The antioxidant activities and polyphenolic levels of "assa peixe," "cambara," and "morrão de candeia" Brazilian honeys were investigated. Phenolic extracts of 11 honeys were evaluated spectrophotometrically to determine their total phenolic and flavonoid contents, and their antioxidant activities were measured using DPPH, ABTS, and FRAP assays. High-performance liquid chromatography coupled with diode array detection was applied to determine the phenolic composition of the honey extracts. The presence of fourteen phenolic compounds was established (eleven phenolic acids and three flavonoids), as well as HMF and abscisic acid. Principal component analysis was applied to classify the honey samples according to their floral origins.

Dezenove dialquilfosforilidrazonas com diferentes substituintes no anel aromático foram avaliadas como inibidores potenciais de tirosinase, que poderiam ser usadas como agentes eficientes no controle de desordens de pigmentação. A atividade inibitória foi medida através de uma modificação do método de UV-Vis de Patil e Zucker. Os ensaios foram realizados com soluções contendo tampão fosfato, L-3,4-diidroxifenilalanina (L-DOPA), EDTA, tirosinase e diferentes concentrações de compostos organofosforados e a formação de dopacromona foi determinada através do monitoramento da absorvância a 475 nm. Três compostos foram os mais ativos da série (CI50 = 105 ± 20 µmol L-1), (CI50 = 127 ± 16 µmol L-1) e (CI50 = 188 ± 27 µmol L-1), sendo de 3 a 7 vezes mais ativos do que o ácido ascórbico (CI50 = 730 µmol L-1), utilizado como controle. O composto mais ativo é apenas 1,5 vezes menos ativo do que o ácido kójico (IC50 = 69,4 µmol L-1), que é utilizado comercialmente. Esta investigação pode levar à descoberta de agentes potentes contra importantes desordens de pigmentação inclusive a hiperpigmentação.

Nineteen dialkylphosphorylhydrazones with different substituents at the aromatic ring were evaluated as potential tyrosinase inhibitors, which could then be used as efficient agents in the control of pigmentation disorders. The inhibition activity was measured by a modified Patil and Zucker UV-Vis method. Briefly, the assays were carried out with solutions containing phosphate buffer, L-3,4-dihidroxyphenylalanine (L-DOPA), (EDTA), tyrosinase and varying concentrations of organophosphorus compounds. The formation of dopachromone was determined by monitoring the absorbance at 475 nm. Three compounds were found to be the most active compounds of the series (IC50 = 105 ± 20 µmol L-1), (IC50 = 127 ± 16 µmol L-1) and (IC50 = 188 ± 27 µmol L-1), being three to seven times more active than ascorbic acid (IC50 = 730 µmol L-1), used as a standard. The most active compound is only 1.5 times less potent than the commercial kojic acid (IC50 = 69.4 µmol L-1). This study may lead to the discovery of potent agents against very important pigmentation disorders including hyperpigmentation.