Molecular screening of glycyrrhizin-based inhibitors against ACE2 host receptor of SARS-CoV-2.

The interaction between SARS-CoV-2 Spike protein and angiotensin-converting enzyme 2 (ACE2) is essential to viral attachment and the subsequent fusion process. Interfering with this event represents an attractive avenue for the development of therapeutics and vaccine development. Here, a hybrid approach of ligand- and structure-based virtual screening techniques were employed to disclose similar analogues of a reported antiviral phytochemical, glycyrrhizin, targeting the blockade of ACE2 interaction with the SARS-CoV-2 Spike. A ligand-based similarity search using a stringent cut-off revealed 40 FDA-approved compounds in DrugBank. These filtered hits were screened against ACE2 using a blind docking approach to determine the natural binding tendency of the compounds with ACE2. Three compounds, deslanoside, digitoxin, and digoxin, were reported to show strong binding with ACE2. These compounds bind at the H1-H2 binding pocket, in a manner similar to that of glycyrrhizin which was used as a control. To achieve consistency in the docking results, docking calculations were performed via two sets of docking software that predicted binding energy as ACE2-Deslanoside (AutoDock, -10.3 kcal/mol and DockThor, -9.53 kcal/mol), ACE2-Digitoxin (AutoDock, -10.6 kcal/mol and DockThor, -8.84 kcal/mol), and ACE2-Digoxin (AutoDock, -10.6 kcal/mol and DockThor, -8.81 kcal/mol). The docking results were validated by running molecular simulations in aqueous solution that demonstrated the stability of ACE2 with no major conformational changes in the ligand original binding mode (~ 2 Å average RMSD). Binding interactions remained quite stable with an increased potential for getting stronger as the simulation proceeded. MMGB/PBSA binding free energies were also estimated and these supported the high stability of the complexes compared to the control (~ -50 kcal/mol net MMGB/PBSA binding energy versus ~ -30 kcal/mol). Collectively, the data demonstrated that the compounds shortlisted in this study might be subjected to experimental evaluation to uncover their real blockade capacity of SARS-CoV-2 host ACE2 receptor.

Separation of Glycyrrhizic Acid and Its Derivants from Hydrolyzation in Subcritical Water by Macroporous Resin.

Glycyrrhizic acid (GL) and its derivants, glycyrrhetinic acid 3-O-mono-ß-d-glucuronide (GAMG) and glycyrrhetinic acid (GA) hydrolyzed in subcritical water, are bioactive substances and edulcorators. In this work, a separation strategy for these three substances was established. The effects of adsorbent and eluent were investigated by static/dynamic adsorption and multi-stage desorption with the mechanism analysis. The adsorption of them onto EXA50 resin was well fitted by the pseudo second-order kinetic model. The optimal dynamic adsorption flow rate was 6 bed volume (BV)/h, and water of pH = 12 was used to elute GL at 4 BV/h, then n-buthanol was used subsequently to elute GA at 1 BV/h, and finally 90% ethanol was applied to elute GAMG at 2 BV/h. As a result, purities of these compounds increased, which demonstrated that this adsorption-desorption technology was simple and efficient, and indicated the potential for large-scale purification and preparation of GL and its derivants in the future.

Prostatotropic Action of Glycyrrhizic Acid Disodium Salt in Benign Prostatic Hyperplasia Models.

The prostatotropic activity of glycyrrhizic acid disodium salt (Na2GA) was studied in the models of benign prostatic hyperplasia (BPH) induced by chronic injection of sulpiride (40 mg/kg intraperitoneally for 8 weeks) or testosterone propionate (20 mg/kg subcutaneously for 4 weeks) in the Wistar rats. The oral administration of Na2GA in a dose of 100 mg/kg produced a moderate antiproliferative effect in both BPH models resulting in reduced volume density of prostatic epithelium (in the testosterone model) and increased volume density of the glandular lumen (in both models). The observed prostatotropic effects of Na2GA were similar to those of Permixon and finasteride, but they were less pronounced as confirmed by smaller drops in epithelial volume density and epithelial-to-stromal ratio compared to the effects of both reference drugs.

