Shelf-life studies on sulphated polysaccharides from some south african seaweeds and their protective effect against diabetic hepatopathy in rats with type-2 diabetes.

Abstract

Diabetic hepatopathy is among the major contributors to mortality and morbidities associated with type 2 diabetes (T2D). Sulphated polysaccharides (SPs) from seaweeds have antidiabetic potential, however, their effects on diabetic hepatopathy, a major diabetic complication is yet to be investigated. This study sought to investigate the protective potential of SPs from Ecklonia maxima and Gracilaria gracilis on diabetic hepatopathy of rats with T2D. Two groups of T2D rats were administered 150 and 300 mg/Kg bodyweight (bw) of E. maxima SPs, respectively. Another two groups administered similar doses for G. gracilis SPs. Water was administered to the T2D and negative control groups, while metformin served as the standard antidiabetic drug. Normal rats administered 300 mg/Kg bw SPs served as the toxicology group. The effect of storage temperature and time on the stability and antidiabetic properties of both SPs were investigated, by storing them at 4, 25 and 37 °C for 6 months. There was significant depletion in glutathione level, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase, while concomitantly exacerbating malondialdehyde level, fructose-1.6biphosphatase, glucose 6- phosphatase, glycogen phosphorylase, and acetylcholinesterase activities in hepatic tissues, on induction of T2D. Furthermore, T2D dysregulated glucose, lipid and amino acid metabolic pathways, and their metabolites. Treatment with SPs from E. maxima and G. gracilis significantly reversed the glutathione and malondialdehyde levels, and enzymes activities, while concomitantly upregulating metabolic pathways and their metabolites. In the stability study, there were no significant changes in the glucose and sulphate levels of SPs stored at 4 and 25 °C. However, these levels were significantly reduced in SPs stored at 37 °C at the 5th and 6th month. Storage at 4 and 25 °C, had no significant effect on the α-glucosidase and αamylase inhibitory activities of the SPs throughout the storage period. However, there was a time dependent decline in the inhibitory activities of these enzymes at 37 °C. These results indicate the hepatoprotective effect of SPs from E. maxima and G. gracilis against diabetic hepatopathy in T2D rats. This is depicted by their ability to mitigate oxidative stress, inflammation and lipotoxicity, while improving glucose and amino acid metabolisms. Furthermore, the stability of the SPs and their antidiabetic activities may be temperature dependent, influenced by storage time.