Vincristine Sulfate EP Impurity E

Chemical Name: Methyl (3aR,4R,5S,5aR,10bR,13aR)-3a-ethyl-9-[(5S,7R,9S)-5-ethyl-5-hydroxy-9-(methoxycarbonyl)-1,4,5,6,7,8,9,10-octahydro-2H-3,7-methanoazacycloundecino[5,4-b]indol-9-yl]-4,5-dihydroxy-8-methoxy-6-methyl- 3a,4,5,5a,6,11,12,13a-octahydro-1H-indolizino[8,1-cd]carbazole-5-carboxylate (as per EP)