1. Field of the Invention
The present invention relates to particular cysteine derivatives. Furthermore, the present invention relates to methods for producing particular cysteine derivatives, cosmetic agents which contain particular cysteine derivatives, and the like.
2. Discussion of the Background
In human pigment cells (melanocytes) in the skin, melanin is produced utilizing L-cysteine and L-tyrosine. When a greater amount of L-tyrosine, which is a starting material for eumelanin, is utilized for the synthesis of melanin, production of eumelanin is promoted and the skin becomes dark. On the other hand, when a greater amount of L-cysteine is utilized for the synthesis of melanin, production of eumelanin is suppressed, and the skin becomes closer to yellow. Therefore, it is considered that production of eumelanin is suppressed by supplying L-cysteine during melanin synthesis.
Heretofore, many attempts have been made to utilize L-cysteine as cosmetics such as whitening agents utilizing L-cysteine and the like. However, L-cysteine is easily oxidized, and has problems such as poor stability and bad odor for formulating as a cosmetic agent or skin external preparation.
To solve such problem, the development of a cysteine derivative with improved stability has been considered. JP-B-48-15938 discloses that L-2-methylthiazolidine-2,4-dicarboxylic acid is extremely stable as compared to conventional cysteine derivatives.
In addition, JP-A-2009-227660 discloses that a cysteine derivative obtained by esterification of L-2-methylthiazolidine-2,4-dicarboxylic acid or a salt thereof is useful as a whitening agent etc. since it has an eumelanin production suppressive effect and is stable. Furthermore, JP-A-2010-1239 discloses that 2-methylthiazolidine-2,4-dicarboxylic acid or a derivative thereof has a whitening action.
On the other hand, J. Biological Chem., (1937)121 539-48 discloses N-acetyl-2-methylthiazolidine-2,4-dicarboxylic acid and N-acetyl-2-methylthiazolidine-2,4-dicarboxylic acid anhydride; however, it does not describe their properties such as stability etc. and physiological activities thereof, nor does it suggest or report use for cosmetic agents or skin external preparations or whitening effects thereof.