BackgroundAcacia catechu (Mimosa family) stem bark extracts have been used traditionally as a dietary supplement as well as a folk medicine given its reported anti-inflammatory, immunomodulatory, hepatoprotective, antioxidant, anti-microbial and anti-tumor activities. The present study was undertaken to evaluate the anti-HIV-1 activity of the extracts from stem bark of A. catechu.MethodsThe aqueous and 50% ethanolic extracts of A. catechu stem bark were prepared and 50% ethanolic extract was further fractioned by successively partitioning with petroleum ether, chloroform and n-butanol. All the extracts and fractions were evaluated for cytotoxicity and anti-HIV-1 activity using different in vitro assays. The active n-butanol fraction was evaluated for its inhibition against HIV-1 reverse transcriptase, integrase, protease, pro-viral genome integration and viral Tat protein mediated transactivation. The effect of n-butanol fraction on the induction of pro-inflammatory cytokines secretion in Vk2/E6E7 cells and transepithelial resistance in Caco-2 and HEC-1A cells was investigated.ResultsThe aqueous and 50% ethanolic extracts of A. catechu showed IC50 values of 1.8 ± 0.18 μg/ml and 3.6 ± 0.31 μg/ml, respectively in cell-free virus based assay using TZM-bl cells and HIV-1NL4.3 (X-4 tropic). In the above assay, n-butanol fraction exhibited anti-HIV-1 activity with an IC50 of 1.7 ± 0.12 μg/ml. The n-butanol fraction showed a dose-dependent inhibition against HIV-1NL4.3 infection of the peripheral blood lymphocytes and against HIV-1BaL(R-5-tropic) as well as two different primary viral isolates of HIV-1 infection of TZM-bl cells. The n-butanol fraction demonstrates a potent inhibitory activity against the viral protease (IC50 = 12.9 μg/ml), but not reverse transcriptase or integrase. Further, in Alu-PCR no effect on viral integration was observed. The n-butanol fraction interfered with the Tat-mediated Long Terminal Repeat transactivation in TZM-bl cells, mRNA quantitation (qRT-PCR) and electrophoretic mobility shift assay (EMSA). The n-butanol fraction did not cause an enhanced secretion of pro-inflammatory cytokines in Vk2/E6E7 cells. Additionally, no adverse effects were observed to the monolayer formed by the Caco-2 and HEC-1A epithelial cells.ConclusionsThe results presented here show a potential anti-HIV-1 activity of A. catechu mediated by the inhibition of the functions of the viral protein and Tat.

The genus Citrus has a number of species and hybrids that are well established for their pharmaceutical and economic importance. The essential oil from Citrus karna Raf (Rutaceae) was analyzed for D-limonene (92.31%), the major chemical constituent, along with other minor constituents such as alpha-pinene (1.23%) and beta-pinene (1.80%). It showed significant inhibition for the oxidation of linoleic acid in the beta-carotene-linoleic acid system. Essential oils A and B obtained from C. sinensis, with 35.08% and 76.68% d-limonene, respectively, were used to evaluate the effect of the d-limonene concentration on antioxidant potential. Studies showed that d-limonene and C. karna essential oil have a similar antioxidant potential (39.6 and 38.3%, respectively). C. sinensis oils A and B showed only 10.5% and 30% antioxidant potential, respectively, indicating the possible role of d-limonene in antioxidant activity.

BackgroundIn the present study, extracts prepared from the leaves of Rhus parviflora Roxb. (Anacardiaceae) were evaluated for their anti-HIV activity, which have been traditionally used for the treatment of neurological disorders such as anxiety, insomnia and epilepsy.MethodsAqueous and 50% ethanolic extracts prepared from leaves of the plant were tested for their cytotoxicity and anti-HIV property using reporter gene based assays as well as human peripheral blood lymphocytes (PBLs). Further these extracts were evaluated for their ability to inhibit HIV-1 reverse transcriptase (RT) and protease activity. Safety profile of the extracts was determined on viability of Lactobacillus sp., secretion of pro-inflammatory cytokines by vaginal keratinocytes and transepithelial resistance.ResultsBoth aqueous (IC50 = 15 μg/ml) and 50% ethanolic (IC50 = 26 μg/ml) extracts prepared from leaves of R. parviflora showed anti-HIV activity in TZM-bl cells wherein the virus was treated with the extracts prior to infection. Further, both the extracts also inhibited virus load in HIV infected CEM-GFP cells and human PBLs. The anti-HIV activity is mediated through inhibition of HIV-1 protease activity. Both the extracts did not disturb the integrity of monolayer formed by intestinal epithelial Caco-2 cells. The extracts when tested up to 100 μg/ml did not significantly reduce the viability of L. plantarum, L. fermentum, L. rhamnosus and L. casei. The extracts (100 μg/ml) did not reveal any cytotoxic effect on vaginal keratinocytes (Vk2/E6E7). Levels of pro-inflammatory cytokines secreted by Vk2/E6E7 cells treated with both the plant extracts were within the non-inflammatory range.ConclusionsThe studies reported herein showed in vitro anti-HIV activity and preliminary safety profile of the extracts prepared from the leaves of R. parviflora.

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