[Study on antioxidant activity of flavonoids from leaves of Psidium guajava].
Zhongguo Zhong Yao Za Zhi. 2018 Feb ;43(4):760-765. PMID: 29600652
The present study is to study the chemical constituents from ethanol extract of Psidium guajava leaves. The constituents were separated and purified by silica gel column chromaiographios over, macroporous resin D-101, Sephadex LH-20, and ODS. Six flavonoids compounds were isolated and identified as quercetin(1), quercetin-3---D-arabinopyranoside(2), quercetin-3---D-ribopyranoside(3), quercetin-3---D-galactopyranoside(4), quercetin-3---D-glucopyranoside(5), and quercetin-3--D-xylpyranoside(6). The antioxidant effects of six flavonoids was evaluated by scavenging ability of DPPH, superoxide anion, ABTS·⁺, and reducing effect of Fe³⁺ as well as total antioxidant capacity(FRAP). Vitamin C was used as positive control. The results indicated that six flavonoids exhibited significant antioxidant effects.