The effect of spray-dried fruit juice of Phyllanthus Emblica on hemin induced lipoprotein oxidation

Abstract

Oxidation of lipoprotein both low-density lipoprotein (LDL) and high-density lipoprotein (HDL) play a major role in the pathogenesis of atherosclerosis. Hemin (Iron (III)-protoporphyrin IX), a degradation product of hemoglobin was found to be elevated in pathological cases like severe hemoglobinopathies, sickle cell anemia and thalassemia. It is a potent oxidative inducer of lipoproteins oxidation. Antioxidant enzymes located in lipoproteins can protect lipoproteins from oxidation such as platelet activating factor acetylhydrolase (PAF-AH) in LDL and paraoxonase (PON) in HDL. Enzyme activities can be depleted in oxidative stress condition. To date, natural substances are widely used for antioxidants. Ma-kham-Pom (Phyllanthus emblica Linn., Euphorbiaceae) is one of plants that is known to be antioxidant activity. Therefore, the aim of this in vitro study is to determine the protective effect of spray-dried fruit juice of Phyllanthus emblica on hemin induced lipoprotein oxidation and its effect on PAF-AH and paraoxonase activity. The pre-incubation of LDL and HDL with 0.5, 1, 2.5, 5, 10 and 20 µg/ml of spray-dried fruit juice of P. emblica were performed for 30 min; L-ascorbic acid was used as a positive control. To induce lipoprotein oxidation, hemin was added into LDL and HDL with a final concentration of 5 µM/300 µg lipoprotein, then further incubate for up to 24 hr. The results showed that TBARs levels were increased in he-oxLDL about 6 fold from 5.3 nmol/mg protein at 0 hr to 36.2 nmol/mg protein at 24 hr while α-tocopherol levels were rapidly decreased until undetectable at 4 hr of incubation. P. emblica was able to protect LDL from lipid peroxidation induced by hemin in a concentration dependent manner. The 50% inhibition concentration (IC₅₀) of TBARs formation was 2.5 and 13 µg/ml for P. emblica and L-ascorbic acid, respectively. The 20 µg/ml of P. emblica at 24 hr exhibited the protective effect by 99.4% inhibition of TBARs formation, and 70.1% remaining of α-tocopherol in LDL. The percent remaining of PAF-AH activity in P. emblica was significantly higher than that in he-oxLDL (93.3% vs. 53.3%; p<0.05). In addition P. emblica can inhibit the decrease of cholesteryl arachidonate (CA), cholesteryl linoleate (CL) and CL/CO ratio 97.5%, 91.5% and 80.6%, respectively. For he-oxHDL, TBARs levels were slightly increased from 2.5 nmol/mg protein to 4.3 nmol/mg protein while α-tocopherol level was remained 16.9%. Paraoxonase activity was rapidly decreased within 2 hr. P. emblica was able to protect HDL oxidation by decrease TBARs formation and inhibiting the depletion of α-tocopherol but it was not able to preserve the paraoxonase activity. We concluded that P. emblica possess an antioxidant activity which protected hemin-induced lipid peroxidation in both LDL and HDL including preserve the PAF-AH activity in LDL.