The concurrent exposure to aluminium and fructose induces liver injury in rats: Protection by monoammonium glycyrrhizinate.

Aluminium is a ubiquitous element that occurs naturally in the soil making human exposure to it unavoidable. It is implicated in the aetiology of different neurodegenerative diseases and can induce liver injury. In addition, insulin resistance (IR) plays an essential role in the pathogenesis and the progression of liver disorders. The increased consumption of fructose contained in soft drinks and western pattern diet results in IR that along with the wide distribution of aluminium make the concurrent exposure conceivable and increase the risk of liver injury. Therefore, the present study explores the hepatotoxic effects of aluminium and fructose administered concurrently and evaluates the possible protection by monoammonium glycyrrhizinate (MAG). Liver injury was induced by the administration of aluminium chloride (34 mg/kg/d) plus 10% (w/v) fructose in drinking water. Male rats were treated with either MAG (40 mg/kg/d) or silymarin (SIL, 100 mg/kg/d). The concurrent administration of aluminium and fructose (FRUAL) induced liver injury manifested as a significant elevation of serum liver enzymes activities, bilirubin level, and prothrombin time, as well as reduction of albumin level. On the other hand, the administration of MAG improved the FRUAL-induced aberrations of liver function tests and hepatic cytoarchitecture. We assume that the MAG-induced suppression of oxidative stress, toll-like receptor 4 pathway activation, inflammation, and apoptosis might play a crucial role in the hepatoprotective effect of MAG in this model. Intriguingly, the hepatoprotective effect MAG against FRUAL-induced liver injury surpasses that of the gold standard SIL, suggesting MAG as a better alternative to SIL.

Glycyrrhizin Acid and Glycyrrhetinic Acid Modified Polyethyleneimine for Targeted DNA Delivery to Hepatocellular Carcinoma.

In the last 2-3 decades, gene therapy represented a promising option for hepatocellular carcinoma (HCC) treatment. However, the design of safe and efficient gene delivery systems is still one of the major challenges that require solutions. In this study, we demonstrate a versatile method for covalent conjugation of glycyrrhizin acid (GL) or glycyrrhetinic acid (GA) to increase the transfection efficiency of Polyethyleneimine (PEI, Mw 1.8K) and improve their targeting abilities of hepatoma carcinoma cells. GA and GL targeting ligands were grafted to PEI via N-acylation, and we systematically investigated their biophysical properties, cytotoxicity, liver targeting and transfection efficiency, and endocytosis pathway trafficking. PEI-GA0.75, PEI-GL10.62 and PEI-GL20.65 conjugates caused significant increases in gene transfection efficiency and superior selectivity for HepG2 cells, with all three conjugates showing specific recognition of HepG2 cells by the free GA competition assay. The endocytosis inhibition and intracellular trafficking results indicated that PEI-GA0.75 and GL10.62 conjugates behaved similarly to SV40 virus, by proceeding via the caveolae- and clathrin-independent mediated endocytosis pathway and bypassing entry into lysosomes, with an energy independent manner, achieving their high transfection efficiencies. In the HepG2 intraperitoneal tumor model, PEI-GA0.75 and PEI-GL10.62 carrying the luciferase reporter gene gained high gene expression, suggesting potential use for in vivo application.

Glycyrrhizic acid derivatives as Dengue virus inhibitors.

