Synthesis of Glycyrrhizic Acid Conjugates with S-Benzyl-L-Cysteine and Their Antiviral Activity.

A new method for the synthesis of glycyrrhizic acid (GA) conjugates with S-benzyl-L-cysteine using 1-ethyl-3-(3-dimethylaminoproopyl)carbodiimide is proposed. It is established that 3-O-{2-O-[N-(ß-D-glucopyranosyluronyl)-L-cysteine-S-benzyl]-N-(ß-D-glucopyranosyluronyl)-L-cysteine-S-benzyl}-(3ß,20ß)-11-oxo-30-(N-carbonyl-L-cysteine-S-benzyl)-30-norolean-12-ene is superior to GA in inhibiting the accumulation of HIV-I virus-specific protein p24 (viral antigen) in MT-4 cell culture (IC50 3 µg/mL, SI 90) and is 50 - 55 times less toxic to cells than azidothymidine.

Synthesis and Anti-HIV-1 Activity of Olean-9(11),12(13)-Dien-30-Oic Acid 3ß-(2-O-ß-D-Glucuronopyranosyl-ß-D-Glucuronopyranoside).

The glycyrrhizic acid (GA) analog olean-9(11),12(13)-dien-30-oic acid 3ß-(2-O-ß-D-glucuronopyranosyl-ß-D-glucuronopyranoside) (II) was synthesized via reduction of GA by NaBH4 in refluxing 2-PrOH:H2O with subsequent work up with HCl (5%). The cytotoxicity and antiviral activity of this glycoside against HIV-1 was studied in MT-4 cell culture. It was found that II was practically non-toxic for MT-4 cells while inhibiting accumulation of virus-specific protein p24 and RNA-dependent DNA-polymerase activity of HIV-1 reverse transcriptase (RT) (IC50 3.1 ±1.0 µg/mL).

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

New conjugates of 18ß- 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 18ß-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.

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

New esters (sulfate, nicotinates, and 4-methoxycinnamate) of 18α-glycyrrhizic acid (18α-GA) were synthesized; these were D/E-trans-isomers of natural 18ß-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.

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

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.

In vitro study of resistance-associated genotypic mutations to nucleoside analogs.

In spite of a rather long period of investigations, the problem of HIV drug resistance remains unsolved, and more that, at present HIV-1 mutants resistant to all known nucleoside inhibitors being used in clinical therapy against the human immunodeficiency syndrome are discovered. In this study we selected HIV-1 mutants resistant to the nucleoside inhibitors of HIV reverse transcriptase (NRTI): 3'-azido-2',3'-dideoxythymidine (AZT), 5'-phosphit 3'-azido-2',3'-dideoxythymidine (ph-AZT), dideoxyinosine (ddI) and didehydrodeoxythymidine (d4T). Selection of resistant mutants was carried out by gradually increasing of drug concentration in the culture medium during propagation of the HIV-1EVK on fresh MT-4 cells. Phenotypic resistance was defined as an increase in ID50 of 160-fold for AZT, 8 for ph-AZT, 10 for ddI, 7 for d4T. In comparison studies it was determined that the viral resistance to these drugs was appeared variously in a similar conditions and duration of selection. The nucleotide sequences of the RT region of the HIV-1 variants were compared with the HIV-1EVK from "0" passage. For some of selected HIV-1 mutants NRTI resistance mutations were detected. Selected AZT resistant variants contained amino acid substitutions in positions D67A and K70R. Our studies was not revealed substitution at position 75 for ph-AZT resistant variants, whereas substitution at position L214F have been observed in both experiments using AZT and ph-AZT. Selected d4T resistant mutants contained amino acid substitutions in positions N54D and P52R. Selected ddI resistant mutants contained only one amino acid substitution in position P143S. Collection of drug-resistant mutants should prove to be a convenient tool for rapid investigations a new antiretroviral agents on cross drug-resistance.

PAcM-AN: poly (N-acryloylmorpholine)-conjugated antisense oligonucleotides.

A new amphiphilic, high-molecular weight poly (N-acryloylmorpholine) (PAcM) polymer has been used to be linked to oligonucleotide chains through a liquid-phase stepwise synthesis. This new conjugate has been investigated for its melting property, nuclease stability and capacity to elicit RNase H activity. Its antisense activity against an HIV-1 target has been also evaluated.