Bioactive metabolite profiles and antimicrobial activity of ethanolic extracts from Muntingia calabura L. leaves and stems

Objective: To determine the bioactive phytochemicals and antimicrobial activity of leaf and stem ethanolic extracts from Muntingia calabura L. (M. calabura). Methods: Dried leaves and stems of M. calabura were extracted with 95% ethanol. The antibacterial and antifungal activities of the extracts were examined using the disc diffusion assay. The minimum inhibitory concentration (MIC) of each extract showing antimicrobial activity was determined. The dried extracts were subjected to phytochemical screening to determine the presence of bioactive components. Total phenolic and flavonoid contents were also determined by the Folin-Ciocalteu method and the aluminum chloride method, respectively. Results: Varying degrees of antimicrobial activity were exhibited by the leaf and stem extracts against Pseudomonas aeruginosa (P. aeruginosa), Salmonella typhimurium, Staphylococcus aureus (S. aureus), Bacillus subtilis, and Candida albicans (C. albicans), with minimal activity against Escherichia coli. Based on the MIC, the extracts showed the highest activity against C. albicans, S. aureus and P. aeruginosa. Phytochemical screening revealed the presence of sterols, flavonoids, alkaloids, saponins, glycosides and tannins in the leaf extract; however, no triterpenes were detected. In the stem extract, triterpenes were detected along with relative amounts of flavonoids, saponins, glycosides and tannins. Alkaloids and sterols were absent in the stem extract. Conclusions: M. calabura leaf and stem ethanol extracts are potential sources of antibacterial agents against P. aeruginosa and S. aureus. This study reports for the first time the high degree of antifungal activity of M. calabura ethanolic extract, especially against C. albicans.