Polyphenols in dietary and botanical matrices are usually present as simple and complex O-glycosides. In fermented dietary materials, the glycosidic moiety is removed and accompanied in some cases by more complex changes to the polyphenol. As for most xenobiotics, polyphenols undergo phase II conjugation in the intestinal wall during their absorption from the gut. In contrast, a few polyphenols, such as puerarin in the kudzu vine, are C-glycosides and are stable in the gut and during absorption, distribution and excretion. Large bowel bacteria reduce polyphenol aglycones, causing opening of the heterocyclic B-ring and ring cleavage. The products are mostly absorbed and enter the bloodstream. Phase I and II metabolism events occur in the intestine and the liver – most polyphenols predominantly circulate as β-glucuronides and sulfate esters with very little as the aglycones, the presumed active forms. In addition, metabolism can occur in non-hepatic tissues and cells including breast tumor cells that have variable amounts of cytochrome P450s, sulfatase and sulfotransferase activities. Inflammatory cells produce chemical oxidants (HOCl, HOBr, ONO2−) that will react with polyphenols. The isoflavones daidzein and genistein and the flavonol quercetin form mono- and dichlorinated products in reaction with HOCl. Genistein is converted to 3′-nitrogenistein in the lung tissue of lipopolysaccharide-treated rats. Whereas polyphenols that can be converted to quinones or epoxides react with glutathione (GSH) to form adducts, chlorinated isoflavones do not react with GSH; instead, they are converted to β-glucuronides and are excreted in bile. Analysis of polyphenols and their metabolites is routinely carried out with great sensitivity, specificity and quantification by LC-tandem mass spectrometry. Critical questions about the absorption and tissue uptake of complex polyphenols such as the proanthocyanins can be answered by labeling these polyphenols with 14C-sucrose in plant cell culture and then purifying them for use in animal experiments. The 14C signature is quantified using accelerator mass spectrometry, a technique capable of detecting one 14C atom in 1015 carbon atoms. This permits the study of the penetration of the polyphenols into the interstitial fluid, the fluid that is actually in contact with non-vascular cells.

The mechanisms by which isoflavones protect against inflammatory vascular disease remain unclear. Our previous observations suggest that one mechanism involves inhibition of monocyte-endothelial cell interactions in a process that is absolutely dependent on flow. The molecular mechanisms involved and the effects of structurally distinct isoflavones on this process are not known and are investigated herein. Using static and flow-dependent monocyte adhesion assays, our data show that exposure of endothelial cells to biologically relevant concentrations of isoflavones inhibits subsequent TNF-alpha induced monocyte adhesion only during flow. This inhibition involved activating endothelial PPARgamma by stimulating promoter sequences containing the PPARgamma response element by isoflavones and attenuating antiadhesive effects by siRNA targeting of PPARgamma. A comparison of structurally distinct isoflavones suggested a critical role for the A-ring. Using chlorinated derivatives of daidzein, a key structural requirement for PPARgamma agonist activity appears to be the presence of the 7-OH group and the lack of chlorine at the 6- or 8-positions in the A-ring. Collectively, these data support 1) a novel flow-dependent anti-inflammatory mechanism for PPARgamma ligands in vascular endothelial cells and 2) exemplify the current concepts of nutrients modulating disease via regulating specific cell signaling pathways.

Traumatic brain injury (TBI) is a significant public health problem in the United States. Despite preclinical success of various drugs, to date all clinical trials investigating potential therapeutics have failed. Recently, sex steroid hormones have sparked interest as possible neuroprotective agents after traumatic injury. One of these is 17b-estradiol (E2), the most abundant and potent endogenous vertebrate estrogen. The goal of our study was to investigate the acute potential protective effects of E2 or the specific G protein-coupled estrogen receptor 1 (GPER) agonist G-1 when administered in an intravenous bolus dose 1 hour post-injury in the lateral fluid percussion (LFP) rodent model of TBI. The results of this study show that, when assessed at 24 hours post-injury, E2 or G-1 confers protection in adult male rats subjected to LFP brain injury. Specifically, we found that an acute bolus dose of E2 or G-1 administered intravenously 1 hour post-TBI significantly increases neuronal survival in the ipsilateral CA 2/3 region of the hippocampus and decreases neuronal degeneration and apoptotic cell death in both the ipsilateral cortex and CA 2/3 region of the hippocampus. We also report a significant reduction in astrogliosis in the ipsilateral cortex, hilus, and CA 2/3 region of the hippocampus. Finally, these effects were observed to be chiefly dose-dependent for E2, with the 5 mg/kg dose generating a more robust level of protection. Our findings further elucidate estrogenic compounds as a clinically relevant pharmacotherapeutic strategy for treatment of secondary injury following TBI, and intriguingly, reveal a novel potential therapeutic target in GPER.

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An important aspect of the risk of cancer is the involvement of the inflammatory response. Currently, antiinflammatory agents are used in chemopreventive strategies. For example, aspirin is recommended for the prevention of colon cancer as well as breast and other cancers. The inflammatory response involves the production of cytokines and proinflammatory oxidants such as hypochlorous acid (HOCl) and peroxynitrite (ONO2-) produced by neutrophils and macrophages, respectively. These oxidants react with phenolic tyrosine residues on proteins to form chloro- and nitrotyrosine. Diets rich in polyphenols (green tea catechins, soy isoflavones) have also been shown to be chemopreventive. The aromatic nature of polyphenols makes them potential targets of HOCl and ONO2-. These reactions may create novel pharmacophores at the site of inflammation. Previous studies in the neutrophil-like cell line, differentiated HL-60 cells, demonstrated the formation of chlorinated and nitrated isoflavones. In this study we have examined whether similar reactions occur in freshly isolated human neutrophils. After induction of a respiratory burst with a phorbol ester, isoflavones and their metabolites were identified by liquid chromatography-tandem mass spectrometry and then quantitatively measured by LC-mass spectrometry using multiple-reaction ion monitoring. The data obtained indicate that both chlorinated and nitrated genistein are formed by human neutrophils. The extent of chlorination of genistein was markedly increased by the phorbol ester whereas the low level of nitration of genistein was constitutive and unaffected. These data imply a potential role for modified forms of genistein that would be produced in the inflammatory environment in and around a tumor.