Protective effects of broccoli (Brassica oleracea) and its active components against radical-induced oxidative damage

The radical scavenging effect and protective potential from oxidative damage by radical generator, 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH), in renal epithelial LLC-PK1 cell of broccoli (Brassica oleracea) were investigated and identified the active components under the bioassay-linked fractionation method. The MeOH extract, and fractions of CH2Cl2, BuOH and H2O from broccoli showed the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging effect in a dose-dependent manner. In addition, they exerted the protective effect against LLC-PK1 cellular damage induced by AAPH dose-dependently. In particular, the BuOH fraction was evaluated as the most active fraction, indicating that the BuOH fraction contains the active components with antioxidative capacity. Employing a bioassay-linked fractionation method, the active principles were isolated and characterized as 1,2-disinapoylgentiobiose and 1-sinapoyl-2-feruloylgentiobiose from the BuOH fraction. These two compounds from broccoli displayed potent antioxidant effects against the DPPH radical, showing the IC50 values of 5.18 and 7.52 microg/mL, respectively. Moreover, the compounds significantly and dose-dependently recovered cell viability lowered by AAPH treatment, suggesting the protective roles from cellular oxidative damage. The present study suggests that broccoli has excellent antioxidative potential and the hydroxycinamic acid esters from broccoli, 1,2-disinapoylgentiobiose and 1-sinapoyl-2-feruloylgentiobiose, are considered as the active components with antioxidative effect.