3H-benz[c]indeno[5,4-e]oxepin-3-one, 10-[(1S,2R,3R,4S)-2,3-dihydroxy-1,4,5-trimethyl[5,6-3H2]hexyl]hexadecahydro-5,6-dihydroxy-7a,9a-dimethyl-, (3aS,5S,6R,7aR,7bS,9aS,10R,12aS,12bS)- tritium-labelled brassinolide