title: Microbiological and chemical transformations of argentatin B.
abstract: Argentatin B is a naturally occurring tetracyclic triterpene isolated from Parthenium argentatum x P. tomentosa. It was microbiologically transformed to 16, 24-epoxycycloartan-3alpha, 25-diol, (isoargentatin D), by Nocardia corallina var. taoka ATCC 31338, Mycobacterium species NRRL B3683 and Septomyxa affinis ATCC 6737. The later microbe also produced 16, 24-epoxycycloartan-3beta, 25-diol (argentatin D) and 1, 2-didehydroargentatin B, (isoargentatin D). Sodium hydroxide converted argentatin B to argentatin D and isoargentatin D. Hydrochloric acid treatment gave cycloartan-25-ol-3, 24-dione. Cerium sulfate/sulfuric acid/aqueous methanol induced scission of the isopropanol moiety and provided an isomeric mixture of 24-methoxy-25-27-trinorargentatin B. Oxidation of this isomeric mixture with pyridinium chlorochromate, selectively, attacked the isomer with the equatorial proton at position-24 to give the corresponding lactone, 24-oxo-25-27-trinorargentatin B. The produced compounds were characterized by spectroscopic methods.
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmacy, University of Mansoura, Mansoura 35516, Egypt. galaltm@yahoo.com
authors.forename: Galal T
authors.initials: GT
authors.lastname: Maatooq
mesh_terms: D019659:Asteraceae / Q000737:chemistry*; D001419:Bacteria / Q000378:metabolism*; D001711:Biotransformation; D008968:Molecular Conformation; D015394:Molecular Structure; D009161:Mycobacterium / Q000378:metabolism; D009615:Nocardia / Q000378:metabolism*; D014315:Triterpenes / Q000737:chemistry* / Q000302:isolation & purification / Q000493:pharmacokinetics*
chemical_list: D014315:Triterpenes; C474473:argentatin B; C465304:argentatin A