed as mean ± standard deviation .

[0162] Results - The electrospun fibers have been designed to enhance capillary strength and improve moisture transport through specific profiles. Contact angle values greater than 90° are consistent with the application scenarios considered, such as wound healing and the creation of three-dimensional structures (scaffolds) . Fluid handling capacity data, measured at 881.95 ± 17.54 g / m2in 24 hours, attest to the remarkable ability of the electrospun fabric to handle fluids. In particular, the proposed fabric is indicated for managing lesions with a mild to moderate level of exudate.

[0163] EXAMPLE 10

[0164] Depolymerization with supercritical fluids

[0165] The tomato skin previously degreased at a temperature between 50- 80°C and at a pressure of 200-350 bar, is added within the same extraction chamber of a 1 M NaOH solution (lg:10 mL) (MeOH, EtOH, H2O) and supercritical carbon dioxide sc-CO 2 at 300-600 bar and T 40-80°C. After a reaction time between 60-90 min, a dynamic extraction is carried out recovering different fractions containing medium- and long-chain fatty acids, medium- and long-chain fatty acids and monomer ( 10 , 16-diHHDA) , solution containing salts. Resul ts - Several fractions were collected, and in particular in the central fractions the presence of the monomer of interest , 10 , 16- diHHDA, was found, analyzed by GC-MS . The fraction of interest has a waxy appearance and a whitish color, free from impurities attributable to the carotenoids present in the structural vesicles of the plant wall of the tomato skin .

[0166] From the above description the advantages brought by the present invention will be immediately clear .

[0167] Firstly, the invention allows recovering and enhancing a waste product of the agri- food industry, available in large amounts and which would otherwise form a biomass intended for another disposal method .

[0168] The process for obtaining the material of the invention advantageously allows extracting the largest amount of oleoresin, thus reducing possible interferences for the subsequent depolymeri zation and oligomeri zation processes .

[0169] Moreover, the extracted oleoresin is rich in lycopene, which represents a product of high value, which can be intended for other uses in the pharmaceutical , food and nutraceutical industries .

[0170] The process described by the present invention has been shown to provide an isolated product with a purity greater than 90% ( demonstrated by GC-MS analysis ) and with a recovery yield greater than 70% (with respect to the cutin present in tomato skin) .

[0171] The material obtained according to the present invention is completely biodegradable and, therefore , has a very minimal environmental impact . Moreover, the material has been shown to possess excellent biocompatibility properties , which make it suitable for use producing biomedical devices and hygiene and personal care products (wet wipes , diapers , etc . ) .

[0172] Such use is particularly suitable by virtue of the antimicrobial properties demonstrated by the material of the invention .

[0173] Such devices and products can also benefit from the excellent breathability properties .

[0174] In particular, the ability of a fabric to allow the passage of water can af fect several critical aspects of the wound healing process ; therefore , the water permeability of the fabric is essential for regulating moisture around the wound .

[0175] An electrospun fabric with adequate water permeability can promote a moist environment , which is often considered beneficial for wound healing, as it can promote cell migration, cell proli feration, and extracellular matrix deposition .

[0176] Water permeability is related to the ability of the fabric to allow good ventilation and aeration; this is important to prevent the retention of unwanted fluids around the wound, reducing the risk of infections and promoting an optimal environment for healing .

[0177] Moreover, the permeability to water can contribute to temperature control around the wound, maintaining a favorable environment for the biological processes involved in wound healing .

[0178] In contrast , the dehydration rate of the electrospun fabric was calculated in order to assess the ef fectiveness of the fabric in creating an environment with optimal moisture to promote the healing process of a wound . A high dehydration rate could lead to the risk of the wound dehydrating, resulting in adhesion of the dressing to the wound itsel f ; this could cause greater pain upon dressing removal and promote the formation of scabs .

[0179] On the other hand, i f the dehydration rate is low, the risk of maceration of the wound and surrounding tissues is increased, in addition to the danger of the dressing itsel f detaching, which exposes the wound to pathogens and increases the risk of infection .

[0180] The dehydration rate is closely related to the chemical features of the formulations ( such as the composition) and to the structural properties of the dressings themselves , including dressing thickness and fiber porosity .

