Vasodilator activity of extracts of field Alpinia purpurata (Vieill) K: Schum and A. zerumbet (Pers.) Burtt et Smith cultured in vitro

Abstract

Nowadays, the high blood pressure is one of the main causes of death and cardiovascular diseases. Vasodilator drugs are frequently used to treat arterial hypertension. Experiments were undertaken to determine whether hydroalcoholic extracts obtained from leaves of field-grown Alpinia purpurata and A. zerumbet cultured in vitro under different plant growth regulators induce a vasodilator effect on Wistar rat mesenteric vascular bed pre-contracted with norepinephrine. Plant extracts were able to induce a long-lasting endothelium-dependent vasodilation. Efficiency on activity of A. purpurata reached 87% at concentration of 60 mg. The extract of A. zerumbet maintained in medium containing IAA, induced the relaxation (17.4%) at 90 μg, as compared to the control (MS0) that showed a better vasodilator effect (60%). These results are in agreement with the quantification of phenolic compounds in the extracts, which were 50% lower for those plants cultured in IAA. A. purpurata was assayed for the first time in relation to its vasodilator activity. This paper showed a strong probability of correlation between the pharmacological activities of A. purpurata with their content in phenolic compounds. Atualmente, a hipertensão arterial é uma das maiores causas de morte e de doenças cardiovasculares. Os vasodilatadores são freqüentemente utilizados no tratamento da hipertensão. Extratos hidroalcoólicos de Alpinia purpurata de campo e de A. zerumbet cultivada in vitro sob diferentes reguladores de crescimento vegetal foram ensaiados no leito mesentérico de ratos Wistar. Os extratos de A. purpurata e A. zerumbet produziram efeito vasodilatador com padrão de resposta dose-dependente de duração prolongada. Extratos da espécie A. purpurata tiveram efeito vasodilatador de 87% na dose de 60 μg. O extrato obtido de folhas de A. zerumbet oriundas das culturas mantidas em meio contendo AIA (ácido indol acético) inibiu o relaxamento (17,4%) na dose de 90 μg em relação ao controle (MS0), com o qual foi verificado melhor efeito vasodilatador (60%). Estes resultados estão de acordo com a concentração de fenóis totais que foi 50% menor para os extratos de plantas cultivadas in vitro em AIA. A espécie A. purpurata foi pela primeira vez ensaiada quanto à atividade vasodilatadora. Os resultados obtidos indicaram a presença de substâncias fenólicas provavelmente correlacionadas à ação terapêutica de A. purpurata.

Hypotensive effect and endothelium-dependent vascular action of leaves of Alpinia purpurata (Vieill) K. Schum

“…We also observed a significant enrichment of polyphenols in AP leaves and EEAP (Table I). A similar result was observed by Victório et al (2009a) using the same method of quantification (30.1 ± 1.8 µg EP mg -1 ). Analysis of the infrared spectrum revealed the inorganic nature of the IAP: bands assigned to C-H stretching (2900-2800 cm -1…”

“…Acetylcholine induced a hypotensive effect both before and after the dose-effect curves of the EEAP and IAP were measured (WKY: -45 ± 5% and -43 ± 3%, respectively; SHR: -53 ± 3% and -51 ± 2%, respectively), indicating vascular integrity. This measurement was important, since vascular relaxation induced by acetylcholine is dependent on the integrity of the endothelial cells (Batlouni, 2001;Victório et al, 2009a). Victório et al (2009a) reported the vasodilatory effect of the hydroalcoholic extract of AP in mesenteric bed from Wistar rats pre-contracted with norepinephrine.…”

“…Several studies have demonstrated medicinal plants' effects on blood pressure by various mechanisms, such as increased release of · NO and EDHF (Rocha et al 2007;Victório et al, 2009a;Khan et al, 2012;Senejoux et al, 2012). The hydroalcoholic and aqueous extracts (De Moura et al, 1998) and essential oils (Victório, Kuster, Lage, 2009b;Barcelos et al, 2010) of the Alpinia zerumbet (Pers.)…”

“…Burtt et Smith (AZ) have been reported to promote a hypotensive effect. Another species of Alpinia, the Alpinia purpurata (Vieill) K. Schum (AP), shows phytochemical similarity with AZ in terms of the composition of its essential oil (Victório et al, 2009a) and the presence of flavonoids therein (Victório, Kuster, Lage, 2009c). Mladenka et al (2010) revised the benefits of flavonoids in the prevention and treatment of cardiovascular diseases, reporting their capacity to reduce blood pressure in hypertensive rats without any normotensive effect.…”

“…Mladenka et al (2010) revised the benefits of flavonoids in the prevention and treatment of cardiovascular diseases, reporting their capacity to reduce blood pressure in hypertensive rats without any normotensive effect. Victório et al (2009a) reported that the hydroalcoholic extract of AP leaves is rich in flavonoids and can elicit relaxation of the mesenteric vascular bed. However, the participation of relaxant factors from the endothelium in this action (and their hypotensive effects) have not been evaluated yet.…”