Characterization of Retinol Stabilized in Phosphatidylcholine Vesicles with and without Antioxidants.

Yekaterina G Chmykh,Jay L Nadeau

doi:10.1021/acsomega.0c02102

Abstract

Retinol stability has been reported to be improved by encapsulation in liposomes, both with and without cholesterol. However, this improvement is limited because of lipid peroxidation. In this study, we compare the stability of retinol in phosphatidylcholine liposomes under ultraviolet (UV) light or standard room air, with and without the addition of antioxidants. Both butylated hydroxytoluene (BHT) and a proprietary mix (StoppOx) improved the shelf stability from <10 to over 30 d. The addition of cholesterol had no effect. Fluorescence imaging showed a heterogeneous distribution of retinol within the vesicles, including within the aqueous layer. Fluorescence lifetimes were equally heterogeneous. Under UV irradiation, StoppOx protected retinol for significantly longer than BHT and via different mechanisms. This suggests that natural antioxidants work well to improve the retinol stability, but that further work to determine the optimal vesicle structure remains to be performed.

Highlights

Retinol is used in pharmaceuticals and cosmetics for dermal applications to correct hyperpigmentation, reduce the appearance of fine lines, and treat acne and atopic dermatitis
Reactive oxygen species (ROS), including singlet oxygen, may be produced.[7−9] Endogenous photosensitizers in cells result in the production of a large number of photoproducts not predicted from simple solutions; these products may damage DNA and cell membranes directly or indirectly (Scheme 1)
We found that StoppOx was as effective as butylated hydroxytoluene (BHT) in preserving retinol under both ambient conditions and UV light

Summary

Introduction

Retinol (vitamin A) is used in pharmaceuticals and cosmetics for dermal applications to correct hyperpigmentation, reduce the appearance of fine lines, and treat acne and atopic dermatitis. Irradiated retinol can activate photosensitizers, such as chlorophyll, rose bengal, or riboflavin, with drastic alteration of the resulting photoproducts.[6] Depending upon the conditions, reactive oxygen species (ROS), including singlet oxygen, may be produced.[7−9] Endogenous photosensitizers in cells result in the production of a large number of photoproducts not predicted from simple solutions; these products may damage DNA and cell membranes directly or indirectly (Scheme 1) Because these effects are well known, most retinoid preparations are intended as “night creams” with use during the day not recommended. Most retinol preparations sold to cosmetics manufacturers are preserved with BHT

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