Effect of n-butanol fraction of A. catechu on HIV-1 protease activity and maturation of virion particles. A) Dose dependent inhibition in HIV-1 protease activity by the n-butanol fraction as compared with Saquinavir used as a reference control in a commercial ELISA kit. **p < 0.01 (as compared to enzyme only control). B) Comparison of the infectivity of TZM-bl cells by the virions released from the infected and n-butanol fraction/Saquinavir (a protease inhibitor) treated PBLs. The culture supernatant collected on 5th day was used to infect TZM-bl cells for 48 hours and relative luminescence unit (RLU) was calculated by lysing the cells as described in Materials and Methods. Y-axis represents the luciferase expression as RLU. Values are expressed as mean ± SE of 2 different experiments performed in duplicate. **p < 0.01 (as compared to cells treated with soup from infected control group without any treatment).