Antitubercular sterols from Thalia multiflora Horkel ex Koernicke.

Bioassay guided isolation of an antitubercular extract of the aerial parts of Thalia multiflora led to the isolation of nine stigmast-5-ene and stigmasta-5,22-dien steroids, four isorhamnetin and quercetin flavonoid glycosides, two ceramides, an indole alkaloid and two simple phenolic compounds. Stigmast-5-en-3β-ol-7-one (2), stigmast-4-ene-6β-ol-3-one (3), stigmast-5,22-dien-3β-ol-7-one (7) and stigmast-4,22-dien-6β-ol-3-one (8) were found to be the most active compounds with MIC values of 1.98 ± 0.02, 4.2 ± 0.17, 1.0 ± 0.06 and 2.2 ± 0.3 µg/mL, respectively. Compounds 2, 3, 7 and 8 were not cytotoxic to Vero cells at 102 µg/mL. This investigation constitutes the first report of a chemical study of a species of the genus Thalia. Copyright © 2005 John Wiley & Sons, Ltd.