10-Hydroxy-2-Decenoic Acid in Royal Jelly Extract Induced Both Filaggrin and Amino Acid in a Cultured Human Three-Dimensional Epidermis Model

Lihao Gu,Haifeng Zeng,Kazuhisa Maeda

doi:10.3390/cosmetics4040048

Abstract

Royal jelly (RJ) is a natural product which the honeybee secretes as a special diet for a queen bee. It is one of the natural products in which various functionalities, such as antibacterial effects, immunomodulating properties, and estrogen-like action, were reported. We investigated the effect of the RJ extract on the moisturizing effect by topical application in humans. The stratum corneum moisture was increased significantly after four weeks by using the RJ extract lotion compared to placebo lotion. RJ extract contained a characteristic ingredient, 10-hydroxy-2-decenoic acid (10H2DA) and 10-hydroxydecanoic acid (10HDAA), etc. However, the mechanism of stratum corneum moisture and its contributing ingredient have not yet been elucidated. We have investigated the effects of 10H2DA and 10HDAA on the free amino acids content in the stratum corneum using a cultured human three-dimensional epidermis model. Additionally, the effect of 10H2DA and 10HDAA on the amounts of filaggrin (FLG) and aquaporin 3 (AQP3) were investigated at the mRNA level and by immunohistochemistry using a cultured human epidermis model. It was determined that 10H2DA increases the free amino acids in the stratum corneum of the cultured human epidermis model, and that it increased FLG on both the mRNA and protein levels. On the other hand, these actions are not observed by treatment of 10HDAA. The mRNA and protein level of AQP3 did not increase with 10H2DA or 10HDAA use. It was thought that the increase in the amount of FLG and the increase in the free amino acids of the epidermis and the stratum corneum, respectively, by 10H2DA were participating in the moisturizing function of the stratum corneum by the continuous use of RJ extract lotion.

Highlights

Dry skin is caused by some factors including insufficient in the emollient oil of the skin surface, the decrease in the natural moisturizing factor (NMF) of the stratum corneum, and the fragility of the stratum corneum barrier function by reduction of intercellular lipids and ceramide, etc. [1,2]
FLG is a protein of epidermal keratinocytes; at first, a precursor of proFLG was made in the cells of the granular cell layer, which becomes the principal ingredient of keratohyalin granules [4]
When the keratinocyte of the granular cell layer turns into the stratum corneum, it is decomposed and the proFLG turns into FLG [4]

Summary

Introduction

Dry skin is caused by some factors including insufficient in the emollient oil of the skin surface, the decrease in the natural moisturizing factor (NMF) of the stratum corneum, and the fragility of the stratum corneum barrier function by reduction of intercellular lipids and ceramide, etc. [1,2]. FLG is a protein of epidermal keratinocytes; at first, a precursor of proFLG was made in the cells of the granular cell layer, which becomes the principal ingredient of keratohyalin granules [4]. When the keratinocyte of the granular cell layer turns into the stratum corneum, it is decomposed and the proFLG turns into FLG [4]. FLG has the action which condenses the keratin fiber of the keratinocyte. For this reason, morphologically and much unlike the granule cells, the stratum corneum cell is made flat [5]. Morphologically and much unlike the granule cells, the stratum corneum cell is made flat [5]

Methods

Results

Conclusion