Evaluation of antidiabetic, antioxidant and vasoprotective effects of Posidonia oceanica extract

The aim of this study is to evaluate antidiabetic, antioxidant and vasoprotective effects of Posidonia oceanica extract (POE) in alloxan diabetic rats. Posidonia oceanica (L) Delile (Posidoniaceae), is a widely allocated phanerogam in Mediterranean and Aegean Sea. Up to date, no published data relevant to use of the plant in traditional medicine are available. However, decoction of the leaves has been quoted to be used as a remedy for diabetes mellitus and hypertension by villagers living by the sea coast of Western Anatolia. Oral administration of extract for 15 days (50, 150, and 250 mg/kg b.wt.) resulted in a dose-dependent decrease in blood glucose. Relaxant responses to acetylcholine (ACh) in diabetic thoracic aorta were restored by POE treatment (50, 150, and 250mg/kg b.wt.). POE also attenuated the augmented phenylephrine (PE) and serotonin (5-HT) contractions. At concentration levels of 150 and 250 mg/kg b.wt., POE exerted a protective effect on the significantly decreased levels of antioxidants namely, glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase and nitric oxide (NO). POE (50 mg/kg b.wt.) produced no effect on alloxan-induced alterations in the antioxidant status while possessing glucose lowering and vasoprotective activities. Furthermore, liver and kidney function markers, leucocyte counts, body weight and liver glycogen content remained unchanged at dose level of 50 mg/kg b.wt., when compared with diabetic control group. These results suggest that antidiabetic and vasoprotective effects of POE may be unrelated to its antioxidant properties. (c) 2007 Elsevier Ireland Ltd. All rights reserved.