In-vitro antibacterial activity and phytochemical analysis of leaf and stem bark crude extracts of Croton macrostachyus against selected pathogens, Wolaita Sodo, South Ethiopia

Abstract

Background: Medicinal plants have long been used as antiseptic, antiallergic, antibacterial, and antiviral medicines to treat human ailments. Croton macrostachyus is one of the important medicinal plants that take an essential part in traditional African medicine, widely used to treat various disorders including diabetes, malaria, and dysentery. Objective: The present research aimed to determine the in-vitro antibacterial activity of ethanol, methanol, and ethyl acetate extracts of C. macrostachyus leaf and stem barks against some selected human bacterial pathogens. Methods: The leaf and stem barks extracts of C. macrostachyus were prepared by by maceration method using three different solvents such as ethanol, methanol, and ethyl acetate. The prepared crude extract was used to determine the antibacterial activity, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) using clinical laboratory standards institute guidelines. Qualitative phytochemical analyses were also performed using the standard protocol. Results: The ethanolic, methanolic, and ethyl acetate crude leaf and stem bark extracts showed inhibitory actions against E. coli, P. aeruginosa and S. aureus. The gram-positive S. aureus was more susceptible to all the crude extracts. The inhibitory activity was concentration-dependent and the leaf crude extracts showed higher activity than stem bark extracts. The methanolic leaf crude extract showed the highest inhibitory activity when compared to ethanol and ethyl acetate. The MIC of methanolic, ethanolic and ethyl acetate crude leaf extracts ranged from 0.625-2.25 mg/ml against selected bacterial pathogens. The MBC results revealed that the methanolic, ethanolic, and ethyl acetate crude leaf extracts showed 1.25-5 mg/ml concentrations against selected bacterial pathogens. The qualitative phytochemical analysis results confirmed the presence of tannins, alkaloids, saponins, flavonoids, glycosides, and phenolic compounds in both ethanolic and methanolic crude leaf extracts and except alkaloids in the ethyl acetate crude leaf extracts. The phytochemical qualitative analysis of stem bark crude extracts results indicated that glycosides were present, alkaloids, flavonoids and phenolic compounds were absent in all three solvent extraction systems, tannins, and saponins were positive with ethanol and ethyl acetate, negative with methanol solvent extractions. Conclusion: The present study concluded that crude leaf extracts showed better antibacterial activity than stem bark extracts against selected pathogens and phytochemical analysis of crude leaf extracts confirmed the presence of phytochemical constituents in the crude extracts prepared from C. macrostachyus and thus, supports the traditional usage of the plant against various diseases.