La corteza del tarmu contién: ourateacatechina (4′-O-methyl-(−)-epigallocatechina), ouratea-proanthocyanidina A (epiafzelechin-(4β→8)-4′-O-methyl-(−)-epigallocatechin) y el trimeric propelargonidina epiafzelechin-(4β→8)-epiafzelechin-(4β→8)-4′-O-methyl-(−)-epigallocatechin.