Protease activated receptor-2(PAR-2)is a G-protein-coupled receptor.Recent studies indicate that PAR-2 is mainly expressed in leukocytes and activated by pancreatin and(or)tryptase,which subsequently induces inflammation through degranulation of leukocytes.Activation of PAR-2 in leukocytes is possibly involved in the pathogenesis of rheumatoid arthritis.

OBJECTIVETo screen the HIV-1 entry inhibitors targeting HIV-1 gp120 from the IBS natural product database by virtual screening based on the binding mode of the neutralizing antibody VRC01 with HIV-1 gp120 and investigate the anti-viral activities of the inhibitors and their action mechanisms.

METHODSThe binding interaction of the candidate molecules binding gp120 and changes of the binding free energy were analyzed by MM-PBSA calculation. The anti-HIV-1 activities of the tested compounds were detected by HIV-1 pseudotyped virus, laboratory-adapted HIV-1 and a cell-cell fusion assay. The cytotoxicity of the studied molecules was examined by XTT colorimetric assay. The mechanisms of the anti-viral activities of the candidate molecules were analyzed using enzyme-linked immunosorbent assay.

RESULTSA total of 19 molecules with distinct reduction of the binding free energy after binding with gp120 were screened from 40000 molecules. Among them, NC-2 showed anti-HIV-1 activities against HIV-1 pseudotyped virus and laboratory-adapted HIV-1, and was capable of blocking HIV-1 envelope-mediated cell-cell fusion. The IC50 of NC-2 for inhibiting HIV-1IIIB and pseudotyped HIV-1JRFL infection were 1.95∓0.44 µmol/L and 10.58∓0.13 µmol/L, respectively. The results of ELISA suggested that NC-2 could inhibit the binding of HIV-1 gp120 to CD4 without blocking the formation of gp41 six-helix bundle in vitro.

CONCLUSIONThis computer-based virtual screening method can be used to screen HIV-1 entry inhibitors targeting gp120. Using this virtual screening approach combined with anti-viral activity screening, we obtained a potent HIV-1 entry inhibitor NC-2 with novel structure.

Anti-HIV Agents ; pharmacology ; Antibodies, Monoclonal ; pharmacology ; Antibodies, Neutralizing ; pharmacology ; Binding Sites ; Cell Fusion ; Cell Line ; Drug Discovery ; Drug Evaluation, Preclinical ; HIV Antibodies ; pharmacology ; HIV Envelope Protein gp120 ; antagonists & inhibitors ; HIV-1 ; drug effects ; Humans ; Microbial Sensitivity Tests

OBJECTIVE: To explore the inhibitory effect of PSB0739 on the formation of semen-derived amyloid fibrils. METHODS: PAP248-286 (440 μmol/L) was incubated with PSB0739 at different concentrations, and at different time points of incubation, aliquots were taken from each sample for Congo red staining to detect the formation of amyloid fibers. The morphology of amyloid fibrils incubated in the presence or absence of PSB0739 was visualized using transmission electron microscope. The effect of PSB0739 on amyloid fibril formation was determined using virus infection assays at different time points, and the surface charges of amyloid fibril incubated with PSB0739 were calculated using a Zeta potentiometer. The cytotoxicity of PSB0739 in Hela cells was determined using MTT assay. The antiviral effect of PSB0738 against HIV- 1 was evaluated by infection assay. RESULTS: PSB0739 inhibited SEVI fibril formation in a dose-dependent manner . At 48 h of incubation, 220 μmol/L of PSB0739 obviously inhibited the formation of amyloid fibrils in 440 μmol/L of SEVI. Transmission electron microscopy revealed that 220 μmol/L PSB0739 prevented PAP248- 286 (440 μmol/L) from forming amyloid fibrils. PSB0739 antagonized SEVI-mediated enhancement of HIV-1 infection, and 1760 μmol/L of PSB0739 completely reversed the positive charge of SEVI ( < 0.05). PSB0739 below the concentration of 62.5 μmol/L showed no obvious cytotoxicity in Hela cells (>0.05). PSB0739 showed a direct anti-HIV activity with an IC of 21.77±5.15 μmol/L. CONCLUSIONS PSB0739 can inhibit the formation of semen-derived amyloid fibrils .
Amyloid ; chemistry ; drug effects ; Anti-HIV Agents ; pharmacology ; Dose-Response Relationship, Drug ; HIV Infections ; drug therapy ; HIV-1 ; drug effects ; HeLa Cells ; Humans ; In Vitro Techniques ; Microscopy, Electron, Transmission ; Purinergic P2Y Receptor Antagonists ; pharmacology ; Semen ; chemistry