Ellagic acid & gallic acid from Lagerstroemia speciosa L. inhibit HIV-1 infection through inhibition of HIV-1 protease & reverse transcriptase activity.

BACKGROUND & OBJECTIVES: Banaba (Lagerstroemia speciosa L.) extracts have been used as traditional medicines and are effective in controlling diabetes and obesity. The aim of this study was to evaluate the anti-HIV property of the extracts prepared from the leaves and stems of banaba, and further purification and characterization of the active components. METHODS: Aqueous and 50 per cent ethanolic extracts were prepared from leaves and stems of banaba and were evaluated for cytotoxicity and anti-HIV activity using in vitro reporter gene based assays. Further, three compounds were isolated from the 50 per cent ethanolic extract of banaba leaves using silica gel column chromatography and characterization done by HPLC, NMR and MS analysis. To delineate the mode of action of the active compounds, reverse transcriptase assay and protease assay were performed using commercially available kits. RESULTS: All the extracts showed a dose dependent inhibition of HIV-1-infection in TZM-bl and CEM-GFP cell lines with a maximum from the 50 per cent ethanolic extract from leaves (IC 50 = 1 to 25 µg/ml). This observation was confirmed by the virus load (p24) estimation in infected CEM-GFP cells when treated with the extracts. Gallic acid showed an inhibition in reverse transcriptase whereas ellagic acid inhibited the HIV-1 protease activity. INTERPRETATION & CONCLUSIONS: The present study shows a novel anti-HIV activity of banaba. The active components responsible for anti-HIV activity were gallic acid and ellagic acid, through inhibition of reverse transcriptase and HIV protease, respectively and hence could be regarded as promising candidates for the development of topical anti-HIV-1 agents.

Antioxidant activity of citrus cultivars and chemical composition of Citrus karna essential oil.

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.

Total phenol, antioxidant and free radical scavenging activities of some medicinal plants.

Phenols, a major group of antioxidant phytochemicals, have profound importance due to their biological and free radical scavenging activities. To identify their potential sources, extracts of some plants were studied for their total phenolic content (TPC), antioxidant (AOA) and free radical scavenging activities (FRSA) by different methods at multiple concentrations followed by specific phenolic composition. The amount of TPC varied from 2.8 mg/g (Withania somnifera, roots) to 107.8 mg/g (Cassia fistula, fruits) and the AOA from 24.2% (Curcuma zeoderia, leaves) to 96.9% (Trewia nudiflora, leaves). Bark of Azadirachta indica, fruits of C. fistula, and leaves and fruits of T. nudiflora were found to have high TPC (89.8- 107.8 mg/g) and high AOA (84.8-96.9%). Promising plant parts were studied for their FRSA and reducing power (RP), where the bark of A. indica, Casuarina equisetifolia and Cinnamomum zeylanicum, flowers of Indigofera tinctoria, fruits of Lawsonia inermis, and fruits and leaves of T. nudiflora showed a very low inhibitory concentration value ranging from 0.14 to 0.26 mg/ml, efficiency concentration value from 6.1 to 11.6 mg/mg DPPH and reducing power value from 0.6 to 2.8 ascorbic acid equivalents (ASE/ml), and reasonably high values (8.5 -16.2) of anti-radical power (ARP), indicating their strong FRSA. They also showed better inhibition of hydroxyl radical induced deoxyribose degradation than that of reference standard. Fruits of C. fistula with high phenols (107.8 mg/g) showed poor reducing power (5.9 ASE/ml) and ARP (4.7); in contrast, the bark of C. equisetifolia and fruits of L. inermis were with comparatively lower phenols (72.1 and 75.8 mg/g) but exhibited good ARP (16.2 and 14.4) and reducing power (0.7 and 0.6 ASE/ ml, respectively). Some of the plants were also found effective in protecting plasmid DNA nicking induced by hydroxyl radicals generated by Fenton's reaction. They were further assayed for their specific phenolic composition through high-performance liquid chromatography and MS/MS, where the amount of caffeic acid varied from 0.312 to 0.797 mg/g, chlorogenic acid from 0.018 to 2.109 mg/g, ellagic acid from 0.009 to 0.902 mg/g, ferulic acid from 0.036 to 0.078 mg/g, gallic acid from 0.192 to 3.597 mg/g, kaempferol from 0.011 to 0.910 mg/g, quercetin from 0.047 to 1.106 mg/g and rutin from 0.059 to 2.029 mg/g.