Abstract
The increased amount of melanin leads to skin disorders such as age spots, freckles, melasma and malignant melanoma. Tyrosinase is known to be the key enzyme in melanin production. Plants and their extracts are inexpensive and rich resources of active compounds that can be utilized to inhibit tyrosinase as well as can be used for the treatment of dermatological disorders associated with melanin hyperpigmentation. Using in vitro tyrosinase inhibitory activity assay, extracts from 13 plant species from Brazilian Cerrado were evaluated. The results showed that Pouteria torta and Eugenia dysenterica extracts presented potent in vitro tyrosinase inhibition compared to positive control kojic acid. Ethanol extract of Eugenia dysenterica leaves showed significant (p<0.05) tyrosinase inhibitory activity exhibiting the IC50 value of 11.88 µg/mL, compared to kojic acid (IC50 value of 13.14 µg/mL). Pouteria torta aqueous extract leaves also showed significant inhibitory activity with IC50 value of 30.01 µg/mL. These results indicate that Pouteria torta and Eugenia dysenterica extracts and their isolated constituents are promising agents for skin-whitening or antimelanogenesis formulations.
Highlights
Tyrosinase is a copper containing enzyme that catalyzes two distinct reactions, involving molecular oxygen with various phenolic substrates: the o-hydroxylation of monophenols to o-diphenols and the subsequent oxidation of o-diphenols to o-quinones [1,2]
Thirteen cerrado plant species were selected for investigation, and 33 extracts were tested for tyrosinase inhibitory activity
The most active extracts tyrosinase belonged to Pouteria species as well as Eugenia dysenterica and Stryphnodendron adstringens
Summary
Tyrosinase (polyphenoloxidase, PPO, E.C. 1.14.18.1) is a copper containing enzyme that catalyzes two distinct reactions, involving molecular oxygen with various phenolic substrates: the o-hydroxylation of monophenols to o-diphenols (monooxygenase or cresolase activity) and the subsequent oxidation of o-diphenols to o-quinones (diphenolase or catecholase activity) [1,2]. Tyrosinase converts L-tyrosine, monophenol, firstly to L-DOPA (o-diphenol) and this to o-dopaquinone, which is spontaneously cyclated in form of leukodopachrome and quickly converted into dopachrome, which polymerizes and form melanin [1,3,4]. Melanin is one of the most widely distributed pigments and is found in bacteria, fungi, plants and animals. The color of mammalian skin and hair is determined by a number of factors, the most important of which is the degree and distribution of melanin pigmentation [5]. The increased amount of melanin results in pigmentary skin disorders and occurs as a result of both genetic and enviromental factors [7,8]
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