UPLC-PDA-ESI-MS/MS Profiling of Clerodendrum inerme and Clerodendrum splendens and Significant Activity Against Mycobacterium tuberculosis

Introduction: Antibiotic resistance is a major problem that is spreading and increasing while the development of new antibiotics is ceasing. As a result, some bacterial infections that were easily treated previously became untreatable. The antibacterial activity of Clerodendrum inerme and Clerodendrum splendens leaves were investigated against Mycobacterium tuberculosis, the widely known multi-drug resistant bacterium. UPLC-PDA-ESI-MS/MS is characterized by high sensitivity, resolution and speed for identification of plant metabolites even the minor ones. The chemical constituents of the leaves of C. inerme and C. splendens were investigated by UPLC-PDA-ESI-MS/MS metabolic analysis. Methods: The antibacterial activity of the ethanol extracts of the leaves of the two species under investigation was evaluated against the multi-ethanol drug resistant bacterium Mycobacterium tuberculosis using MABA assay. The methanol extracts of the leaves of C. inerme and C. splendens were subjected to comparative UPLC-PDA-ESI-MS/MS analysis. Results: The ethanol extract of C .inerme leaves showed significant antibacterial activity against Mycobacterium tuberculosis, while that of C. splendens showed moderate activity. The UPLC-PDA-ESI-MS/MS analysis revealed a total of 36 metabolites detected and tentatively identified in the two species under investigation, among them 28 chromatographic peaks were assigned in C. inerme while only 14 were assigned in these C. splendens. The main classes of secondary metabolites detected were Phenylpropanoid and, iridoid glycosides, flavonoids, diterpenoids, phenolic acid and fatty acid derivatives. Conclusion: The results of the antibacterial activity and UPLC-PDA-ESI-MS/ MS analysis showed stronger activity and higher number of metabolites for C. inerme as compared to C. splendens.