Study of mechanism of action of the n-butanol fraction of Acacia catechu . A) Inhibitory activity of n-butanol fraction against Tat-mediated HIV-1 genes transactivation by pTat transfection in TZM-bl cells. Values are expressed as average of 2 different experiments performed in duplicates. B) The effect of n-butanol fraction on luciferase gene expression at mRNA level. The n-butanol fraction prepared from 50% ethanolic extract of stem bark of A. catechu was added to TZM-bl cells post-transfection with pTat. Reduction in the expression of luciferase gene was validated by qRT-PCR. qRT-PCR data is expressed as fold change in expression as compared to control. Values are expressed as mean ± SE of 2 different experiments performed in duplicate. C) The inhibitory activity of n-butanol fraction using Tat based Electrophoretic Mobility Shift Assay (EMSA). Tat protein was incubated with DNA probe in presence or absence of the active n-butanol fraction of the plant. Samples were run in 6% non-denaturing polyacrylamide gel. Lane 1 is with Tat transcription factor (TF) DNA probe + Tat protein (nuclear extract prepared from transfected TZM-bl cells) + n-butanol fraction (50 μg/ml); Lane 2, TF DNA probe + Tat protein; Lane 3, TF DNA probe only; Lane 4 - TF DNA probe + Cold TF DNA probe + Tat protein.