Evaluation of anti-inflammatory and analgesic activities of Cymbopogon citratus (DC) STAPF. on in vivo models

R Garcia1, J Pinto Ferreira1,3, T Santos1,3, G Costa2,3, M Caramona1,3, T Batista2,3, M Castel-Branco1,3, I Vitória1,3. 1Faculdade de Farmácia, Universidade de Coimbra, Laboratório de Farmacologia e Cuidados Farmacêuticos, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal, 2Faculdade de Farmácia, Universidade de Coimbra, Laboratório de Farmacognosia, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal, 3Faculdade de Farmácia, Universidade de Coimbra, Centro de Estudos Farmacêuticos, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal

Introduction: Cymbopogon citratus (lemongrass) is one of the most common herbs used in popular medicine because it comprises a wide range of indications such as anti-inflammatory and antioxidant activities. A previous phytochemical study of the essential oil-free infusion obtained from C. citratus has revealed the presence of tannins, phenolic acids (caffeic and p-coumaric acid derivatives) and flavonoids (O- and C-glycosyl derivatives of apigenin and luteolin) [1,2]. Objectives: Taking into account that C. citratus extract shows anti-inflammatory and antioxidant properties, the aim of this work was to evaluate the anti-inflammatory and analgesic activities of C. citratus leaves essential oil-free infusion (CcE), flavonoid-rich fraction (CcF) and tannin-rich fraction (CcT) in animal models of acute inflammation and pain. Materials and methods: The evaluation of the anti-inflammatory activity of CcE (D1 - 34.12 mg/kg and D2 - 68.24 mg/kg), CcF (D1 - 3.71 mg/kg and D2 - 7.42 mg/kg) and CcT (D1 - 2.98 mg/kg and D2 - 5.96 mg/kg) was performed in the carrageenan-induced rat paw edema model and compared with a non steroidal anti-inflammatory drug, diclofenac sodium [3]. The central analgesic activity was evaluated in mice by resorting to the hot plate test, employing the central analgesic morphine as reference drug, and the peripheral analgesic activity was evaluated by the acetic acid-induced writhing test, also in mice, employing diclofenac sodium as reference drug [4]. Data obtained was expressed as mean±S.E.M. Variance analysis (ANOVA) followed by the Bonferroni’s test was used to compare means. Values of p<0.05 were considered to be statistically significant. Results: C. citratus infusion and fractions, given orally before carrageenan administration, significantly prevent edema formation in a dosage-dependent manner compared with the negative control group. The results obtained for the inflammation model in percentage of edema inhibition were 70.80% for CcE D1, 82.30% for CcE D2, 59.00% for CcF D2, 61.00% for CcT D2 and 84.00% for positive control group, suggesting that oral treatment with CcE, CcF and CcT significantly prevents carrageenan-induced swelling in a dosage dependent manner. Results also suggest that the effect of the higher dosage of CcE overlaps the effect produced by the reference drug diclofenac. For the peripheral pain evaluation, results showed a pain reduction of 57.00% for CcE D2, 54.60% for CcF D2, 52.20% for CcT D2 and 83.00% for positive control group. However, despite the positive results obtained for inflammation and peripheral pain, there was no evidence suggesting any central analgesic activity of CcE. Conclusions: This study demonstrates that C. citratus is able to reduce inflammation and peripheral pain and helps to justify this popular use as an anti-inflammatory agent. References: 1. Figueirinha, A et al.. Food Chemistry. 2008, 110, 718-728. 2. Figueirinha, A. et al. Journal of Medicinal Food. 2010, 13, 681-690. 3. Winter et al., Proc. Soc. Exp. Biol. Med. 1962; 111: 544-547. 4. Jürgensen S. et al., Pharmacol. Biochem. and Behavior 2005; 81: 466-477.