Reference

Effects of physical and chemical conditions on the in vitro oxidation of tea leaf catechins

Effects of physical and chemical conditions on the in vitro oxidation of tea leaf catechins. Robertson, Alaistair (Dep. Biochem., Univ. Cambridge, Cambridge, UK). Phytochemistry, 22(4), 889-96 (English) 1983. CODEN: PYTCAS. ISSN: 0031-9422. 989-51-5 and 490-46-0 are also occured in this study. DOCUMENT TYPE: Journal CA Section: 17 (Food and Feed Chemistry) The use of a model fermn. system contg. purified green tea shoot catechins and partially purified polyphenol oxidase (EC 1.14.18.1) provided important data on theaflavin (I) [4670-05-7] and thearubigin (II) [12698-96-3] formation. Low O concn. during fermn., as a result of inadequate aeration or high enzyme concn., and enhanced by high temps., inhibited I and promoted II prodn. Anal. of catechin oxidn. under low O tension suggests that the quinones of epicatechin [490-46-0] and epicatechin gallate [863-03-6], by virtue of their low redox potentials, are acting as electron carriers in the preferential oxidn. of epigallocatechin [970-74-1], epigallocatechin gallate [989-51-5], and I intermediates. Temp. changes between 20° and 30° had little effect on I values, whereas II prodn. increased dramatically. II/I ratios over this temp. range increased in O from 1.5:1 to 2.5:1. The pH optima for I and II formation were 5 and 6, resp. The optimization of this factor, together with O concn., temp., and enzyme concn., for I formation, resulted in I levels 115% higher than those obtained from similar model fermns. occurring under the conditions assocd. with black tea manuf. in Malawi (pH 5.6; 30 ′ 10-8 kat of polyphenol oxidase; 27°, 20% O). .

Effects of tea pigments on experimental atherosclerosis in rabbits and patients with hyperfibrinogenemia

Effects of tea pigments on experimental atherosclerosis in rabbits and patients with hyperfibrinogenemia. Lou, Fuqing; Yang, Zucai; Yuan, Weilong; Xia, Shunying; Song, Jifen; Zhang, Meifang (2nd Affiliated Hosp., Zhejiang Med. Univ., Hangzhou, Peop. Rep. China). 12698-96-3 and 4670-05-7 are cas registry numbers. These chemicals are also mentioned in this article. Zhonghua Yixue Zazhi, 63(10), 632-4 (Chinese) 1983. CODEN: CHHTAT. ISSN: 0300-2578. DOCUMENT TYPE: Journal CA Section: 1 (Pharmacology) The effects of a tea pigment prepn. contg. 0.95, 16.82, and 82.23% yellow (theaflavins), red (thearubigins), and brown pigments, resp., on blood coagulation, fibrinolysis, exptl. atherosclerosis, and hyperfibrinogenemia were studied. Both in vitro and in vivo expts. revealed that the tea pigment prepn. had fibrinolysis-stimulating, platelet-adhesion-lowering, and atherosclerosis-regulating activities in rabbits. Oral administration of 75-150 mg tea pigment/day for 30 days improved the clin. indexes (lowering of blood lipids, fibrinogen, and fibrinogen degrdn. products) in 85% of patients with hyperfibrinogenemia. .