title: Antifungal jujubogenin saponins from Colubrina retusa.
abstract: Antifungal assay-guided isolation of the 95% ethanol extract of the stems of Colubrina retusa yielded jujubogenin 3-O-alpha-L-arabinofuranosyl(1-->2)-[beta-D-glucopyranosyl (1-->3)]-alpha-L-arabinopyranoside (1), which showed modest growth-inhibitory effects against Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus (MICs, 50 microg/mL). In addition, two new minor saponins, jujubogenin 3-O-alpha-L-arabinofuranosyl(1-->2)-[2-O-(trans, cis)p-coumaroyl-beta-D-glucopyranosyl(1-->3)]-alpha-L-arabinopy ranosi de (2), and jujubogenin 3-O-(5-O-malonyl)-alpha-L-arabinofuranosyl (1-->2)-[beta-D-glucopyranosyl(1-->3)]-alpha-L-arabinopyranoside (3), were obtained. Saponin 2 was marginally active against only C. neoformans, with a MIC of 50 microg/mL, while 3 was inactive. NMR spectroscopy was used extensively for the structure determination of these compounds. The previously reported ambiguity of the NMR assignments of jujubogenin saponins for carbons -26 to -29 was clarified by a comprehensive analysis of the NMR spectra of 1.
authors.affiliation: National Center for the Development of Natural Products, Research Institute of Pharmaceutical Sciences and Department of Pharmacognosy, School of Pharmacy, The University of Mississippi, University, Mississippi 38677, USA.
authors.forename: X C
authors.initials: XC
authors.lastname: Li
authors.forename: H N
authors.initials: HN
authors.lastname: ElSohly
authors.forename: A C
authors.initials: AC
authors.lastname: Nimrod
authors.forename: A M
authors.initials: AM
authors.lastname: Clark
mesh_terms: D000935:Antifungal Agents / Q000302:isolation & purification / Q000494:pharmacology*; D002240:Carbohydrate Sequence; D005658:Fungi / Q000187:drug effects; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D018547:Plant Stems / Q000737:chemistry; D010944:Plants / Q000737:chemistry*; D012503:Saponins / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D000935:Antifungal Agents; D012503:Saponins