Journal of Ethnopharmacology 89 (2003) 25–36 Evaluation of the anti-asthmatic property of Asystasia gangetica leaf extracts P.A. Akah a,∗ , A.C. Ezike a , S.V. Nwafor a , C.O. Okoli a , N.M. Enwerem b a Department of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of Nigeria, Nsukka, Enugu State, Nigeria b Department of Medicinal Plant Research and Traditional Medicine, National Institute for Pharmaceutical Research and Development (NIPRD), Abuja, Nigeria Received 11 October 2002; received in revised form 19 May 2003; accepted 21 May 2003 Abstract The leaf of Asystasia gangetica T. Adams (Acanthaceae) is used in many parts of Nigeria for the management of asthma. This study was aimed at investigating the anti-asthmatic property of hexane, ethylacetate, and methanol extracts of the leaves of Asystasia gangetica, obtained by successive sohxlet extraction. The results indicated that the extracts did not exhibit contractile or relaxant activity in isolated tissue preparations; however, they inhibited the contraction evoked by spasmogens; the IC 50 were calculated, where possible. The extracts relaxed histamine-precontracted tracheal strips in the following degree of potency—ethylacetate extract > hexane extract = methanol extract. The extracts also exhibited anti-inflammatory activity in the order of magnitude—methanol extract > hexane extract > ethylacetate extract. Acute toxicity test estimated an i.p. LD 50 of 2150 mg/kg in mice for methanol extract while phytochemical screening showed the presence of carbohydrates, proteins, alkaloids, tannins, steroidal aglycones, saponins, flavonoids, reducing sugars, and triterpenoids, with the methanol extract having the highest number of constituents. The study justified the use of the leaf of Asystasia gangetica in the management of asthma in Nigerian folk medicine. © 2003 Elsevier Ireland Ltd. All rights reserved. Keywords: Asystasia gangetica; Anti-asthmatic; Anti-inflammatory; Isolated tissues 1. Introduction Asthma is a chronic disease of the airways/respiratory system with a worldwide incidence of 155 million (Cokson, 1999), and it is a disease that does not respect the bound- aries of race, age, and gender. The availability of effective medications notwithstanding, the prevalence of asthma is increasing (Rona et al., 1995; Cokson, 1999) with 5–10% rate reported for Nigeria (Chukwu et al., 2000). There are incresing demand for the use of traditional medicines in the management of asthma, and Asystasia gangetica (L) T. Adams (Family Acanthaceae) is one of such plants with ac- claimed potency in asthma. Asystasia gangetica is a straggling herb usually found among short grasses and along pathways. The leaves are green, oval-shaped with rounded base, very slightly saw- edged, and smooth (Saunders, 1958). The plant is recognized ∗ Corresponding author. E-mail address: peterakah@hotmail.com (P.A. Akah). as a potential food source because the leaves have been shown to contain high amounts of proteins, amino acids, minerals, sugars, lipids, and fiber (Yeoh and Wong, 1993). In the traditional medicine of East Africa (Kenya), Asys- tasia gangetica is used as an anthelmintic. The leaves are crushed, boiled in water, and the decoction drunk as a cure for intestinal worms (Kokwaro, 1976). In Nigeria, the leaves of Asystasia gangetica are claimed to be highly effective in the local treatment of asthma (personal communication, 2000). The fresh leaves are macerated in local gin for 24 h or expressed and the extract drunk. Over 70% of Nigeria’s more than 100 million people live in rural areas where traditional medicine practice is well established and patronized. The success of the practice has continued to reveal the potential of plants as therapeutic agents. As part of our continued efforts to screen Nigerian herbal remedies for pharmacological activity (Akah et al., 1997; Okoli and Akah, 2000; Nwafor et al., 2002), and in consideration of the claimed efficacy of Asystasia gangetica in native therapy of asthma, we investigated the leaves for anti-asthmatic activity. 0378-8741/$ – see front matter © 2003 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/S0378-8741(03)00227-7