Abstract

Camellia sinensis (tea) seeds have been identified as potential sources of nutraceutical compounds. In this study, caffeine and theaflavanoside IV were annotated as the most abundant phytochemicals in the seed shells of C. sinensis. Both compound displayed potent inhibitions against protein tyrosine phosphatase 1B (PTP1B) with IC₅₀ values of 37.9 ± 3.5 and 8.7 ± 1.1 µM, respectively. In the kinetic study, caffeine inhibited PTP1B with mixed type I mode, which prefers to bind to free enzyme. Theaflavanoside IV showed competitive and reversible simple slow-binding inhibition [k₃ = 0.1 µM⁻¹·min⁻¹, k₄ = 0.002 min⁻¹, K_i^app = 0.0002 µM]. This is the first report on PTP1B-inhibitory activity of these compounds and their action mechanisms. These results suggest their potential in the development of antidiabetic agents.

摘要

Camellia sinensis（茶）种子已被确定为营养保健化合物的潜在来源。在这项研究中，咖啡因和茶黄素苷 IV 被注释为C. sinensis种子壳中最丰富的植物化学物质。两种化合物均显示出对蛋白酪氨酸磷酸酶 1B (PTP1B) 的有效抑制作用，IC ₅₀值分别为 37.9 ± 3.5 和 8.7 ± 1.1 µM。在动力学研究中，咖啡因以混合 I 型模式抑制 PTP1B，该模式更喜欢与游离酶结合。Theaflavanoside IV 显示出竞争性和可逆的简单缓慢结合抑制 [ k ₃ = 0.1 µM ^-1 ·min ^-1 , k ₄ = 0.002 min ^-1 ,K _i ^app = 0.0002 µM]。这是关于这些化合物的 PTP1B 抑制活性及其作用机制的第一份报告。这些结果表明它们在开发抗糖尿病药物方面的潜力。