Renal Protective Effects of Extracts from Guava Fruit (Psidium guajava']java L.) in Diabetic Mice

This study analyzed the content of phenolic acids and flavonoids in extracts of guava fruit (Psidium guajava L.), and examined the renal protective effects of guava aqueous extract (GAE) and ethanol extract (GEE) in diabetic mice. GAE had more caffeic acid, myricetin, and quercetin; and GEE had more cinnamic, coumaric and ferulic acids. GAE or GEE at 1 and 2 % was supplied in diet for 12 weeks. GAE or GEE intake at 2 % significantly reduced glucose and blood urea nitrogen levels, increased insulin level in plasma of diabetic mice (p < 0.05). GAE or GEE treatments dose-dependently reserved glutathione content, retained activity of catalase and glutathione peroxidase, and decreased reactive oxygen species, interleukin (IL)-6, tumor necrosis factor-alpha and IL-1 beta levels in kidney (p < 0.05). GAE and GEE treatments at 2 % significantly declined renal N (epsilon)-(carboxymethyl)lysine, pentosidine and fructose levels (p < 0.05), and suppressed renal activity of aldose reductase (p < 0.05). These findings support that guava fruit could protect kidney against diabetic progression via its anti-oxidative, anti-inflammatory and anti-glycative effects.