Comment on: effect of pomegranate flower extract oncis platin-induced nephrotoxicity in rats

Implication for health policy/practice/research/medical education: Antioxidant supplements have generally beneficial effects, however, several factors such as the kind of the antioxidant and the dose should be considered to avoid the potential negative effects. Dear editor We read with respect the paper " effect of pomegranate flower extract on cisplatin-induced nephrotoxicity in rats " by Motamedi et al. (1), in your esteemed journal " Journal of Nephropathology ". It is an interesting paper, however, I would like to add some complementary comments to it. Other than antioxidant activity, this paper was designed to investigate the protective effect of pomegranate flower extract (PFE) on cisplatin (CP) induced-renal toxicity. Thirty two male Wistar rats were divided into five groups. The animals in groups 1 to 3 received PFE (25 mg/kg), PFE (50 mg/ kg), and placebo (saline), respectively, for 9 days, and from day 3 on, they also received CP (2.5 mg/kg/day). Groups 4 and 5 were treated with PFE (25 and 50 mg/kg/day) alone. Finally, the animals were sacrificed at day 9 after collecting blood samples. The kidneys were removed, weighted, and underwent histological investigation. The results of the study showed an increase in the mean serum level of creatinine in group 3 (treated with CP and placebo) (p<0.05), but the value decreased significantly (p<0.05) when low dose of PFE was added to CP (group 1). Kidney weight and weight loss in group 1 were non-significantly lower than those in other CP-treated groups (groups 2 and 3). The data from histological staining also indicated less tissue damage in group 1 (when low dose of PFE was added to CP) compared with group 3. They did not observed protective role of PFE in 50 mg/kg against CP-induced toxicity in this animal model. This effect of pomegranate flower extract was, in part, attributed to the antioxidant activity of the extract. However, surprisingly, pomegranate flower extract at 50 mg/kg had no effect on inhibition of CP-induced nephrotoxicity, while the best effective dose was 25 mg/kg. The high doses of some other antioxidants in other experiments have not shown protective effect, too, and even exacerbated more tissue damage (2). Here, I would like to explain the possible mechanisms. The involvement of oxidative stress in pathogenesis of CP-induced nephrotoxicity is indisputable. CP-induced renal toxicity is accompanied by production of reactive oxygen species in the kidney. Free radicals have important effects on membrane lipid peroxidation and tissue injury …