MATERIALS AND METHODS: Methanol was used as the extraction solvent, 2,2 - diphenyl-1-picrylhydrazil (DPPH) for free radical scavenging activity and ferric reducing antioxidant power (FRAP) assays. Phenolic compounds were measured using Total flavonoid, Phenolic acid and Polyphenols content assay to evaluate the quality of the antioxidant capacity of the rhizomes and vitamin C as positive control.
RESULTS: The results obtained revealed that Curcuma longa and Zingiber officinale had the highest free radical scavenging capacity of 270.07mg/TE/g DW and 266.95mg/TE/g DW and FRAP assay, Curcuma longa and Zingiber officinale also gave the highest ferric reducing power of 231.73mg/TE/g DW and 176.26mg/TE/g DW respectively. For Phenolic compounds, Curcuma longa and Curcuma xanthorrhiza gave the highest values of flavonoid (741.36mg/NGN/g DW and 220.53mg/NGN/g DW), phenolic acid (42.71mg/GAE/g DW and 22.03mg/GAE/g DW) and polyphenols (39.38mg/GAE/g DW and 38.01mg/GAE/g DW) respectively. Significant and positive linear correlations were found between Total antioxidant capacity and Phenolic compounds (R = 0.65 - 0.96).
CONCLUSION: This study provides evidence that extracts of Zingiberaceae (Ginger) rhizomes are a potential source of natural antioxidants and could serve as basis for future drugs and food supplements.
RESULTS: Studies were carried out on drying of papaya leaves using hot air (60, 70 and 80 °C), shade and freeze drying. Effective diffusivities were estimated ranging from 2.09 × 10-12 to 2.18 × 10-12 m2 s-1 from hot air drying, which are within the order of magnitudes reported for most agricultural and food products. The activation energy to initiate drying showed a relatively low value (2.11 kJ mol-1 ) as a result of the thin leave layer that eased moisture diffusion. In terms of total polyphenols content and antioxidant activities, freeze-dried sample showed a significantly higher (P
METHODOLOGY/PRINCIPAL FINDINGS: The in vitro study demonstrated that T. indica fruit pulp had significant amount of phenolic (244.9 ± 10.1 mg GAE/extract) and flavonoid (93.9 ± 2.6 mg RE/g extract) content and possessed antioxidant activities. In the in vivo study, hamsters fed with high-cholesterol diet for ten weeks showed elevated serum triglyceride, total cholesterol, HDL-C and LDL-C levels. Administration of T. indica fruit pulp to hypercholesterolaemic hamsters significantly lowered serum triglyceride, total cholesterol and LDL-C levels but had no effect on the HDL-C level. The lipid-lowering effect was accompanied with significant increase in the expression of Apo A1, Abcg5 and LDL receptor genes and significant decrease in the expression of HMG-CoA reductase and Mtp genes. Administration of T. indica fruit pulp to hypercholesterolaemic hamsters also protected against oxidative damage by increasing hepatic antioxidant enzymes, antioxidant activities and preventing hepatic lipid peroxidation.
CONCLUSION/SIGNIFICANCE: It is postulated that tamarind fruit pulp exerts its hypocholesterolaemic effect by increasing cholesterol efflux, enhancing LDL-C uptake and clearance, suppressing triglyceride accumulation and inhibiting cholesterol biosynthesis. T. indica fruit pulp has potential antioxidative effects and is potentially protective against diet-induced hypercholesterolaemia.