Separation of floridoside and isofloridosides by HPLC and complete 1H and 13C NMR spectral assignments for d-isofloridoside

Isofloridosides (1-O-α-d-galactopyranosylglycerol) and floridoside (2-O-α-d-galactopyranosylglycerol) were extracted from the red alga Porphyra umbilicalis (Linné) Kützing (Bangiales, Rhodophyta). Their separation was achieved by HPLC (NH2 P50 column) after successive purification of the crude extract by ion-exchange chromatography and HPLC (Sugar-Pak TM1 column). 1D and 2D NMR spectroscopy experiments allowed to completely assign the 1H and 13C spectra of d-isofloridoside.