The flavanones are the first flavonoid products of the flavonoid biosynthetic pathway. They are characterized by the presence of a chiral center at C2 and the absence of the C2-C3 bond. The flavanone structure is highly reactive, and they have been reported to undergo hydroxylation, glycosylation, and O-methylation reactions. Flavanones are present in high levels in citrus fruits, with the most common glycoside known as hesperidin (hesperetin-7-o-ruti-noside), which is present in citrus peel. Interestingly, flavanone rutinosides are tasteless, whereas the fla-vanone neohesperidoside conjugates (e.g., neohe-speridin) from bitter orange and naringenin (naringenin-7-o-neohesperidoside) from grapefruit peel have an intensely bitter taste.
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