Antiviral agent

Abstract

The present invention relates to an anti-coronavirus agent containing a licorice-derived saponin or a licorice extract.

Description

antiviral agents

[0001] The present invention relates to an anti-coronavirus agent comprising a saponin derived from licorice or a licorice extract.

[0002] Human infection with the novel coronavirus SARS-CoV-2 has caused enormous damage worldwide, and effective infection prevention and treatment methods are needed. In particular, vaccines have been developed as infection prevention methods, and several companies have already put them into practical use. However, there is a risk that vaccines will become ineffective due to viral mutations, and other effective infection prevention measures are needed. Therefore, as a new point of action for antiviral agents, attention has been focused on angiotensin-converting enzyme type II, which serves as a foothold for viruses to enter the body via the spike protein present on their surface. This angiotensin-converting enzyme type II is present in various parts of the body, but is particularly abundant in gastrointestinal mucosal epithelial cells, including the oral cavity and pharynx (Non-Patent Document 1). Therefore, viruses ingested through the mouth easily bind to angiotensin-converting enzyme type II and invade cells. Therefore, as part of the search for antiviral agents, drugs that inhibit the binding of this viral spike protein to angiotensin-converting enzyme type II have been sought. In this situation, the effectiveness of glycyrrhizinic acid derived from licorice has already been demonstrated through virtual screening (Non-Patent Document 2). However, there have been no cases in which its effectiveness against the novel coronavirus has been demonstrated through actual screening, and no mention has been made of other licorice-derived saponins. Furthermore, it has already been reported that glycyrrhizinic acid is useful as an antiviral agent against SARS, although the mechanism of action is unknown (Non-Patent Document 3). While vaccines only protect against infection, if an antiviral agent with infection-protective properties also has therapeutic effects, its usefulness would obviously be even greater.

[0003] Zu H et al., International Journal of Oral Science, 2020, 12, 2S Mahdian et al., Journal of Diabetes & Metabolic Disorders, 2020, 19, 691Cinati J et al., Lancet, 2003, 361, 2045

[0004] An object of the present invention is to provide an anti-coronavirus agent that effectively prevents infection by coronaviruses such as the novel coronavirus SARS-CoV-2.

[0005] In order to solve the above problems, the present inventors have conducted extensive research into the inhibitory activity of individual licorice-derived saponins, including glycyrrhizinic acid, on the binding of the virus to human angiotensin-converting enzyme type II, and as a result have confirmed the inhibitory activity of glycyrrhizin, and have further found that licorice saponin H2, which contains liquiritic acid, a stereoisomer of glycyrrhetinic acid, as its sapogenin, inhibits the binding of the virus to human angiotensin-converting enzyme type II more strongly than glycyrrhizin, and have completed the present invention based on this finding.

[0006] [1] An anti-coronavirus agent comprising licorice-derived saponin or licorice extract; [2] The anti-coronavirus agent according to [1], wherein the coronavirus is SARS-CoV2; [3] The anti-coronavirus agent according to [1] or [2], for use in humans; [4] The anti-coronavirus agent according to any of [1] to [3], for preventing coronavirus infection; [5] The anti-coronavirus agent according to [4], for administration of licorice saponin H2 at a dose of 5 to 15 mg / day / human and licorice extract at a dose of 50 to 200 mg / day / human.

[0007] In another aspect, the present invention is as follows: [1] Formula (1): An antiviral agent comprising at least one compound selected from the group consisting of a compound represented by formula (I), a salt thereof, and a solvate thereof, and having an infection-protecting effect of inhibiting the binding of viruses to angiotensin converting enzyme type II. [2] The antiviral agent according to [1], which is used for application to humans. [3] The antiviral agent according to [2], which is a medicine and / or food. [4] An antiviral agent comprising a licorice extract containing 5 to 50% of the compound represented by formula 1, and which inhibits the binding of viruses to angiotensin converting enzyme type II. [5] The antiviral agent according to [4], which is used for application to humans.

[0008] The antiviral agent of the present invention is highly safe for living organisms and can prevent infection by coronaviruses such as the novel coronavirus SARS-CoV-2.

[0009] Inhibitory effect of glycyrrhizin and licorice saponin H2 on the interaction between ACE2-His and SARS-CoV-2 Spike-Fc (RBD). The vertical axis represents the amount of luminescence from HRP, and the horizontal axis represents the concentration (nM) of SARS-CoV-2 Spike-Fc (RBD).

