Hindawi Publishing Corporation Evidence-Based Complementary and Alternative Medicine Volume 2013, Article ID 402364, 8 pages http://dx.doi.org/10.1155/2013/402364 Research Article Antipoliovirus Activity of the Organic Extract of Eupatorium buniifolium: Isolation of Euparin as an Active Compound María Florencia Visintini Jaime, 1 Rodolfo H. Campos, 1 Virginia S. Martino, 2 Lucía V. Cavallaro, 1 and Liliana V. Muschietti 2 1 C´ atedra de Virolog´ ıa, Facultad de Farmacia y Bioqu´ ımica, Universidad de Buenos Aires, Jun´ ın 956 4 P, 1113 Buenos Aires, Argentina 2 C´ atedra de Farmacognosia, IQUIMEFA (UBA-CONICET), Facultad de Farmacia y Bioqu´ ımica, Universidad de Buenos Aires, Jun´ ın 956 2 P, 1113 Buenos Aires, Argentina Correspondence should be addressed to Liliana V. Muschietti; lmusch@fyb.uba.ar Received 9 April 2013; Revised 11 June 2013; Accepted 13 June 2013 Academic Editor: Rafaele Capasso Copyright © 2013 Mar´ ıa Florencia Visintini Jaime et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. he antiviral activity of the organic extract (OE) of Eupatorium buniifolium against poliovirus type 1 was determined by in vitro assays with an efective concentration 50 (EC 50 ) of 23.3 ± 3.3 g/mL. Bioassay-guided fractionation of the OE allowed the isolation of an active principle that was identiied by spectroscopic methods ( 1 H- and 13 C-NMR, EI-MS, UV, and IR spectroscopy) as the benzofuran euparin. he plaque reduction assay in Vero cells was used to assess the antiviral activity of euparin against poliovirus types 1, 2, and 3 with EC 50 values of 0.47, 0.12, and 0.15 g/mL, respectively. Moreover, this compound showed high selectivity indexes of 284.9, 1068, and 854.7, respectively. In order to identify the mechanism by which euparin exerts its antiviral activity, the virucidal efect, the pretreatment of Vero cells, and the time of action on one viral replication cycle were evaluated. Results obtained demonstrated that euparin exerts its efect during the early events of the replication cycle, from the virus adsorption to cells up to the irst twenty minutes ater infection. his is the irst report on the presence of euparin in E. buniifolium and its antiviral activity. 1. Introduction Poliomyelitis is caused by poliovirus (PV), which can afect the nervous system causing permanent paralysis. PV is an RNA virus that belongs to the genus Enterovirus of the large family of Picornaviridae. here are three serotypes of PV (i.e., PV-1, PV-2, and PV-3). Two trivalent polio vaccines have been available since 1961: the intramuscular inactivated vaccine of Salk and the oral attenuated vaccine of Sabin. Both of them stimulate the production of neutralizing antibodies antipolioviruses that protect from the disease. Polioviruses have been eradicated from the United States in 1980 and from the Western Hemisphere in 1991. In 1999, the Global Polio Eradication Initiative wiped out PV-2. Nowadays, and according to the World Health Organization, poliomyelitis remains endemic in Afghanistan, Nigeria, and Pakistan and transmission has been reestablished in three countries which were previously declared as polio-free (Angola, Chad, and the Democratic Republic of the Congo) [1]. In 2006, the “Committee on Development of a Polio Antiviral and Its Potential Role in Global Poliomyelitis Eradication” highlighted the importance of the potential role of an antiviral drug in the context of polio eradication [2] that would be used: (i) for immunodeicient people who are chronically shedding poliovirus, (ii) for people exposed to poliovirus, for example, through unintentional labora- tory exposure, (iii) for communities exposed to circulating vaccine-derived poliovirus outbreaks in the posteradication era (likely in conjunction with inactivated polio vaccine). One strategy for the development of antiviral agents is the search for novel compounds from natural sources. A variety of lead molecules, mainly those isolated from higher plants, have already been reported: terpenoids, lavonoids, coumarins, alkaloids, and lignans [3–6]. Among the numer- ous medicinal plants growing in our country, Eupatorium