Dengue virus (DENV) is one of the most geographically distributed pathogenic flaviviruses transmitted by mosquitoes Aedes sps. In this study, the structure-antiviral activity relationships of Glycyrrhizic acid (GL) derivatives was evaluated by the inhibitory assays on the cytopathic effect (CPE) and viral infectivity of DENV type 2 (DENV2) in Vero E6 cells. GL (96% purity) had a low cytotoxicity to Vero E6 cells, inhibited DENV2-induced CPE, and reduced the DENV-2 infectivity with the IC50 of 8.1 µM. Conjugation of GL with amino acids or their methyl esters and the introduction of aromatic acylhydrazide residues into the carbohydrate part strongly influenced on the antiviral activity. Among compounds tested GL conjugates with isoleucine 13 and 11-aminoundecanoic acid 17 were found as potent anti-DENV2 inhibitors (IC50 1.2-1.3 µM). Therefore, modification of GL is a perspective way in the search of new antivirals against DENV2 infection.

Selective and competitive inhibition of kynurenine aminotransferase 2 by glycyrrhizic acid and its analogues.

The enzyme kynurenine aminotransferase (KAT) catalyses the conversion of kynurenine (KYN) to kynurenic acid (KYNA). Although the isozymes KAT1-4 have been identified, KYNA is mainly produced by KAT2 in brain tissues. KNYA is an antagonist of N-methyl-D-aspartate and α-7-nicotinic acetylcholine receptors, and accumulation of KYNA in the brain has been associated with the pathology of schizophrenia. Therefore, KAT2 could be exploited as a therapeutic target for the management of schizophrenia. Although currently available KAT2 inhibitors irreversibly bind to pyridoxal 5'-phosphate (PLP), inhibition via this mechanism may cause adverse side effects because of the presence of other PLP-dependent enzymes. Therefore, we identified novel selective KAT2 inhibitors by screening approximately 13,000 molecules. Among these, glycyrrhizic acid (GL) and its analogues, glycyrrhetinic acid (GA) and carbenoxolone (CBX), were identified as KAT2 inhibitors. These compounds were highly selective for KAT2 and competed with its substrate KYN, but had no effects on the other 3 KAT isozymes. Furthermore, we demonstrated that in complex structures that were predicted in docking calculations, GL, GA and CBX were located on the same surface as the aromatic ring of KYN. These results indicate that GL and its analogues are highly selective and competitive inhibitors of KAT2.

An Approach to Treatment of Liver Cancer by Novel Glycyrrhizin Derivative.

BACKGROUND: Liver cancer is a life threating disease as it is the fifth most common cancer and the third most common cause of death worldwide with no safe, efficient, and economic drug available for treatment. METHODS: This study intended to investigate glycyrrhizin and its derivatives for possible use as a cytotoxic agent and as a drug for liver cancer treatment. Thus, after treatment of liver cancer cell line HepG-2 with 50 µM of each compound, cell viability was determined. RESULTS: The cytotoxicity assay showed glycyrrhizin derivatives ME-GA (18ß-Glycyrrhetinic-30-methyl ester) and AKBA (3-acetyl-11- keto-ß-Boswellic acid) to be the most potent drug against liver cancer cell line HepG-2 with IC50 values 25.50 ± 1.06 and 19.73 ± 0.89 µM, respectively. Both the compounds showed higher selectivity towards hepatocellular carcinoma rather than the normal lung fibroblast cell line WI-38. The presence of methyl ester at C-30 greatly increased the cytotoxicity of ME-GA which might be attributed to its higher activity and selectivity. Both ME-GA and AKBA contributed to inhibit cancer cell migration in the wound healing assay and impeded colony formation. The use of flow cytometry to carry out cell cycle analysis and the determination of possible mechanisms of action for apoptosis revealed that ME-GA arrested the cell cycle at G2/M that led to the inhibition of hepatocellular carcinoma and induced apoptosis via the extrinsic pathway and its ability to increase p53 transactivation. CONCLUSION: This work highlights the cytotoxicity of glycyrrhizin and its derivatives for possible use as a chemotherapeutic agent against hepatocellular carcinoma cells HepG-2. The most cytotoxic compound was ME-GA (18ß-Glycyrrhetinic-30-methyl ester) with no cytotoxic effect on the normal cell line. In summary, this new derivative may be used as an alternative or complementary medicine for liver cancer.

