Flavonoid Rich Fraction of Dioscorea bulbifera Linn. (Yam) Enhances Mitochondrial Enzymes and Antioxidant Status, Thereby Protects Heart from Isoproterenol Induced Myocardial Infarction

K.      S. Jayachandran; Hannah      R. Vasanthi; G.      V. Rajamanickam

Abstract

With recent advances in nutrition sciences, natural products and health-promoting foods have received extensive attention from both health professionals and the common population. The flavonoid rich fraction (FRF) of Dioscorea bulbifera Linn. has a strong free radical scavenging activity. FRF (150 mg/kg) when intervened for a period of 35 days prior to isoproterenol (ISO) challenge to rats maintained the creatine kinase – MB (CK-MB) activity in serum without elevation. Alterations in the antioxidant status in the mitochondria were recognized in the heart tissue of ISO induced rats. ISO induced rats pretreated with FRF (150 mg/kg) ameliorated the lipid peroxidation and thereby enhanced the antioxidant status as evidenced by the increase in the reduced glutathione (GSH) content and the activity of antioxidant enzymes. Moreover, the tricarboxylic acid cycle enzymes such isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH) and α-ketoglutarate dehydrogenase (α-KGDH), which were found decreased in the ISO induced rats showed an enhanced activity in FRF (150 mg/kg) pretreated rats. The activity of NADH dehydrogenase and cytochrome- C-oxidase, the enzymes which transfer the electron in the electron transport chain (ETC) was also increased significantly (p < 0.05) in FRF (150 mg/kg) pretreated rats, when compared with ISO induced rats. These results suggest the cardioprotective effect of FRF of Dioscorea bulbifera Linn. in ISO induced MI by attenuating the lipid peroxidation by scavenging free radicals and modulating the energy producing mitochondrial enzymes.

Keywords: Isoproterenol, mitochondrial enzymes, antioxidant, free radical, lipid peroxidation, flavonoids, flavonoid rich fraction (FRF), reduced glutathione (GSH), isocitrate dehydrogenase (ICDH), malate dehydrogenase (MDH), a-ketoglutarate dehydrogenase (a-KGDH), electron transport chain (ETC), Dioscorea bulbifera, anti-helmentic, anti-diabetic, hematological disorders, antinutritional, anti-fungal, anti-tumor, ethylacetate fraction, Tetradecanoylphorbol-13-acetate, sarcolemmal membrane, crude extract (CE), Nitric oxide (NO), creatinephosphokinase, lactate dehydrogenase, thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione-S-transferase, glutathione, isocitrate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, chromatography (HPTLC), flavonoid rich fraction, polyunsaturated fatty acids (PUFA), guanylate cyclase, tricarboxylic acid (TCA), reactive oxygen species (ROS)