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

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

Isolation, partial purification and characterization of antifungal trypsin inhibitor protease from the seed of Blighia sapida K.D. Koenig (Ackee)

Seed proteins have been evaluated for their nutritive value and biological activity. Proteases and proteinase inhibitors have been of immense benefit to both agriculture and therapeutic purposes. The seed proteins of Blighia sapida was evaluated for both structure and biological activity in this study. The matured dried seeds were pulverized and sequentially extracted using 10 mM Tris/HCl pH 7.4, 10 mM ammonium acetate and 10 mM sulphuric acid. Crude protein extracts were concentrated and the protein concentrations were estimated. Proteins were purified by 70% ammonium sulphate precipitation, Sephadex G50 reversed phase chromatography and finally by HPLC on a C18 column. Two bands were obtained from SDS-PAGE electrophoresis and they were identified by ESI/MS using in gel tryptic digestion. The seed protein from B. Sapida consists of two single polypeptide chains each with mass of about 24 to 27 KDa as established by a combination of SDS-PAGE and ESI/MS. Proteins exhibited protease activity, which was confirmed by zymography. Protease activity was characterized for effect of temperature, pH, divalent metal ions and chelating agents. The crude protein from the seed of B. sapida showed antimicrobial activity and the antifungal activity was comparable with the reference drug, Ticonazole.Keywords: Blighia sapida, chromatography, protease activity, in-gel trypsin digestion/mass spectrophotometry, antimicrobial activity.African Journal of Biotechnology, Vol 13(29) 2996-300

Anti-Diabetic And Hypolipidemic Studies Of Telifairia occidentalis On Alloxan Induced Diabetic Rabbits

The biochemical effects of the methanol extract of Telifairia occidentalis on plasma cholesterol, glucose, protein, triglyceride and creatinine levels were studied in alloxan induced diabetic rabbits. The extract reduced the plasma glucose, cholesterol, creatinine and triglycerides levels of diabetic rabbits, but had no effect on the plasma protein level. Polydipsia in untreated diabetic animals was reduced to normal in those administered with the plant extract. Key words: Telifairia occidentalis, Curcubitaceae, antihyperglycaemic, hypolipidemic, alloxan diabetic rabbits. Nig. J. Nat. Prod. and Med. Vol.8 2004: 45-4

Heavy metal contamination of some vegetables and spices in Nigeria

Analytical results are presented for the determination of Cd, Pb, Cu, Cr, Ni, Fe and Zn contents in some species of fresh vegetables and spices (Abelmoschus esculentus, Amarathus spinosis, Cucumis sativa, Taliniumtriangulare, Daucus carrota, Phaseolus vulgaris, Vernonia amygdalina, Piper nigrum, Lycopersicon esculentum, Telfaria occidentalis, Cochorus olitorius, Allium cepa, Brassica oleraca Tephrosia densiflora, Capsicum annum, Citrullus vulgaris, Tetrapleura tetraptera, Anisophylea spp Piper guineensis, Mynstica fragrans, Aframomum melegueta and Allium sativum ) collected from markets in Warri and its environs (Nigeria) between February to May, 2007. The mean concentrations of these elements in vegetables and spices ranged from 0.01-11.5 mg.kg-1 for Pb; 0.01-0.2 mgkg-1 for Cu; 0.17-4.2 mg.kg-1 for Cd, 0.01 mg.kg-1 for Cr; 0.01-16.8 mg.kg-1 for Ni; 30-44.02 mg.kg-1 for Zn; 4.08-310.66 mg.kg-1 for Fe. The results indicate that some of the vegetables and spices were contaminated with Cd and Pb and Ni. More than 80% of the examined samples had concentrations of these metals below statutory safe limits