Extracts from Amazonian plants have inhibitory activity against tyrosinase: an in vitro evaluation

Dermatological disorders related to pigmentation result in tenuous hyper or hypopigmentation Cosmetic and pharmaceutical products containing depigmenting substances are used in the treatment of patients who have high pigmentation disorders, such as melasma or chloasma, post-inflammatory hyperpigmentation, senile lentigo and ephelides. Skin lightening agents are not yet totally effective or safe and therefore intensive research for the discovery of new agents is continuous. Enzyme inhibitors involved in melanogenesis, such as tyrosinase, have been discovered in Asian countries, including those isolated from plant extracts. The Brazilian flora has the highest species diversity in the world, and the chemical, pharmacological and cosmetic potential for the discovery of new skin whitening agents is in proportion with this biodiversity. For these reasons, 25 aqueous and 24 organic extracts obtained from 19 plants native to the Amazon rain forest and to the Atlantic forest, belonging to 11 different families, were evaluated as tyrosinase inhibitors. Nine out of 49 extracts showed inhibitory activity in the screening process. The 50% inhibitory activity (IA50) was calculated, revealing that the most active extracts were the organic extracts from the leaves and stem of Ruprechtia sp. (IA50 33.76 mg.mL -1) and the organic extract from the aerial organs of Rapanea parviflora (IA50 64.19 mg.mL -1).