Characterization of Antioxidant Compounds and Antioxidant Activity of Indian Rice Varieties

Abstract

The present work is aimed at characterisation of phenolic acids and rice bran oil (RBO) of Njavara, a medicinal red rice variety and other rice varieties. The antioxidant activities of the rice polyphenols were also studied by radical scavenging assay, reducing power and microsomal lipid peroxidation. Pigmented rice varieties (Njavara and Jyothi) had high antioxidant activities than non-pigmented variety (IR 64). Acetone extracts showed higher phenol content and antioxidant potency compared to methanol and ethanol extracts. Njavara showed higher reducing capability and higher soluble (15%–46%) and insoluble phenolic acids (51%–75%) compared to Jyothi and IR 64. An array of phenolic acids were identified, the major being ferulic and p-coumaric acid. The ferulic acid concentration of Njavara in soluble and insoluble form was 33%-66% and 51%–75% higher, respectively, than non-medicinal rice. Njavara RBO was a better source of tocopherols. However, oryzanol composition of Njavara was similar to Jyothi and IR 64.

Keywords:

• Njavara
• phenolic acids
• DPPH radicals
• reducing power
• lipid peroxidation

Acknowledgments

The authors thank Dr. V. Prakash, Director, Central Food Technological Research Institute, Mysore, India, for his support in the present study. Ms. Deepa Gopinath, CSIR, SRF, gratefully acknowledges the financial support from CSIR, New Delhi in carrying out these investigations. This work was supported by a project awarded to KAN by Department of Science and Technology, New Delhi, India.