Khim Phin Chong, Januarius Gobilik and Syahriel Abdullah
Sustainable Palm Oil Research unit (SPOR), Faculty of Science and Natural Resources, Universiti Malaysia Sabah, 88400, Kota Kinabalu, Sabah, Malaysia
Cynodon dactylon (L.) Pers. is belonging to Poaceae family which used as folk medicine to treat many diseases and infections. The present study reports the antibacterial activity and mechanism of action of C. dactylon Solid Phase Extract (SPE) against Bacillus cereus, Bacillus subtilis, Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus pneumonia along with the possible antibacterial compounds. Antibacterial activity and Minimum Inhibitory Concentrations (MICs) were evaluated using disc-diffusion and micro-broth dilution bioassays respectively. Mode of action study was done via assessment on the leakage of 260nm-absorbing materials, fluorometric assay and Scanning Electron Microscope (SEM) observation for membrane disintegration effect while luminometric assay was used for metabolic inhibition assessment. Remarkable antibacterial activity was observed from flush fraction of C. dactylon SPE against the tested bacterial pathogens (MICs=10.00 mgmL-1). Assessment on membrane degradation based on 260nm-absorbing material leakage and fluorometric assay showed membrane disruption on B. cereus, B. subtilis and E. coli after treated with the plant extract. SEM observation further confirmed the membrane disruption. Luminometric assay based on ATP quantification suggests the bacterial death was probably due to other metabolic factor. Liquid Chromatography-Mass Spectrometry (LCMS) analysis revealed some possible antibacterial compounds including peptides, polyketides, triterpenoid, cardenolide glycoside and some steroidal compounds.
Keywords: Cynodon dactylon, antibacterial, mode of action, phytochemical.