Nutraceutical properties of whole dried sugarcane extracts studied by proteomics

Many chronic diseases are associated with the activation of inflammatory mediators. This can lead to excessive release of pro-inflammatory cytokines and the generation of reactive oxygen species (ROS). Some nutraceuticals are rich in polyphenols providing strong antioxidant attributes which have been reported to counteract some of the deleterious effects of ROS. However, cellular mechanisms underlying nutraceutical therapeutic properties are often not well elucidated. In this thesis, the anti-inflammatory properties of the nutraceutical, whole dried sugarcane (WDS), was investigated using proteomic techniques. Chemical assays of WDS ethanol extracts (WDS EE) showed the presence of polyphenols and flavonoids conferring potent antioxidant activity. In lipopolysaccharide (LPS)-stimulated SW480 colon cancer cells, WDS EE reversed the phosphorylation of NFκB and inhibited the secretion of IL-8 in a mechanism shown to be dependent of C-Raf and AKT phosphorylation. Mass spectrometry (MS)-based proteomics using label-free SWATH-MS demonstrated WDS EE to alter the expression of oxidative stress mediators FOXRED1 and the selenoprotein SELH, amongst others. Based on protein expression, prediction analysis proposed the down-regulation of NFκB pathway members TLR2, TLR4, NIK and IκB. In the same model, phosphoproteomics studies indicated that WDS EE interferes in the phosphorylation of cell stress regulator proteins c-Jun, EGFR, PKA, PKCβ and SIRT1, interpreted as regulating anti-inflammatory related signalling mechanisms. As a feed supplement to mice on high-fat diet (HFD), WDS was shown to reduce the plasma concentration of the circulating markers of inflammation IL-1β and GM-CSF. The proteomic analysis of liver tissue from WDS-feed, HFD mice showed changes to STAT3 and the selenium associated proteins SEP15 and SecS. Prediction analysis based on protein expression indicated the down-regulation of inflammatory-related hepatic functions. Taken xvitogether, this thesis has revealed some of the mechanisms associated with the anti-inflammatory properties of WDS extracts in in vitroand in vivomodels.