Phytochemical Screening and Antimicrobial Activities of Polar and Non-Polar Solvent Leaf Extracts of Gongronema latifolium (Asclepiadaceae)

Aim: This study was designed to assess the phytochemical constituents and antimicrobial activities of leaf extracts of Gongronema latifolium (Benth).

Methodology: The methods adopted were manual grinding of the air-dried leaves and maceration in polar and non-polar solvents (Ethanol and N-hexane) for 72 hrs. The resultant crude extracts were kept in dry, sterile airtight McCartney bottles and stored in the refrigerator. Thereafter, they were assayed for the presence of phytochemicals. Moreover, the plant extracts were screened for antimicrobial activities against Bacillus subtilis, Staphylococcus aureus, Salmonella typhi, Escherichia coli, Candida albicans and Aspergillus fumigatus.

Results: The results of the phytochemical screening revealed the presence of saponins, alkaloids, tannins, anthraquinones, steroids, flavonoids and terpenoids in the ethanol extracts while anthraquinones, steroidsand terpenoids were absent in the N-hexane extract of the plant. Moreover, the results of the antimicrobial activity assay of the plant extracts revealed a concentration dependent trend as higher activities was observed as the concentration gradient increased. S. aureus (20.33±0.01) and E. coli (19.67±0.00) showed the highest susceptibility to the plant extracts while B. subtilis (12.67±0.01) showed the least susceptibility against the plant extracts at 300 mg/ml. However, the plant extracts appeared not to have antifungal activity. The lowest minimum inhibitory concentration (MIC) was observed in ethanol extract against E. coli (6.25 mg/ml), while the highest MICwas recorded in N-hexane extract against B. subtilis and S. typhi (100 mg/ml). The ethanol extract of plant leaf was more active against the selected pathogens compared with N-hexane extract.

Conclusion: The outcome this investigation shows that the G. latifolium leaf extracts contain bioactive constituents such as saponins, alkaloids, tannins, anthraquinones, steroids, flavonoids and terpenoids which may account for the antibacterial activities recorded.