RESUMO
In our searching for novel tyrosinase inhibitors from natural sources, (S)-N-trans-feruloyloctopamine isolated from garlic skin was found to be a potential mushroom tyrosinase inhibitor. Here, we examined the effects of the potential tyrosinase inhibitor in B16F10 cells on intracellular melanin contents, cytotoxicity, and the signaling mechanism involved in the expression of tyrosinase. The results showed the inhibitor displayed little or no cytotoxicity at all concentrations examined and decreased the relative melanin contents in a dose-dependent manner in the α-MSH-stimulated B16F10 cells. Real-time PCR and Western blot analysis showed that it inhibits melanogenesis signaling by down-regulates mRNA and protein expression levels of tyrosinase, which leads to a lower melanin contents. These results suggested that (S)-N-trans-feruloyloctopamine was an ideal tyrosinase inhibitor, and could be used in food and medical industry.
Assuntos
Ácidos Cumáricos/farmacologia , Inibidores Enzimáticos/farmacologia , Alho/química , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Melaninas/metabolismo , Melanoma/metabolismo , Monofenol Mono-Oxigenase/antagonistas & inibidores , Monofenol Mono-Oxigenase/genética , Octopamina/análogos & derivados , Agaricales/enzimologia , Animais , Linhagem Celular Tumoral , Ácidos Cumáricos/química , Ácidos Cumáricos/isolamento & purificação , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/química , Inibidores Enzimáticos/isolamento & purificação , Melanoma/patologia , Camundongos , Monofenol Mono-Oxigenase/metabolismo , Octopamina/química , Octopamina/isolamento & purificação , Octopamina/farmacologia , Relação Estrutura-AtividadeRESUMO
Reverse-phase HPLC coupled with photodiode array detection was used for the simultaneous separation and determination of naturally occurring adrenergic amines (octopamine, synephrine and tyramine) in fruits and dry extracts of Citrus aurantium L. var. amara and in herbal medicines derived therefrom. Synephrine was the main component in fruits (0.10-0.35%) and in dry extracts (3.00-3.08%) and was present in the range 0.25-0.99% in herbal medicines. Flavanones were analysed in the same samples using a reverse-phase HPLC technique which allowed the identification and quantification of neoeriocitrin, narirutin, naringin, hesperidin, neohesperidin, naringenin and hesperetin. C. aurantium fruits and derivatives contained mainly glycosylated flavanones: in particular, naringin and neohesperidin were found to be the major flavonoids and their concentrations ranged from 1.80 to 26.30 and from 3.90 to 14.71 mg/g, respectively. The levels of aglycones were very low in all samples tested.