Anti-inflammatory activity of Nerium indicum by inhibition of prostaglandin E2 in murine splenic lymphocytes

Objective: Nerium indicum Mill (syn. N. oleander L. and N. odorum Aiton; family: Apocynaceae) is a medicinal plant, used in the treatment of diverse ailments including various chronic inflammatory diseases in traditional medicine. We have previously demonstrated the immunomodulatory activity of a bioactive fraction of Nerium indicum leaf (NILE) by studying up-regulation of interleukin-2 (IL-2), IL-10, interferon-gamma and down regulation of IL-4, tumor necrosis factor-alpha (TNF-alpha), nitric oxide, cyclooxygenase-1 (COX-1) and COX-2 activities. Therefore, this study aimed to confirm the anti-inflammatory activity of NILE by inhibition of prostaglandin E-2 (PGE(2)) activity in murine splenic lymphocytes in vitro. Materials and Methods: Murine lymphocytes were isolated from spleen and stimulated with 5 mu g/mL concanavalin A in RPMI-1640, supplemented with 50 U/mL penicillin, 50 U/mL streptomycin, 50 U/mL nystatin and 10% fetal bovine serum. Different concentrations (0-80 mu g/mL) of NILE were added and the cells were cultured for 48 h. The culture supernatants were thereafter collected by centrifugation and assayed for expression of PGE(2) level. The data were analyzed statistically. Results: The results demonstrated a 2.26-fold inhibition of PGE(2) level at 80 g/mL of NILE. Half maximum inhibitory concentration (IC50) was calculated to be 44.95 +/- 0.45 mu g/mL. Linear correlation analysis of the dose-dependent PGE(2) inhibition with other pro- and anti-inflammatory mediators demonstrated high inter-correlation between the parameters. Conclusions: Thus, the present study remains in accordance with our previous report and confirms the anti-inflammatory claim of N. indicum, mentioned in the traditional medicine.