Abstract
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.
Highlights
Tyrosinase (EC 1.14.18.1), a copper-containing oxidoreductase with a complex structure, is the key enzyme and rate-limiting enzyme in melanin synthesis, and it is closely related to many pigmentation disorders, malignant melanoma, insect fusion and browning of fruits and vegetables [28]
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
Summary
Tyrosinase (EC 1.14.18.1), a copper-containing oxidoreductase with a complex structure, is the key enzyme and rate-limiting enzyme in melanin synthesis, and it is closely related to many pigmentation disorders, malignant melanoma, insect fusion and browning of fruits and vegetables [28]. C. camphora, as a traditional Chinese medicine in China, contains complex chemical components, including volatile oil, lignans, flavonoids, glycosides and so on [7]. It has excellent biological activity, with antibacterial, antioxidant, anti-inflammatory, insecticidal, analgesic, anticancer, and other pharmacological effects [35, 12, 15, 11, 10]. To make full use of C. camphora, separating PAs from the leaves and branches of C. camphora and examining their biological activities to offer a academic theoretical reference for the exploration of new efficient and safe antioxidants and anti-tyrosinase agents are warranted
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