槲皮素对黄粉虫血淋巴酚氧化酶的生理效应

用酶标仪法测定了槲皮素对黄粉虫Tenebrio molitor酚氧化酶（phenoloxidase, PO）的生物活性。结果表明：在离体条件下，对黄粉虫血淋巴PO的IC₅₀为0.625 mmol/L。在活体情况下，当槲皮素-DMSO溶液或槲皮素水悬浮液（5 μL）注入虫体后，在浓度低于1.0 mmol/L时对黄粉虫血淋巴PO具有激活作用，当浓度高于2.0 mmol/L时则对PO具有明显的抑制作用；单独注射5 μL DMSO溶液对PO活性亦有一定的激活作用。试虫被注射槲皮素后，PO活性在2～4 h内迅速下降，然后缓慢上升，处理8 h左右达到最高点，其后低浓度处理PO活性保持不变，而高浓度处理则逐渐下降，提示低浓度槲皮素可以引起试虫的免疫反应。在PO测活体系中加入0.5％的BSA后对PO活性无影响，并能使槲皮素在测活体系中保持稳定。

Physiological effect of quercetin on phenoloxidase from Tenebrio molitor

The physiological effect of quercetin on phenoloxidase (PO) from Tenebrio molitor was determined in vitro and in vivo. The results showed that the inhibition concentration showing 50% of the maximum inhibition (IC₅₀) was 0.625 mmol/L. The PO activity of hemolymph in vivo was increased when the quercetin-DMSO solution or quercetin-water suspension (5 μL) with concentration of 0.2-1.0 mmol/L was injected into the larvae of T. molitor;but the compound would decrease the PO activity when the concentration of quercetin was above 2.0 mmol/L. In addition, the PO activity was also increased when DMSO (5 μL) was injected into the tested insect in vivo.During 2-4 hours after injection of quercetin into the body of the insect, the PO activity was decreased rapidly, then went slowly up and reached the highest level 8 h after injection of the compound, and then dropped again except the low concentration treatment. The results suggest that quercetin at low concentration can cause immune response to the tested insect. When 0.5% BSA was added to the assay system, it had no effect on the PO activity, but could prevent quercetin from sedimentating.