title: Dibothrioclinin I and II, epimers from Gerbera piloselloides (L.) Cass.
abstract: Dibothrioclinin I and II, namely (+)-(11R,12S,25R,27S)- and (+/-)-(11RS,12RS,25RS,27SR)-3,3,7,17,21-pentamethyl-4,12,18,26-tetraoxaheptacyclo[15.11.1.0(2,15).0(5,14).0(6,11).0(19,28).0(20,25)]nonacosa-5(14),6,8,10,19(28),20,22,24-octaene-13,27-dione, respectively, are C(30)H(28)O(6) epimers which are derived from two bothrioclinin moieties joined so as to create an additional six-membered ring. Structurally, the epimers differ only by inversion at one C atom of a central ring junction and the corresponding six-membered rings have similar conformations in each molecule, except for one ring adjacent to this inversion site.
authors.affiliation: Institute Materia Medica, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100050, People's Republic of China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Wang
authors.forename: Qitai
authors.initials: Q
authors.lastname: Zheng
authors.forename: Yang
authors.initials: Y
authors.lastname: Lu
authors.forename: Ying
authors.initials: Y
authors.lastname: Xiao
authors.forename: Jianbei
authors.initials: J
authors.lastname: Li
authors.forename: Yi
authors.initials: Y
authors.lastname: Ding
mesh_terms: D019659:Asteraceae / Q000737:chemistry*; D003374:Coumarins / Q000737:chemistry*; D018360:Crystallography, X-Ray; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D003374:Coumarins; C479124:bothrioclinin