Journal of Ethnopharmacology 103 (2006) 241–245 Antinociceptive effect of the aqueous extract obtained from roots of Physalis angulata L. on mice G.N.T. Bastos a , A.R.S. Santos c , V.M.M. Ferreira a , A.M.R. Costa a , C.I. Bispo a , A.J.A. Silveira b , J.L.M. Do Nascimento a,∗ a Departamento de Fisiologia, Centro de Ciˆ encias Biol ´ ogicas, Universidade Federal do Par´ a, Bel´ em 66075-900, Brazil b Departamento de Qu´ ımica, Centro de Ciˆ encias Exatas e Naturais, Universidade Federal do Par´ a, Bel´ em 66075-900, Brazil c Departamento de Ciˆ encias Fisiol´ ogicas, Centro de Ciˆ encias Biol ´ ogicas, Universidade Federal de Santa Catarina, Florian´ opolis 88040-900, Brazil Received 22 June 2004; received in revised form 5 August 2005; accepted 9 August 2005 Available online 19 September 2005 Abstract In this study, we attempted to identify the possible antinociceptive action of aqueous extract (AE) obtained from roots of Physalis angulata, known in Brazil as “Camapu”, used to treat various pain-related physiological conditions. The AE of Physalis angulata (10–30 mg/kg) given by i.p. or p.o. route, 0.5 and 1 h prior, produced significant inhibition of abdominal constrictions caused by acetic acid, with ID 50 values of 18.5 (17.4–19.8) and 21.5 (18.9–24.4) mg/kg and inhibitions of 83 ± 8 and 66 ± 5%, respectively. The AE (10–60mg/kg, i.p.) also caused significant inhibition of the late-phase of formalin-induced pain, with an ID 50 value of 20.8 (18.4–23.4) mg/kg and inhibition of 100%. Treatment of mice with AE (60 mg/kg, i.p.) or with morphine (10 mg/kg, i.p.) produced a significant increase of the reaction time in the hot-plate test. These results demonstrate, for the first time, that the AE of Physalis angulata produce marked antinociception against the acetic acid-induced visceral pain and inflammatory pain responses induced by formalin in mice. The mechanism by which the AE produces antinociception still remains unclear. However, pharmacological and chemical studies are continuing in order to characterize the mechanism(s) responsible for the antinociceptive action and also to identify the active principles present in Physalis angulata. Moreover, the antinociceptive action demonstrated in the present study supports, at least partly, the ethnomedical uses of this plant. © 2005 Elsevier Ireland Ltd. All rights reserved. Keywords: Physalis angulata; Antinociception; Formalin test; Writhing test; Hot-plate test 1. Introduction Physalis angulata L. belongs to the Solanaceae family and includes about 120 species with herbal characteristics and peren- nial habits (Corrˆ ea, 1962; Kissmann and Groth, 1995). It is distributed throughout the tropical and subtropical regions of the world (Kissmann and Groth, 1995; Santos et al., 2003). Extracts or infusions from this plant have been used in various countries in popular medicine as a treatment for a variety of illnesses, such as malaria, asthma, hepatitis, dermatitis and rheumatism (Chiang et al., 1992a; Lin et al., 1992; Santos et al., 2003; Soares et al., 2003). In Brazil, Physalis angulata is popularly known as “Camapu”, “Bucho de R˜ a”, “Ju´ a de Capote” or “Mata-Fome” (Branch and Silva, 1983), and its juice is considered to be seda- ∗ Corresponding author. Tel.: +55 91 2111545; fax: +55 91 2111601. E-mail address: jlmn@ufpa.br (J.L.M. Do Nascimento). tive and depurative against rheumatism and earache. The leaves are sometimes used against inflammations of the bladder, spleen and liver. The whole plant cooked is recommended in baths for inflammatory processes, such as rheumatism (Lorenzi, 1982). It has been demonstrated that some of the extracts or active principles obtained from Physalis angulata have a broad spec- trum of biological activities, including antibacterial, molluscici- dal, antiprotozoal, anticancer, cytotoxic and immunomodulatory activities (Kastelein and Camargo, 1990; Lee et al., 1991; Chiang et al., 1992a,b; Lin et al., 1992; C´ aceres et al., 1995; Freiburghaus et al., 1996; Pietro et al., 2000; Ismail and Alam, 2001; Januario et al., 2002; Santos et al., 2003; Soares et al., 2003). Phytochemical studies of Physalis angulata have demon- strated the presence of steroids, known as physalins (D, I, G, K, B, F, E), physagulins (E, F and G), with anolides and flavonoids (Row et al., 1978, 1980; Lee et al., 1991; Chiang et al., 1992a,b; Shingu et al., 1992; Ismail and Alam, 2001). In the present study, we have attempted to investigate the antinociceptive action of 0378-8741/$ – see front matter © 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.jep.2005.08.008