Evaluation of phytochemical constituents and in vitro antimicrobial activities of leaves extracts of Calotropis procera against certain human pathogens

Abstract

Calotropis procera, a well-known and commonly used plant in Nigeria to treat many infectious diseases, has been documented to possess constituents with proven antimicrobial potentials. The type of solvent used in herbal extraction determines the number of phytoconstituents extracted, therefore it was investigated the effect of some solvents selected based on polarity on the phytoconstituents and antimicrobial efficacy of leaves of C. procera. Phytochemical screening of extracts from leaves of C. procera obtained from five solvents (acetone, hexane, ethylactate, mixture “acetone, hexane, ethyl acetate 50/30/20 v/v/v” and sterile distilled water) was carried out. Disc diffusion assay, Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and Minimal Fungicidal Concentration (MFC) of the extracts were compared with those of commercial drugs (chloramphenicol, gentamicin and griseofulvin) against Candida albicans, S. aureus ATCC 25923 and E. coli ATCC 25922. Tannins, steroids, alkaloids, saponins, glycosides, terpenoids, proteins, flavonoids, coumarins and anthraquinones were detected in higher numbers in ethyl acetate and sterile distilled water extracts, while the least number of constituents were detected in hexane extracts. A dose- dependent broad spectrum of bacteriostatic/fungistatic and bactericidal activities was produced by the extracts against the tested pathogens. Wider inhibition zone (19.80 mm) was produced at 100 mg/mL concentration by the mixture of solvents and ethylacetate extract, respectively, while the lowest inhibition zone (7.6 mm) was produced by sterile distilled water extract at 25 mg/mL. The present study provided plausible information to corroborate the medicinal value of the investigated plant, as claimed by herbal medicine users.