Extraction optimization, antidiabetic and antiglycation potentials of aqueous glycerol extract from rice (Oryza sativa L.) bran

Abstract

The purpose of this investigation was to explore aqueous glycerol as food grade solvent for rice bran polyphenolic antioxidants extraction and investigate the antidiabetic and antiglycation potential of the extract and its major polyphenols. Response surface methodology (Box-Behnken design) was implemented to optimize experimental conditions for rice bran polyphenols and antioxidants extraction. The optimum conditions provided a very satisfactory outcome in total polyphenols (549.6 ± 8.05 mg gallic acid equivalent per 100 g dry weight) and DPPH scavenging activity (57.83 ± 1.8%). The chromatographic separation of the extract showed higher concentrations of ferulic acid, ρ-coumaric acid and chlorogenic acid followed by caffeic acid, syringic acid and rutin. Moreover, the extract inhibited α-amylase, α-glucosidase, and lipase activity as 34.2 ± 3.2%, 29.9 ± 1.0%, and 12.4 ± 2.3%, respectively. Furthermore, fructose readily forms Advanced Glycation End Products (AGEs) fluorescence with basic amino acids in low concentration in simulated intestinal digestion conditions. The extract inhibited AGEs formation by 52.6% at 20 μL/mL. Our study indicated that the antidiabetic and antiglycation potential of rice bran extract was mainly driven by the extract polyphenols. Rice bran glycerol extract could be employed as a natural antidiabetic and antiglycation remedy, and as economically and eco-friendly source of potent bioactive compounds with satisfactory outcome.