Antinociceptive and gastroprotective effects of diterpenes from the flower buds of Egletes viscosa.

Centipedic acid and 12-acetoxy-hawtriwaic acid lactone, diterpenes isolated from the flower buds of Egletes viscosa (Asteraceae) were assayed for antinociceptive and gastroprotective activities in animal models of nociception and gastric ulcer. In the chemical nociception induced in mice by intraperitoneal acetic acid and subplantar formalin injections, both diterpenes (25 and 50 mg/kg, p. o.) exerted potent antinociception in a manner similar to indomethacin (5 mg/kg, p. o.). In the formalin test, only the late phase nociceptive response (20 - 25 min) and not the early phase response (0 - 5 min) was inhibited by these diterpenes. However, these compounds were found to be ineffective against thermal nociception in the hot-plate test. Further, the diterpenes reduced the severity of absolute ethanol-induced gastric lesions in rats. At the dose of 50 mg/kg, both centipedic acid and 12-acetoxy hawtriwaic acid suppressed the gastric lesions by 53 % and 63 %, respectively. Against the gastric ulceration induced by indomethacin, only centipedic acid (25 and 50 mg/kg) showed significant inhibition by about 47 - 49 %. The data suggested the gastroprotective and peripheral analgesic properties of diterpenes isolated from E. viscosa.