ABSTRACT

Bioactive compounds such as vitamin C, carotene (β-carotene), “avonoids, limonoids, essential oil, acridone alkaloids, œbers, minerals, vitamin B, and other related nutrients such as thiamine, ribo“avin, nicotinic acid/niacin, pantothenic acid, pyridoxine, folic acid, and so on are present in citrus fruits (Benavente-Garcia et al., 1997; Hamdan et al., 2011). Of all the “avonoids, “avanone glycosides (polymethoxy “avones) present in citrus have a constructive in“uence on human health. In addition, these compounds seek scientiœc attention because of their physiological and pharmacological beneœts. Flavonoids are a large group of phenolic bioactives that are found in a range of plant-derived foods, mainly in citrus peel, skin of grapes, and epidermis of tea leaves (Denny and Buttriss, 2007). Flavonoids have a unique structure based on three phenyl rings, A, B, and C, as shown in Figure 20.1 where ring B may bind to position 3 at fused ring C to form iso“avonone (Bohm, 2006). Variations in substitution pattern to ring C in the structure of these compounds result in the major “avonoid classes: “avonols (found in onions, e.g., quercetin), “avones (found in parsley/ celery, e.g., apigenin), “avanones (found abundantly in citrus fruits, e.g., naringin and hesperitin), iso“avones (leguminous plants such as soybean, e.g., genestein), “avanols (found in tea/apple/apricot, e.g., catechins), and anthocynadins (found in blackcurrants/blueberries, e.g., cyanidins). The biological effects of “avonoids depend on their chemical structure. The position of hydroxyl groups (OH) and other features are important for antioxidant and free-radical-scavenging effects (Hosseinimehr, 2010; Martins et al., 2011).