Objective: To evaluate the antimicrobial properties of Kappaphycus alvarezii (K. alvarezii) and Andrographis paniculata (A. paniculata) and to compare the microbial inhibition activities between these two crude extracts. Methods: Both K. alvarezii and A. paniculata were extracted with methanol before the commencement of antimicrobial properties studies. There were a total of eight species of bacteria, including Gram-positive bacteria Bacillus cereus, Bacillus subtilis, Staphylo-coccus aureus and Staphylococcus epidermidis and Gram-negative bacteria, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Salmonella enterica. The antimicrobial activity was tested by disk diffusion method. Results: Crude extract of K. alvarezii was found not effective against both Gram-positive and Gram-negative bacteria. In contrast, A. paniculata showed higher inhibi-tion towards the growth of Gram-positive bacteria compared to Gram-negative bacteria. Results revealed that Bacillus subtilis was susceptible at lower concentration of A. paniculata crude extract however Staphylococcus epidermidis was the most suscep-tible towards A. paniculata at higher concentration. Although the inhibition zones pro-duced by the crude extract were smaller than that of the positive control, streptomycin disc, A. paniculata crude extract still can be considered as potential antimicrobial agents either because it is a natural product or the active compound which is yet identified from its crude extract. Conclusions: Crude extract of K. alvarezii has zero inhibition in bacteria growth whereas A. paniculata exerted higher inhibition towards Gram-positive bacteria. The bioactive compounds contained by A. paniculata can be evaluated in order to yield a better vision towards the mode of action.

Objective To evaluate the antimicrobial properties of Kappaphycus alvarezii (K. alvarezii) and Andrographis paniculata (A. paniculata) and to compare the microbial inhibition activities between these two crude extracts. Methods Both K. alvarezii and A. paniculata were extracted with methanol before the commencement of antimicrobial properties studies. There were a total of eight species of bacteria, including Gram-positive bacteria Bacillus cereus, Bacillus subtilis, Staphylococcus aureus and Staphylococcus epidermidis and Gram-negative bacteria, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Salmonella enterica. The antimicrobial activity was tested by disk diffusion method. Results Crude extract of K. alvarezii was found not effective against both Gram-positive and Gram-negative bacteria. In contrast, A. paniculata showed higher inhibition towards the growth of Gram-positive bacteria compared to Gram-negative bacteria. Results revealed that Bacillus subtilis was susceptible at lower concentration of A. paniculata crude extract however Staphylococcus epidermidis was the most susceptible towards A. paniculata at higher concentration. Although the inhibition zones produced by the crude extract were smaller than that of the positive control, streptomycin disc, A. paniculata crude extract still can be considered as potential antimicrobial agents either because it is a natural product or the active compound which is yet identified from its crude extract. Conclusions Crude extract of K. alvarezii has zero inhibition in bacteria growth whereas A. paniculata exerted higher inhibition towards Gram-positive bacteria. The bioactive compounds contained by A. paniculata can be evaluated in order to yield a better vision towards the mode of action.