An experimental study on depigmenting activity of 4-(p-hydroxyphenyl)-2-butanone in C57 black mice

The authors previously reported three cases of occupational leukoderma in workers engaged in a 4-(p- hydroxyphenyl)-2-butanone (HPB, Raspberry Ketone) manufacturing process. These cases suggested that HPB might be a chemical causing the leukoderma and it had depigmenting activity. The purpose of this study is to evaluate the depigmenting activity of HPB by using laboratory animals. HPB, its two crude products and monomethyl ether of hydroquinone as the positive control were topically applied to the dorsal surface of C57 black mice. Depigmentation was shown in black mice to which HPB and its crude products were topically applied but the effect produced by these chemicals was weaker than that seen with monomethyl ether of hydroquinone. Though evidence of a reduction in melanocytes and pigmentation was not documented in the microscopic analysis, spectrophotometric assay showed a decrease in melanin content in the hair of mice to which HPB and the crude product had been applied. The results indicated a depigmenting activity of HPB and supported the conclusion that the leukoderma which we reported in a companion paper was induced by exposure to HPB and/or its crude products. Nevertheless, the potential of this depigmenting activity is so weak that the development of leukoderma due to these chemicals may be limited to those who are occupationally exposed.