Journal of Ethnopharmacology 78 (2001) 33 – 37 Neuropharmacological effect of the aqueous extract of Sphaeranthus senegalensis in mice Samson Amos *, B. Adzu, L. Binda, C. Wambebe, K. Gamaniel Department of Pharmacology and Toxicology, National Institute for Pharmaceutical Research and Deelopment, Idu Industrial Area, PMB 21, Garki, Abuja, Nigeria Received 9 January 2001; received in revised form 29 May 2001; accepted 17 July 2001 Abstract Effects of the aqueous extract of Sphaeranthus senegalensis Vaill. (Family: Compositae) were studied on spontaneous motor activity, exploratory behaviour, rota-rod performance and pentobarbital sleeping time in mice. Preliminary phytochemical evaluation and acute toxicity (LD 50 ) values were also studied. The extract (50 and 100 mg/kg p.o.) produced reduction in spontaneous motor activity, exploratory behaviour and motor coordination and prolonged pentobarbital sleeping time. Gly- cosides, saponins and tannins were shown to be present in the extract. The i.p. LD 50 in mice was 2735.61 and 5000 mg/kg orally. The results suggest that the aqueous extract of S. senegalensis contains some active principles, which may be sedative in nature. © 2001 Published by Elsevier Science Ireland Ltd. Keywords: Sphaeranthus senegalensis ; Sedation; Spontaneous motor activity; Exploratory behaviour; Motor coordination; Pentobarbital sleeping time www.elsevier.com/locate/jethpharm 1. Introduction Medicinal herbs constitute the cornerstone of tradi- tional medicinal practice worldwide. These herbs are relatively cheap and available and their use depends on ancestral experience (Marin-Bettolo, 1980). These medicinal plants represent a great deal of untapped reservoir of drugs and the structural diversity of their component molecules makes a valuable source of novel lead compounds (Farnsworth, 1989). Sphaeranthus senegalensis Vaill. (Compositae) is a sprawling annual and strongly aromatic herb. It grows in tropical Africa and Asia and is widely refuted to be medicinal. For the crushed leaves is laid on the bed of a sick person to soothe and induce sleep (Dalziel, 1937). It has also been reported to have beneficial effects in rheumatic pains and as anthelmintic, diuretic and laxative (Burkill, 1985). A number of natural product scientists believe that the initial selection of plants with diverse applica- tion in traditional medicine might be encouraged by their easily noticeable psychotropic effects (Etkin, 1988). There is very little scientific data on the possible central nervous system effects of this widely used medicinal plant. It was on this basis that we investi- gated the pharmacological effects of the aqueous ex- tract of the plant on spontaneous motor activity, exploratory behaviour, rota-rod (tread mill) perfor- mance and, pentobarbital sleeping time. Preliminary acute toxicity and phytochemical tests were also carried out to evaluate the secondary metabolites present and the safety of this widely used plant. 2. Materials and methods 2.1. Preparation of plant extract The herbal material was collected from Abranami Ezekiel (Consultant Herbalist, Kala’a, Adamawa State, Nigeria). The identity of the plant material was confi- rmed by A.O. Ohaeri of the Department of Medicinal Plant Research and Traditional Medicine, National Institute for Pharmaceutical Research and Develop- ment (NIPRD), Abuja, Nigeria. A voucher specimen * Corresponding author. Tel.: +234-9-523-9089; fax: +234-9-523- 1043. E-mail address: samsonamos@yahoo.co.uk (S. Amos). 0378-8741/01/$ - see front matter © 2001 Published by Elsevier Science Ireland Ltd. PII:S0378-8741(01)00316-6