ABSTRACT

In this study, total phenols (TP) and proanthocyanidins (PAs) in the leaves and branches of Cinnamomum camphora were investigated, and isolated PAs were determined using reversed-phase high performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI-MS). The anti-tyrosinase and antioxidant activities were also evaluated. Furthermore, scanning study and dihydroxyphenylalanine (L-DOPA) oxidation were performed to further analyze the inhibition mechanism of PAs on tyrosinase catalytic activity. PAs had strong inhibitory effects on tyrosinase monophenolase activity, with effectively prolonged the delay time and decreased the steady-state of monophenolase activity. For diphenolase activity, PAs both showed reversible and mixed inhibition. Moreover, the PAs showed strong antioxidant activities in scavenging 2,2-Diphenyl-1-picrylhydrazyl (DPPH), 1,2ʹ-azino-bis(3-ethylbenzthiazoline-6-sulphonicacid) (ABTS) and the ferric reducing antioxidant power (FRAP) assays. The PAs in leaves showed stronger anti-tyrosinase and antioxidant capacity, suggesting that C. camphora may be a good resource for tyrosinase inhibitors and antioxidants. This study could provide a scientific basis for the resource utilization of C. camphora and the development of new natural tyrosinase inhibitors and antioxidants in medical, cosmetic, food, and agricultural industries.

摘要

本研究对香樟叶和枝条中的总酚 (TP) 和原花青素 (PAs)进行了研究，并使用反相高效液相色谱电喷雾电离质谱 (HPLC-ESI-MS) 测定了分离的 PA。还评估了抗酪氨酸酶和抗氧化活性。此外，还进行了扫描研究和二羟基苯丙氨酸（L-DOPA）氧化，以进一步分析 PAs 对酪氨酸酶催化活性的抑制机制。PAs对酪氨酸酶单酚酶活性有较强的抑制作用，有效延长延迟时间，降低单酚酶活性稳态。对于二酚酶活性，PA 均表现出可逆和混合抑制。此外，PAs 在清除 2,2-Diphenyl-1-picrylhydrazyl (DPPH)、1、2ʹ-azino-bis(3-ethylbenzthiazoline-6-sulphonicacid) (ABTS) 和铁还原抗氧化能力 (FRAP) 测定。叶片中的 PA 表现出更强的抗酪氨酸酶和抗氧化能力，表明C. camphora可能是酪氨酸酶抑制剂和抗氧化剂的良好资源。该研究可为樟脑资源化利用以及在医药、化妆品、食品、农业等行业开发新型天然酪氨酸酶抑制剂和抗氧化剂提供科学依据。