Abstract

Objective: The aim of this study was to evaluate the antioxidant capacity of cold pressed rice bran oil of six different Thai rice varieties using online-HPLC-DPPH method. Methods: The target-guidance of DPPH-HPLCexperimentwas used for screening of antioxidant γ-oryzanol in cold pressed rice bran oil. An HPLC method was developed and successfully used to simultaneously determine individual γ-oryzanol. Results: Four peaks were detected in rice bran oil, and there were identified as cycloartenylferulate, 24-methyl-cycloartenylferulate, campesterylferulate andβ-sitosterylferulate by LC-MS/MS.24-methylcycloartenylferulate possessed the strongest radical scavenging capacity.Base on HPLC-DPPH method, Sang-Yot rice bran oil demonstrated the highest antioxidant capacity with the IC50 values of 0.77mg/mL.Furthermore, HPLC method for quantitative analysis of γ-oryzanol was developed and validated. The method involvesthe Agilent 1260 series andseparation was achieved at 25 °C on a Poroshell 120 EC-C18 column. Acetonitrile and methanol (60:40 v/v) were used as mobile phase and was pumped at a flow rate of 0.8 mL/min. The quantitation wavelength was set at 325 nm. Conclusions: Online-HPLC-DPPH methodwas successfully developed in this study fordetermining of antioxidant γ-oryzanol in rice bran oil. A high degree ofspecificity as well as repeatability and reproducibility were also achieved by the developed HPLC method.