Engineering and Biomedical Effects of Commercial Juices of Berries, Cherries, and Pomegranates With High Polyphenol Content

Abstract

The juices of berries or red fruits are appreciated as a source of antioxidants with potential health effects. However, they are rich in carbohydrates, an aspect that could be considered negative in view of diabetes and obesity epidemics. Indeed, it is the high polyphenol content of these beverages that is beneficial. When drinking such natural beverages, the consumers have the feeling of following a diet rich in fruit, recognized to reduce the risk of oxidative stress, cardiovascular injury, cancer, and neurodegenerative disorders. In this chapter, the polyphenol content will be compared between cranberry (Vaccinium macrocarpon), blueberry (Vaccinium myrtillus), sour cherry (Punica granatum), and pomegranate (P. granatum) juices. These juices are not a source of resveratrol, the most known polyphenol found in red wines, but the phenolic compounds they contain (punicalagins, ellagic acid, phenolic acids, and kuromanin) are more than mere antioxidants. These polyphenols exhibit superoxide radical scavenging activity and bacteriostatic properties and are protective for their plant of origin. Once ingested, they interact with various enzymes in human tissues, and with intestinal microbiota. We will focus attention on the interplay between extracts of such juices and monoamine oxidase (MAO) activity. MAO is involved in the metabolism of brain neurotransmitters and is expressed in peripheral tissues such as adipose tissue and produces hydrogen peroxide when degrading dietary amines (e.g., tyramine). We report that lyophilisates of fruit juices and their polyphenols inhibit human MAO. In addition, the red fruit polyphenols inhibit alpha-glucosidase, a key enzyme of glucose metabolism. Thus, polyphenols of red fruits juices should have beneficial effects on consumers not only in terms of antioxidant potential, but also as a consequence of modulation of amine degradation and metabolism, potentially acting on the mood and adiposity of the consumers.