Adaramoye O A, Farombi E O, Adeyemi E O, Emerole G O.
Comparative study on the antioxidant properties of Flavonoids of Garcinia kola seeds.
Pak J Med Sci Jan ;21(3):331-9.

Objective: Oxidative damage has been suggested to be a contributory factor in the development and complications of atherosclerosis, and of recent the beneficial effects of antioxidants against some pathologies have gained considerable interest. We evaluated the protective effects of flavonoids from Garcinia kola seeds on the oxidation of human low- density lipoprotein (LDL) and their ability to scavenge reactive oxygen species (ROS) in vitro. Setting: Department of internal medicine, Faculty of Medicine & Health Sciences, UAE University, Al Ain, UAE. Methods: Human low- density lipoprotein (LDL) was prepared from fresh blood donated by volunteers with informed consent. The inhibitory effect of varying concentrations of flavonoids from Garcinia kola seeds, namely; Kolaviron (KV), Garcinia biflavanone (GB) 1, GB 2 and kolaflavanone (KF) on Fe/ ascorbate- induced peroxidation in LDL was investigated. Likewise the scavenging effect of these flavonoids on superoxide radicals and hydrogen peroxide in vitro was examined. Results: In the present study, KV, GB1, GB2 and KF exhibited marked scavenging effect (41- 93 %) on H2O2, in vitro and the scavenging activities of these flavonoids were concentration dependent. Furthermore, KV, GB1, GB2 and KF showed marked activity as superoxide radicals (O2. ) scavenger. At 1 mg/ ml, KV, GB1, GB2 and KF scavenged O2. by 71%, 52 %, 66 % and 48 %, respectively. In addition, KV, GB1, GB2 and KF showed marked reducing property on potassium ferricyanide in vitro. KV, GB1 and GB2 were effective at preventing LDL lipid peroxidation (LPO) induced by Fe/ ascorbate system. Specifically at 0.01 mM, 0.1 mM and 1.0 mM, KV inhibited LPO by 29 %, 61 % and 79 %, while GB1 inhibited LPO by 29 %, 56 % and 86 %, respectively. At these concentrations, GB2 reduced LPO by 41 %, 72 % and 91 %, respectively. However, the inhibition of LDL peroxidation by KV, GB1 and GB2 were concentrations dependent. KF showed significant (p<0.05) inhibition of LDL peroxidation at 1.0 mM only. The inhibition of LDL peroxidation by these flavonoids follow the trend GB2 > GB1 > KV > KF at 1.0 mM. Conclusion: These flavonoids are active scavengers of H2O2 and O2. radicals in vitro and their anti- lipoperoxidative effect might be linked to free radical scavenging ability, and this could be a pointer to their possible anti- atherogenic property.

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