Identification of proglycemic and antihyperglycemic activity in antioxidant rich fraction of some common food grains

Methanolic extract of some common food grains were evaluated for antioxidant activities with respect to their total polyphenolic and anthocyanins content, prevention of ABTS oxidation, scavenging of free radicals ABTS^·+, DPPH, and H2O2. In vitro inhibition of rat intestinal α-glucosidase and formation of AGEs were also studied. These extracts were further evaluated for their influence on blood glucose level in normal rats with starch tolerance test. Polyphenolic content was observed in all the extracts. Bran rice, and black gram yielded maximum amount. Anthocyanins were detected in bran rice, Bengal gram, black gram and green pea extracts. All the extracts displayed varying degrees of ABTS^·+ radical scavenging activity. A significant positive correlation between polyphenolic content and ABTS^·+ radical scavenging activity was observed. Black gram, bran rice, pearl millet, and white gram extracts mitigated ABTS oxidation also. Bengal gram, pearl millet, black gram, white gram and green pea scavenged H2O2. Bran rice and polished rice extracts were potent in scavenging DPPH radical. Pearl millet, black gram and bran rice inhibited formation of AGEs. Except polished rice, other extracts displayed very mild α-glucosidase inhibition. Interestingly, pearl millet, white gram, black gram and white rice extracts despite the presence of antioxidant properties displayed pro-glycemic pattern. However, in addition to antioxidant activities, bran rice, barley and Bengal gram extracts exhibited antihyperglycemic property. This is the first report identifying proglycemic and antihyperglycemic activity in antioxidant rich fraction from food grains.