Bioactive components and properties of ethanolic extract and its fractions from Gynura procumbens leaves

The bioactive components and properties of various extracts from Gynura procumbens leaves were investigated. The leaves of G. procumbens were initially extracted with 95% ethanol and then sequentially fractionated according to the solvent polarity of chloroform, ethyl acetate and n-butanol. Total phenolic and total flavonoid contents of the crude ethanolic extract and its fractions ranged from 0.8-24.4 mgGAE/g and 0.1-17.3 mgCE/g, respectively. The ethyl acetate fraction (EAF) showed the most potent radical scavenging activity on DPPH, ABTS+, OH and H2O2, with IC50 values of 0.22, 0.06, 0.01 and 0.03 mg/ml, respectively. Lipid peroxidation inhibition and oxidative protein damage protecting activities were superior for EAF compared to the other fractions, including ascorbic acid. All extracts possessed strong anti-glycation activity with IC50 values between 0.04 mg/ml in the EAF and 0.15 mg/ml in the chloroform fraction. Correlation analysis showed the phenolic and flavonoid contents were highly positively correlated with the antioxidant and anti-glycation activities. The individual bioactive compounds, as determined using HPLC, were remarkably different, especially gallic, p-coumaric and ferulic acids for phenolic acids, and myricetin, quercetin and kaempferol for flavonoids. These findings suggest that the strongest bioactive properties of EAF from G. procumbens were because of these phenolics and flavonoids.