Phytochemical constituents of methanolic and chloroform extracts of citrus sinensis peels and their antimicrobial effects on some human pathogens

Abstract

The study investigated the phytochemical constituents and antimicrobial effects of chloroform fractions and residual methanolic extracts of Citrus sinensis peels dried at different environmental conditions on Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger (test pathogens) using the Agar - Well diffusion method. The results of the analysis showed that the phytochemical constituents of Citrus sinensis peels were not affected by the different drying conditions of the peels. The presence of tannins, alkaloids, cardiac glycosides, flavonoids and phenols was observed in both residual methanolic extracts (A and B) while no saponins and anthroquinones were found in the extracts. Only cardiac glycoside was present in the chloroform fractions (X and Y). Significant inhibitory effects of all the extracts on some of the organisms were recorded. The minimum inhibitory concentration (MIC) values for the extracts ranged between 12.5 to 50 mg/ml. Extract A indicated the best MIC value of 12.5 mg/ml for Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa. Also, the minimum bactericidal concentration (MBC) values of the extracts, ranged between 25 to 100 mg/ml. An extended inhibitory activity was observed for extract B against Escherichia coli possibly due to the drying condition of the peels, however, with a higher MIC value of 50 mg/ml and a bacteriostatic effect. None of the extracts showed antifungal activity. The moderate antibacterial activity demonstrated by the extracts, depicts the medicinal potentials of Citrus sinensis peels thus, justifying its use in ethnomedicine against bacterial pathogens.