Beneficial effects of hydroalcoholic extract and flavonoids from Zuccagnia punctata in a rabbit model of vascular dysfunction induced by high cholesterol diet

Abstract

Abstract This study evaluated the effects of a Zuccagniapunctata standardized hydroalcoholic extract (ZpE) and threeof its major flavonoids [2′,4′-dihydroxychalcone (DHC), 7-hydroxyflavanone (HF) and 3,7-dihydroxyflavone (DHF)] onthe vascular reactivity of aortic rings with endothelial dysfunctioninduced by feeding rabbits on a high cholesteroldiet. Rabbits were fed with either normal chow or a dietcontaining 1% cholesterol for 5?6 weeks. Isometric contractionswere measured. Concentration response curves to ZpE(range from 4×10−2 to 4 ×10 μg gallic acid equivalent/ml),DHC, DHF or HF (range from 10−9 to 10−4 M) showedconcentration-dependent relaxation of arteries pre-contractedwith phenylephrine. ZpE (4×10−2, 4 ×10−1 and 4 μg gallicacid equivalent/ml), HF (10−9, 10−7, 10−5 M), DHC (10−9M) and DHF (10−9 M) added to the bath improved acetylcholineaffinity. Pre-treatment of arteries with ZpE (4×10−2 μg gallic acid equivalent/ml) and DHC (10−9 M)reduced phenylephrine-induced contraction. Incubationwith the higher dose of ZpE (4 μg gallic acid equivalent/ml)reduced the angiotensin II-maximal contraction (Cmax) actingas a non-competitive antagonist, while DHC and DHF(10−5 M) caused a non-parallel rightward of the angiotensinII-concentration response curves and reduced the Cmaxacting as mixed antagonists. ZpE (4 × 10−2 μg gallic acidequivalent/ml), DHC and DHF (10−9 M) caused a rightwarddisplacement of angiotensin II-concentration responsecurves acting as competitive antagonists. In conclusion, thepresent study demonstrated that a ZpE and its major flavonoidshad beneficial effects in arteries with vasculardysfunction induced by hypercholesterolemia. Therefore itsuse as herbal medicine to prevent cardiovascular risks factorsmay be promising.