title: Inhibitory effect of sterols from Ruprechtia triflora and diterpenes from Calceolaria pinnifolia on the growth of Mycobacterium tuberculosis.
abstract: Bioactivity-guided fractionation of the CH 2 Cl 2 /MeOH extract of the aerial part of Ruprechtia triflora Griseb. led to the identification of several sterols and a triterpene as the active components against Mycobacterium tuberculosis. This is the first report of a chemical investigation of a member of the genus Ruprechtia. The novel acylated sterol, 5alpha,8alpha-epidioxyergosta-6,22-dien-3beta-yl stearate, was isolated and its structure determined on the basis of spectral evidence including NMR (especially selective 1D NOE, selective 1D TOCSY, HSQC, HMBC) and MS (HR-FAB). In addition, several terpenes obtained from Calceolaria pinnifolia Cav. were also evaluated for their antimycobacterial activity. In a microplate alamar blue assay, sterols from R. triflora were found to be active with MIC values ranging from 2 - 128 microg/mL, with 5alpha,8alpha-epidioxyergost-6,22-dien-3beta-ol, 5alpha,8alpha-epidioxystigmasta-6,22-dien-3beta-ol and stigmast-4-en-6beta-ol-3-one being the most active, each with an MIC value of 2 microg/mL. Among the diterpenes from C. pinnifolia, 19-malonyloxydehydroabietinol and 19-methylmalonyloxy- ent-isopimara-8(9),15-diene were most active each with an MIC value of 4 microg/mL. MIC values for the triterpenes 3-epi-ursolic acid and 3-epi-oleanolic acid from C. pinnifolia were determined to be 8 and 16 microg/mL, respectively.
authors.affiliation: Department of Pharmacology and Toxicology, Division of Medicinal and Natural Products Chemistry, College of Pharmacy, University of Arizona, Tucson, AZ, USA.
authors.forename: Girma M
authors.initials: GM
authors.lastname: Woldemichael
authors.forename: Scott G
authors.initials: SG
authors.lastname: Franzblau
authors.forename: Fangqiu
authors.initials: F
authors.lastname: Zhang
authors.forename: Yuehong
authors.initials: Y
authors.lastname: Wang
authors.forename: Barbara N
authors.initials: BN
authors.lastname: Timmermann
mesh_terms: D000995:Antitubercular Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D001118:Argentina; D004224:Diterpenes / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D019684:Magnoliopsida / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D010840:Phytosterols / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D010946:Plants, Medicinal / Q000737:chemistry; D019664:Polygonaceae / Q000737:chemistry*
chemical_list: D000995:Antitubercular Agents; D004224:Diterpenes; D010840:Phytosterols