Isolation of a novel glycyrrhizin metabolite as a causal candidate compound for pseudoaldosteronism.

Pseudoaldosteronism is a common adverse effect associated with traditional Japanese Kampo medicines. The pathogenesis is mainly caused by 3-monoglucuronyl glycyrrhetinic acid (3MGA), one of the metabolites of glycyrrhizin (GL) contained in licorice. We developed an anti-3MGA monoclonal antibody (MAb) and an ELISA system to easily detect 3MGA in the plasma and urine of the patients. However, we found that some metabolites of GL cross-reacted with this MAb. Mrp2-deficient Eisai Hyperbilirubinemia rats (EHBRs) were administered glycyrrhetinic acid (GA), and we isolated 22α-hydroxy-18ß-glycyrrhetyl-3-O-sulfate-30-glucuronide (1) from the pooled urine with the guidance of positive immunostaining of eastern blot as the new metabolite of GL. The IC50 of 1 for type 2 11ß-hydroxysteroid dehydrogenase (11ß-HSD2) was 2.0 µM. Similar plasma concentrations of 1 and GA were observed 12 h after oral administration of GA to EHBR. Compound 1 was eliminated via urine, whereas GA was not. In Sprague-Dawley (SD) rats orally treated with GA, compound 1 was absent from both the plasma and the urine. Compound 1 was actively transported into cells via OAT1 and OAT3, whereas GA was not. Compound 1, when produced in Mrp2-deficiency, represents a potential causative agent of pseudoaldosteronism, and might be used as a biomarker to prevent the adverse effect.

Resveratrol-loaded glycyrrhizic acid-conjugated human serum albumin nanoparticles wrapping resveratrol nanoparticles: Preparation, characterization, and targeting effect on liver tumors.

In this study, glycyrrhizic acid-conjugated human serum albumin nanoparticles wrapping resveratrol nanoparticles were prepared to establish a tumor targeting nano-sized drug delivery system. Glycyrrhizic acid was coupled to human serum albumin, and resveratrol was encapsulated in glycyrrhizic acid-conjugated human serum albumin by high-pressure homogenization emulsification. The average particle size of sample nanoparticles prepared under the optimal conditions was 108.1 ± 5.3 nm with a polydispersity index (PDI) of 0.001, and the amount of glycyrrhizic acid coupled with human serum albumin was 112.56 µg/mg. The drug encapsulation efficiency and drug loading efficiency were 83.6 and 11.5%, respectively. The glycyrrhizic acid-conjugated human serum albumin nanoparticles wrapping resveratrol nanoparticles were characterized through laser light scattering, scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, thermogravimetric analyses, and gas chromatography. The characterization results showed that resveratrol in glycyrrhizic acid-conjugated human serum albumin nanoparticles wrapping resveratrol nanoparticles existed in amorphous state and the residual amounts of chloroform and methanol in nanoparticles were separately less than the international conference on harmonization (ICH) limit. The in vitro drug-release study showed that the nanoparticles released the drug slowly and continuously. The inhibitory rate of glycyrrhizic acid-conjugated human serum albumin nanoparticles wrapping resveratrol nanoparticles was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2 H-tetrazolium bromide method. The IC50 values of glycyrrhizic acid-conjugated human serum albumin nanoparticles wrapping resveratrol nanoparticles and resveratrol were 62.5 and 95.5 µg/ml, respectively. The target ability of glycyrrhizic acid-conjugated human serum albumin nanoparticles wrapping resveratrol nanoparticles for HepG2 cells was evaluated using fluorescence-modified albumin techniques. The uptake rate of glycyrrhizic acid-conjugated human serum albumin nanoparticles wrapping resveratrol nanoparticles was higher than that of pure resveratrol and increased with increased nanoparticles concentration. The in vivo body distribution of glycyrrhizic acid-conjugated human serum albumin nanoparticles wrapping resveratrol nanoparticles labeled with the near-infrared fluorophore Cy5 was monitored in H22 tumor-bearing mice through near-infrared fluorescence imaging systems. Glycyrrhizic acid-conjugated human serum albumin nanoparticles wrapping resveratrol nanoparticles exhibited effective target orientation to liver tumor and sustained-release property.

