Effects of the 70% ethanolic stem bark extract of Pterocarpus erinaceus Poir were investigated in
some isolated smooth muscles preparations of experimental animals. Preliminary phytochemical
studies of the ethanolic extract revealed the presence of tannins, carbohydrates, proteins, amino acids flavonoids and steroids. The ethanolic stem bark extract of P.erinaceus (6.4mg/ml) relaxed the isolated pregnant rat uterus. Oxytocin induced contractions of the pregnant rat uterus was blocked by the extract at a higher dose. The studies on isolated guinea- pig ileum and rabbit
jejunum smooth muscles demonstrated that the ethanolic stem bark extract of P.erinaceus produced a dose dependent relaxation of these muscles. The extract also attenuated the contractile effects of acetylcholine on these tissues dose dependently. This finding might lend credence to the use of the stem bark of the plant in the treatment of diarrhea and dysentery traditionally. From the results of this work and information from literature, flavonoids and tannins identified during phytochemical screening of the extract may be the biologically active components responsible for the gastrointestinal effects of the ethanolic stem bark extract of P.erinaceus.