Hesperetin, a selective phosphodiesterase (PDE)4 inhibitor, is present in the traditional Chinese medicine, ?€?Chen Pi.?€? Hesperetin is a citrus flavonoid that has been reported to lower plasma cholesterol. Hesperetin reduces the transcription of ACAT-2 mRNA in Hep-G2 cells and reduces ApoB protein synthesis in a dose-dependent manner. It also is a potential therapy for carcinoid cancer.