Gas Chromatography-Mass Spectrometry (GC-MS) analysis and antimicrobial investigation of the ethyl acetate extract of <i>“Gorongo” - Solanum macrocarpum</i> L.

Abstract

Solanum macrocarpum Linn. (Solanaceae) is used in East and West African Ethnomedicine for treating constipation, cardiac diseases and hyperlipidaemia. The aqueous extract of the fruit had been shown to lower high blood pressure, relieve constipation and lower hyperlipidaemia. The plant was therefore investigated for its chemical constituents and antimicrobial properties. The crude ethyl acetate extract (CEAE) of the unripe fruit was therefore analysed using gas chromatography-mass spectrometry (GC-MS). The microorganisms used included Gram-positive bacteria (Staphylococcus aureus, Streptococcus pyogenes, Cornybacterium spp. and Bacillus subtilis); Gram-negative bacteria (Echerichia coli, Salmonella tyhii, Pseudomonas aeruginosa and Kleibsiella pneumonia); and three fungal strains (Candida albicans, Penicillium spp and Aspergillus niger). The antimicrobial effect was assayed using the disc diffusion antimicrobial selectivity test. All the microorganisms used were resistant to CEAE. γ-Sitosterol, a tetracylic triterpenoid with a steroidal nucleus, is believed to be the main chemical compound responsible for the hypolipidaemic effect ascribed to the fruit of the plant. Other compounds of CEAE, identified through GC-MS were ethyl palmitate, ethyl stearate, 4-(1-methyl-1-[4-(proprioxy) phenyl] ethyl phenyl propionate, 1-nonadecene, 9-eicosene, glycerol acetate, glycerol diacetate, 5-(1-methyl-1(-imidazol)-2-γ-sulponyl-1-phenyl tetrazole and 1-heptadecene.

Keywords: Solanum macrocarpum; GC-MS; Antimicrobial activity; Ethyl acetate extract