Physicochemical and structural properties of glycerin gel prepared using glycyrrhizic acid diethyl ester.

Glycyrrhizic acid diethyl ester (GZ-DE) was developed as a prodrug of glycyrrhizic acid (GZ), a hepatitis therapeutic drug. We fortuitously found that GZ-DE gels with glycerin selectively while searching for a safe solvent with which to dissolve GZ-DE. Based on this gelation, the aim of this study was to investigate the preparation of the gel and study the rheology, physicochemical and structural properties of the glycerin gel by differential scanning calorimeter (DSC), capillary electrophoresis (CEP), nuclear magnetic resonance (NMR), and small angle X-ray scattering (SAXS). The glycerin gel was prepared by the addition of at least 2.0% w/w GZ-DE. This gel did not flow at room temperature. After mixing glycerin and GZ-DE, a gel was formed after 2 days at 25°C or 3 h at 60°C. Glycerin gel containing 2.4% w/w GZ-DE provided the following results: 1) The glycerin gel exhibited creep at a constant stress of less than 10 Pa, but it is a fragile gel, showing Newtonian flow at 10 Pa stress. 2) Dynamic viscoelastic measurements showed that the elastic modulus (G') exceeds the viscous modulus (G''), indicating that glycerin gel has solid-like properties. 3) DSC showed a significant difference between the glass transition temperature of glycerin and glycerin gel. 4) CEP did not reveal a new compound in the glycerin gel. 5) NMR confirmed that glycerin gel is a physical gel. 6) SAXS measurements revealed that the glycerin gel has an oval-shaped basic frame (119 nm long and 65 nm wide).

Synthesis, molecular docking and biological evaluation of glycyrrhizin analogs as anticancer agents targeting EGFR.

Glycyrrhizin (GA) analogs in the form of 3-glucuronides and 18-epimers were synthesized and their anticancer activities were evaluated. Alkaline isomerization of monoglucuronides is reported. In vitro and in vivo studies showed that glycyrrhetinic acid monoglucuronides (GAMGs) displayed higher anticancer activities than those of bisglucuronide GA analogs, while anticancer activity of the 18α-epimer was superior to that of the 18ß-epimer. 18α-GAMG was firstly nicely bound to epidermal growth factor receptor (EGFR) via six hydrogen bonds and one charge interaction, and the docking calculation proved the correlation between anticancer activities and EGFR inhibitory activities. Highly active 18α-GAMG is thus of interest for the further studies as a potential anticancer agent.

Intestinal absorption and biliary elimination of glycyrrhizic acid diethyl ester in rats.

BACKGROUND: The purpose of this study was to evaluate absorption and elimination from the gastrointestinal tract of glycyrrhizic acid diethyl ester (GZ-DE) which was prepared as a prodrug of glycyrrhizic acid (a poorly absorbed compound) in rats. METHODS: After the GZ-DE solution was administered via the intravenous, intraduodenal, intraileal, and stomach routes, GZ-DE and GZ concentrations in bile were determined by high-performance liquid chromatography. The stability of GZ-DE was estimated from residual GZ-DE and GZ produced in GZ-DE solutions prepared with distilled water, a pH 1.2 solution, 0.9% NaCl solution, and phosphate-buffered solution (pH 7.4) at 37°C. RESULTS: GZ-DE was eliminated into bile by the pharmacokinetic parameters of apparent distribution rate constant (4.56 ± 0.36 per hour) and apparent elimination rate constant (0.245 ± 0.042 per hour). After intravenous and intraduodenal administration of GZ-DE, the concentration ratio of GZ-DE to GZ in bile was approximately 4:1, and the bioavailability of GZ containing GZ-DE was three-fold higher compared with the bioavailability of GZ after intraduodenal administration. GZ-DE was immediately precipitated in pH 1.2 solution and was converted to GZ by hydrolysis in pH 7.4 solution. CONCLUSION: Improvement of intestinal absorption of GZ was made possible by administration of GZ-DE into the intestine where absorption of GZ is lower than in the strong acidic environment of the stomach. However, because the elimination rate in bile simulated from kinetic parameters of GZ-DE was higher than the conversion rate from GZ-DE to GZ by hydrolysis, it is thought that the availability of GZ as a revolutionary prodrug was not high from the viewpoint of bioavailability of GZ in the liver by intestinal administration of GZ-DE.

