A series of prenylflavonoids with multiple hydroxyl groups were synthesized and evaluated for their vasorelaxant activities against rat aorta rings pre-contracted by phenylephrine (PE), as well as their neuroprotective effects against OGD induced PC12 cell injury. The results indicated that the prenyl group at A-ring of prenylflavonoids, as well as hydroxyl groups at B-ring was important for their activities. (+/-)Leachianone G 1b, bearing 8-prenyl and 2',4'-dihydoxyl groups, exhibited the most potent vasorelaxant and neuroprotective effects.