Abstract
Despite its classification as a non-life-threatening disease, increased skin pigmentation adversely affects quality of life and leads to loss of self-confidence. Until now, there are no recommended remedies with high efficacy and human safety for hyperpigmentation. This study aimed to investigate anti-melanogenic activity and underlying mechanism of cajanin, an isoflavonoid extracted from Dalbergia parviflora Roxb. (Leguminosae) in human melanin-producing cells. Culture with 50 μM cajanin for 48–72 h significantly suppressed proliferation in human melanoma MNT1 cells assessed via MTT viability assay. Interestingly, cajanin also efficiently diminished melanin content in MNT1 cells with the half maximum inhibitory concentration (IC50) at 77.47 ± 9.28 μM. Instead of direct inactivating enzymatic function of human tyrosinase, down-regulated mRNA and protein expression levels of MITF and downstream melanogenic enzymes, including tyrosinase, TRP-1 and Dct (TRP-2) were observed in MNT1 cells treated with 50 μM cajanin for 24–72 h. Correspondingly, treatment with cajanin modulated the signaling pathway of CREB and ERK which both regulate MITF expression level. Targeted suppression on MITF-related proteins in human melanin-producing cells strengthens the potential development of cajanin as an effective treatment for human hyperpigmented disorders.
Highlights
IntroductionA cellular pigment presented in hair, skin and eyes, is generated through melanogenesis pathway in melanocytes that are located at the bottom layer of epidermis [1]
Published: 5 October 2021Melanin, a cellular pigment presented in hair, skin and eyes, is generated through melanogenesis pathway in melanocytes that are located at the bottom layer of epidermis [1].As a photoabsorbent, melanin plays a protective role against skin damage induced by ultraviolet (UV) radiation
72 h had been reported as a doubling time of human melanocytes [18], the MNT1 cells cultured under the present condition was found to have the doubling time of 13.75 h
Summary
A cellular pigment presented in hair, skin and eyes, is generated through melanogenesis pathway in melanocytes that are located at the bottom layer of epidermis [1]. Melanin plays a protective role against skin damage induced by ultraviolet (UV) radiation. Because of the low efficacy and serious adverse effects associated with available hypopigmentation remedies, the search for a novel, safe and effective anti-melanogenic treatment has been continuously carried on. It has been well accepted that the regulation of tyrosinase, a rate-limiting step enzyme in melanogenesis, is the most effective therapy providing sustained benefits for hyperpigmentation treatment [3]. Various natural extracts have been introduced as tyrosinase inhibitors which are commercially used in cosmeceutical products as depigmenting agents [4]
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