Chemical and cellular antioxidant activity of flavone extracts of Labisia pumila before and after in vitro gastrointestinal digestion

Two kinds of flavone extracts were extracted and purified from Labisia pumila (LP). High-performance liquid chromatography (HPLC) analysis was used to determinate the flavones in the extracts, and catechin, glycitin, rutin, naringin, and myricetin were identified in the LP leaf extract (LPL-F) while genistin, naringin, and myricetin were found in the stem extract (LPS-F). Specific flavonol compounds mediated the satisfactory scavenging abilities. The flavone leaf extracts performed better than the stem extracts in chemical antioxidative activities but worse in cellular antioxidative capabilities. The chemical and cellular antioxidative activities were not obviously changed by gastrointestinal digestion but slightly changed at the last 2 hours of intestinal digestion because prolonged exposure to alkaline conditions could destroy the structure of flavonoids. Changes in MDA and GSH content, and enzyme activities of SOD and GSH-Px in human erythrocytes during GI digestion indicated the possible intracellular antioxidant-detoxifying mechanisms were through attenuating AAPH-induced oxidative stress by inhibiting ROS generation, in which stem extracts performed the better.