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-α), 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 E₂ (PGE₂) activity in murine splenic lymphocytes in vitro.
Materials and methods: Murine lymphocytes were isolated from spleen and stimulated with 5 ΅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 μg/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 PGE₂ level. The data were analyzed statistically.
Results: The results demonstrated a 2.26-fold inhibition of PGE2 level at 80 μg/mL of NILE. Half maximum inhibitory concentration (IC₅₀) was calculated to be 44.95 ± 0.45 ΅g/mL. Linear correlation analysis of the dose-dependent PGE₂ 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.
Keywords: Anti-inflammatory; cyclooxygenase; lymphocyte; nerium; prostaglandin.