Effects of 3,3' ,4' ,5,7-pentamethylquercetin on intimal hyperplasia of vein grafts

Abstract

Objective Pentamethylquercetin (PMQ) has a role in cardiovascular protection. We investigate the effects of 3,3' ,4' ,5,7-pentamethylquercetin, a derivative of PMQ, on intimal hyperplasia of the vein grafts in rats both in vivo and in vitro. Methods The proliferation of vascular smooth muscle cells ( VSMC ) was induced with Ang Ⅱ (0. 1μmol/L, 24 h)while PMQ was administrated at six different dosages (0. 1, 0.3, 1,3, 10 and 30 μmoL/L). Cell viability was identified with MTT; ROS was measured with DCFH-DA; and the expression of NADPH oxidase subunits Nox1, p47phox, and p22phox mRNA were measured with real-time PCR. For the experiment in vivo, 24 SD rats were randomly assigned to control group and PMQ groups, the latter was further divided into three different dosage groups. In the control group, solvent was administrated daily via gavage. In PMQ groups, PMQ ( 12.5 mg/kg, 25 mg/kg, 50 mg/kg) was administrated daily respectively in the same way.All SD rats received operation performed by one person. Reversed external jugular vein was implanted into the external carotid of the same side with interrupted suture. 4 weeks after operation, all vein grafts were harvested. Status of the vein grafts was observed and tissue sections were analyzed with HE staining. The intimal hyperplasia ( intima/media area index and intima/media thickness index) of the vein grafts was assessed. Results Cell viability and ROS of VSMC induced by Ang Ⅱ were suppressed by PMQ. Cell viability and ROS of VSMC were increased substantially when treated with Ang Ⅱ. The therapeutic effects of PMQ could be initially identified at dose of0. 3 μmol/L, with a peak at 3 μmol/L. The effects decreased from 30μmol/L to 10 μmol/L. PMQ at dose of 0.1 μmol/L had no effect on cell viability and ROS of VSMC induced by Ang Ⅱ. PMQ also downregulated the mRNA expression of NADPH oxidase subunits Nox1, p47phox and p22phox induced by Ang Ⅱ. A peak effect was observed at 3μmoL/L and decreased at 30 μmol/L. PMQ at o. 1 μmol/L had no effect on mRNA expression of NADPH oxidase subunits induced by Ang Ⅱ. As compared with control group, PMQ decreased intima/media area index ( 1. 64 ±0.20 in control, 0. 74 ±0.18 at 12.5 mg/kg, 1.09 ±0.17 at 25 mg/kg, 1.21 ± 0. 21 at 50 mg/kg) and intima/media thickness index ( 1.34 ± 0. 24 in control, 0.67 ± 0. 17 at 12.5 mg/kg, 0. 74 ± 0.14 at 25 mg/kg, 0.93 ± 0. 18 at 50mg/kg) at three dosages after implantation. Conclusion PMQ may suppress the proliferation of VSMC and inhibit neointima hyperplasia of vein grafts in rats. The effects may be attributed to the anti-oxidative activity and the downregulation of mRNA expression of NADPH oxidase subunits Noxl, p47phox and p22phox. Key words: Pentamethylquercetin; Graft occlusion, vascular; Restenosis; Ang Ⅱ; NADPH oxidase