Phoenix dactylifera L. Seed Extract Exhibits Antioxidant Effects and Attenuates Melanogenesis in B16F10 Murine Melanoma Cells by Downregulating PKA Signaling.

Huey-Chun Huang,Wang-Ping Ko,Tsong-Min Chang,Shr-Shiuan Wang,Tsang-Chi Tsai

doi:10.3390/antiox9121270

Abstract

Background: The mode of action of Phoenix dactylifera seed extract in skin care has never been explored. Methods: P. dactylifera L. seeds were extracted by ultrasonic extraction. The antioxidant characteristics of the extract were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-di-(3-ethylbenzthiazoline sulfonic acid) (ABTS+) assays and scavenging methods. The total phenolic content, reducing capacity, iron (II) ion-chelation, and intracellular reactive oxygen species (ROS)-scavenging capacities were also investigated. The effects of P. dactylifera L. seed extract on melanogenesis were evaluated spectrophotometrically by a mushroom tyrosinase activity assay, determination of intracellular tyrosinase activity, and melanin content. The expression levels of melanogenesis-related proteins were analyzed by Western blotting. Results: The results revealed that the P. dactylifera L. seed extract exerted apparent antioxidant capacity and significantly decreased intracellular ROS content at concentrations of 0.245 and 0.49 (mg/mL). Furthermore, the extract decreased the expression of melanocortin 1 receptor (MC1R), microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein-1 (TRP1), and tyrosinase-related protein-2 (TRP2), and inhibited melanogenesis in B16F10 cells. Conclusions: Our results revealed that P. dactylifera L. seed extract attenuated melanogenesis in B16F10 cells by downregulating protein kinase A (PKA) signaling pathways. Hence, the extract could be used as a type of skin-whitening agent in skin care products.

Highlights

Antioxidants have been widely applied to prevent or treat oxidative stress-related disorders in cosmetic and dermatological fields
The results indicated that higher concentrations of P. dactylifera L. seed extract still exhibited a smaller inhibitory effect on α-melanocyte-stimulating hormone (α-MSH)-induced tyrosinase activity in B16F10 cells than arbutin
The results indicate that treatment with various concentrations of P. dactylifera L. seed extract led to reduced levels of melanocortin 1 receptor (MC1R), microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein-1 (TRP1), and tyrosinase-related protein-2 (TRP2)

Summary

Introduction

Antioxidants have been widely applied to prevent or treat oxidative stress-related disorders in cosmetic and dermatological fields. It is reported that free radicals and reactive oxygen species (ROS) are associated with several diseases, such as aging and age-related diseases [1]. Antioxidants are reported to interfere with the oxidation process by scavenging free radicals and ROS or by chelating oxidation-catalytic metals [4]. Among the ROS derived from melanocytes and keratinocytes, nitric oxide, NO, stimulates melanin synthesis by enhancing protein expression levels of tyrosinase and tyrosinase-related protein 1 (TRP1) [8,9]. The effects of P. dactylifera L. seed extract on melanogenesis were evaluated spectrophotometrically by a mushroom tyrosinase activity assay, determination of intracellular tyrosinase activity, and melanin content. Results: The results revealed that the P. dactylifera L. seed extract exerted apparent antioxidant capacity and significantly decreased intracellular ROS content at concentrations of 0.245 and 0.49 (mg/mL). The extract could be used as a type of skin-whitening agent in skin care products

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