title: Puerins A and B, two new 8-C substituted flavan-3-ols from Pu-er tea.
abstract: Pu-er tea is a special treated fermented tea produced from crude green tea, which is prepared from the leaves of Camellia sinensis var. assamica. It is a traditional beverage having been used in China, particularly the southern areas, for a long time. Chemical investigation led to the identification of two new 8-C substituted flavan-3-ols, puerins A (1) and B (2), and two known cinchonain-type phenols, epicatechin-[7,8-bc]-4alpha-(4-hydroxyphenyl)-dihydro-2(3H)-pyranone (3) and cinchonain Ib (4), together with other seven known phenolic compounds, 2,2',6,6'-tetrahydroxydiphenyl (5), (-)-epicatechin-8-C-beta-d-glucopyranoside (6), (-)-epicatechin (EC) (7), (-)-epigallocatechin (EGC) (8), (+/-)-gallocatechin (GC) (9), gallic acid (10), and myricetin (11), in addition to caffeine (12). Their structures were determined by spectroscopic methods. The compounds 1-5, which might be formed in the postfermentative process of Pu-er tea, were isolated from tea and theaceous plants for the first time.
authors.affiliation: State Key Laboratory of Phytochemistry and Plant Resources of West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, People's Republic of China.
authors.forename: Zhi-Hong
authors.initials: ZH
authors.lastname: Zhou
authors.forename: Ying-Jun
authors.initials: YJ
authors.lastname: Zhang
authors.forename: Min
authors.initials: M
authors.lastname: Xu
authors.forename: Chong-Ren
authors.initials: CR
authors.lastname: Yang
mesh_terms: D028241:Camellia sinensis / Q000737:chemistry*; D005285:Fermentation; D005419:Flavonoids / Q000032:analysis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D018515:Plant Leaves / Q000737:chemistry*; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013053:Spectrophotometry; D013662:Tea / Q000737:chemistry*
chemical_list: D005419:Flavonoids; D013662:Tea; C506358:puerin A; C506357:puerin B; C404987:flavan-3-ol