New furanocoumarins detected from grapefruit juice retentate.

Grapefruit (Citrus paradisi Macf.) furanocoumarins and related compounds have been shown to interact with the enterocyte cytochrome P450, CYP3A4, and as a result they affect the bioavailibility of certain drugs. Only a few grapefruit furanocoumarins have been identified so far. In this study, grapefruit juice retentate, rich in furanocoumarins, was extracted and then separated by flash chromatography for the examination of new compounds. Finally, nine new furanocoumarins were detected in different fractions according to their UV spectra and mass spectrometric properties by LC-MS (liquid chromatography mass spectrometry) and tentatively designated as FC 338, FC 420, FC 524, FC 530, FC 540, FC 546, FC 552, FC 570 and FC 614.