Biocatalytic solutions to cyclomethicones problem in cosmetics

Silicones are polymers that have properties of great interest for cosmetic and personal care industry, especially D₄ (octamethylcyclotetrasiloxane) and D₅ (decamethylcyclopentasiloxane), generically named cyclomethicones. However, different studies show the hypothesis that the use of these products is harmful and, therefore, several countries have adopted legislative actions to limit their use in personal care and cosmetic products. Faced with this new situation, different cosmetic companies began to look for different alternatives to cyclomethicones, mainly: organomodified silicones or esters. The former are based on the addition of functional groups to the main chain of silicon and oxygen. The latter represent a totally different line, since their functional group is the ester, but they have properties similar to silicones. Esters, especially branched-chain ones are currently the more promising alternative to replace cyclomethicones in cosmetic formulations. Nowadays, most of them are obtained by chemical reactions that require high temperatures and non-selective /contaminant catalysts that lead to low-quality final products. As an alternative, biocatalytic synthesis occurs always at mild operation conditions supplying ultra-pure, odor, and colorless products with less wastes and side reactions. Therefore, biocatalysis is a valid and environmentally sustainable option for the synthesis of silicone-substitute esters used in cosmetic formulations.