Anitimycobacterial activity and potential mechanism of action of Campnosperma auriculatum shoot extract

Tuberculosis (TB) is a great public health challenge and a number one cause of morbidity and mortality worldwide. Around one-third of the global populations are latently infected with TB. C. auriculatum is medicinal plant used by the Jakun tribe of Endau Romping, Johor, Malaysia in the treatment of coughing with blood (hemoptysis). C. auriculatum shoot was collected from Taman Negara Johor Endau Rompin, Mersing, Johor, and extracted with hexane, ethyl acetate, methanol, and water. The antimycobacterial activity of the C. auriculatum shoot extracts was tested against Mycobacterium smegmatis mc2 155 (ATCC 700084) using broth microdilution assay technique to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). The cells of M. smegmatis were exposed to most active extract, and then time-kill assay and scanning electron microscopy were carried out to investigate the effect on cell growth and morphology. Gas Chromatography-Mass Spectrometry (GC-MS) was used to investigate the compound present extract. The methanol extract exhibited the best antimycobacterial activity against M. smegmatis with the MIC and MBC values of 1.56 and 3.13 mg/mL respectively. The methanol extract resulted in a significant reduction of colony counts. Furthermore, the appeared elongated, filamentous, swollen with lesions, and there was the appearance of small globular debris. Five compounds were identified with 1-Methyl-trans-decahydroquinol- 5(equat)-ol (80.32%) been dominant. The results demonstrated that C. auriculatum have a great potential in TB-drug research if further investigated.