Background:While curcuminoids have been reported to possess diverse biological activities, the anti-inflammatory activity of polar extracts (devoid of curcuminoids) of Curcuma longa (C. longa) has seldom been studied. In this study, we have investigated immune-stimulatory and anti-inflammatory activities of an aqueous based extract of C. longa (NR-INF-02) and its fractions in presence and absence of mitogens.Materials and Methods:Effects of NR-INF-02 (Turmacin™, Natural Remedies Pvt. Ltd., Bangalore, India) on proliferation, nitric oxide (NO), monocyte chemotactic protein-1 (MCP-1), interleukins (ILs) and prostaglandin (PGE2) levels of mouse splenocytes and mouse macrophage (RAW264.7) cells were determined.Results:NR-INF-02 increased splenocytes number in presence and absence of lipopolysaccharide (LPS) or concanavalin A. Treatment of NR-INF-02 showed a significant increase of NO, IL-2, IL-6, IL-10, IL-12, interferon (IFN) gamma, tumor necrosis factor (TNF) alpha and MCP-1 production in unstimulated mouse splenocytes and mouse macrophages. Interestingly, NR-INF-02 showed potent inhibitory effect towards release of PGE2 and IL-12 levels in LPS stimulated mouse splenocytes. Further, NR-INF-02 was fractionated into polysaccharide fraction (F1) and mother liquor (F2) to study their immune-modulatory effects. F1 was found to be more potent than F2 toward inhibiting PGE2 and IL-12 in LPS stimulated splenocytes.Conclusion:Present findings revealed the novel anti-inflammatory property of NR-INF-02 and its polysaccharide fraction by inhibiting the secretion of IL-12 and PGE2 in vitro.