Clinical and Experimental Pharmacology and Physiology (2006) 33, 109 – 113 Blackwell Publishing, Ltd. Original Article C. lyratiloba on cardiac and smooth muscles RR Almeidaet al. ACTIVITY OF CECROPIA LYRATILOBA EXTRACT ON CONTRACTILITY OF CARDIAC AND SMOOTH MUSCLES IN WISTAR RATS Roberta Ramos Almeida,* † Juliana Montani Raimundo,* Rodrigo Rodrigues Oliveira, ‡ Maria Auxiliadora Coelho Kaplan, ‡ Cerli Rocah Gattass, † Roberto Takashi Sudo* and Gisele Zapata-Sudo* *Departamento de Farmacologia Básica e Clinica, Instituto de Ciências Biomédicas, † Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde and ‡ Núcleo de Pesquisa de Produtos Naturais, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil SUMMARY 1. Brazilian forests show high diversity of medicinal plants and several are used in folk medicine for the treatment of hyper- tension and asthma. The aim of the present study was to inves- tigate the effects of a methanol extract (ME) of Cecropia lyratiloba and its flavonoid fraction (FF) on the contractility of cardiac, vascular and tracheal smooth muscles. 2. Twitches of rat papillary muscles were obtained with elec- trical stimulation and were recorded before and after exposure to increasing concentrations of ME and FF. 3. Cardiac depression was induced by FF. At 500 mg/mL FF, the amplitude of twitches was reduced to 56.7 ± 5.1% of control values (P < 0.05). 4. The contractile response to a single concentration of adren- aline (10 mmol/L) was measured before and after exposure to ME and FF in rat aorta rings with intact endothelium. Both ME and FF inhibited adrenaline-induced contractions of the aorta in a concentration-dependent manner. Adrenaline-induced con- trations were reduced to 46.4 ± 9.9 and 34.2 ± 6.9% (P < 0.05) of control in the presence of 500 mg/mL ME and FF, respectively. 5. The flavonoids isolated from FF, namely isoorientin and a mixture of orientin and isovitexin, were also tested in the aorta. These flavonoid do not seem to be responsible for the vasorelax- ant effects of ME and FF. 6. No changes were observed in acetylcholine-precontracted trachea when exposed to ME or FF. 7. Endothelium-dependent vasodilation induced by FF is likely to be mediated by the release of nitric oxide because vas- cular relaxation was abolished in the presence of N w -nitro-l- arginine methyl ester, an inhibitor of nitric oxide synthase. 8. In conclusion, vascular relaxation induced by ME and FF could explain the traditional use of the extract of C. lyratiloba for treatment of arterial hypertension. Key words: cardiac contractility, Cecropia lyratiloba, flavonoids, vasodilation. INTRODUCTION Brazilian forests show a high herbal diversity of medicinal plants, representing considerable potential for studies on the pharmacology, toxicology and chemistry of new drugs. 1 The Moraceae family, of the order Urticales, superorder Malviflorae, 2 has 19 genera in Brazil, including the Cecropia genus, which has more than 50 species widely distributed throughout Brazil. 3 Plants of the Cecropia genus are traditionally used for the treatment of bronchits, asthma, 4 arterial hypertension, 5 pulmonary infections 6 and anxiety. 7 Leaves of Cecropia hololeuca are used for the treatment of asthma and high blood pressure. Cecropia catharinenses has the same properties and is also used as a diuretic and antispasmodic agent. 6 There are ethnopharmacological reports of Cecropia glazioui Sneth being used as an antihypertensive, cardiotonic and anti-asthmatic agent. 7 The antihypertensive properties of Cecropia obtusifolia and Cecropia pachystachya have also been described previously. 8,9 However, the pharmacological properties of Cecropia lyratiloba have not yet been studied. It is important to find new products that produce vasodilation because the relaxation of vascular smooth muscle is the principal basis for the treatment of hypertension. Con- sidering the biological activities described for the plants of Moraceae family, including their cardiovascular effects, we investigated the actions of C. lyratiloba on cardiac and smooth muscles. In the present study, we used a methanol extract (ME) of Cecropia lyratiloba, its flavonoid fraction (FF) and two purified fractions. METHODS Plant material and extraction Cecropia lyratiloba was collected at Serra do Mendanha, Rio de Janeiro, Brazil. Botanical identification was performed at Núcleo de Pesquisa de Produtos Naturais by Dr Jorge Pedro Pereira Carauta and a voucher specimen (GUA 47028) has been deposited at the Alberto Castellanos Herbarium at Fundação Estadual de Engenharia do Meio Ambiente (FEEMA, Rio de Janeiro, Brazil). Leaves from C. lyratiloba (1.1 kg) were air-dried at 36∞C and extracted with methanol at room temperature. The dried methanol (MeOH) extract was suspended in H 2 O and partioned with hexane, dichloromethane, ethyl acetate (AcOEt) and butanol (BuOH). The ethyl acetate phase (15.4 g) was chromatographed on a silica gel column using CHCl 3 : MeOH : H 2 O (70 : 30 : 5) as the eluent and yielded three subfractions: (i) terpenoidic (0.3 g); (ii) flavonoid (2.3 g); and (iii) a tannin (3.5 g). The flavonoidid fraction was first purified and concen- trated in the stationary phase by high-speed countercurrent chromatography (HSCCC) using CHCl 3 : MeOH : H 2 O (46 : 25 : 29), the lower phase was used with mobile phase. Analysis of this flavonoid material by HPLC showed Correspondence: Dr Gisele Zapata-Sudo, Departamento de Farmacologia Basica e Clinica, Universidade Federal do Rio de Janeiro, Centro de Ciencias da Saude, Instituto de Ciencias Biomedicas, Bloco J, Sala 14, Rio de Janeiro, Brazil, 21941-590. Email: gsudo@farmaco.ufrj.br Received 4 March 2005; revision 23 September 2005; accepted 28 September 2005. © 2006 Blackwell Publishing Asia Pty Ltd