Phenolic–protein interactions (PPI), which naturally occur in most food systems, are being intentionally designed to enhance functional performance of phenolic compounds (PC). PPI have been primarily associated with changes related to sensorial, nutritional, and nutraceutical features of foods. Furthermore, these interactions affect properties such as astringency, protein digestibility, absorption, and bioavailability of antioxidants. Therefore, new product development should pay attention to these interactions and not only on the concentration of PC. PPI protect PC from degradation due to enzymatic attack or pH changes in the lumen of the intestinal tract. Due to PPI, PC are delivered to the colon where they are metabolized by the microbiota and generate an antioxidant environment. Interactions with proteins also may enhance the antiproliferative activity of PC in some specific tumor cell lines. In this review, the effects of PPI that affect both food properties and health benefits are discussed.

Opuntia ficus-indica(OFI) has been widely used in Mexico as a food and for the treatment of different health disorders such as inflammation and skin aging. Its biological properties have been attributed to different phytochemicals such as the isorhamnetin glycosides which are the most abundant flavonoids. Moreover, these compounds are considered a chemotaxonomic characteristic of OFI species. The aim of this study was to evaluate the effect of OFI extract and its isorhamnetin glycosides on different inflammatory markersin vitroandin vivo. OFI extract was obtained by alkaline hydrolysis of OFI cladodes powder and pure compounds were obtained by preparative chromatography. Nitric oxide (NO), cyclooxygenase-2 (COX-2), tumor necrosis factor- (TNF-)α, and interleukin- (IL-) 6 production were measured. NO production was tested in lipopolysaccharide-stimulated RAW 264.7 cells whilein vivostudies were carried on croton oil-induced ear edema model. OFI extract and diglycoside isorhamnetin-glucosyl-rhamnoside (IGR) at 125 ng/mL suppressed the NO productionin vitro(73.5 ± 4.8% and68.7±5.0%, resp.) without affecting cell viability. Likewise, IGR inhibited the ear edema (77.4±5.7%) equating the indomethacin effects (69.5±5.3%). Both IGR and OFI extract significantly inhibited the COX-2, TNF-α, and IL-6 production. IGR seems to be a suitable natural compound for development of new anti-inflammatory ingredient.

Solid state fermentation (SSF) is a sustainable process that uses low amounts of water and transforms plant-based agro-industrial residues into valuable products such as enzymes, biofuels, nanoparticles and other bioactive compounds. Many fungal species can be used in SSF because of their low requirements of water, O₂ and light. During SSF, plant-based wastes rich in soluble and insoluble fiber are utilized by lignocellulolytic fungi that have enzymes such as lignases, celullases or hemicelullases that break fiber hard structure. During the hydrolysis of lignin, some phenolic compounds are released but fungi also synthetize bioactive compounds such as mycophenolic acid, dicerandrol C, phenylacetates, anthraquinones, benzofurans and alkenyl phenols that have health beneficial effects such as antitumoral, antimicrobial, antioxidant and antiviral activities. Another important group of compounds synthetized by fungi during SSF are polysaccharides that also have important health promoting properties. Polysaccharides have antioxidant, antiproliferative and immunomodulatory activities as well as prebiotic effects. Fungal SSF has also proved to be a process which can release high contents of phenolics and it also increases the bioactivity of these compounds.