The ability of active fraction from Kappaphycus alvarezii (Doty) Doty Ex.P.C.Silva to Decrease Glucose Levels inhibit advanced Glycation End-Products (AGEs) Formation and RAGE (AGER) Gene Expression in Diabetic Rats

Abstract

Background. Kappaphycus alvarezii (Doty) Doty ex P.C.Silva is a widely used seaweed that has antioxidant and antiglycation activities. The purpose of this study was to examine the ability of active fraction from Kappaphycus alvarezii to decrease glucose level and inhibit glycation process. Methods. This study used bioassay-guided fractionation through three stages of the extraction, partition, and fractionation processes that were monitored using Thin Layer Chromatography and BSA-Glucose test. Inhibition of glycation was known by calculating percentage of inhibition and IC50. Selected active fraction was used for in vivo tests using 24 Wistar male rats. Measurement of glucose levels used GOD-PAP method, while levels of glycated albumin (GA) and Nε- (carboxymethyl) lysine (CML) were measured using ELISA. Analysis of RAGE gene expression used qPCR. Results Glycation test showed a significant difference (p < 0.05) between all treatments. Chloroform extract showed higher percentage of inhibition (62.4 ± 3.45%) with lower IC50 (0.33 ± 0.01 mg/ml) compared to methanol extract (0.52 ± 0.03 mg/ml). Methanol-soluble extracts had a higher percentage of inhibition (51.10 ± 1.64%) with IC50 0.45 ± 0.05 mg/ml compared to methanol-insoluble extract (1.25 ± 0.05 mg/ml). Fraction II had a higher percentage of inhibition (53.37 ± 1.92%) with IC50 0.12 ± 0.01 mg/ml compared to other fractions. Selected active fraction reduced blood glucose by 1.3% and 5.2% and CML levels by 50.6% and 42.4% at concentrations of 0.17 and 0.255 mg/ml in diabetic rats. RAGE gene expression was lower in the diabetic rat groups treated with active fraction compared to untreated diabetic group. Conclusions The active fraction has ability for reducing blood glucose, antiglycation, or reducing CML levels, and RAGE gene expression.