Study On Phenolic, Antioxidant And Anti - Inflammatory Activities In Tartary Buckwheat By Solid State Fermentation

In the present work, tartary buckwheat is used as experiment materials to investigate the effect of solid-state fermentation with three filamentous fungi (Rhizopus oryzae, Rhizopus oligospous and Rhizopus oryzae 40503) on total phenolics content (TPC), flavonoids, and antioxidant activities of tartary buckwheat. Meanwhile, the effects of phenolics extracts of differently treated tartary buckwheat on NO release and iNOS transcription were also studied using mouse macrophage cell line RAW264.7 pretreated by lipid-polysaccharide (LPS). The main results were concluded as follows:(1) Filamentous fungi fermentation can significantly improve the TPC, flavonoids of tartary buckwheat with the increased fermentation time. Compared with non-fermented tartary buckwheat, the TPC and total flavonoids of the tartary buckwheat fermented with Rhizopus oryzae for 96h were about 2.53 times and 2.45 times higher, respectively. The tartary buckwheat fermented with Rhizopus oligospous for 96h increased 1.87 times and 1.51times, respectively. And the fermented tartary buckwheat with Rhizopus oryzae 40503 for 96h increased 1.87 times and 1.51 times, respectively.(2) The analysis results of LC-MS and HPLC indicated:Rutin was the main phenolic compound in tartary buckwheat, and could be significantly improved by fermentation. The contents of rutin in the fermented tartary buckwheat with R. oryzae, R. oligospous and R. oryzae 40503 for 96h were about 2.12 times,1.55 times and 1.79 times higher, respectively, in comparison with that of non-fermented tartary buckwheat. Besides, tartary buckwheat also contained fewquercetin, hyperin, kaempferol-3-O-rutinoside, chlorogenic acid, kaempferol.(3) In vitro antioxidant activities determined by different methods indicated: Fermentation can significantly improve the antioxidant activities of tartary buckwheat, and the fermented tartary buckwheat for 96h showed the strongest antioxidant activities. The R. oryzae 40503-fermented tartary buckwheat for 96h showed the strongest DPPH’radical scavenging activity (IC50:214.86 ± 3.56 ug tartary buckwheat/mL). The 96h-fermented tartary buckwheat with R. oryzae had the strongest ferric reducing capacity, increased about 1.54 times higher than that of unfermented tartary buckwheat. The 96h-fermented tartary buckwheat with R. oligospous showed the strongest ABTS+· radical scavenging activity (IC50:130.77 ± 11.01 μg tartary buckwheat/mL), and supercoiled plasmid DNA strand protection effect with 73.4%. ± 2.3% protection ratio at 400.00 μg tartary buckwheat/mL. Correlation analysis showed that phenolics, especially rutin, in tartary buckwheat were the main antioxidant compounds.(4) Anti-inflammatory assay showed that rutin, quercetin fermentation and non-fermented tartary buckwheat can effectively inhibit NO release and iNOS mRNA transcription. Inhibition order of tartary buckwheat with different treatments on NO release was as follows:R. oryzae 40503 fermentation> R. oryzae fermentation-non-fermentation> R. oligospous fermentation. Moreover, the inhibition effect of rutin was better than that of quercetin. The inhibition ratios of correspondingly treated tartary buckwheat, rutin and quercetin were 82.62%、60.66%、59.46%、18.39%、 92.41% and 84.86%, respectively.(5) Fermentation and unfermented tartary buckwheat are purified by MPLC.The phenolics content and antioxidant activities of purified samples are increased significantly, especially for that of fermented tartary buckwheat.