Regulation of inducible nitric oxide synthase by arabinoxylans with molecular characterisation from wheat flour in cultured human monocytes

The immunomodulatory activity of the arabinoxylans (AXs) extracts from cereal sources has beenreported to impart health benefits in terms of immune enhancement. This study investigated the effect ofenzymatic extraction on extraction yield and structure of AXs from wheat flour pentosan fraction. Underthe optimised conditions, the extraction yield of AXs reached up to 81.25%. Furthermore, the studydetermined whether water-extracted AXs (WEAXs) and enzyme-extracted AXs (E-WEAXs) from wheatflour were able to differentially stimulate nitric oxide (NO) secretion through increased levels of induciblenitric oxide synthase (iNOS) in human U937 monocytes. The results indicated that AXs concomitantlyinduced (P < 0.05) both NO and iNOS productions in U937 monocytes compared to untreated cells.Compared with WEAXs, E-WEAXs resulted in a higher proportion of low Mw (1– 10 KDa) AXs(49.51% vs. 19.11% in WEAXs), a higher A/X ratio (0.83 vs. 0.48 in WEAXs) and a higher yield(12.83  0.35% vs. 7.54  0.47% in WEAXs). Moreover, E-WEAXs induced significantly (P < 0.05)greater NO and iNOS production per million viable cells (61.8  2.7 lM and 42.41  3.83 ng respec-tively) than WEAXs (51.6  2.6 lM and 33.46  1.48 ng, respectively). The findings suggest AXs mayheighten innate immune activity in the absence of infection or disease through an iNOS-mediated stimula-tion of NO production. The immunomodulatory activity of the wheat-derived AXs was enhanced byenzyme treatment, with low Mw and high A/X ratio associated with elevated NO/iNOS levels in humanmonocytes compared to water extraction.