Citrus Ă— sinensis is the group of oranges that includes the commonly eaten navel orange and the blood orange. The peels and fruit are a rich source of citrus bioflavonoids. But our interest went beyond just including a generic citrus bioflavonoid mixture. What we were really interested in is a specific polymethoxylated flavone called nobiletin. Nobiletin has been identified as clock-enhancing small molecule, so is a key nutrient to support body clock functions.