Antiinflammatory and analgesic effects of Psidium guajava Linn. (Myrtaceae) leaf aqueous extract in rats and mice.

In many parts of Africa, the leaf, stem-bark, and roots of Psidium guajava Linn. (Family: Myrtaceae) are used traditionally for the management, control, and/or treatment of an array of human disorders. In an effort to scientifically appraise some of the ethnomedical properties of P. guajava leaf, and probe its efficacy and safety, the present study was undertaken to examine the antiinflammatory and analgesic properties of the plant's leaf aqueous extract in some experimental animal paradigms. The antiinflammatory property of the aqueous leaf extract was investigated in rats, using fresh egg albumin-induced pedal (paw) edema, while the analgesic effect of the plant extract was evaluated by the "hot-plate" and "acetic acid" test models of pain in mice. Diclofenac (100 mg/kg, i.p.) and morphine (10 mg/kg, i.p.) were used respectively as standard, reference antiinflammatory and analgesic agents for comparison. P. guajava leaf aqueous extract (PGE, 50-800 mg/kg, i.p.) produced dose-dependent and significant (p < 0.05-0.001) inhibition of fresh egg albumin-induced acute inflammation (edema) in rats. The plant extract (PGE, 50-800 mg/kg, i.p.) also produced dose-dependent and significant (p < 0.05-0.001) analgesic effects against thermally and chemically induced nociceptive pain in mice. The numerous tannins, polyphenolic compounds, flavonoids, ellagic acid, triterpenoids, guiajaverin, quercetin, and other chemical compounds present in the plant are speculated to account for the observed antiinflammatory and analgesic effects of the plant's leaf extract. In summary, the findings of this experimental animal study indicate that the leaf aqueous extract of P. guajava possesses analgesic and antiinflammatory properties, and thus lend pharmacological credence to the suggested ethnomedical, folkloric uses of the plant in the management and/or control of painful, arthritic and other inflammatory conditions in some rural communities of Africa.