Naringin
Naringin is a flavanone glycoside. It is a major flavonoid in grapefruit and gives the grapefruit juice its bitter taste. It is metabolized to the flavanone naringenin in humans. Both naringenin and hesperetin, which are the aglycones of naringin and hesperidin, occur naturally in citrus fruits.
Read more about Naringin.