Determination of anti-inflammatory activities of standardised preparations of plant- and mushroom-based foods

Chronic inflammatory processes contribute to the pathogenesis of many age-related diseases. In search of anti-inflammatory foods, we have systematically screened a variety of common dietary plants and mushrooms for their anti-inflammatory activity. A selection of 115 samples was prepared by a generic food-compatible processing method involving heating. These products were tested for their anti-inflammatory activity in murine N11 microglia and RAW 264.7 macrophages, using nitric oxide (NO) and tumour necrosis factor-alpha (TNF-alpha) as pro-inflammatory readouts. Ten food samples including lime zest, English breakfast tea, honey-brown mushroom, button mushroom, oyster mushroom, cinnamon and cloves inhibited NO production in N11 microglia, with IC50 values below 0.5 mg/ml. The most active samples were onion, oregano and red sweet potato, exhibiting IC50 values below 0.1 mg/ml. When these ten food preparations were retested in RAW 264.7 macrophages, they all inhibited NO production similar to the results obtained in N11 microglia. In addition, English breakfast tea leaves, oyster mushroom, onion, cinnamon and button mushroom preparations suppressed TNF-alpha production, exhibiting IC50 values below 0.5 mg/ml in RAW 264.7 macrophages. In summary, anti-inflammatory activity in these food samples survived 'cooking'. Provided that individual bioavailability allows active compounds to reach therapeutic levels in target tissues, these foods may be useful in limiting inflammation in a variety of age-related inflammatory diseases. Furthermore, these foods could be a source for the discovery of novel anti-inflammatory drugs.