Objective: To investigate the inhibitory activities of caffeoyl glucopyranoses purified from Balanophora japonica Makino on HIV entry and their mechanism.
Methods: HIV-1 Env pseudovirus was used to evaluate the anti-HIV-1 activity of those compounds. ELISA and molecular docking were used to study the mechanism of the actions of the active compounds.
Results: We used the HIV-1 Env pseudovirus to test the anti-HIV-1 activity of the six phenolic compounds (final concentration 25 microg/ml), and found that only 1,2,6-Tri-O-caffeoyl-beta-D-glucopyranose (TCGP) and 1,3-Di-O-caffeoyl-4-O-galloyl-beta-D- glucopyranose (DCGGP) could effectively inhibit the entry of HIV-1 Env pseudovirus into the target cells in a dose-dependent manner, with IC(50) values of 5.5-/+0.2 and 5.3-/+0.1 microg/ml, respectively. These two compounds could also blocked the gp41 six-helix bundle formation. Molecular docking analysis suggested that they might bind to the hydrophobic cavity of the gp41 N-trimeric coiled-coil.
Conclusion: TCGP and DCGGP are potent HIV-1 entry inhibitors targeting gp41 and can serve as lead compounds for developing novel anti-HIV-1 microbicides for prevention of sexual HIV-1 transmission.