Inhibition of lipoxygenase activity by canola huh phenolic extracts

摘要

Crude phenolic (CP) extracts from Cyclone canola hulls were extracted into 30 to 80% (v/v) aqueous acetone and 30-80%(v/v) aqueous methanol and lyop hilized. The 70% acetone and 80% methanol CP extracts were fractionated on a Sephadex LH-20column into non-tannin and tannin fractions. The total content of phenolics in the prepared extracts ranged from 15 to 136 mg sinapic acid equivalents per gram of extract. Higher level of condensed tannins were detected in the acetone extracts than in the corresponding methanolic counterparts. Lipoxygenase (LOX) activity was assayed colorimetrically by measuring the conjugated dienes at 234 nm. The LOX inhibitory effect of CP extracts, IC50, was expressed in mg extract required for a 50%inhibition of LOX activity in the reaction mixture. The 70% acetone and 80% methanol CP extracts displayed markedly stronger LOX inhibitory effects than any other CP extract investigated. The inhibitory effect of tannin fraction was over two times greater than that of corresponding CP extract. Statistically significant (P≤0.05) linear correlations were found between the IC50 values and total phenolic contents, the IC50 values and condensed tannin contents as well as the IC50 values and protein precipitating potential of CP extracts.