Pharmacological properties of the ubiquitous natural product betulin.

Birch bark research and development

The saponins: polar isoprenoids with important and diverse biological activities

Licorice is one of the oldest and most frequently used herbs in traditional Chinese medicine. It contains more than 20 triterpenoids and 300 flavonoids. In recent years, a lot of studies have reported that the active compounds isolated from licorice possess antitumor, antimicrobial, antiviral, anti-inflammatory, immunoregulatory, and several other activities that contribute to the recovery and protection of the nervous, alimentary, respiratory, endocrine, and cardiovascular systems. In this paper, nine different pharmacological activities of licorice are summarized. The active compounds responsible for these pharmacological activities, the molecular mechanisms, and in vivo and in vitro studies are listed in detail. Furthermore, the clinical therapeutics and toxicity studies of licorice are also discussed. We hope this work can provide a basis for further studies concerning with the safe and effective use of licorice.

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The Pharmacological Activities of Licorice

Plant-derived triterpenoids and analogues as antitumor and anti-HIV agents.

The review is devoted to the problem of creating new antiviral drugs based on glycyrrhizic acid (GA), the major triterpene glycoside extracted from roots of common and Ural licorice (Glycyrrhiza glabra L. and G. uralensis Fisher, respectively). Published data on the natural GA sources, antiviral activity of GA and its derivatives, clinical applications of GA-based drugs, and the properties of GA-containing biologically active nutrient additives are summarized. Possible mechanisms of the antiviral activity of GA and its derivatives are examined. It is shown that chemical modification of GA is a promising way of designing new highly active antiviral drugs for the prophylaxis and treatment of HIV, hepatitis B and C, corona-virus, and herpes simplex virus infections.

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Prospects for the creation of new antiviral drugs based on glycyrrhizic acid and its derivatives (a review).

The assignment of NMR resonances of lupane triterpenoids was refined by the example of 3O,28O-dinicotinoylbetulin, obtained by acylation of betulin. Hepatoprotective, antiulcer, antiinflammatory, reparative, and anti-HIV activities were found for the compound. In addition, it was demonstrated to have immunomodulatory activity, for the first time detected among lupane triterpenoids.

Synthesis and pharmacological activity of betulin dinicotinate

New glycyrrhizic acid (GA) conjugates were synthesized with the use of tert-butyl esters of amino acids or benzyl esters of dipeptides; they contained two residues of L-amino acids (Met, Phe, Pro, and Ile or dipeptides Gly-Leu and Gly-Phe). Activation of GA carboxy groups was carried out with the help of N-hydroxysuccinimide, N,N′-dicyclohexylcarbodiimide, or N-hydroxybenzotriazole with dicyclohexylcarbodiimide. A proline-containing GA derivative is a low-toxic substance; it raises the level of agglutinins by 3.7 times in the blood of mice and 3 times that of hemolysins compared with the control. Dipeptide GA derivatives possess an expressed anti-HIV-1 activity in cultures of MT-4 cells and are 90-70 times less cytotoxic than azidothymidine. The selectivity index of the compounds exceeds those of GA by 110 and 34 times, respectively.

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Synthesis and biological activity of new glycyrrhizic acid conjugates with amino acids and dipeptides

New esters (sulfate, nicotinates, and 4-methoxycinnamate) of 18α-glycyrrhizic acid (18α-GA) were synthesized; these were D/E-trans-isomers of natural 18β-GA (GA), which is the major triterpene glycoside in the roots of Spanish licorice and Urals licorice (Glycyrrhiza glabra L. and Gl. uralensis Fisher). Changes in the stereochemistry of the GA aglycone led to significant decreases in its anti-HIV-1 activity.

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Synthesis and antiviral activity of 18α-glycyrrhizic acid and its esters.

New conjugates of 18β- and 18α-glycyrrhizic acids (GAs) each containing two di- or α-methyl esters of L-aspartic acid in the carbohydrate part of the glycosides were synthesized by the activated ester method using the N-hydroxysuccinimide (HOSu) and N,N'-dicyclohexylcarbodiimide. It was found that the conjugate of 18β-GA with Asp(OMe)(OMe) (4) at a concentration of 250 μg/mL inhibited effectively RT of HIV-1 and the accumulation of virus antigen p24 in MT-4 cell culture (95–97 %) and protected cells from the cytopathogenic action of the virus.

https://link.springer.com/content/pdf/10.1007%2Fs10600-012-0217-1.pdf

O. A. Plyasunova

Papers

Prospects for the creation of new antiviral drugs based on glycyrrhizic acid and its derivatives (a review).

Synthesis and pharmacological activity of betulin dinicotinate

Synthesis and biological activity of new glycyrrhizic acid conjugates with amino acids and dipeptides

Synthesis and antiviral activity of 18α-glycyrrhizic acid and its esters.

Synthesis and anti-HIV-1 activity of new conjugates of 18β- and 18α-glycyrrhizic acids with aspartic acid esters.