Phytochemical and Antifungal Activity of Leaf Extracts of Corchorus olitorius and Gongronema latifolium on Fungi Associated with Post-Harvest Deterioration of Maize (Zea mays) Seeds in Oban Community, Nigeria

This study was carried out to investigate the fungal pathogens associated with post-harvest deterioration of maize seeds in storage in Oban community, Cross River State, Nigeria, determine the effect of the pathogens on the nutritional content of the maize seeds through biochemical analysis as well as evaluate the phytochemical contents and antifungal activity of ethanolic leaf extracts of Corchorus olitorius and Gongronema latifolium in controlling the isolated fungi in vitro. The fungal pathogens isolated as the causative agents of post-harvest deterioration of maize seeds in this study were Penicillium sp., Fusarium sp., Aspergillus sp., and Rhizopus stolonifer. The result of biochemical analysis of fungal infected and non-infected maize seeds carried out showed a significant increase (P ≤ 0.05) in the moisture content of the fungal infected maize seeds as compared to healthy ones (control), while there was a significant decrease (P ≤ 0.05) in the crude fibre, fat, ash, protein and carbohydrate contents of the fungal infected maize seeds as compared to the healthy ones (control). For the in vitro antifungal assay, various concentrations of the extracts ranging from 20g/200ml, 40g/200 ml, 60g/200 ml, 80g/200 ml and 100g/200 ml were separately added to PDA media. Results shows that at 60g/200 ml and 80g/200 ml and 100g/200 ml concentrations, ethanolic leaf extracts of C. olitorius completely inhibited the radial growth of Penicillium sp., Fusarium sp., Aspergillus sp., and R. stolonifer after seven days observation period while those of ethanolic extracts of G. latifolium completely inhibited the redial growth of the fungal pathogens at 40g/200 ml, 60g/200 ml, 80g/200 ml and 100g/200 ml concentrations. Results, however, shows that the extracts had a significant effect (P ≤ 0.05) on the radial growth of the fungal pathogens at all the different concentrations tested as compared with the control. Phytochemical screening of the extracts revealed the presence of cardiac glycosides, reducing sugars, flavonoids, saponnins, tannins, hydocyanin, and anthraquinones with traces of alkaloids.