Dhawan Alok, Anderson Diana, de Pascual-Teresa Sonia, Santos-Buelga Celestino, Clifford Michael N, Ioannides Costas
School of Biological Sciences, Molecular Toxicology Group, University of Surrey, Guildford, GU2 7XH, Surrey, UK.
Mutat Res. 2002 Mar 25;515(1-2):39-56. doi: 10.1016/s1383-5718(01)00347-3.
The polyphenolic dimers, epicatechin-4beta-8-catechin (B1), epicatechin-4beta-8-epicatechin (B2), catechin-4beta-8-catechin (B3), catechin-4beta-8-epicatechin (B4), and the gallate ester epicatechin-4beta-8-epicatechin gallate (B'2G) were isolated from grape seeds, and theaflavins and theafulvins from black tea brews. The ability of these naturally-occurring polyphenols to afford protection against the genotoxicity of the heterocyclic amine 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) was compared with that of the monomeric tea flavanols, (+)-catechin (C), (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin (EGC) and (-)-epigallocatechin gallate (EGCG). Genotoxic activity was evaluated in human peripheral lymphocytes using the Comet assay. At the concentration range of 1-100 microM, neither the monomeric nor the dimeric flavanols prevented the lymphocyte DNA damage induced by Trp-P-2. In contrast, both of the black tea polyphenols, theafulvins and theaflavins, at a dose range of 0.1-0.5 mg/ml, prevented, in a concentration-dependent manner, the DNA damage elicited by Trp-P-2. Finally, neither the monomeric and dimeric polyphenols (100 microM) nor the theafulvins and theaflavins (0.5mg/ml) caused any DNA damage in the human lymphocytes. These studies illustrate that black tea theafulvins and theaflavins, if absorbed intact, may contribute to the anticarcinogenic potential associated with black tea intake.
从葡萄籽中分离出多酚二聚体表儿茶素 - 4β - 8 - 儿茶素（B1）、表儿茶素 - 4β - 8 - 表儿茶素（B2）、儿茶素 - 4β - 8 - 儿茶素（B3）、儿茶素 - 4β - 8 - 表儿茶素（B4）以及没食子酸酯表儿茶素 - 4β - 8 - 表儿茶素没食子酸酯（B'2G），从红茶冲泡液中分离出茶黄素和茶褐素。将这些天然存在的多酚对杂环胺3 - 氨基 - 1 - 甲基 - 5H - 吡啶并[4,3 - b]吲哚（Trp - P - 2）遗传毒性的防护能力与单体茶黄烷醇（+） - 儿茶素（C）、（ - ） - 表儿茶素（EC）、（ - ） - 表儿茶素没食子酸酯（ECG）、（ - ） - 表没食子儿茶素（EGC）和（ - ） - 表没食子儿茶素没食子酸酯（EGCG）的防护能力进行了比较。使用彗星试验在人外周血淋巴细胞中评估遗传毒性活性。在1 - 100微摩尔的浓度范围内，单体和二聚体黄烷醇均不能预防Trp - P - 2诱导的淋巴细胞DNA损伤。相反，两种红茶多酚，茶褐素和茶黄素，在0.1 - 0.5毫克/毫升的剂量范围内，以浓度依赖的方式预防了Trp - P - 2引起的DNA损伤。最后，单体和二聚体多酚（100微摩尔）以及茶褐素和茶黄素（0.5毫克/毫升）均未在人淋巴细胞中引起任何DNA损伤。这些研究表明，如果完整吸收，红茶茶褐素和茶黄素可能有助于与饮用红茶相关的抗癌潜力。
