Isolation and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity of active compound from Jujube tree (Zizyphus mauritiana Auct. non Lamk.)

Increased reactive oxygen species causes cells or tissue damages and is associated with some degenerative diseases, such as coronary heart diseases and cancer. This research is intended to isolate and to identify the antiradical compounds from the bark of Jujube tree (Zizyphus mauritiana Auct. non Lamk.). The methanol extract of the bark was successively fractionated with n-hexane and ethyl acetate to give n-hexane fraction, ethyl acetate fraction, and methanol extract residue, respectively. The extract and fractions were examined for its radical scavenging activity using 2,2’-diphenyl-1-picrylhydrazil radical. The ethyl acetate fraction, having the most active 2,2’-diphenyl-1-picrylhydrazil radical scavenging, was further repeatedly separated using vacuum liquid chromatography, and the purification was carried out using preparative thin layer chromatography (TLC) in order to obtain an active isolate. The purity of the isolate was evaluated using thin layer chromatography method and melting point measurement. The structure of the isolate was identified chemically using various spray reagent and ultraviolet-visible, infrared, infrared, Liquid Chromatography-Mass Spectrometry (LC-MS) and Proton Magnetic Resonance (1H-NMR) spectroscopic methods. The extract, fraction, and sub-fractions were determined for its total contents of phenolic and flavonoid. The results showed that the methanol extract residue contained the highest total phenolic (36.29% wt/wt gallic acid equivalent), while fraction E4 of the ethyl acetate extract contained the highest total flavonoids (21.31% wt/wt quercetin equivalent). The active isolate showed to have 2,2’-diphenyl-1-picrylhydrazil radical scavenging activity with IC50 of 7.58 ?/mL and is identified as trans-p-coumaroyl triterpene. Detail structure of the triterpene needs to be identified further.