Quercetin is one of the most abundant
flavonoids and the defense secondary metabolites in plants. In this study, the effect of
quercetin on the growth of the silkworm larvae was investigated.
Cytochrome P450 monooxygenases (P450s),
glutathione S-
transferases (
GSTs), and
carboxylesterases (COE) were assayed after exposure to different concentrations of
quercetin for 3 d (short-term) and 7 d (long-term), respectively. The results showed that the
weight gain of the silkworm larvae significantly decreased after the larvae were treated by different concentrations of
quercetin except for the treatment with 0.5%
quercetin. Activities of P450, GST, and COE were induced by 0.5 or 1% concentration of
quercetin. In the midgut, the induction activity of P450s was reached to the highest level (2.3-fold) by 1%
quercetin for 7 d, the highest induction activities of
GSTs toward CHP and CDNB were 4.1-fold and 2.6-fold of controls by 1%
quercetin after 7 d exposure, respectively. For COEs, the highest activity (2.3-fold) was induced by 0.5%
quercetin for 7 d. However, P450s in whole body were higher inducible activities in short-term treatment than those in long-term treatment. The responses of eight
cytochrome P450 (CYP) genes belonged to CYP6 and CYP9 families and seven GST genes were detected with real-time polymerase chain reaction. In addition, the genes induced by
quercetin significantly were confirmed by qRT-PCR. CYP6AB5, CYP6B29, and GSTe8 were identified as inducible genes, of which the highest induction levels were 10.9-fold (0.5%
quercetin for 7 d), 6.2-fold (1%
quercetin for 7 d), and 7.1-fold (1%
quercetin for 7 d), respectively.