Structure and Anti-TB Activity of Trachylobanes from the Liverwort Jungermannia exsertifolia ssp. cordifolia
Résumé
In the critical search for new antituberculosis lead compounds, bryophytes represent a largely untapped resource of chemically diverse structures. From the liverwort Jungermannia exsertifolia subsp. cordifolia, 11 new trachylobane diterpene derivatives, as well as three known compounds, were isolated. Their structures were elucidated by spectroscopic means, and full 1H NMR spin analysis of one model compound confirmed the relative configurational assignments of the congeners. Four of the isolates exhibited noticeable activity against virulent Mycobacterium tuberculosis H37Rv with minimal inhibitory concentrations of 61−24 μg/mL. This finding suggests that bryophytes in general and trachylobanes in particular deserve further attention in the search for new antimycobacterial leads.