Antioxidant

 The term Antioxidant generally refers to compounds that are used to stop the free radical lipid oxidation process. The phenolic AOs BHT (butylated hydroxytoluene) and BHA (butylated hydroxyanisole) are the most important ingredients presently used. They act as radical scavengers, strongly inhibiting radical chain reactions.

Metal ions catalyze radical generation and product deterioration. Therefore, chelating agents are often combined with phenolic antioxidants to form synergistic mixtures, enhancing the efficacy of the specific free radical scavengers.

Product deterioration is not only due to oxidative radical generation (autoxidation), which is most prominent in the case of natural oils, unsaturated fatty acids, and certain fragrances. Direct exposure to light can also result in photolytic radical generation, which has to be efficiently controlled using antioxidants. Therefore, products filled in transparent or translucent packaging and preparations directly exposed to light during use (e.g., bar soaps) often contain antioxidants as protectants.

Moreover, UVs can be used in these cases to reduce the degree of photolysis. Generally, water—and/or oil-soluble benzophenone derivatives are applied. If not, photofading of colored formulations, reduction of viscosity in gels and shampoos, and loss of fragrance activity are often observed.

After application, antioxidants in personal care products protect cell membranes and DNA in the nucleus from free radicals and oxidative damage. Many botanical extracts and oils, especially those derived from plants growing in extreme conditions, contain considerable amounts of potent natural antioxidants effective against many types of reactive species.