Version 2: Phytochemical screening and in vitro antibacterial evaluation of Plectranthus amboinicus (Lour) spreng against selected four pathogenic bacteria

Background: Traditional medicine is still utilized around the globe, particularly in developing countries such as Ethiopia, where the majority of people maintain their health through the use of plant medicines. The primary challenges that needed to be addressed were the requirement for scientific backing for adequate documentation and drug development. The current study intended to screen phytochemical and antibacterial activities of Plectranthus amboinicus crude extracts, against selected pathogenic bacteria. 

Methods: The study were designed in Complete Randomized Design based on laboratory bioassay with three replications involves a 2x2x3x4x3 (2 sources i.e. leaf and stem; 2 solvent, i.e. Ethanol, and aqueous water; 3 concentration levels, i.e. 100mg/ml, 120 mg/ml and 150mg/ml; 4 bacterial species; and 3 replications). Qualitative analysis or susceptibility was carried out using standard protocol and phytochemical and antimicrobial activities were determined by disc diffusion and broth dilution method. 

Result: According of study indicated the presence of six phytochemical compounds among the tested compounds, while, Saponin and Terpenoid were absent in ethanol extract and present in water extract. Phlobotanin possess negative at all in both ethanol and water extract. Based on observed susceptibility test the highest inhibition zone 14.6mm was recorded against S. Pyogenes at a concentration of 150 mg/ml, while 9.1 mm inhibition zone was observed against E. coli in concentration of 100 mg/ml. Minimum inhibitory concentration values, in the range 25 mg/mL to 100 mg /ml gram positive and gram negative, minimum bactericidal concentration values ranged 50 mg/ml to 100 mg/ml respectively recorded. 

Conclusion: Plectranthus amboincus plant showed presence of secondary metabolites, possesses bio-active compounds against selected human pathogenic bacterial species, thereby justifying the application of their crude extracts as medicinal plants. Further studies are required against more bacteria and fungus pathogens.