J Ethnopharmacol. 1988 Dec; 24(2-3): 219-31.

Effects on mice locomotor activity of a narcotic-like principle from Psidium guajava leaves.

Lutterodt GD, Maleque A.

Department of Pharmacology, School of Medical Sciences, Universiti Sains Malaysia, Penang.

Studies were carried out on the suppression of both exploratory and spontaneous locomotor activities in the mouse by a non-polar fraction from a methanol extract of the dried leaves of Psidium guajava. Shortly after intraperitoneal administration of this fraction, typical narcotic-like effects were observed, including catalepsy, analgesia, Straub tail, shallow respiratory movements and exophthalmos. The dose for 90% suppression of exploratory activity was between 3.3 and 6.6 mg/kg intraperitoneally and the onset of action was 6-8 min. The duration of activity was dose-dependent and, for a dose of 13.2 mg/kg given intraperitoneally, it was found to be more than 6 h. Qualitatively similar results on exploratory activity were obtained when the extract was administered orally. Doses of 3.3-6.6 mg/kg i.p. depressed spontaneous locomotor activity and tunnel running was curtailed. Higher doses abolished the spontaneous locomotor reflex action. A flavonoid compound or compounds appear to account for the activity seen.