Non steroid treatment for eczema: results from a controlled and randomized study.

AIM: This study assesses the efficacy of a new non steroid anti-inflammatory product in comparison to Hydrocortisone Butyrate 0.1% Cream in healing eczematous dermatitis. METHODS: A bilateral controlled randomized pilot study was conducted in Italian adults affected by eczema with at least two symmetric lesions at baseline, respectively assigned to a non steroid cream or Hydrocortisone. The severity of lesions was judged through the Global Clinical Score (GCS) and the recovery was defined as a GSC equal to 0. The study investigated: 1) the differences in GCS between four points in time during therapy (baseline, four, eight, twelve weeks), according to medication received; 2) treatment efficacy. RESULTS: The study showed that time, treatment and interaction between treatment and time were associated with GCS; moreover, lesions treated with Hydrocortisone went better on the whole but the post-hoc analysis showed a significant clinical improving at each point in time only for the non steroid cream. At the end of the study, in the intention to treat analysis, lesions recovered in 76.1% and 40.3% patients treated with Hydrocortisone and with the non steroid cream respectively; in the per protocol population, recovery was achieved in 91.7% and 58.3% of cases. CONCLUSION: According to the results, the non steroid cream has been demonstrated effective in reducing the severity of eczema and may be used with continuing success in the long term treatment of the disease.

Synthesis, biological evaluation, and molecular modeling of glycyrrhizin derivatives as potent high-mobility group box-1 inhibitors with anti-heart-failure activity in vivo.

Novel glycyrrhizin (GL) derivatives were designed and synthesized by introducing various amine or amino acid residues into the carbohydrate chain and at C-30. Their inhibitory effects on high-mobility group box 1 (HMGB1) were evaluated using a cell-based lipopolysaccharide (LPS) induced tumor necrosis factor α (TNF-α) release study. Compounds 10, 12, 18-20, 23, and 24, which had substituents introduced at C-30, demonstrated moderate HMGB1 inhibition with ED50 values ranging from 337 to 141 µM, which are values comparable to that of the leading GL compound (1) (ED50 = 70 µM). Compounds 23 and 24 emerged as novel and interesting HMGB1 inhibitors. These compounds were able to extend the survival of mice with chronic heart failure (CHF) and acute heart failure (AHF), respectively. In addition, molecular modeling studies were performed to support the biological data.

Glycyrrhizic acid and 18ß-glycyrrhetinic acid modulate lipopolysaccharide-induced inflammatory response by suppression of NF-κB through PI3K p110δ and p110γ inhibitions.

The roots and rhizomes of licorice ( Glycyrrhia ) species have been used extensively as natural sweeteners and herbal medicines. The aim of this work was to determine the in vitro anti-inflammatory effects of glycyrrhizic acid (GA) and 18ß-glycyrrhetinic acid (18ßGA) from licorice in a lipopolysaccharide (LPS)-stimulated macrophage model. The results showed that treatment with 25-75 µM GA or 18ßGA did not reduce RAW 264.7 cell viability but did significantly inhibit the production of LPS-induced nitric oxide (NO), prostaglandin E(2) (PGE(2)), and intracellular reactive oxygen species (ROS). Western blotting and reverse transcriptase polymerase chain reaction (RT-PCR) analyses revealed that GA and 18ßGA significantly reduced the protein and mRNA levels of iNOS and COX-2 in LPS-induced macrophages. Both GA and 18ßGA inhibited the activation of NF-κB and the activities of phosphoinositide-3-kinase (PI3K) p110δ and p110γ isoforms and then reduced the production of LPS-induced tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-1ß in a dose-dependent manner. In conclusion, these results indicate that GA and 18ßGA may provide an anti-inflammatory effect by attenuating the generation of excessive NO, PGE(2), and ROS and by suppressing the expression of pro-inflammatory genes through the inhibition of NF-κB and PI3K activity. Thus, the results suggest that GA and 18ßGA might serve as potential agents for the treatment of inflammatory-mediated diseases.

