Allelopathy has gained much attention in recent times in the sustainable agricultural systems. Allelochemicals released by different plants interact differently with each other, it therefore becomes imperative to study the possible biochemical processes underlying the allelopathy of some plants on other plants. In the present study, investigation was carried out on the phytochemical composition of aqueous and methanolic extracts of <em>Tithonia diversifolia</em> and their allelopathic effect on the growth of <em>Vigna unguiculata</em>. Phytochemical analyses indicated the presence of cardiac glycosides, flavonoids, and alkaloids in the methanolic extract, and in addition anthraquinones and saponins in the aqueous extract. The methanolic extract was found to be more phytotoxic than the aqueous extract; and the seed germination and seedling growth inhibition was concentration dependent. Both the methanolic and aqueous extracts increased significantly the concentration of proline and the level of antioxidant enzymes (superoxide dismutase and catalase) in <em>Vigna unguiculata,</em> while protein concentration and chlorophyll content were significantly reduced. There was however no significant difference in the amount of total soluble sugar. Cytological examination of the root tips of <em>Allium cepa</em> treated with both extracts showed no disparity in mitotic index and there was no chromosomal aberration. The study concluded that the extracts of <em>T. diversifolia</em> affected the seed germination and growth of <em>Vigna unguiculata</em>.

This study determined the degree of hydrolysis of Mormyrus rume muscle proteins by digestive proteases and the antioxidant potential of the hydrolysates produced was evaluated. The proteins were extracted with distilled water adjusted to neutral pH. The proteases used include trypsin, chymotrypsin and pepsin and the degree of hydrolysis was determined using trichloroacetic acid precipitation method. The antioxidative activities of the hydrolysates were evaluated using different in-vitro antioxidant assay methods such as 1,1-diphenyl-2picrylhydrazyl (DPPH) radical scavenging, hydrogen peroxide scavenging, metal chelating capacity and reductive potentials. Degree of hydrolysis was generally low and ranges between 17.68% and 32.20% with pepsin given the highest degree of hydrolysis. The protein hydrolysates obtained with trypsin exhibited the highest antioxidant activities when assessed with metal chelating activity assay with half maximal inhibitory concentration (IC ) of 0.32 ± 0.01 mg/ml; hydrogen peroxide scavenging assay with IC of 0.18 ± 0.01 mg/ml 50 50and reductive potential of 0.41 ± 0.002 units at the highest concentration tested (1.0 mg/ml). Pepsin-produced hydrolysates showed the highest DPPH radical scavenging potential at all concentrations with IC of 0.35 ± 50 0.003 mg/ml. The study concluded that the hydrolysates produced contain bioactive peptides which possessed significant amount of antioxidant activities, which may be a promising health promoting agent if isolated.ABSTRACT 431

No abstract

A lectin was purified from the tuber, Dioscorea mangenotiana in this study. The lectin agglutinated erythrocytes from human and rabbit, and the activity was inhibited by glucose and N-acetyl-Dglucosamine with minimum inhibitory concentration (MIC) of 50 and 25 mM, respectively. The lectin was composed of two isoforms, DML I and DML II. The apparent native molecular mass of DML I was estimated at 51 kDa and the subunit molecular mass at 25 kDa, suggesting a dimeric structure. The lectin was stable up to 90°C and within the physiological pH range. The lectin when incorporated in artificial diet at concentrations of 10 to 160 µg ml -1 and fed ad libitum to the second instar larvae of Eldana saccharina, prolonged the development period and significantly inhibited the pupation and emergence of the insect in a dose-dependent manner. The LC 50 calculated based on mortality after 72 h of treatment was 66.6 mg/ml. The activities of hydrolytic enzymes -acid phosphatase, alkaline phosphatase and acetylcholine esterase in the larvae reared on diet containing lethal dose of the lectin were significantly affected as compared to those fed on diet without the lectin. The results showed that DML I has promising anti-insect potential and could be employed in a biotechnological strategy for the pest management.

Objective: This study was carried out to purify and characterize a carbohydrate-binding and cell-agglutinating protein, lectin, from Pterocarpus osun seeds and also to evaluate its antioxidant and antibacterial potential. Methods: Isolation and purification of the lectin were done by ammonium sulphate precipitation and size exclusion chromatography on Sephadex G-100. Physicochemical properties of the lectin were determined and antioxidant activity was evaluated by DPPH radical scavenging, lipid peroxidation inhibition and ferric reducing antioxidant potential assay. A disc diffusion method was used for antibacterial effect. Results: Lectin was detected in the seeds and was able to agglutinate native and enzyme-treated rabbit erythrocytes but only enzyme-treated erythrocytes of human blood were agglutinated. Mannose, Maltose and α-methylmannoside inhibited the divalent cation-independent hemagglutinating activity, which was stable up to 60°C and at pH range of 3-13. It showed antioxidant activity with IC50 of 1.17 ± 0.08, 0.58 ± 0.03, and 2.51 ± 0.03 mg/ml for those methods respectively. No antibacterial activity was observed. Conclusion: Pterocarpus osun seeds lectin possess properties similar to other lectins from Dalbergieae tribe and its ability to scavenge free radical and inhibit lipid peroxidation show the presence of a valuable health promoting agent in the seeds.