Antitussive, expectorant and analgesic effects of the ethanol seed extract of Picralima nitida (Stapf) Th. & H. Durand

Picralima nitida is used traditionally for management of cough. This study, therefore, investigated the antitussive, expectorant, and analgesic properties of the ethanolic seed extract of Picralima nitida (PNE), and ascertained its safety for use. Presence of secondary metabolites, and safety of PNE (10-2000 mg/kg) were evaluated by preliminary phytochemical screening, and by Irwin's test respectively. Percentage reduction in cough count, percentage increase in latency of cough, and percentage protection offered by PNE were established by the citric acid-induced cough, acetylcholine- and Histamine-induced bronchoconstriction models. Dunkin-Hartley guinea pigs were treated with 100-500 mg/kg PNE or reference drugs, dihydrocodiene, atropine, mepyramine. Expectorant property of PNE (100-1000 mg/kg) was determined using the tracheal phenol red secretion; with ammonium chloride as a reference medication. Percentage maximal possible analgesic effect in the tail immersion test and the total nociceptive score in acetic acid-induced abdominal writhes, after treatment of BALB/c mice with PNE (100-500 mg/kg), diclofenac, and morphine were also estimated. Phytochemical screening revealed the presence of tannins, alkaloids, glycosides, saponins, steroids, terpenoids and anthraquinones. PNEdid not cause any extract-related physical, pharmacological and CNS toxicities or mortality; sedation was observed at doses 1000-2000 mg/kg. It showed significant dose-dependent reduction in cough count, and increased cough latency. PNE (1000 mg/kg) enhanced tracheal phenol red secretion. PNE (100–500 mg/kg) significantly and dose dependently increased tail withdrawal latencies, and nociceptive score. PNE has antitussive, expectorant, and analgesic properties, with an LD(50)>2000 mg/kg.