title: Antimycobacterial ergosterol-5,8-endoperoxide from Ajuga remota.
abstract: In a bioassay-guided search for antimycobacterial natural products from higher plants, we have chemically investigated the methanol extract of aerial parts of Ajuga remota Benth. (Labiatae) for its active constituent(s). Bioactive chromatographic fractions of the crude extract provided the known triterpene ergosterol-5,8-endoperoxide plus the diterpenes clerodin, ajugarin-I, and ajugarin-II, which had been previously isolated from A. remota. This is the first report on the isolation of ergosterol-5,8-endoperoxide from this plant. The above compounds were tested in a radiorespirometric bioassay for activity against Mycobacterium tuberculosis. Ergosterol-5,8-endoperoxide showed a minimum inhibitory concentration (MIC) of 1 microgram/ml, while ergosterol-5,8-endoperoxide acetate, ergosterol, and ergosta-5,7,9(11),22-tetraen-3 beta-ol gave MICs of 8 micrograms/ml, > 128 micrograms/ml, and 128 micrograms/ml, respectively. Clerodin, ajugarin-I, and ajugarin-II were inactive with MICs of > 128 micrograms/ml.
authors.affiliation: Department of Chemistry, Louisiana State University, Baton Rouge, USA. cantrell@mail.ncifcrf.gov
authors.forename: C L
authors.initials: CL
authors.lastname: Cantrell
authors.forename: M S
authors.initials: MS
authors.lastname: Rajab
authors.forename: S G
authors.initials: SG
authors.lastname: Franzblau
authors.forename: F R
authors.initials: FR
authors.lastname: Fronczek
authors.forename: N H
authors.initials: NH
authors.lastname: Fischer
mesh_terms: D000995:Antitubercular Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D018360:Crystallography, X-Ray; D004875:Ergosterol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D010936:Plant Extracts / Q000494:pharmacology*; D010944:Plants / Q000737:chemistry*
chemical_list: D000995:Antitubercular Agents; D010936:Plant Extracts; C036071:ergosterol-5,8-peroxide; D004875:Ergosterol