Micronutrients and phytochemicals content in various rice (Oryza sativa Linn.) samples control carbohydrate digestion variedly and present differential antioxidant activities: an in vitro appraisal

Abstract

High starch and carbohydrate content in rice (Oryza sativa Linn.) disparages this food responsible for postprandial hyperglycemic excursions. However, rice is an Asian food synonym. Additionally, in traditional Indian healing practices, rice is used for treatment of various disorders. In this research, we analyzed micronutrient and phytochemical contents in different rice samples available in market. Effect of aqueous-ethanol extract of each type of rice was evaluated against intestinal α-glucosidase to examine extract’s influence on carbohydrate digestion. Free-radicals scavenging activities as a measure of antioxidant potential in different rice were also examined. Brown-rice presented highest (54%) α-glucosidase inhibition followed by parboiled-rice (52%), idly-rice (48%), hand-pounded rice (42%), dosa-rice (40%) and basmati-rice (39%). Polished white sona-masoori rice presented least enzyme inhibitory (31%) activity. Presence of higher α-glucosidase inhibitory activity was regarded as slow digesting rice that would impart lesser postprandial glycemic excursion. Brown and parboiled-rice presented highest ABTS֗⁺ radical scavenging (74%) activity whereas; idly-rice displayed highest DPPH scavenging (50%) activity. Higher polyphenol and niacin contents in rice were found significantly (p<0.0001 and p<0.01 respectively) correlated with enzyme inhibitory activity. Higher polyphenol content was found responsible for enhanced free-radicals scavenging activity. Increasing concentrations of niacin and pantothenic acid correlated with ABTS֗⁺ radical scavenging activity.