Inhibitors of melanogenesis: a patent review (2009 - 2014).

INTRODUCTION: Melanogenesis is the process of producing the melanin pigment, in which a series of chemical and enzymatic pathways are involved. Modulation at any level of this process would become an important approach in the treatment of hyper- or hypopigmentation-related diseases. Since hyperpigmentation covers important issue in cosmetics, there is a need of such review to understand and update this field to the public domain. AREAS COVERED: In this review, authors discuss most recent melanogenesis inhibitors published in the patents since 2009. The up-to-date overview of classical catechol-based tyrosinase inhibitors to non-classical melanogenesis inhibitors with different mechanism of action is discussed. Inhibitors including small-interfering RNA and peptides from ∼ 30 patents and their associated literature are also discussed. EXPERT OPINION: Although a huge number of melanogenesis inhibitors have been reported, the future studies should be focused towards the identification of new inhibitors with a clear mechanism. The next breakthrough in the field therefore, is likely to come from the detailed structure-activity relationship studies of thioureas with improved therapeutic profiles. Targeting other parameters such as number or size of melanosomes, maturation of melanosomes and expression of melanogenic enzymes may give the best results to overcome toxicity and other formulation problems.