title: Three ginkgolide hydrates from Ginkgo biloba L.: ginkgolide A monohydrate, ginkgolide C sesquihydrate and ginkgolide J dihydrate, all determined at 120 K.
abstract: A low-temperature structure of ginkgolide A monohydrate, (1R,3S,3aS,4R,6aR,7aR,7bR,8S,10aS,11aS)-3-(1,1-dimethylethyl)-hexahydro-4,7b-dihydroxy-8-methyl-9H-1,7a-epoxymethano-1H,6aH-cyclopenta[c]furo[2,3-b]furo[3',2':3,4]cyclopenta[1,2-d]furan-5,9,12(4H)-trione monohydrate, C(20)H(24)O(9) x H(2)O, obtained from Mo K alpha data, is a factor of three more precise than the previous room-temperature determination. A refinement of the ginkgolide A monohydrate structure with Cu K alpha data has allowed the assignment of the absolute configuration of the series of compounds. Ginkgolide C sesquihydrate, (1S,2R,3S,3aS,4R,6aR,7aR,7bR,8S,10aS,11S,11aR)-3-(1,1-dimethylethyl)-hexahydro-2,4,7b,11-tetrahydroxy-8-methyl-9H-1,7a-epoxymethano-1H,6aH-cyclopenta[c]furo[2,3-b]furo[3',2':3,4]cyclopenta[1,2-d]furan-5,9,12(4H)-trione sesquihydrate, C(20)H(24)O(11) x 1.5H(2)O, has two independent diterpene molecules, both of which exhibit intramolecular hydrogen bonding between OH groups. Ginkgolide J dihydrate, (1S,2R,3S,3aS,4R,6aR,7aR,7bR,8S,10aS,11aS)-3-(1,1-dimethylethyl)-hexahydro-2,4,7b-trihydroxy-8-methyl-9H-1,7a-epoxymethano-1H,6aH-cyclopenta[c]furo[2,3-b]furo[3',2':3,4]cyclopenta[1,2-d]furan-5,9,12(4H)-trione dihydrate, C(20)H(24)O(10) x 2H(2)O, has the same basic skeleton as the other ginkgolides, with its three OH groups having the same configurations as those in ginkgolide C. The conformations of the six five-membered rings are quite similar across ginkgolides A-C and J, except for the A and F rings of ginkgolide A.
authors.affiliation: National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, University, MS 38677, USA.
authors.forename: Jianping
authors.initials: J
authors.lastname: Zhao
authors.forename: Ilias
authors.initials: I
authors.lastname: Muhammad
authors.forename: D Chuck
authors.initials: DC
authors.lastname: Dunbar
authors.forename: Ikhlas A
authors.initials: IA
authors.lastname: Khan
authors.forename: Nikolaus H
authors.initials: NH
authors.lastname: Fischer
authors.forename: Frank R
authors.initials: FR
authors.lastname: Fronczek
mesh_terms: D018360:Crystallography, X-Ray; D004224:Diterpenes; D020441:Ginkgo biloba / Q000737:chemistry*; D046934:Ginkgolides; D006860:Hydrogen Bonding; D007783:Lactones / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular
chemical_list: D004224:Diterpenes; D046934:Ginkgolides; D007783:Lactones; C058295:ginkgolide C; C045856:ginkgolide B; C075228:ginkgolide J