A new ellagitannin, jolkinin (2), was isolated from the fresh whole plant of Euphorbia jolkinii, and its
structure, including absolute configuration, was determined on the basis of spectroscopic and chemical
evidence. A highly oxygenated acyl group with unique hexacyclic structure is attached to the 2,4-positions
of 1-O-galloyl-3,6-(R)-hexahydroxydiphenoyl-â-D-glucopyranose. The structural similarity to elaeocarpusin
(4) suggests that jolkinin is produced by a condensation reaction between ascorbic acid and geraniin (1),
the dominant ellagitannin in this plant, which contains a dehydrohexahydroxydiphenoyl group. A plausible
mechanism for jolkinin formation is also proposed.