Since whitening is mentioned, then we have to pay attention to melanin.

Melanin is a kind of bio-pigment synthesized by melanocytes, which usually gather together to form melanocytes. The form and amount of melanin determine a person's skin color, hair color and pupil color. Simply put, melanin can be divided into two forms, one is eumelanin and the other is pheomelanin. The more eumelanin, the more black it appears. Conversely, the more pheomelanin, the more red it is.

The synthesis of eumelanin and pheomelanin shares an initial pathway and is divided into two branches in the middle. Both eumelanin and pheomelanin start from tyrosine or dopa and are catalyzed by tyrosinase. Next, add oxygen to synthesize dopaquinone. Starting from DQ, it is divided into two branches. With the participation of Cysteine, it moves towards the pheomelanin route. On the contrary, it leads to the synthesis of eumelanin.

Studies have shown that glutathione can indeed interfere with the synthesis of melanin, and its mechanisms mainly include:
1. Directly inhibit the activity of tyrosinase.

2. Free radicals can activate tyrosinase, and glutathione can scavenge free radicals and inhibit the activation of tyrosinase.

3. Glutathione is hydrolyzed to cysteine, so that the melanin synthesis pathway tends to pheomelanin.