Extracts of Moringa oleifera Lam. showing inhibitory activity against early steps in the infectivity of HIV-1 lentiviral particles in a viral vector-based screening

Moringa oleifera Lam. (Moringaceae) is one of the many medicinal plants employed by herbalist to treat or manage people living with HIV/AIDS (PLWHA) in African Traditional Medicine (ATM) and there are many claims to the fact that it improves quality of life and reverses the course of the HIV/AIDS disease progression. This practice and the claims of efficacy spurred the present study in which the inhibitory activities of three different extracts of M. oleifera on lentiviral vector infectivity were studied on HeLA cells by measuring the expression of green fluorescent protein (GFP) transgene in the vector using flow cytometry. An infectious VSV-G-pseudotyped, human immunodeficiency virus type 1-based, self-inactivating lentiviral vector particles were generated by transient co-transfection of the vector plasmid (pHIV-1 CSCG) with packaging plasmids encoding tat, rev, gag-pol (pCMV Delta R8.2), a VSV-G expression plasmid (pHIT-G), a secretory alkaline phosphate expression plasmid (pSEAP) which are all necessary for viral infectivity. The extracts studied were obtained by solvent extraction of the leaf powder of M. oleifera with ethyl ether (EM), methanol (MM) and water (AM). All the extracts (EM, MM, and AM) were active against the HIV-1 lentiviral vector and inhibited the early events of the viral replication cycle on HeLa cells in a concentration-dependent manner with IC sub(50) of 7.59 mu g EM/ml, 7.72 ug MM/ml and 7.17 mu g AM/ml, respectively. Cytotoxicity of the extracts evaluated in parallel on HeLA cells by the MTT assay method showed TC sub(50) values of 32.33 mu g EM/ml, 38.88 mu g MM/ml and 41.58 mu g AM/ml with selectivity indices (SI) of 4.26, 5.04 and 5.8, respectively. In this study, M. oleifera leaf extracts showed potent and selective inhibition of early steps in HIV-1 infectivity and could serve as source of antiretroviral lead molecules. The outcome of this investigation could partly explain the benefits and improvement in quality of life claimed by PLWHA in the use of this medicinal plant as supplement.