In Vitro Antioxidant Activities of Polyphenols Purified from Four Plant Species Used in Rice Beer Preparation in Assam India

Abstract

The purified phenolic extracts of Artocarpus heterophyllus, Oldenlandia corymbosa, Cyclosorus extensa, and Alpinia malaccensis were tested for the presence of various polyphenols and antioxidant activities. The polyphenols were extracted with ethanol and purified by stepwise dialysis and column elution. High-performance liquid chromatography was performed to detect and quantitate the polyphenols and 10 different in vitro methodologies were used to measure antioxidant properties. Quercetin, ferulic acid, and salicylic acid were present in all the species. Chlorogenic and p-coumaric acid in A. heterophyllus; p-coumaric acid, caffeic acid, naringin, catechol, and resorcinol in C. extensa; chlorogenic, caffeic, and quinic acid in O. corymbosa and naringin, quinic acid and catechol in A. malaccensis were detected with varied concentrations. The 2-deoxyribose, 1,1-diphenyl-2-picryl-hydrazyl and 2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) assays exhibited high radical scavenging activities and they were also able to combat •OH radicals and H₂O₂ to an extent of 25.53 and 71.23% respectively. Superoxide anions and nitric oxide radicals were scavenged up to 63.85 and 56.24%, respectively, and the extracts exhibited ferric ions chelation and ferrous ions reduction capacity. A reduction in the level of lipid peroxidation was also observed. All four species were found to be potent sources of polyphenols having antioxidative property. The results fully justified the use of these plants in the beer making process of Assam, India.

Keywords:

• Rice beer starters
• Polyphenols
• HPLC
• Free radicals
• Antioxidant activity

Additional information

Funding

The authors are thankful to the Ministry of Food Processing Industries, Government of India, New Delhi for financial support of a project on functional attributes of rice beer of Assam and other Northeastern states of India.