Zinc(II) Complexes of Amino Acids as New Active Ingredients for Anti-Acne Dermatological Preparations.

Elżbieta Płuciennik,Piotr Nowaczyk,Katarzyna Zawadzka,Urszula Kalinowska-Lis,Aleksandra Felczak,Michał Abendrot,Ewelina Piątczak

doi:10.3390/ijms22041641

Abstract

Zinc compounds have a number of beneficial properties for the skin, including antimicrobial, sebostatic and demulcent activities. The aim of the study was to develop new anti-acne preparations containing zinc–amino acid complexes as active ingredients. Firstly, the cytotoxicity of the zinc complexes was evaluated against human skin fibroblasts (1BR.3.N cell line) and human epidermal keratinocyte cell lines, and their antimicrobial activity was determined against Cutibacterium acnes. Then, zinc complexes of glycine and histidine were selected to create original gel formulations. The stability (by measuring pH, density and viscosity), microbiological purity (referring to PN-EN ISO standards) and efficacy of the preservative system (according to Ph. Eur. 10 methodology) for the preparations were evaluated. Skin tolerance was determined in a group of 25 healthy volunteers by the patch test. The preparations containing zinc(II) complexes with glycine and histidine as active substances can be topically used in the treatment of acne skin due to their high antibacterial activity against C. acnes and low cytotoxicity for the skin cells. Dermatological recipes have been appropriately composed; no irritation or allergy was observed, and the preparations showed high microbiological purity and physicochemical stability.

Highlights

Zinc acts as cofactor for over 1000 biochemical reactions impacting the growth, differentiation and development of cells in different tissues [1]
The present study evaluated their cytotoxicity against human skin fibroblasts (1BR.3.N cell line) and human epidermal keratinocytes
Antimicrobial activity must be evaluated for products that may demonstrate microbial growth during use or storage

Summary

Introduction

Zinc acts as cofactor for over 1000 biochemical reactions impacting the growth, differentiation and development of cells in different tissues [1]. It is an essential microelement and its proper skin content plays a key role in the prevention of many skin diseases [2]. Several mechanisms have been proposed for the effects of zinc in acne-affected skin, with the most significant being antimicrobial activity against C. acnes and lipase inhibition, reduction in sebum production [6], anti-inflammatory effects [6,7] and 5α-reductase inhibition [8]. The pathogenesis of acne vulgaris is extremely complex and has not been fully described; it is believed that this disease is caused by the excessive production of androgen hormones, follicular hyperkeratinization and the colonization of hair follicles by bacteria, including strains of Cutibacterium acnes and Staphylococcus epidermidis [9,10]

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