Phenolic compounds in rice (Oryza sativa L.) bran : identification and quantification, angiogenic potential, anti-inflammatory activity and free-radical scavenging activity

Date

4-2010

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Evelyn B. Rodriguez

Abstract

The occurrence, levels, anti-angiogenic potential, anti-inflammatory and free radical scavenging activities of phenolic compounds in rice (Oryza sativa L.) bran were determined. Total phenolic content of rice bran was found to be 1.92 ± 0.07 mgGAE/g rice bran and 1.96 ± 0.08 mgQE/g rice bran. Phenolic profiling using two-dimensional paper chromatography and silica gel thin-layer chromatographic analyses showed occurrence of hydroxycinnamic acids and a flavonol glycoside. Further isolation and characterization of phenolic compounds in rice bran were done using preparative thin-layer chromatography and IR analysis. Ferulic acid, diferulic acid and quercetin glycoside were found to be the major phenolic components of rice bran. HPLC analysis of the non-hydrolyzed, base hydrolyzed and acid hydrolyzed fraction of rice bran phenolic extract confirmed ferulic acid as the major phenolic component of rice bran (47.91 ± 2.25 mg / 100g rice bran). Vanillic acid, protocatechuic acid, gallic acid and sinapic acid were also found as minor phenolic acid components of rice bran. The antioxidant activity of rice bran phenolic extract was evaluated using the DPPH assay and nitric oxide assay. Based on the DPPH assay and the nitric oxide assay, rice bran phenolic extract exhibited free-radical scavenging activity. The modified in vivo CAM assay using duck embryos was employed in evaluating the anti-inflammatory and anti-angiogenic activities of rice bran phenolic extract. Results showed that rice bran phenolic extract exhibited comparable anti-inflammatory activities towards quercetin and hydrocortisone standards. Evaluation of anti-angiogenic activity revealed that rice bran phenolic extract exhibited potent anti-angiogenic activity as evident to the suppression of blood vessel growth. In conclusion, rice bran, an underutilized by-product of rice milling can potentially be a source of potent bioactive phenolic phytochemicals which could improve human health by promoting disease prevention.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2010 C42 /A45

Document Type

Thesis

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