New lupeol esters as active substances in the treatment of skin damage.

Jan Ogonowski,Maciej Szaleniec,Mohammad Saleem,Irena Eris,Elzbieta Sikora,Monika Pasikowska-Piwko,Barbara Miroslaw,Magdalena Malinowska,Agnieszka M. Wojtkiewicz

doi:10.1371/journal.pone.0214216

Abstract

The purpose of the research was to obtain new derivatives of natural triterpene lupeol and to evaluate their potential as active substances in the treatment of skin damage. Four new lupeol esters (propionate, succinate, isonicotinate and acetylsalicylate) and lupeol acetate were obtained using an eco-friendly synthesis method. In the esterification process, the commonly used hazardous reagents in this type of synthesis were replaced by safe ones. This unconventional, eco-friendly, method is particularly important because the compounds obtained are potentially active substances in skin care formulations. Even trace amounts of hazardous reagents can have a toxic effect on damaged or irritated tissues. The molecular structure of the esters were confirmed by 1H NMR, 13C NMR and IR spectroscopy methods. Their crystal structures were determined using XRD method. To complete the analysis of their characteristics, physicochemical properties (melting point, lipophilicity, water solubility) and biological activity of the lupeol derivatives were studied. Results of an irritant potential test, carried out on Reconstructed Human Epidermis (RHE), confirmed that the synthesized lupeol derivatives are not cytotoxic and they stimulate a process of human cell proliferation. The safety of use for tested compounds was determined in a cell viability test (cytotoxicity detection kit based on the measurement of lactate dehydrogenase activity) for keratinocytes and fibroblasts. The results obtained showed that the modification of lupeol structure improve its bioavailability and activity. All of the esters penetrate the stratum corneum and the upper layers of the dermis better than the maternal lupeol. Lupeol isonicotinate, acetate and propionate were the most effective compounds in a stimulation of the human skin cell proliferation process. This combination resulted in an increase in the concentration of cells of more than 30% in comparison to control samples. The results indicate that the chemical modification of lupeol allows to obtain promising active substances for treatment of skin damage, including thermal, chemical and radiation burns.

Highlights

Human skin, as the biggest organ in the human body, acts as a protective barrier
Atopic dermatitis, skin allergies and inflammatory reactions are nowadays a problem which is affecting more and more people. Another cause of skin damage is burn injury, which can be caused by heat, radioactivity, electricity, friction or contact with chemicals [2]
Cancer treatments using radiotherapy are a source of increasing numbers of skin damage

Summary

Introduction

As the biggest organ in the human body, acts as a protective barrier. Among other, it prevents toxic substances from penetrating into deeper, more hydrophilic skin structures. Other external conditions, including air pollution, electronic device radiation (blue ray) and the presence of controversial self-care product ingredients, may cause skin damage. Atopic dermatitis, skin allergies and inflammatory reactions are nowadays a problem which is affecting more and more people. Another cause of skin damage is burn injury, which can be caused by heat, radioactivity, electricity, friction or contact with chemicals [2]. Some of cancer therapies create an extensive surface area of wounds that are difficult to heal

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Conclusion