Interaction of Polyphenols with the Intestinal and Placental Absorption of some Nutrients and other Compounds

Infrared Spectroscopy as a Tool to Study the Antioxidant Activity of Polyphenolic Compounds in Isolated Rat Enterocytes

“…PCA of these spectra (data not shown) also showed that most polyphenolic treatments protected cells from H 2 O 2 -induced oxidative damage but treatment of cells with polyphenols in the absence of H 2 O 2 induced a mild prooxidant effect. It has been reported that small polyphenols have a direct action against ROS but also show a prooxidant effect [ 6 ]. Both phenolic acids (ChA and GA) showed the lowest antioxidant effect in all the analyzed treatments, indicating that the formation of aldehydes is higher than the capacity of the phenolic acids to exert their antioxidant effect.…”

“…However, due to their low bioavailability, there is controversy about their mechanism of action, and direct in vivo ROS-scavenging activity is questionable [ 1 , 2 ]. An indirect antioxidant effect of polyphenols has been recently proposed, through the upregulation of the cellular antioxidant defense system (phase 2 enzymes), via activation of the Nrf2-Keap1 pathway [ 3 – 6 ]. Polyphenols may be autooxidized with the formation of H 2 O 2 and quinoidal products and both chemical species may participate in electrophilic conjugation reactions with cysteine residues of the Nrf2-Keap1 complex, allowing the translocation of Nrf2 and thus starting the pathway [ 6 – 8 ].…”

“…In this scenario, autooxidation products of polyphenols are actually mild prooxidants. Alternatively, polyphenols may activate the Nrf2 pathway by mechanisms apparently independent of their electrophilic properties [ 6 – 8 ].…”

“…Enterocytes are a good model to study the mechanisms by which polyphenols exert their antioxidant activity, because they are the first cells to interact with polyphenols during the absorption process and, consequently, they are exposed to the highest concentrations of polyphenols among all cell types in the body. However, there is little information about what happens in these cells when they are under oxidative stress and in presence of polyphenols [ 6 ]. Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) Spectroscopy and synchrotron radiation-based Fourier Transform Infrared Microspectroscopy (FTIRM) have been recently used to evaluate oxidative stress, like photo-oxidative damage, X-ray radiation, and H 2 O 2 stressors in different types of cells like fibroblast, carcinogenic cells, and plasmatic cells, being able to correlate the shifts in the infrared signals with lipid and protein peroxidation [ 9 – 11 ].…”

Evaluation of biochemical constituents and inhibitory effect of tea clone 100 on colorectal cancer cell line HCT- 116

“…The major catechins present in tea are (-)epigallocatechin, (+)-catechin, (-)epigallocatechin gallate, (-)-epicatechin and (-)epicatechin gallate [5] (Figure 1). Studies have shown that public awareness about the benefits of tea has increased in the recent past [6].…”