Phytochemical screening and evaluation of antimicrobial activity of Pterolobium stellatum root extract

Abstract

Background: Medicinal plants have been used in the treatment of numerous diseases as they possess potential biological activities. Pterolobium stellatum is a native medicinal plant whose leaves and root parts are used in different African countries for the treatment of diseases such as tuberculosis, diarrhea, pneumonia, goiter, epilepsy, tumor, snake bites, stomachache, headache, and rheumatic pain. Even though it is used traditionally for the management of several diseases, the antimicrobial activity of the root part has not been exhaustively studied. Thus, the overall objective of the study was to carry out a phytochemical screening test and evaluate the antimicrobial activity of the root extract of the plant against some pathogenic microorganisms. Methods:The shade-dried root part of the plant was extracted by 70% ethanol and the extract was partitioned into three fractions using three solvents (hexane, chloroform, and ethyl acetate) by liquid-liquid extraction technique. The extract was subjected to phytochemical screening tests. The antibacterial and antifungal activities of ethanolic crude extract and fractions were assessed using agar well diffusion and disc diffusion methods, respectively, against four bacterial strains (Staphylococcus aureus, Bacillus cereus, Escherichia coli and, Salmonella typhi) and one fungal strain (Candida albicans).Results: Phytochemical screening of the extract revealed the presence of phenols, flavonoids, glycosides, tannins, saponins, and terpenoids. The extract and fractions displayed promising antibacterial and antifungal activities against tested microorganisms. The ethyl acetate fraction exhibited the highest antibacterial and antifungal activities against Bacillus cereus (20 mm) and Candida albicans (11 mm) followed by the chloroform fraction which showed better antibacterial activity against Staphylococcus aureus (12 mm) and Bacillus cereus (17 mm). Conclusion:Overall, the root of Pterolobium stellatum possesses some secondary metabolites. The root extract and fractions of the plant exhibited remarkable antibacterial and antifungal activities against tested strains. The study corroborates the ethno-medicinal use of the plant and acclaims its consideration as a possible source of antimicrobial agents for the treatment of bacterial infections. Bioactivity-guided isolation and characterization of the active principles will be recommended.