[0181] An optimal dehydration rate is also essential i f the electrospun fabric is used as a scaf fold in the context of tissue regeneration .

[0182] The material obtained according to the present invention is also compatible with other polymers , biodegradable and not , so as to obtain materials with particular and optimal properties .

[0183] Finally, the material of the invention utili zes a raw material widely available at low costs and can be obtained by means of a costef fective process .

Claims

CLAIMS1. A process for the preparation of a monomer or oligomer from tomato skin comprising the steps of:I) purification of the tomato skin by means of a supercritical phase fluid,II) depolymerization of the cutin contained in the tomato skin, obtaining the monomer represented by 10 , 16-dihydroxypalmitic acid, said depolymerization comprising the steps:Ila) of treatment with a base in a suitable solvent performed with NaOH in alcohol, followed by treatment with an acid to a pH of about 3.5, lib) of extraction and isolation of the monomer 10,16- dihydroxypalmitic acid in a suitable solvent, and lie) of purification in a suitable solvent; and possibly the further step of:III) oligomerization of said monomer obtaining an oligomer, wherein said step III) comprises melting in solvent at the temperature of about 50-90°C and in the presence of lipase.

2. A process according to the preceding claim, wherein before the purification step I) , the tomato skin, separated from the pulp, is subjected to a pre-treatment step 0) comprising the steps of:0a) separation of the skin from the seeds,Ob) drying,0c) micronization,Od) washing with water.

3. A process according to claim 1 or 2, wherein in step Ila) said alcohol is represented by methanol or ethanol, or a mixture thereof .

4. A process according to any one of the preceding claims, wherein in step Ila) said solvent is represented by dichloromethane.

5. A process according to any one of the preceding claims, wherein in step lib) said solvent is represented by dichloromethane.

6. A process according to any one of the preceding claims, wherein in step lie) said solvent is represented by ethyl acetate.

7. A process according to any one of the preceding claims, wherein said step II) is performed by using a supercritical phase fluid .

8. A process according to any one of the preceding claims, wherein in step I) and step II) said supercritical phase fluid is represented by supercritical phase carbon dioxide.

9. A process according to any one of the preceding claims, wherein said step I) and said step II) are carried out one-pot.

10. A process for the preparation of a material comprising the oligomer obtained according to any one of the preceding claims.

11. A process for the preparation of a material comprising the monomer 10 , 16-dihydroxypalmitic acid obtained according to the process of any one of the preceding claims 1 to 9.

12. A process for the preparation of a material according to the preceding claim 10 or 11, wherein said material comprises a second polymer or a mixture of second polymers.

13. A process for the preparation of a material according to the preceding claim, wherein said second polymer or mixture of second polymers is biodegradable .14 . A process for the preparation of a material according to the preceding claim, wherein said second polymer or mixture of second polymers is represented by polylactic acid ( PLA) , polylactide-co- glycolide ( PLGA) , polycaprolactone ( PLC ) , and co-polymers thereof .15 . A process for the preparation of a material according to any one of the preceding claims 10 to 14 , comprising the steps of : i ) preparation of a mixture comprising said monomer 10 , 16- dihydroxypalmitic acid or said oligomer, and possibly said second polymer or mixture of second polymers , in a suitable solvent or in a mixture of suitable solvents , ii ) electrospinning of said mixture .

16. A process for the preparation of a material according to the preceding claim, wherein the mixture of step i ) comprises the monomer 10 , 16-dihydroxypalmitic acid, polylactic acid and polycaprolactone in dichloromethane and dimethyl formamide .17 . A process for the preparation of a material according to the preceding claim, wherein said electrospinning step ii ) is performed under the following conditions :

18. A material obtained by the process according to any one of claims 10 to 18.

19. A product made from the material according to the preceding claim.

20. A product according to the preceding claim represented by a biomedical device or a hygiene and personal care product.

21. A product according to the preceding claim chosen from: facial masks, surgical masks, dressings, medical supports for tissue regeneration and medical devices for human or veterinary use, wet ipes, diapers, gauze.T1

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