Antioxidant activity and in vitro inhibition human plasma LDL oxidation of defatted rice bran var. Menthikwangi extract
2017
Hartati, S. | Suparmo | Santoso, U. | Marsono, Y
Defatted Rice Bran (DRB), a by-product of the rice milling process, which has been separated from its lipid content, is a source of natural antioxidant mainly hydrophilic antioxidant suchas ρ-coumaric and ferulic acid. The objective of this research was to evaluate the antioxidant potential of DRB var. Menthikwangi extracts. Defatted rice bran samples were prepared by removing lipid content with hexane solvent. Three different DRB extracts were prepared, including: (1) METE (methanol extract) was obtained from extraction of DRB with methanol,(2) RESE (residue extract) was obtained from extraction of the hydrolyzate of METE residue,(3) DRBE (DRB extract) was obtained from extraction of hydrolyzed DRB using ethyl acetate. Results showed that total phenolic content (TPC) of METE, RESE, and DRBE extracts were 39.54±2.92,305.83±18.40, 285.00±23.38 mg ferulic acid (FA) equivalents/g DRB extract, respectively. Antioxidant activities (expressed as IC-50 of a free radical scavenger of DPPH) of FA, DRBE, RESE, and METE were 33.37±1.10, 143.37±12.40, 177.41±12.40, and 19,525±28.28 ppm, respectively. The ρ-coumaric and ferulic acid content of DRBE and RESE (based on DRB extract) were 4.17±0.10 and 4.91±0.15%, and 3.80±0.09% and 4.31±0.09%,respectively, but not detected in the extract of METE. In vitro inhibitory of LDL oxidation (IC50 value) of ferulic acid (FA) was 8.8327µg/ml, while for ρ-coumaric (CUM) was 25.8346 µg/ml. IC-50 values of METE, DRBE and RESE were 77.0561 µg/ml, 25.7528 µg/ml and 29.7190 µg/ml respectively. Defatted rice bran extracts especially DRBE and RESE showed potentiality as antioxidant.
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