Abstract

The plant Asparagus racemosus is used traditionally in Kenya for a variety of medicinal purposes including in the management of pain, asthma, and premature labour. However, a dearth of empirical studies means that there is limited information on the acute toxicity and pharmacological effects to support these uses by the local variety of the plant. The aim of this study was, therefore, to evaluate the acute toxicity, analgesic, and smooth muscle relaxation effects of the aqueous root extract of the plant. The powdered root of the locally sourced plant was extracted using decoction method. Analgesic activity was determined using both the hot plate and writhing methods whereas the effects on smooth muscle contraction were evaluated on the rabbit isolated ileum, rat uterus and guinea pig trachea. Acute toxicity was also evaluated in rodents. The LD50 of the root extract in mice was 505 mg/kg and dose-dependent analgesic effects were observed with 65% pain reduction at a dose of 400 mg/kg compared to 77% produced by morphine (20 mg/kg). Concentration-dependent smooth muscle relaxation effects were also observed on the isolated rabbit ileum and rat uterus. Similarly, guinea pig tracheal bronchodilation was observed to be concentration-dependent with over 90% relaxation at an organ bath concentration of 4 mg/ml. In conclusion, the aqueous root extracts of the Kenyan variety of A. racemosus produces analgesic, antispasmodic, tocolytic and bronchodilator activities. Future phytochemical analysis, isolation, and characterisation of candidate compounds responsible for these actions are recommended.

Key words: Asparagus racemosus extracts, analgesic, antispasmodic, tocolytic activities.