3 years ago

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

Julieta Roco, Liliana Sierra, María Ines Isla, Susana Jerez, Gabriela Alarcón, Iris Catiana Zampini

Abstract

This study evaluated the effects of a Zuccagnia punctata standardized hydroalcoholic extract (ZpE) and three of its major flavonoids [2′,4′-dihydroxychalcone (DHC), 7-hydroxyflavanone (HF) and 3,7-dihydroxyflavone (DHF)] on the vascular reactivity of aortic rings with endothelial dysfunction induced by feeding rabbits on a high cholesterol diet. Rabbits were fed with either normal chow or a diet containing 1% cholesterol for 5–6 weeks. Isometric contractions were 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) showed concentration-dependent relaxation of arteries pre-contracted with phenylephrine. ZpE (4 × 10−2, 4 × 10−1 and 4 µg gallic acid equivalent/ml), HF (10−9, 10−7, 10−5 M), DHC (10−9 M) and DHF (10−9 M) added to the bath improved acetylcholine affinity. Pre-treatment of arteries with ZpE (4 × 10−2 µg gallic acid equivalent/ml) and DHC (10−9 M) reduced phenylephrine-induced contraction. Incubation with the higher dose of ZpE (4 µg gallic acid equivalent/ml) reduced the angiotensin II-maximal contraction (C max) acting as a non-competitive antagonist, while DHC and DHF (10−5 M) caused a non-parallel rightward of the angiotensin II-concentration response curves and reduced the C max acting as mixed antagonists. ZpE (4 × 10−2 µg gallic acid equivalent/ml), DHC and DHF (10−9 M) caused a rightward displacement of angiotensin II-concentration response curves acting as competitive antagonists. In conclusion, the present study demonstrated that a ZpE and its major flavonoids had beneficial effects in arteries with vascular dysfunction induced by hypercholesterolemia. Therefore its use as herbal medicine to prevent cardiovascular risks factors may be promising.

Publisher URL: https://link.springer.com/article/10.1007/s00044-017-1934-6

DOI: 10.1007/s00044-017-1934-6

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