In vitro induction of apoptosis, necrosis and genotoxicity by cosmetic preservatives: application of flow cytometry as a complementary analysis by NRU.

Abstract	Preservatives are used in cosmetics to prevent microbial contamination; however, some preservatives are not free of allergenic and cytotoxic potential. Allergenicity and cytotoxicity potential values are major aspects of preservative safety, which determine limitations and maximum concentration dose in a cosmetic product. The purpose of this study was to investigate and compare the in vitro apoptosis, necrosis and genotoxicity-inducing potential of five different types of preservatives: Phenoxyethanol (PE), Propylparaben (PP), Methylparaben (MP), Benzyl Alcohol (BA) and Ethylhexyl Glycerine (EG). In vitro experiments were carried out on human dermal fibroblasts by a quantitative flow cytometry method, using specific cell markers (Annexin V, Propidium Iodide and H2AX). We compared the resulting cell viability by means of neutral red uptake (NRU) and established the IC(50) . Our results showed that PE, PP, MP and BA have similar cytotoxic mechanisms (high apoptosis and necrosis levels only at the test concentration of 1%), whereas EG showed only an apoptosis pathway. For genotoxicity, both parabens yielded the highest values. Results obtained by flow cytometry for necrosis were comparable to those produced by NRU; however, NRU does not distinguish apoptosis from necrosis. We propose that flow cytometry is a more sophisticated methodology for understanding the cytotoxic mechanisms of cosmetic preservatives and can be used to complement the NRU.
Authors	C M de Carvalho, P F C Menezes, G C Letenski, C E O Praes, I H S Feferman, M Lorencini
Journal	International journal of cosmetic science (Int J Cosmet Sci) Vol. 34 Issue 2 Pg. 176-82 (Apr 2012) ISSN: 1468-2494 [Electronic] England
PMID	22118339 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Copyright	© 2011 Grupo Boticário. ICS © 2011 Society of Cosmetic Scientists and the Société Française de Cosmétologie.
Chemical References	Cosmetics Preservatives, Pharmaceutical
Topics	Adult Apoptosis (drug effects) Cells, Cultured Cosmetics Flow Cytometry Humans In Vitro Techniques Inhibitory Concentration 50 Mutagenicity Tests Necrosis Preservatives, Pharmaceutical (toxicity)

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