Acute anti-inflammatory and anti-nociceptive activities of crude extracts, alkaloid fraction and evolitrine from Acronychia pedunculata leaves

ETHNOPHARMACOLOGICAL RELEVANCE

Acronychia pedunculata (family: Rutaceae) is one of the commonly used medicinal plants in Sri Lankan traditional medicine. Different parts of this plant are used for the treatment of inflammatory conditions in the form of medicinal oils and herbal porridge.

AIM OF THE STUDY

The present study aimed to evaluate the anti-nociceptive activity and anti-inflammatory activity with their mechanisms and the acute toxicity of crude extracts of the fresh leaves of A. pedunculata for scientific validation of the ethnopharmacological claims for this plant. Further, attention has been focused on the isolation of active compounds from active fractions of the crude extracts.

MATERIALS AND METHODS

The acute anti-inflammatory effect of the aqueous (AELA) and 70% ethanol crude extracts (EELA) and alkaloid fraction of A. pedunculata leaves were evaluated by the determination of inhibition of hind paw oedema induced by carrageenan in Wistar rats. Evolitrine was identified as the major alkaloid with significant bioactivities by column chromatography and NMR. The anti-nociceptive and anti-histamine activities of EELA and evolitrine were evaluated by acetic acid induced writhing and wheal formation tests respectively. In addition, in-vitro (2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay) and in-vivo (lipid peroxidation assay) anti-oxidant activity, nitric oxide (NO) inhibitory activity and acute toxicity of EELA were evaluated.

RESULTS

Acute anti-inflammatory activity of AELA and EELA were dose-dependent. EELA was more active than AELA. The 200 mg/kg body weight (b. w.) dose of EELA was found as the minimum effective dose with maximum inhibition (78%) of oedema at 5th hour compared to the negative control (p < 0.05). Evolitrine was isolated and identified as an active anti-inflammatory and analgesic compound from active alkaloid fraction of EELA. Evolitrine showed activity enhancement when compared with crude EELA. The anti-inflammatory and analgesic activities of evolitrine (50 mg/kg b. w.) were comparable to that of reference drugs indomethacin (5 mg/kg b. w) and acetylsalicylic acid (100 mg/kg b. w.). The significant (p < 0.05) anti-histamine activity, DPPH scavenging in-vitro anti-oxidant activity, in-vivo lipid peroxidation inhibitory activity in-vivo, NO inhibitory activity of EELA as compared with relevant negative controls, were identified as probable mechanisms which mediated its anti-inflammatory action. Further, EELA showed a high safety margin in the limited dose acute toxicity study.

CONCLUSION

The findings of the current study rationalize the usage of leaves of A. pedunculata in Sri Lankan traditional medicine as an analgesic and anti-inflammatory agent. Possible mechanisms mediating this activity included anti-histamine, anti-oxidant and NO inhibitory activities. Evolitrine is the major analgesic and anti-inflammatory compound isolated from the active alkaloid fraction of EELA.

Anti-inflammatory activity of dried flower extracts of Aegle marmelos in Wistar rats

ETHNOPHARMACOLOGICAL RELEVANCE

Almost all part of the plant Aegle marmelos (Bael tree) has been used in the traditional medicine systems of Asian countries to treat various diseases over many centuries. The water extract of the dried flowers of Aegle marmelos is a commonly used beverage among Sri Lankan population in rural areas. Although extensive investigations done on many parts of the plant there are no experimental data available on the extracts of flowers. Anti-inflammatory effect of the water extract of dried flowers of Aegle marmelos (WEAM) was evaluated in the present study.

MATERIALS AND METHODS

The anti-inflammatory effect of the WEAM was evaluated by inhibition of the rat paw oedema, induced by carrageenan. The mechanism of the anti-inflammatory effect was assessed by the inhibition of production of nitric oxide (NO) by rat peritoneal cells, infiltration of rat peritoneal cells, anti-histamine effect, membrane stabilization activity, the antioxidant capacity and inhibition of lipid peroxidation by the WEAM.

RESULTS

The maximum percentage inhibition of paw oedema was exhibited by the dose of 200 mg/kg at 2 h. The WEAM showed a significant increment of rat peritoneal cell infiltration, inhibition of NO production by rat peritoneal cells and inhibition of wheal formation on the skin of the rat after injection of histamine. The WEAM protected the erythrocyte membrane from heat-induced lysis in a dose-dependent manner and showed a significant anti-oxidant effect and lipid peroxidation inhibition activity.

CONCLUSION

The WEAM possesses significant anti-inflammatory effect by multiple mechanisms in Wistar rats.