Design of Novel Hybrid Vitamin C Derivatives: Thermal Stability and Biological Activity.
作者:Kazuo MORISAKI、Shoichiro OZAKI
DOI:10.1248/cpb.44.1647
日期:——
Novel hybrid L-ascorbic acid (vitamin C) derivatives with other biologically active substances, 5-hydroxy-2-hydroxymethyl-β-pyrone (kojic acid) and α-tocopherol (vitamin E), linked at the C-2 or C-3 hydroxyl group were synthesized, and their thermal stability and inhibitory effects on tyrosinase activity, active oxygen species (AOS), and free radicals were estimated in vitro. It was found that a hydrophilic derivative, 2-O-(5-hydroxy-4H-pyran-4-one-2-methyl)-L-ascorbic acid (1), exyhibited good thermal stability and inhibitory activities against tyrosinase-catalyzed melanin formation, AOS, and free radicals compared to vitamin C and its conventional derivatives (such as the 2-phosphate, 6-stearate and 2, 6-dipalmitate, and 2-O-octadecylascorbic acid), as well as vitamin E, kojic acid, and arbutin. It is apparent that 1 has the biological properties of vitamin C and kojic acid, and acts synergistically. The hydroxyl groups at the C-3 position of the vitamin C moiety and the C-5 position of the kojic acid moiety are critical for the biological activities. We consider that the kojic acid moiety of 1 counterbalances the diminution of the biological activity due to shielding of the biologically important C-2 hydroxyl group of the vitamin C moiety. In addition, the thermal stability was significantly improved relative to not only vitamin C but also kojic acid. Further, a lipophilic derivative, 3-O-[α-tocopheryloxy)-2-hydroxypropyl]-L-ascorbic acid, 2, was far more stable than vitamin C and its typical lipophilic derivatives. Compound 2 exhibited almost the same inhibitory activities against tyrosinase-catalyzed melanin formation, AOS, and free radicals as typical lipophilic derivatives, although these biological activities of 2 were lower than those of vitamin C.
合成了在 C-2 或 C-3 羟基上连接其他生物活性物质--5-羟基-2-羟甲基-β-吡喃酮(曲酸)和α-生育酚(维生素 E)--的新型杂合 L-抗坏血酸(维生素 C)衍生物,并在体外评估了它们的热稳定性以及对酪氨酸酶活性、活性氧(AOS)和自由基的抑制作用。研究发现,亲水性衍生物 2-O-(5-羟基-4H-吡喃-4-酮-2-甲基)-L-抗坏血酸(1)具有良好的热稳定性和抑制酪氨酸酶催化黑色素形成的活性、与维生素 C 及其传统衍生物(如 2-磷酸酯、6-硬脂酸酯、2, 6-二棕榈酸酯和 2-O-十八烷基抗坏血酸)以及维生素 E、曲酸和熊果苷相比,1 具有良好的热稳定性和抑制酪氨酸酶催化的黑色素形成、AOS 和自由基的活性。显然,1 具有维生素 C 和曲酸的生物特性,并能发挥协同作用。维生素 C 的 C-3 位羟基和曲酸的 C-5 位羟基对生物活性至关重要。我们认为,1 的曲酸分子可以抵消由于维生素 C 分子中具有重要生物活性的 C-2 羟基被屏蔽而导致的生物活性降低。此外,与维生素 C 和曲酸相比,热稳定性也有了显著提高。此外,亲脂性衍生物 3-O-[α-生育酚氧基]-2-羟基丙基]-L-抗坏血酸 2 比维生素 C 及其典型的亲脂性衍生物要稳定得多。化合物 2 对酪氨酸酶催化的黑色素形成、AOS 和自由基的抑制活性与典型的亲脂性衍生物几乎相同,但 2 的这些生物活性低于维生素 C。