Vasorelaxant and hypotensive effects of the extract and the isolated flavonoid rutin obtained from Polygala paniculata L

• Published in: Journal of pharmacy and pharmacology Vol. 63; no. 6; pp. 875 - 881
• Main Authors: da Rocha Lapa, Fernanda, Soares, Kelly Cristina, Rattmann, Yanna Dantas, Crestani, Sandra, Missau, Fabiana Cristina, Pizzolatti, Moacir Geraldo, Marques, Maria Consuelo Andrade, Rieck, Lia, Santos, Adair Roberto Soares
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-06-2011
• Subjects: Animals; Antihypertensive Agents - pharmacology; Aorta - drug effects; Aorta - physiology; Atropine - pharmacology; Dose-Response Relationship, Drug; Enzyme Inhibitors - pharmacology; Guanylate Cyclase - antagonists & inhibitors; hypotensive; Male; Methylene Blue - pharmacology; NG-Nitroarginine Methyl Ester - pharmacology; nitric oxide; Phytotherapy; Plant Extracts - pharmacology; Polygala - chemistry; polygala paniculata; Potassium Channel Blockers - pharmacology; Pyrilamine - pharmacology; Rats; Rats, Wistar; rutin; Rutin - pharmacology; Vasodilator Agents - pharmacology; vasorelaxant
• ISSN: 0022-3573; 2042-7158
• DOI: 10.1111/j.2042-7158.2010.01240.x

Objectives  This study aimed to investigate the in‐vitro and in‐vivo cardiovascular effects of the crude hydroalcoholic extract from Polygala paniculata (HEPP) in rats.
Methods  The procedures were performed on aortic rings and on normotensive anaesthetized rats.
Key findings  When tested in endothelium‐intact aorta rings, HEPP (30–1000 µg/ml) produced a significant non‐concentration‐dependent relaxing effect (∼40%), which was completely prevented by incubation with L‐NAME (nitric oxide synthase inhibitor), ODQ (soluble guanylate cyclase inhibitor) and partially inhibited by tetraethylammonium (TEA; a non‐selective potassium channel blocker) and charybdotoxin (a large‐ and intermediate‐conductance calcium‐activated potassium channel blocker). In contrast, atropine (a muscarinic receptor antagonist) or pyrilamine(a histamine H1 receptor antagonist) had no effect. Furthermore, oral administration of HEPP (30–300 mg/kg) in anaesthetized rats caused a dose‐dependent and sustained hypotensive action. This effect was unchanged by atropine or TEA, but was strongly reduced in rats continuously infused with L‐NAME or methylene blue. Moreover, rutin (1–3 mg/kg) administered by an intravenous route also caused a dose‐dependent hypotensive effect in rats.
Conclusions  Our results demonstrated that the extract obtained from P. paniculata induces potent hypotensive and vasorelaxant effects that are dependent on the nitric oxide/guanylate cyclase pathway. These effects could be related, at least in part, to the rutin contents in this extract.