Bioactivity-guided fractionation of the petroleum ether extract of Azo
rella madreporica Clos has led to the isolation of the novel, antitube
rcular mulinane diterpenoid 1. The structure has been elucidated on th
e basis of its 1D and 2D NMR spectra and by comparison with mulinolic
acid 2 and a dehydration product 3 obtained from 1. The MIC of 1 for g
rowth inhibition of the H(37)Rv Strain of Mycobacterium tuberculosis'
was determined as 20 mu g/mL. LC-MS and NMR have suggested the presenc
e of this new compound in four other species of Azorella.