Farrerol can attenuate the aortic lesion in spontaneously hypertensive rats via the upregulation of eNOS and reduction of NAD(P)H oxidase activity.

Farrerol, a typical natural flavanone, is the major active component of Rhododendron dauricum L. The objective of this study was to evaluate the attenuation effect of farrerol against the aortic lesions in spontaneously hypertensive rats (SHR) for the first time. Twelve-week-old male SHR were orally administered with farrerol (50mg/kg/day), verapamil (50mg/kg/day, positive control), or vehicle for 8 weeks (n=10 in each group). Age-matched Wistar-Kyoto rats (WKY) served as normal controls (n=10). Our results revealed that farrerol significantly reduced the systolic blood pressure in SHR (from 177±4mmHg to 158±5mmHg) and also dramatically attenuated the aortic lesion, which is characterized by decreased media thickness, wall area, media-lumen ratio, nuclei size and an increased nuclei number (P<0.05). Moreover, the levels of O2(-) along with NAD(P)H oxidase activity were reduced (P<0.05), while the activity of endothelial nitric oxide synthase (eNOS) was elevated (P<0.05) in aortic homogenates after the intervention of farrerol. Furthermore, farrerol upregulated the expression of eNOS in both of mRNA and protein levels, accompanied by the downregulated mRNA and protein expression of p22(phox) (P<0.05), an essential subunit for NADPH oxidase activity. Our findings indicated that farrerol has a significant protective effect against the aortic lesion in SHR, which may be related to the enhanced eNOS activity and reduced NAD(P)H oxidase activity.