Antitubercular Activity of Mycelium-Associated <i>Ganoderma</i> Lanostanoids

In a continuation of our research into antitubercular lanostane triterpenoids from submerged cultures of <i>Ganoderma</i> species, three strains, <i>Ganoderma orbiforme</i> BCC 22325, <i>Ganoderma</i> sp. BCC 60695, and <i>Ganoderma australe</i> BCC 22314, have been investigated. Fourteen new lanostane triterpenoids, together with 35 known compounds, were isolated. Antitubercular activities of these mycelium-associated <i>Ganoderma</i> lanostanoids against <i>Mycobacterium tuberculosis</i> H37Ra were evaluated. Taken together with the assay data of previously isolated compounds, structure–activity relationships of the antitubercular activity are proposed. Most importantly, 3β- and 15α-acetoxy groups were shown to be critical for antimycobacterial activity. The most potent compound was (24<i>E</i>)-3β,15α-diacetoxylanosta-7,9­(11),24-trien-26-oic acid (<b>35</b>)