Abstract: This study investigated the phytochemical composition and the antibacterial properties of Andrographis paniculata (serpentina) and Vitex negundo (lagundi) in crude extracts with various concentrations: 100%, 80%, 60%, and 20%, against Staphylococcus aureus and Klebsiella pneumoniae. Standard techniques revealed significant phytochemicals such as alkaloids, cardiac glycosides, flavonoids, phenols, saponins, and tannins. The antibacterial properties were assessed using disk diffusion method and broth microdilution method, which determined the zone of inhibition and minimum inhibitory concentration, respectively, and results were then compared with those of amoxicillin and gentamicin. Serpentina and lagundi extracts at all concentrations showed minimal zone of inhibition, whereas the mixture of both plants exhibited the highest zone of inhibition against Staphylococcus aureus. On the contrary, none of the plant extracts, at any concentration, exhibited zones of inhibition against Klebsiella pneumoniae. The lack of antibacterial property was disbarred in broth microdilution, where all crude leaf extracts showed inhibition against the bacteria. The discrepancy could be attributed to several fact, including the difference of medium used in the two methods. Statistical analysis employed one-way analysis of variance (ANOVA) to assess the significant difference between the experimental group and the controlled group, resulting to a p-value>0.05. Thus, a concentration-dependent relationship was observed, with higher concentrations of the extracts leading to greater bacterial inhibition, emphasizing the therapeutic potential in combating bacterial infections. Based on the findings, it was recommended that further studies to investigate the problems and/or factors that led to discrepancy between the disk diffusion method and the broth microdilution method.

College of Health Sciences Bachelor of Science in Medical Technology