The aim of this study was to investigate the antiinflammatory potential of an aqueous leaf extract (ALE) of Ixora coccinea (Rubiaceae) in rats after oral administration (500, 1000 and 1500 mg=kg). This was done using the carrageenan-induced paw edema (acute inflammatory model) and cotton pellet granuloma tests (chronic inflammatory model). In the former test, ALE significantly impaired both early and late phases of the inflammatory response and also the edema maintained between the two phases. In the latter test, it significantly suppressed granuloma formation (only highest dose tested). Collectively, these data show promising anti-inflammatory activity against both acute and chronic inflammation. ALE showed strong antihistamine and antioxidant activities that can account for its anti-inflammatory potential. In addition, inhibition of prostaglandins and bradykinins may play a role.

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In Sri Lankan traditional medicine, the endemic plant Vernonia zeylanica (L.) Less (Asteraceae) is recommended for the treatment of boils and bone fractures. A strong possibility thus exists that this plant could possess antinociceptive activity, but this has not been scientifically tested. The aim of this study was to investigate the antinociceptive potential of aqueous stem extract (ASE) of V. zeylanica in rats using two models of nociception (hot-plate and tail-flick tests) and different concentrations (750, 1500, and 2500 mg=kg, given orally). The results showed that ASE possessed marked and significant (p < 0.05) antinociceptive activity (in terms of prolongation of reaction time) when evaluated in the hotplate test but not in the tail-flick test. The antinociceptive action had rapid onset (within 1 h) and moderately long duration of activity (up to 3 h), but was 2-to 5-fold weaker than morphine. Further, the ASE significantly suppressed the number of paw lickings and the time spent on paw licking in both phases of the formalin test. Naloxone, an opioid receptor antagonist, blocked the antinociceptive activity of ASE. Collectively, these observations suggest that ASE-induced antinociception was mediated centrally at the supraspinal level via opioid receptor mechanisms and is also effective against neurogenic and inflammatory pain. The ASE had mild antioxidant and moderate sedative actions, which are likely to contribute to its antinociceptive action. The ASE is well tolerated (in terms of overt signs, or renal, hepatic, or hemotoxicities) and nontoxic (by brine shrimp lethality assay). Phytochemical analysis revealed the presence of alkaloids, phenols, and steroids, which could contribute to the antinociceptive action. It is concluded that ASE of V. zeylanica has safe and moderate oral antinociceptive action.

Scopoletin (7-hydroxy-6-methoxy coumarin) which inhibited the conidial germination of Corynespora cassiicola was isolated from the uninfected mature leaves of Hevea brasiliensis. Scopoletin was not detected in uninfected immature rubber leaves. The immature leaves produced scopoletin after being infected with C. cassiicola. The concentration of scopoletin in infected leaves was higher than in uninfected mature leaves. Scopoletin also inhibited the conidial germination of other fungal pathogens of H. brasiliensis. However, no correlation was observed between scopoletin accumulation and clonal resistance.

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The aim of this study was to examine the antinociceptive potential of leaves of Ixora coccinea (family: Rubeaceae). One of four doses (500, 750, 1000 or 1500 mg/kg, n = 8/dose) of aqueous leaf extract (ALE) or 1 ml of distilled water was orally administered to male rats and antinociceptive activity was ascertained using three models ofnociception (tail flick, hot plate and formalin tests). The results showed that ALE possesses considerable antinociceptive activity (when evaluated in hot plate and formalin test but not in tail flick test). The antinociceptive activity of the ALE had a rapid onset (within 1h) and a fairly long duration of action (up to 5 h) with a peak effect at 3 h. Further, the antinociceptive activity was dose-dependent and was not associated with harmful side-effects or toxicity even following subchronic administration. The antinociceptive action was mediated centrally at the supraspinal level mainly via dopaminergic mechanism. In addition, it is likely that antioxidant activity of the ALE could have played an auxiliary role in inducing antinociception. Dopaminergic and antioxidative activities of ALE could arise, respectively, from its quaternary base alkaloid and flavonoid constituents.

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