There is growing interest in the use of plant bioresources for managing type 2 diabetes. In this study, Rhodamnia cinerea, which is used traditionally to manage diseases in Malaysia, was explored for its antidiabetic effects. Type 2 diabetic rats were managed for 4 weeks using aqueous extract of R. cinerea or quercetin. Weights and fasting glucose were measured weekly, while serum lipid profiles, insulin, antioxidant status, urea, creatinine and liver enzymes were assayed at the end. Sorbitol contents, antioxidant capacities and aldose reductase activities of the kidney, lens and sciatic nerve were also assessed. The results showed that the aqueous extract of R. Cinerea mainly contained Myricitrin and it reduced glycemia (p>0.05), lipid profiles (p<0.05), F2-isoprostanes (p<0.05) and overall metabolic condition of type 2 diabetic rats. R. cinerea also attenuated sorbitol contents of the nerve (p<0.05) and kidney (p<0.05), partly through regulating the activity of aldose reductase (p<0.05 for nerve) and sorbitol dehydrogenase (p<0.05 for kidney) in comparison with diabetic untreated group. Quercetin is a known aldose reductase inhibitor and can improve several metabolic indices related to Type 2 diabetes. In this study, the results of R. cinerea were comparable to or better than those of quercetin, suggesting that R. cinerea extract can be a good candidate for managing Type 2 diabetes and its complications related to sorbitol accumulation.
Microcystin Leucine-Arginine (MC-LR) is a toxin produced by the cyanobacteria Microcystis aeruginosa. It is the most encountered and toxic type of cyanotoxins. Oxidative stress was shown to play a role in the pathogenesis of microcystin LR by the induction of intracellular reactive oxygen species (ROS) formation that oxidize and damage cellular macromolecules. In the present study we examined the effect of acute MC-LR dose on the cardiac muscle of BALB/c mice. Afterwards, melatonin and N-acetyl cysteine (NAC) were assayed and evaluated as potential protective and antioxidant agents against damages generated by MC-LR. For this purpose, thirty mice were assigned into six groups of five mice each. The effect of MC-LR was first compared to the control group supplied with distilled water, then compared to the other groups supplied with melatonin and NAC. The experiment lasted 10 days after which animals were euthanized. Biomarkers of toxicity such as alkaline phosphatase activity, lipid peroxidation, protein carbonyl content, reduced glutathione content, serum lactate dehydrogenase and serum sorbitol dehydrogenase were assayed. Results showed that toxin treated mice have experienced significant oxidative damage in their myocardial tissue as revealed by noticeable levels of oxidative stress biomarkers and by the reduction in alkaline phosphatase activity. Whereas, melatonin and NAC treated mice manifested lesser oxidative damages. Our findings suggest a potential therapeutic use of melatonin and N-acetyl cysteine as antioxidant protective agents against oxidative damage induced by MC-LR.