Abstract
Two main tannins have been isolated from the leaf of a Japanese medicinal plant, Mallotus japonicus Muell. Arg. (Euphorbiaceae) used for gastric ulcer. One was identified with geraniin which is the main tannin of Geranium species. The other one, mallotusinic acid, was obtained as yellow amorphous powder, C48H32O32⋅xH2O, and was found to be a new ellagitannin. Condensation with o-phenylenediamine gave a phenazine derivative, C54H34N2O29⋅y H2O, which gave upon hydrolysis, “phenazine C”, a known hydrolysis product of “phenazine A” and “phenazine B” prepared from geraniin, and also the residual part of the original molecule, which was named mallotinic acid.
The struc ture of mallotinic adid was shown to be 1-galloy1-3, 6- (+)-valoneoy1-β-D-glucopyranose, by the results of hydrolysis of mallotinic acid and of methanolysis of methyl undecaO-methylmallotinate and methyl trideca-O-tnethylmallotinate, and also by the NMR and MS spectral data. Two carboxyl groups on the biphenyl ring of valoneic acid were assigned to form ester bonds with O-3 and O-6 of D-glucose in mallotinic acid.
These results together with the 1H and 13C-NMR spectral da ta of mallotusinic acic and its derivatives indicate that mallotusinic acid has a dehydrohexahydroxybiphenyl-2, 2'-dicarbonyl group on 0-2 and 0-4 of D-glucopyranose of mallotinic acid. The dehydrohexahydroxybiphenyl2, 2'-dicarbonyl group in mallotusinic acid is always present as a mixture of the six-membered and five-membered hemiacetal structures.
Mallotinic acid was also detected in the extract of the leaf.
