The molecule is an organic heterotetracyclic compound and 19-membered macrocyclic lactam antibiotic originally isolated from the Ethiopian shrub Maytenus serrata but also found in other Maytenus species. It exhibits cytotoxicity against many tumour cell lines. It has a role as a plant metabolite, an antimicrobial agent, an antineoplastic agent, a tubulin modulator and an antimitotic. It is an epoxide, a carbamate ester, an organochlorine compound, an alpha-amino acid ester, an organic heterotetracyclic compound and a maytansinoid.
[(1S,2R,3S,5S,6S,16E,18E,20R,21S)-11-chloro-21-hydroxy-12,20-dimethoxy-2,5,9,16-tetramethyl-8,23-dioxo-4,24-dioxa-9,22-diazatetracyclo[19.3.1.110,14.03,5]hexacosa-10,12,14(26),16,18-pentaen-6-yl] (2S)-2-[acetyl(methyl)amino]propanoate