Role of nutraceutical starch and proanthocyanidins of pigmented rice in regulating hyperglycemia: Enzyme inhibition, enhanced glucose uptake and hepatic glucose homeostasis using in vitro model

Abstract

Dysregulation of glucose homeostasis result in hyperglycemia and pigmented rice, unique combination of high quality starch and phenolics has the potential in regulating it. In this study, pigmented rice was characterized in terms of nutraceutical starch (NS) and phenolic content. Further the effect of rice phenolics on carbolytic enzyme inhibition, glucose uptake, hepatic glucose homeostasis and anti-glycation ability was analyzed in vitro. The most relevant effect on enzyme inhibition (α-amylase: IC₅₀-42.34 µg/mL; α-glucosidase: IC₅₀:63.89 µg/mL), basal uptake of glucose (>39.5%) and anti-glycation ability (92%) was found in red rice (RR), than black rice (BR). The role of RR phenolics in regulating glucose homeostasis was deciphered using hepatic cell line system, which found up-regulation of glucose transporter 2 (GLUT2) and glycogen synthase 2 (GYS2); while expression of gluconeogenic genes were found down regulated. To our knowledge this study is the first report validating the role of starch-phenolic quality towards anti-hyperglycemic effect of RR.

Keywords: 4-Nitrophenyl α-D glucopyranoside (PubChem CID92969); Acarbose (PubChem CID41774); Anti-hyperglycemic; Black rice; C(14)glucose (PubChem CID6451569); Dinitrosalicyclic acid (PubChem CID11873); Folin’s reagent (PubChem CID10636); Gallic acid (PubChem CID370); Gentamycin (PubChem CID3467); Glucose homeostasis; Glucose uptake; Hepatocyte; Penicillin (PubChem CID5904); Pigmented rice; Proanthocyanidins; Propidium iodide (PubChem CID104981); Red rice; Rutin (PubChem CID45479757); Serum albumin (PubChem CID16132389); Starch soluble (PubChem CID 134690613); Streptomycin (PubChem CID19649).