RESUMO
In insects, tyrosinase plays important roles in normal developmental processes, such as cuticular tanning, scleration, wound healing, production of opsonins, encapsulation and nodule formation for defense against foreign pathogens. Thus, tyrosinase may be regarded as a potential candidate for novel bioinsecticide development. A family of alkyl 3,4-dihydroxybenzoates (C6-C9), new tyrosinsase inhibitors, were synthesized. Their inhibitory effects on the activity of tyrosinase have been investigated. The results showed all of them could inhibit the activity of tyrosianse effectively. The order of potency was nonyl 3,4-dihydroxybenzoate (C9DB) > octyl 3,4-dihydroxybenzoate(C8DB) > heptyl 3,4-dihydroxybenzoate(C7DB) > hexyl 3,4-dihydroxybenzoate (C6DB). The kinetic analysis of these four compounds on tyrosinase was taken to expound their inhibitory mechanism. The research of the control of insects in agriculture was taken as C6DB for example. C6DB could inhibit the development and molting of Plutella xylostella effectively. To clarify its insecticidal mechanism, we researched the expression of tyrosinase in the P. xylostella treated with C6DB by real-time quantitative PCR. The results showed C6DB could inhibit the expression of tyrosinase in the P. xylostella as expected.