In Vitro and In Vivo Anti‐Hyperglycemic and Antioxidant Effects of Phenolic Compounds isolated from Oryza sativa L.(Keun‐nun‐Jami) Variety

Abstract

Type 2 diabetes, one of the chronic diseases, is a problem in both developed and developing countries. In particular, excessive ingestion of grain, such as rice, can result in hyperglycemia and type 2 diabetes. Therefore, a Oryza sativa L. variety, Keun‐nun‐Jami (KNJM) extracts were investigated for their anti‐hyperglycemic effect using in vitro and animal models. In vitro study inhibitory activities of both ethyl alcohol extracts of bran and germ against rat intestinal sucrase and maltase were evaluated. Oxygen radical absorbance capacity (ORAC) was also investigated. Ethyl alcohol extract of KNJM bran (EKB) had the highest sucrase inhibitory activity followed by ethyl alcohol extract of KNJM germ (EKG). Taxifolin, a flavonol, was isolated from the extract of KNJM along with three unknown compounds using HPLC and semi‐prep HPLC systems. Their structures were elucidated by extensive spectroscopic analysis, including 1D and 2D NMR, and FTICR‐MS. Furthermore, post‐prandial blood anti‐hyperglycemic effect of the extacts and taxifolin were measured using SD (Sprague Dawley) rat model. Postprandial blood glucose levels were tested for 3 hr after sucrose and starch administration with or without 500 mg of EKB, EKG, and taxifolin, respectively. Similar to result in vitro study, EKB which has higher content of taxifolin than that of EKG had stronger anti‐hyperglycemic effect than that of EKG. These results indicate that taxifolin from KNJM serves to reduce post‐prandial blood glucose rise and slower absorption of glucose in the small intestine, via carbohydrate hydrolyzing enzymes inhibition. These findings suggest that EKB has better potential for this bioactivity and this observation possibly correlates with the taxifolin contents observed in both extracts. Selected variety of colored rice, KNJM may provide the potential to contribute as a dietary strategy for controlling postprandial hyperglycemia.Support or Funding InformationThis work was supported by a grant from the Next‐Generation BioGreen 21 Program (No.PJ01314003), Rural Development Administration, Republic of KoreaThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.