L-Cystine+L-Glutathione: efficacy for a bright innovation

 The desire for white skin originally comes from traditional Asian values and beliefs. But this desire has also been reinforced by Western influences (for instance Caucasian models are often used in adverts for European or American cosmetic brands sold in Asian countries). A very interesting historical and cultural analysis of the relationship between beauty and white skin in China, India, Japan and Korea, as well as its translation into marketing messages, was published ten years ago.1 Whitening/lightening products are among the best-selling products in the Asian cosmetic industry and are also becoming very important in Middle-East, Africa and South America. In these areas, for many people, hyperpigmentation and skin dark spots are not only considered as aesthetic problems, but they are also synonymous of decreased self-esteem, premature skin ageing and may facilitate the occurrence of skin damages, exacerbated by sun exposure. 

The colour of the skin depends on the amount and localisation of cutaneous pigments: hemoglobin in the dermis, carotenoids  and the most important, melanin in the epidermis. Together with skin structures, these chromophores absorb, reflect and scatter the incident light, thus contributing to the perceived colour sensations.2-3 Asian people are particularly concerned by excessive or nonhomogeneous melanic pigmentation resulting in age spots, mottled pigmentation, melasma, etc. Therefore, they usually try to protect themselves from the sun and their obsession to attain a lighter skin tone is very well-known. That is why many skin lightening products are proposed in the Asian market, mainly used as topical products but also as food supplements. These treatments are based on different approaches which target either melanin biosynthesis or its transfer from melanocytes into keratinocytes or its degradation rate. Accelerating the epidermal turnover and desquamation by exfoliation is another way to achieve a skin-lightening effect by removing the outermost layers of keratinocytes with their melanin content.4-5 Many reviews discussing the melanogenesis and the factors which regulate and control the skin colour have been published.6 Briefly, melanin synthesis occurs in small organelles from melanocytes, catalysed by several enzymes, tyrosinase being the rate-limiting enzyme. Then, the melanosomes are transferred from melanocytes to the cytoplasm of keratinocytes through dendrites to produce the visible skin colour (Fig 1). Therefore, most strategies to achieve a lightening of the skin have been based on the modulation of the tyrosinase activity (i.e. inhibition of tyrosinase mRNA transcription, inhibition of tyrosinase catalytic activity, acceleration of tyrosinase degradation). A few other approaches have focused on blocking or reducing the transfer of the melanosomes between melanocytic cells and surrounding keratinocytes. 

All the above skin lightening treatments usually involve topical products. This article will present another approach with systematically administered actives, based on the fact that two types of melanin exist: a ‘light’ melanin (pheomelanin) and a ‘dark’ melanin (eumelanin), the latter being the major type in dark-skinned persons. Several ingredients such as amino acids, vitamin C, vitamin E and various botanicals are used by oral route to help lightening the skin. Among them, glutathione, a powerful intracellular antioxidant, has a special status. One can understand the use of antioxidants for skin lightening activity by their neutralising effects on reactive oxygen species which are known to activate melanogenesis or by their interaction with the tyrosinase enzyme. Interesting fact: pheomelanin is a polymer formed by the conjugation of cysteine or glutathione. We hypothesised that the oral supplementation with a food supplement containing BCF Life Sciences L-Cystine associated with glutathione could modify the balance between eumelanin and pheomelanin towards the ‘clear’ melanin type, producing consequently a whitening/lightening effect (Fig 1).