Anti-inflammatory Activity of Decoctions of Leaves and Stems of Anisomeles indica at Preflowering and Flowering Stages

Abstract

A decoction of leaves and stems of Anisomeles indica (Lamiaceae) is claimed to possess anti-inflammatory activity in Sri Lankan traditional medicine. The plants at both preflowering and flowering stages are used as an anti-inflammatory agent. However, the anti-inflammatory activity of the plant has not been scientifically evaluated thus far. The aims of this study were to evaluate scientifically the anti-inflammatory activity of decoctions of leaves and stems of A. indica at pre-flowering and flowering stages and possible toxic effects of the decoctions. Three doses of the freeze-dried decoction of a pre-flowering plant (E1) (125, 250 and 500 mg/kg) and one dose of the decoction of a plant at flowering stage (E2) (500 mg/kg) were orally administered to rats. The anti-inflammatory activity was evaluated using the carrageenan-induced paw edema, formaldehyde-induced paw edema and adjuvant-induced paw edema models in rats. E1 demonstrated a significant (P < 0.01) and dose-dependent anti-inflammatory effect in all three models, while E2 did not demonstrate significant anti-inflammatory activity. E1 demonstrated a significant (P < 0.01) and dose-dependent antihistamine activity and free radical scavenging activities in addition to the previously reported membrane stabilising and cyclooxygenase-I inhibitory activities. However, E1 failed to impair significantly the in vitro activity of lipoxygenase. A 30-day treatment with 500 mg/kg of E1 was not liver toxic or renotoxic, and it did not have a significant effect on body weights. It was concluded that the anti-inflammatory activity of E1 is contributed by cyclooxygenase-1 inhibition, plasma membrane stabilisation, antihistamine and free radical scavenging activities, but not by the inhibition of lipoxygenase. These observations prove scientifically the anti-inflammatory activity of A. indica, mentioned in the Sri Lankan traditional medicine, while revealing a loss of the activity after flowering.