title: Unusual C25 steroid isomers with bicyclo[4.4.1]A/B rings from a volcano ash-derived fungus Penicillium citrinum.
abstract: Eleven new unusual C25 steroid isomers with bicyclo[4.4.1]A/B rings, 24- epi-cyclocitrinol (1), 20-O-methyl-24-epi-cyclocitrinol (3), 20-O-methylcyclocitrinol (4), 24-oxocyclocitrinol (7), 12 R-hydroxycyclocitrinol (8), neocyclocitrinols B (10) and D (12), erythro-23-O-methylneocyclocitrinol (13), threo-23-O-methylneocyclocitrinol (14), isocyclocitrinol B (15), and precyclocitrinol B (18), and five known steroids, cyclocitrinol (2), neocyclocitrinols A (9) and C (11), isocyclocitrinol A (16), and 22-O-acetylisocyclocitrinol A (17), were characterized from cultures of the volcanic ash-derived fungus Penicillium citrinum HGY1-5. Their structures and absolute configurations were established by spectroscopic and chemical methods together with X-ray diffraction analysis. Compounds 3, 4, and 10- 14 were determined to be artifacts on the basis of acidic transformation of 1- 4. The biosynthetic origin of these steroids derived from ergosterol was investigated by feeding (13)C-labeled acetates to the growing cultures of P. citrinum HGY1-5. The biological activities of all 16 steroids were tested using the cAMP assay on GPR12-CHO and WT-CHO cells. The results showed that compounds 1, 2, 10, 11, and 14 could induce the production of cAMP in GPR12-transfected CHO cells.
authors.affiliation: Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, People's Republic of China.
authors.forename: Lin
authors.initials: L
authors.lastname: Du
authors.forename: Tianjiao
authors.initials: T
authors.lastname: Zhu
authors.forename: Yuchun
authors.initials: Y
authors.lastname: Fang
authors.forename: Qianqun
authors.initials: Q
authors.lastname: Gu
authors.forename: Weiming
authors.initials: W
authors.lastname: Zhu
mesh_terms: D000818:Animals; D001643:Bridged Bicyclo Compounds / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D007536:Isomerism; D015394:Molecular Structure; D010407:Penicillium / Q000737:chemistry*; D013256:Steroids / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D018707:Volcanic Eruptions
chemical_list: D001643:Bridged Bicyclo Compounds; D013256:Steroids