Excessive melanin production causes serious dermatological conditions as well as minor aesthetic problems (i.e. freckles and solar lentigo) The downregulation of tyrosinase, the key enzyme in melanin biosynthetic pathway, is a common strategy to treat such hyperpigmentation disorders and plant extracts have often proven to be valuable sources of tyrosinase inhibitors. Citral (a mixture of two structural isomers, cis- and trans-3,7-dimethyl-2,6-octadienal, also known as neral and geranial, in the typical 1/3 and 2/3 ratio) is an important fragrance ingredient which has shown anti-tyrosinase potential . It is highly concentrated in the essential oils (EOs) of Cymbopogon schoenanthus (L.) Spreng., Litsea cubeba (Lour.) Pers., Melissa officinalis L. and Verbena officinalis L. however to the best of the authors’ knowledge, only L. cubeba EO has been investigated as potential skin-whitening agent . This work evaluates the in-vitro tyrosinase inhibitory activity of these EOs and studies through a bio-assay oriented fractionation whether the different chemical compositions influence the EOs overall inhibitory activities by possible synergistic, additive and/ or competitive interactions among EOs components. The inhibitory activities of C. schoenanthus and M. officinalis EOs with negligible ( + )-citronellal amounts were in-line with their citral content. Contrary, L. cubeba and V. officinalis EOs inhibited mushroom tyrosinase to considerably greater extent as they contained β-myrcene which additively contributed to the EOs overall activities. Similar considerations were done for M. officinalis EO with high ( + )-citronellal content which increased citral activity potentially via synergistic interaction as it displayed no activity when tested individually. Conflict of Interest; Funding (Source, ID) The authors declare no conflict of interest References  Matsuura et al. J. Agric. Food Chem.2006, 54, 2309–2313.  Huang et al. J. Essent. Oil Res.2013, 25, 112–119
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