Metabolic profiling of roots of liquorice (Glycyrrhiza glabra) from different geographical areas by ESI/MS/MS and determination of major metabolites by LC-ESI/MS and LC-ESI/MS/MS.

Liquid chromatography electrospray mass spectrometry (LC-ESI/MS) has been applied to the full characterization of saponins and phenolics in hydroalcoholic extracts of roots of liquorice (Glycyrrhiza glabra). Relative quantitative analyses of the samples with respect to the phenolic constituents and to a group of saponins related to glycyrrhizic acid were performed using LC-ESI/MS. For the saponin constituents, full scan LC-MS/MS fragmentation of the protonated (positive ion mode) or deprotonated (negative ion mode) molecular species generated diagnostic fragment ions that provided information concerning the triterpene skeleton and the number and nature of the substituents. On the basis of the specific fragmentation of glycyrrhizic acid, an LC-MS/MS method was developed in order to quantify the analyte in the liquorice root samples. Chinese G. glabra roots contained the highest levels of glycyrrhizic acid, followed by those from Italy (Calabria).

Monoammonium glycyrrhizinate inhibited the inflammation of LPS-induced acute lung injury in mice.

Monoammonium glycyrrhizinate (MAG) was the aglycone of glycyrrhizin derived from licorice. In this study, the anti-inflammatory effects of MAG on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice and the possible mechanisms involved in this protection were investigated. Pretreatment with MAG prior to the administration of intratracheal LPS significantly induced a decrease in lung wet weight/dry weight ratio, in total leukocyte number and neutrophil percent in the BALF, and in myeloperoxidase (MPO) activity of lung in dose-dependent manners. At the same time, pretreatment with MAG also significantly improved the super oxide dismutase (SOD) activity and induced the malondialdehyde (MDA) content in the bronchoalveolar lavage fluid (BALF). Importantly, pretreatment with MAG prevented an increase in cyclic adenosine monophosphate-phosphodiesterase (cAMP-PDE) activity of lung in a dose-dependent manner. In addition, it can up-regulate the interleukin-10 (IL-10) level and down-regulate the tumor neurosis factor-α (TNF-α) level in the lung tissue of ALI mice. These results showed that anti-inflammatory effects of MAG against the LPS-induced ALI may be due to its ability of primary inhibition of cAMP-PDE activity, oxidative stress and its regulation of cytokine effects. Thus the results support that use of MAG is beneficial in the treatment of ALI and ARDS.

[Biosensor analysis of interaction of potential dimerization inhibitors with HIV-1 protease].

Currently inhibitors of protein-protein interactions are considered as perspective prototypes of new generation of drugs. The most attractive targets for such inhibitors are the oligomeric enzymes which active sites are formed by amino acid residues from different subunits. The classic example of such enzyme is HIV protease (HIVp), active only in the homodimeric form. We have developed a new approach for experimental screening of HIVp dimerization inhibitors. It is based on the original biosensoric test-system for differential analysis of interaction of tested substances with HIVp dimers and monomers. Using this test-system we have analyzed the most perspective candidate substances predicted by method of virtual screening, and some derivatives of glycyrrhizin, triterpenic and steroid glycosides. As a result we found one compound, which mainly interacts with HIVp monomers and inhibits in vitro activity of this enzyme with IC50 of about 10(-6) M.

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

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.