Anti-hepatitis C virus effect of citrus unshiu peel and its active ingredient nobiletin.

We investigated the effects of water and ethyl acetate extracts of Citrus unshiu peel (Aurantii Nobilis pericarpium) on hepatitis C virus (HCV) absorption in MOLT-4 cells (a human lymphoblastoid leukemia cell line). By reverse transcription polymerase chain reaction (RT-PCR), we showed that both the ethyl acetate layer of Citrus unshiu peel extract and fraction 7 decreased HCV absorption in MOLT-4 cells. Furthermore, we demonstrated that 3',4',5,6,7,8-hexamethoxyflavone (nobiletin) is the active ingredient that markedly inhibited HCV infection in MOLT-4 cells.