Isolation, Characterization and Anti-Pepsin (HIV-Protease) Activity of Vernonia amygdalina Del and Cymbopogon citratus (de Condole) Stapf

Abstract

The anti-pepsin enzyme (HIV-1) activities of crude extract of Vernonia amygdalina and Cymbopogon citratus were investigated using standard methods. A portion (0.5cm3) of pepsin enzyme solution was measured and transferred into viels, 2 cm3 of hemoglobin and 1 cm3 of the extracts were mixed together. The procedure was repeated for all the different extract. A standard control was also prepared using hemoglobin, enzyme and the various concentrations of the anti-retroviral drugs. A negative control was ran using only hemoglobin and pepsin enzyme whereas positive control was ran along with the standard using hemoglobin, enzyme and various concentrations of antiretroviral drugs. The mixture was allowed to incubate at 37 ºC, after 20 mins, 700 µl of 5% TCA was added to stop the reaction. It was then centrifuged at 14000 rev/min for 5 mins and the supernatant was collected. Absorbance was recorded spectrophotometrically at 280 nm. Each sample was taken in triplicate. UV-Visible spectrophotometer was used to detect the absorbance at 280 nm. The results of the anti-pepsin enzyme (HIV-1) activities showed that petroleum ether fraction of Cymbopogon citratus exhibited wavelength of maximum absorption (גmax) ranging from 0.788 nm - 0.789 nm and its ethyl acetate fraction exhibited גmax absorption ranging from 0.785 nm- 0.788 nm. Petroleum ether fraction of Vernonia amygdalina exhibited גmax absorption ranging from 1.383 nm-1.399 nm while its ethyl acetate fraction exhibited גmax absorption ranging from 1.384 nm-1.400 nm. The result of this work shows that both Cymbopogon citratus and Vernonia amygdalina ethyl acetate fraction have higher activity with Vernonia amygdalina being the highest. Column chromatography of the ethyl acetate fraction of Vernonia amygdalina led to the isolation of the compound which shows higher activity (1.384 nm- 1.400 nm). Available spectroscopic data using 1H NMR, 13C NMR and IR showed that the compound could be β-Sitosterol. The result of this work therefore showed that the extract from the leaves of Vernonia amygdalina could be used for the treatment of HIV-1(since it has the same sequence and family with the pepsin enzyme) and other diseases caused by targeted virus.