Water Extract of Leaves and Stems of Preflowering but not Flowering Plants of Anisomeles indica Possesses Analgesic and Antihyperalgesic Activities in Rats

Abstract

According to Sri Lankan traditional medicine, a decoction made from stems and leaves of Anisomeles indica Kuntze (Lamiaceae) possesses analgesic activity. However, the validity of this claim has not been scientifically tested. The aim of this study was to investigate analgesic and antihyperalgesic activities of this plant using a water extract made from the leaves and stems. The water extracts were made from leaves and stems of both preflowering (E1) and flowering plants (E2). E1 showed a dose-dependent analgesic effect up to 6 h of treatment when tested in rats using the hot plate and the tail flick techniques. Further, the analgesic effect of E1 was not accompanied by toxic effects. This effect was neither gender dependent nor dependent on the stage of the estrous cycle. E1 also showed a dose-dependent antihyperalgesic activity in the hot plate test. In contrast, E2 did not show any analgesic effect (500 mg/kg). The analgesic effect produced by E1 was not abolished by naloxone. E1 dose-dependently retarded the amplitude of the spontaneous contractions of isolated dioestrous rat uterus. Further, E1 induced a dosedependent plasma membrane stabilisation effect on rat erythrocytes. Collectively, these observations suggest that the analgesic and antihyperalgesic effects of E1 are mediated from inhibition of COX-1, thus impairing the synthesis of prostaglandins. A change in chemical contents that accompanies flowering could be one possible reason for the inability of E2 to demonstrate analgesic effect.

Antinociceptive, anti-inflammatory and antipyretic effects of Muntingia calabura aqueous extract in animal models

“…The observed pharmacological activities, particularly the antinociceptive activity, of the extract were concomitant with our recent report on M. calabura antinociceptive activity [6]. The ability of the extracts/drugs to show antinociceptive activity when assessed using the abdominal constriction and hot plate tests has been associated with their ability to affect the peripheral and central nociceptive mechanism [13][14][15], a mechanism shown by opioid drugs like morphine.…”

Leaf extract of Crinum bulbispermum has antinociceptive activity in rats

“…This activity was evaluated using heat-induced haemolysis of rat erythrocytes in vitro as described by Dharmasiri et al (2003). Vials containing 20 l fresh rat blood in 1 ml of phosphate buffered saline were treated in triplicate with the ALE so that the final concentrations of the extracts in the vials become 3125, 1062.5, 31.25, 15.62 and 7.81 g/ml.…”

Antinociceptive Potential of the Sri Lankan Endemic PlantVernonia zeylanica.

“…This suggests that the antinociception is not mediated via dopaminergic mechanisms. Antinociception can result from a membrane stabilizing effect and=or rising of the nociception threshold, as reported with some herbal drugs (Dharmasiri et al, 2003), but the ASE failed to inhibit heat-induced hemolysis of rat erythrocytes in vitro. Thus, ASE-induced antinociception was not mediated via membrane stabilization.…”