A sulphate ester of tetraphyllin B, (lS, 4S)-l-(B-D-glucopyranosyloxy)-4-hydroxy-2-cyclopentene-lcarbonitrile-4-0-sulphate, was isolated from four PassiJlora species (P. caerulea, quadrangularis, racemosa and hybrida) by anion exchange. The structural assignment is founded on sulphation-induced shifts in 'H and 13C NMR spectra, negative-ion FABMS, and acid-catalysed desulphation to tetraphyllin B.