title: Isolation of six isoprenylated biflavonoids from the leaves of Garcinia subelliptica.
abstract: The acetone-soluble parts of Garcinia subelliptica leaves were analyzed and six new biflavonoids were isolated, i.e., garciniaflavones A-F (1-6), as well as the five known biflavonoids amentoflavone (7), podocarpusflavone A (8), (+)-morelloflavone (9), (+)-morelloflavone-7"-O-β-glucopyranoside (10), and (+)-4'''-O-methylmorelloflavone (11) and the three triterpenoids oleanan-3-one, β-amyrin, and cycloartenol. The structures of the isolates were established based on spectroscopic analyses, including a detailed NMR spectroscopic investigation. The new biflavonoids are rare mono-isoprenylated derivatives that have a flavone-(3'-8")-flavone core (1-4: amentoflavone type) and a flavanone-(3-8")-flavone core (5, 6: morelloflavone type). The absolute configurations of the morelloflavone-type biflavonoids (5, 6) were confirmed by circular dichroism to be 2R,3S. The biflavonoids with an isoprenyloxy group (1) and a 2-hydroxy-3-methyl-3-butenyl group (2), and the morelloflavone-type biflavonoids with a C(5) unit are the first examples in nature. We found that 7, one of the major biflavonoids, strongly inhibited hypoxia-inducible factor-1 in human embryonic kidney 293 cells under hypoxic conditions.
authors: Laboratory of Pharmacognosy, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan. teito@gifu-pu.ac.jp
authors: Tetsuro
authors: T
authors: Ito
authors: Renpei
authors: R
authors: Yokota
authors: Tatsuya
authors: T
authors: Watarai
authors: Koki
authors: K
authors: Mori
authors: Masayoshi
authors: M
authors: Oyama
authors: Hideko
authors: H
authors: Nagasawa
authors: Hideaki
authors: H
authors: Matsuda
authors: Munekazu
authors: M
authors: Iinuma
mesh_terms: D044946:Biflavonoids / Q000737:chemistry / Q000302:isolation & purification*; D029760:Garcinia / Q000737:chemistry*; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification*; D018515:Plant Leaves / Q000737:chemistry*; D054876:Prenylation; D013237:Stereoisomerism
chemical_list: D044946:Biflavonoids; D010936:Plant Extracts