Inhibition of HIV-1 RT by semi purified extract of Psidium guajava L. leaves and docking studies of the compounds identified by high-resolution mass spectrometry

Abstract

Abstract Background Present antiretroviral therapy reduces the viremia among HIV infected individuals but fails to eradicate the viral genome from the host. Consequently, the infected individuals are not cured of HIV and they depend on the antiretroviral therapy for their life time. Frequent emergence of drug resistant strains and drug induced toxicity entails the development of new anti-HIV drugs. The present study evaluated the anti-HIV potential of guava leaf extracts. Methods Dried P.guajava L. leaves were subjected to bioassay guided fractionation using different solvents followed by silica gel column chromatography and preparative TLC. Viral inhibition was examined by in vitro primer extension and intrinsic fluorescence quenching and in cell culture by GFP reporter expression, RT-PCR and western blotting. Compounds were identified by HR-LCMS and analyzed in silico for interaction with HIV-1 RT. Results The chromatographically purified fraction A2 showed 97.3% inhibition of HIV-1 RT activity by in vitro primer extension assay and 87% quenching of intrinsic fluorescence of HIV-1 RT. In cell culture, ~72% and ~68% inhibition of viral replication was observed by RT-PCR and western blotting, respectively. By HR-LCMS, 11 compounds were identified in A2 fraction. Molecular docking indicated 5 of them, 18-acetoxy-PGF2alpha-11-acetate, irigenindibenzyl ether, colforsin, deoxygedunol acetate and dihydromyricetin strongly bind in the catalytic domain of HIV-1 RT. In silico analysis indicated 18-acetoxy-PGF2alpha-11-acetate interacted with HIV-1 RT similar to nevirapine, the known HIV-1 RT inhibitors. It showed -11.4 kcal/mol binding energy while the efavirenz and zidovudine the two positive controls had -6.2 and -6.3 kcal/mol binding energies, respectively. Conclusions The present findings indicate strong anti HIV potential of P. guajava extract. Further studies with the individual compounds will establish the P. guajava as cost effective complementary medicine as well as an alternative drug to counter the frequent emergence of new drug resistant strains of HIV.