Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/24/2011
Publication Date: 3/25/2011
Citation: Kim, S., Kang, M., Lee, I., Park, J., Nam, S., Friedman, M. 2011. Composition of liquid rice hull smoke and anti-inflamatory effects in mice. Journal of Agricultural and Food Chemistry. 59:4570-4581. Interpretive Summary: Rice (Oryza sative L) is a major source of nourishment for the world’s population, especially in Asia. World production of rice is estimated at around 680 million tons. The United States produces about 10 million tons. About 20% of the harvested rice consists of hulls, which protect rice seeds during growth. The non-digestible lignin- and silica- containing hulls are removed during milling to form brown rice, which is further milled to remove the bran layer to yield white rice. The ash residue after burning of the hulls is mostly silica, which has numerous industrial applications. Another byproduct of the combustion of rice hulls is the smoke that is generated. There is recent interest in utilizing this smoke as a new source of liquid smoke flavorings, the wood-derived versions of which, with reported high antimicrobial activity, are now widely used in foods. To help stimulate interest in the potential food uses of the rice hull-derived liquid smoke, we investigated in a collaborative study carried out in Korea, antioxidative, anti-allergic, and antiinflammatory effects of the liquid smoke in chemical, cell, and mouse assays and determined several in vivo molecular biomarkers associated with these beneficial effects. The findings suggest the potential value of rice hull liquid smoke to serve as a possible new food additive and as an antimicoribal and antiinflammatory bio-material. Antimicrobial and anti-toxin properties of the liquid rice hull product merit study.
Technical Abstract: Antioxidative, antiallergic, and antiinflammatory activities of a new liquid rice hull (husk) smoke extract prepared by pyrolysis of rice hulls followed by liquefaction of the resulting smoke were assessed in vitro and in vivo. At pH 5, the liquid smoke extract inhibited 1-diphenyl-2-picrylhydrazyl (DPPH) free radicals, and suppressed nitric oxide (NO) and ß–hexosaminidase releases from lipopolysaccharide (LPS)-induced RAW264.7 mouse macrophage leukemia cells and ionophore A23187-stimulated RBL-2H3 rat basophilic cells, respectively. In a second set of experiments, 12-O¬-tetradecanolylphorbol-13-acetate (TPA) was applied to the ears of CD-1 mice to induce inflammation (edema), which was accompanied with increases in a series of biomarkers. Topical application of 1% of the liquid rice hull extract significantly reduced the expression of the following biomarkers associated with the TPA-induced inflammation: tumor necrosis factor-a (TNF-a), IL-1ß, interleukin-1ß (IL-1ß), interleukin-6 (IL-6), leukotriene B4 (LTB4), prostaglandin E2 (PGE2), myeloperoxidase (MPO). These in vitro and in vivo findings demonstrate the potential value of rice hull smoke extract to serve as a new antiinflammatory rice hull-derived bio-material for the treatment and prevention of inflammation-associated disorders. Possible applications of the liquid rice hull smoke to improve quality and safety of food are discussed.