Effect of Heat on Antioxidant Activity of Some Tropical Leafy Vegetables

The present study examined the effect of different cooking times on total phenolics, total flavonoids, ascorbic acid content and antioxidant properties of seven tropical leafy vegetables: Pterocarpus mildbraedii, Gongronema latifolium, Ocimum gratissimum, Solanecio biafrae, Piper guineense, Celosia argentea and Solanum melongena. The thermal treatments employed were both long simmer (20 minutes at 80oC) and short simmer (5 minutes at 80oC). The result show that both short and long simmer results to a significant decrease (P< 0.05) in the ascorbic acid content in all the vegetables. There was a significant increase in the total phenol, total flavonoid, DPPH radical scavenging ability, reducing property, Fe2+ chelating ability and hydroxyl radical scavenging ability. In like manner, short simmer treatment enhances the total antioxidant activities of all the vegetables. These results suggest that although thermal treatments enhances the nutritional value of vegetables by increasing the bio-accessible phenolic content and total antioxidant activity, long simmer treatment results in the disruption of the phytochemicals constituents present. The study therefore concludes that short time simmer treatment may result to optimum yield of antioxidant activities in leafy vegetables.Keywords: Antioxidant activity, Ascorbic acid, Leafy vegetables, Total flavonoids, Total phenolic

Tissue correlation of nitrite in plant parts of cassava (manihot esculenta crantz) and nitrosamine toxicity in wistar rat

Aim: This study was designed to determine the correlation in nitrite content of cassava (Manihot esculenta Crantz) as present in the various parts (roots, stems and leaves) and the possible hepatotoxicity when Wistar rats are exposed to N-nitrosamine precursors. Methods: Cassava cultivar used for this experiment was collected from International Institute of Tropical Agriculture, Ibadan, Nigeria (IITA). Various parts (Roots, Stems and Leaves) was weighed and homogenized separately. The homogenate was filtered to get clear solution and nitrite content therein was analyzed. Thirty Wistar rats divided into three groups, classified into; Group 1, Group 2 and Group 3 were used for the in-vivo experiment. The urine nitrite content and serum biomarkers of toxicity namely; Serum alanine transaminase (ALT), aspartate transaminase (AST), alkalin phosphatase (ALP) and gamma-glutamyl transferase (GGT) was estimated and the histopathological changes in the liver was examined in order to evaluate the extent of toxicity. Results: The nitrite levels in the roots, stems and leaves of these cassava cultivars were estimated as follows: roots; 110.8±23.7 μg/50 g, stems; 14.4±17.7 μg/30 g and leaves; 112.0±30.4 μg/5 g. The nitrite correlations between the roots and leaves is r = 0.97, correlations between the roots and stems is r = 0.65 while the correlations between the stems and leaves is r = 0.63. Urinalysis test carried out shows urine is the major sources of excretion of N-nitrosamines from the system. Both Group II and Group III animals had a significant increase in ALT, AST, ALP and GGT levels in t he serum. Histopathology study of liver is in agreement with these results. Conclusion: This study shows that there was a correlation in nitrite levels between the roots and leaves of cassava and the level of toxicity found in the liver of rat administer with N-nitrosamine precursors (DMA.HCL and NaNO2)

PROTECTIVE EFFECT OF AQUEOUS EXTRACTS OF AFRAMOMUM MELEGUETA ON γ-RADIATION-INDUCED LIVER DAMAGE IN MALE WISTAR RATS

This study was carried out to evaluate the radioprotective potential of aqueous extract of seeds of Aframomum melegueta (A.M.) against gamma radiation-induced (6Gy) liver damage in male Wistar rats. Thirty male rats were randomly distributed into six groups of five animals each and aqueous extract of A.M. was administered at a dose of 200 or 400 mg/kg b. wt., orally for 2 weeks prior to irradiation and 4 weeks after irradiation, when they were sacrificed. The hepatic antioxidant status; reduced glutathione (GSH), catalase (CAT) and glutathione peroxidase (GPx) as well as the extent of lipid peroxidation (LPO) were estimated. The activities of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined and histological examination was carried out. Exposure of animals to irradiation significantly increased LPO levels in comparison with the normal control group, reduced the level of GSH as well as CAT and GPx activity. On the other hand, there was a significant elevation in the activities of serum ALT and AST after irradiation exposure. Administration of aqueous extract of A.M. at a dose of 200 or 400 mg/kg before and after irradiation significantly decreased the elevated levels of LPO, restored GSH level near normal and enhanced CAT and GPx activities as well as significantly decreasing the elevated levels of serum ALT and AST activities. The histological examination and results from this study collectively indicate that aqueous extracts of A.M. could protect the liver from radiation-induced damage probably by enhancing the hepatic antioxidant defense mechanism in rats