Journal of Ethnopharmacology 108 (2006) 395–397 Antigiardial activity of methanolic extracts from Helianthemum glomeratum Lag. and Rubus coriifolius Focke in suckling mice CD-1  Elizabeth Barbosa a,b,∗ , Fernando Calzada a,∗ , Rafael Campos b a Unidad de Investigaci´ on Medica en Farmacolog´ ıa de Productos Naturales, Hospital de Pediatr´ ıa, 2 Piso, Centro Medico Nacional Siglo XXI, IMSS, Av. Cuauhtemoc 330, Col. Doctores, CP 06725 M´ exico D.F., Mexico b Instituto Polit´ ecnico Nacional, Escuela Superior de Medicina, Plan de San Luis y D´ ıaz Mir ´ on, CP 11340 M´ exico D.F., Mexico Received 9 February 2006; received in revised form 24 May 2006; accepted 25 May 2006 Available online 2 June 2006 Abstract The antigiardial activity of crude methanolic extracts from Helianthemum glomeratum and Rubus coriifolius, plants used in Mexican traditional medicine for the treatment of diarrhea and dysentery, were demonstrated using experimental infections of Giardia lamblia in suckling female CD-1 mice. In vivo antigiardial activity was studied to determine the dose required to kill 50% of the trophozoites (ED 50 ). Five single-doses between 1.25 and 20 mg extract/kg body weight were tested. Drugs metronidazole and emetine were used as reference. The ED 50 (mg/kg) obtained for the extracts and drugs used as reference was 0.125 for Helianthemum glomeratum, 0.506 for Rubus coriifolius, 0.194 for metronidazole and 0.167 for emetine. Both methanolic extracts showed antigiardial activity, the extract of Helianthemum glomeratum was more active than Rubus coriifolius, and its activity is comparable to metronidazole and emetine. Our results hold the perspective for the utilization of the extracts of these plants as an option to develop of novel antigiardial phytodrugs. © 2006 Elsevier Ireland Ltd. All rights reserved. Keywords: Helianthemum glomeratum Lag.; Rubus coriifolius Focke; Giardia lamblia; Antigiardial activity 1. Introduction Giardia lamblia is an intestinal protozoan parasite infecting humans and various other mammalian hosts. The most important clinical signs of giardiasis are diarrhea and malabsorption syn- drome. The giardiasis is a worldwide infection; the prevalence is higher between 1–9 year-old children and 30–39 year-old adults (Adam, 2001; Hlavsa et al., 2005). There are some agents to treat the giardiasis, such as metronidazole, tinidazole, fura- zolidone, paramomycin and nitazoxanide (D´ avila et al., 2002; Morrone et al., 2004; Sullayman et al., 2002). However, many problems are associated with the currently used chemotherapeu- tic agents, including treatment failures, unpleasant side effects, activity against normal intestinal flora, possible carcinogenicity, and parasite resistance is a potential problem (Ellis et al., 1993; Petri, 2003; Upcroft et al., 1999).  Part of this work was taken from the Ph.D. thesis of Elizabeth Barbosa. ∗ Corresponding authors. Tel.: +52 5627 6900x22410; fax: +52 5761 0952. E-mail address: fercalber1@hotmail.com (F. Calzada). In Mexico, an important segment of population uses medici- nal plants for the treatment of gastrointestinal disorders as diar- rhea and dysentery. Some of these plants have demonstrated in vitro antigiardial properties; however, it is necessary to demon- strate their in vivo effect (Aguilar et al., 1994; Calzada et al., 1998). In vitro antigiardial properties of two species object of study of this work, Helianthemum glomeratum Lag. and Rubus coriifolius Focke, and their isolated metabolites kaempferol, tiliroside and (-)-epicatechin have been reported. Both extracts and their metabolites showed activity against protozoa Giardia lamblia with IC 50 (g/ml) of 62.92 for Helianthemum glomer- atum, 77.82 for Rubus coriifolius, 8.73 for kaempferol, 17.36 for tiliroside, and 1.64 for (-)-epicatechin (Alan´ ıs et al., 2003; Calzada et al., 1999; Meckes et al., 1999). In this work crude methanolic extracts from Helianthe- mum glomeratum and Rubus coriifolius were assayed for activ- ity against trophozoites of Giardia lamblia in experimentally infected mice. It is important to notice that none of these species or their isolated metabolites have been previously evaluated in vivo as antigiardial agents, therefore the results will provide important information to give continuity to the study of the 0378-8741/$ – see front matter © 2006 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.jep.2006.05.026