Obt. from citrus fruits, Clymenia polyandra (clymenia) and Origanum vulgare (oregano) Naringin is the major flavonoid glycoside in grapefruit and gives grapefruit juice its bitter taste. It is metabolized to the flavonone naringenin in humans. Both naringin and hesperetin, which are the aglycones of naringin and hesperidin, occur naturally in citrus fruits. Narinigin exerts a variety of pharmacological effects such as antioxidant activity, blood lipid-lowering, anticarcinogenic activity, and inhibition of selected cytochrome P450 enzymes including CYP3A4 and CYP1A2, which may result in several drug interactions in-vitro.