Title

 

Authors

R. Bertin^a, M. Montopoli^a, L. Soldà^b, M. Martínez-Vázquez^d, A. García-Argaéz^c, L. Caparrotta^a, G. Froldi^a*
 
aDepartment of Pharmacology and Anaesthesiology, University of Padova, Largo E. Meneghetti 2, 35131 Padova, Italy. ^bDepartment of Chemical Sciences, University of Padova, via Marzolo 1, Padova 35131, Italy. ^cDepartment of Pharmaceutical Sciences, University of Padova, Via Marzolo 5, 35131 Padova, Italy. ^dInstituto de Química,  Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Coyoacán 04510, México D.F. 

 

Abstract

The genus Casimiroa (Rutaceae) includes few spontaneous species in Central America and Mexico; among these C. edulis Llave et Lex., C. pubescens Ramirez and C. calderoniae  F. Chiang & Medrano are the most common. The best known species is C. edulis, commonly named "zapote blanco”, an evergreen tree known for its edible fruits and for traditional medicinal uses, now cultivated in many subtropical countries. The decoction of the leaves or the seeds is traditionally used for treating anxiety, insomnia and hypertension. We studied the properties of hexanic and methanolic extracts of Casimiroa (20 μg/ml) and of isolated coumarin and flavonoid compounds on rat arterial smooth muscle. Further, we determined their scavenging activities by using DPPH method. The extracts always gave a relaxation of precontracted rat arterial tissues; the dilatation was higher for seed methanolic extracts from C. edulis and C. pubescens. Also, isolated phenolic compounds such as imperatorin, herniarin and 5,6,2’,3’,4’-pentamethoxyflavone induced vasorelaxation on phenylephrine-precontracted arterial tissues. To study the pharmacological mechanism involved in the vasorelaxation, we used selective inhibitors of different receptor subtypes or enzymes as atropine, pyrilamine, nifedipine, L-N^G-nitro-argininemethylester (L-NAME) and diethyl-dithiocarbamate (DDTC). Further, we compared the action of extracts and isolated compounds with the vasorelaxation induced by acetylcholine and sodium nitrite.
The second step of our research was the determination of antioxidant activities by DPPH method. The scavenging activities of Casimiroa extracts were higher in comparison to each phenolic compound. C. edulis hexanic leaf extract, seed extract and methanolic seed extract at 600 mg/ml showed an antiradical activity of 77.0±9.2%, 24.2±2.9% and 72.0±5.6%, respectively. Also C. pubescens methanolic leaf extract and seed extract at the same concentrations pointed out an antioxidant activity of 84.7±0.2% and 58.4±4.3%, respectively. Among the compounds isolated from Casimiroa extracts, imperatorin and pentamethoxyflavone (5mM) revealed an antioxidant activity of 71.3±0.2% and 30.7±1.3%, while the coumarin derivatives showed a very low antioxidant profile (11.5±2.5% for herniarin and 4.8±0.4% for pentamethoxyflavone). Always the Casimiroa extracts showed an antioxidant activity less pronounced than the one displayed by quercetin, a well known antioxidant used as standard. In particular, leaf extracts induced higher antioxidant activity than the seed one. Among the organic compounds imperatorin showed the most relevant antioxidant activity, followed by herniarin and pentamethoxyflavone.
The experimental remarks support the traditional use in Mexican medicine of Casimiroa as hypotensive treatment. Also, the antioxidant synergism among the compounds which are in Casimiroa extracts could be useful in preventing cardiovascular diseases.