Aqueous extracts obtained from five Malaysian brown seaweeds, Sargassum duplicatum, Sargassum binderi, Sargassum fulvellum, Padina australis, and Turbinaria turbinata, were investigated for their abilities to inhibit nitric oxide (NO) production in lipopolysaccharide (LPS)-induced macrophage RAW 264.7 cell lines as well as to determine their chemical composition. The percentage yield of extracts varied among species, with P. australis having the lowest yield and T. turbinata having the highest yield. The chemical compositions of the extracts showed that the percentage of sulfate ions as well as uronic acid and total sugar content varied significantly. All extracts contained high fucose and inhibited NO secretion in a dose-dependent manner. Extracts of P. australis and T. turbinata dosed at 200 μg/mL were able to inhibit NO secretion by > 75%. Furthermore, cytotoxicity assays revealed that some extracts were moderately toxic, while others were not. Based on these results, brown seaweed of Malaysian origin should be investigated for the production of additional anti-inflammatory compounds.
HP0986 protein of Helicobacter pylori has been shown to trigger induction of proinflammatory cytokines (IL-8 and TNF-α) through the activation of NF-κB and also to induce Fas mediated apoptosis of human macrophage cells (THP-1). In this study, we unravel mechanistic details of the biological effects of this protein in a murine macrophage environment. Up regulation of MCP-1 and TNF-α in HP0986-induced RAW 264.7 cells occurred subsequent to the activation and translocation of NF-κB to the cell nucleus. Further, HP0986 induced apoptosis of RAW 264.7 cells through Fas activation and this was in agreement with previous observations made with THP-1 cells. Our studies indicated activation of TNFR1 through interaction with HP0986 and this elicited the aforementioned responses independent of TLR2, TLR4 or TNFR2. We found that mouse TNFR1 activation by HP0986 facilitates formation of a complex comprising of TNFR1, TRADD and TRAF2, and this occurs upstream of NF-κB activation. Furthermore, FADD also forms a second complex, at a later stage, together with TNFR1 and TRADD, resulting in caspase-8 activation and thereby the apoptosis of RAW 264.7 cells. In summary, our observations reveal finer details of the functional activity of HP0986 protein in relation to its behavior in a murine macrophage cell environment. These findings reconfirm the proinflammatory and apoptotic role of HP0986 signifying it to be an important trigger of innate responses. These observations form much needed baseline data entailing future in vivo studies of the functions of HP0986 in a murine model.