[0010] In the present invention, licorice saponin H2 is a saponin derived from a plant belonging to the genus Glycyrrhiza, and its IUPAC name is (2S,3S,4S,5R,6R)-6-{[(3S,4aR,6aR,6bS,8aS,11R,12aR,14aR,14bS)-11-carboxy-4,4,6a,6b,8a,11,14b-heptamethyl-14-oxo-1, 2,3,4,4a,5,6,6a,6b,7,8,8a,9,10,11,12,12a,14,14a,14b-icosahydropicen-3-yl]oxy}-5-{[(2R,3R,4S,5S,6S)-6-carboxy-3,4,5-trihydroxyoxan-2-yl]oxy}-3,4-dihydroxyoxane-2-carboxylic acid, and the structural formula is as follows. The genus Glycyrrhiza is a perennial plant of the Fabaceae family that grows naturally in the Mediterranean region, Asia Minor, southern Russia, Central Asia, northern China, North America, etc. In the present invention, for example, Glycyrrhiza acanthocarpa, G. aspera, G. astragalina, G. bucharica, G. echinata (Russian licorice), G. eglandulosa, G. foetida, G. foetidissima, G. glabra (Spanish licorice), G. gontscharovii, G. iconica, G. inflate, G. korshinskyi, G. lepidota (American licorice), G. pallidiflora, G. G. squamulosa, G. triphylla, G. uralensis (Ural licorice), G. yunnanensis, and G. inflata (Xinjiang licorice) can be used. These can be used alone or in combination of two or more.

[0011] The licorice saponin H2 used in the present invention can be extracted, isolated, and purified from licorice extract using a conventional method. Specifically, a purified product with a purity of 70% or higher can be obtained by removing fat-soluble coloring components from the licorice extract using a synthetic resin column or organic solvent extraction, followed by separation and purification using high-performance liquid chromatography. On the other hand, when using licorice extract, the roots and / or stems of the plant can be appropriately processed and used. In the present invention, commercially available licorice extracts can be used, or those produced by methods known in the art can also be used. The licorice saponin H2 content of the licorice extract used in the present invention is 5% or more, preferably 10% or more, and more preferably 13% or more.

[0012] The target viruses of the agent of the present invention are not particularly limited, but include, for example, the common cold coronavirus known as coronavirus, SARS-CoV virus, SARS-CoV-2, and the like.

[0013] Examples of applications for application to living organisms include medicines and foods. In this case, the target of application is not particularly limited, and examples include various mammals such as humans, monkeys, mice, rats, dogs, cats, rabbits, pigs, horses, cows, sheep, goats, and deer.

[0014] By applying the antiviral agent of the present invention to a living body, the agent can exert a protective effect against viral infection at the site where the active ingredient comes into contact.

[0015] The form of the agent of the present invention is not particularly limited, and depending on the intended use of the agent of the present invention, it may take a form that is commonly used for each intended use.

[0016] Regarding the form, when the application is pharmaceutical, it is desirable to consider that angiotensin converting enzyme type II, to which the virus attaches during infection, is widely distributed in mucous membranes, including the oral cavity, digestive tract, and alveoli, when selecting the dosage form. Examples include formulations suitable for oral ingestion, such as sprays (oral aerosols), eye drops, gels, eye ointments, nasal drops, and tablets (including orally disintegrating tablets, chewable tablets, effervescent tablets, lozenges, and jelly drops), with lozenges being particularly preferred, as they can retain the active ingredient in the oral cavity. In the case of foods, candy or lozenge tablet forms that can be retained in the oral cavity for a long time are also desirable.

[0017] The dosage of licorice saponin H2 of the present invention is 5 to 10 mg / day / human, preferably 10 to 15 mg / day / human. The dosage of licorice extract is 50 to 100 mg / day / human, preferably 100 to 200 mg / day / human. In this case, the dosage is divided into 5 to 10 doses per day.

[0018] The administration period of the licorice saponin H2 or licorice extract of the present invention may be any period as long as the desired effect is obtained. It is particularly desirable to continue the administration during periods when viral infections are spreading.

[0019] The virus inhibition assay method for test substances was outlined as follows. ACE2-His was bound to a nickel-coated 96-well plate. Next, SARS-CoV-2 Spike-Fc (RBD) and test substances, such as glycyrrhizinic acid and licorice saponin H2, were added and incubated on the plate to allow SARS-CoV-2 Spike-Fc (RBD) to bind to ACE2-His. Finally, HRP-labeled Anti-Fc antibody was added to the plate, and the amount of luminescence was measured after adding a chemiluminescent substrate for HRP. The interaction between ACE2-His and SARS-CoV-2 Spike-Fc (RBD) and the inhibitory effect of the test substance were determined.

[0020] As a result, the results shown in Figure 1 were obtained. In the case of glycyrrhizinic acid, a tendency for inhibition was observed at 5000 nM, but the difference was not significant, whereas licorice saponin H2 exhibited a dose-dependent inhibitory activity, with approximately 40% inhibition at 1000 nM and approximately 35% (significant) inhibition at 5000 nM.

[0021] These results indicate that licorice-derived saponins, such as licorice saponin H2, have protective effects against viral infections, and we were able to confirm that licorice saponin H2 has particularly strong activity.

[0022] The antiviral agent of the present invention is useful for preventing infection with coronaviruses such as COVID-19.

Claims

1. An anti-coronavirus agent comprising saponin derived from licorice or licorice extract.

2. The anti-coronavirus agent according to claim 1, wherein the coronavirus is SARS-CoV2.

3. The anti-coronavirus agent according to claim 1 or 2, for use in humans, wherein the licorice saponin H2 is administered at a dose of 5 to 15 mg / day / human, or the licorice extract is administered at a dose of 50 to 200 mg / day / human, for the prevention of coronavirus infection.