Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6118169 | International Journal of Antimicrobial Agents | 2012 | 6 Pages |
Abstract
In a project to characterise new antibacterial chemotypes from plants, hyperenone A and hypercalin B were isolated from the hexane and chloroform extracts of the aerial parts of Hypericum acmosepalum. The structures of both compounds were characterised by extensive one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy and were confirmed by mass spectrometry. Hyperenone A and hypercalin B exhibited antibacterial activity against multidrug-resistant strains of Staphylococcus aureus, with minimum inhibition concentration ranges of 2-128Â mg/L and 0.5-128Â mg/L, respectively. Hyperenone A also showed growth-inhibitory activity against Mycobacterium tuberculosis H37Rv and Mycobacterium bovis BCG at 75Â mg/L and 100Â mg/L. Neither hyperenone A nor hypercalin B inhibited the growth of Escherichia coli and both were non-toxic to cultured mammalian macrophage cells. Both compounds were tested for their ability to inhibit the ATP-dependent MurE ligase of M. tuberculosis, a crucial enzyme in the cytoplasmic steps of peptidoglycan biosynthesis. Hyperenone A inhibited MurE selectively, whereas hypercalin B did not have any effect on enzyme activity.
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Authors
Khadijo Osman, Dimitrios Evangelopoulos, Chandrakala Basavannacharya, Antima Gupta, Timothy D. McHugh, Sanjib Bhakta, Simon Gibbons,