4,5-Dihydroxy-3,4,5-trimethyl-4,5,8,10,12,13,13a,13b-octahydro-2H-[1,6]dioxacycloundecino[2,3,4-gh]pyrrolizine-2,6(3H)-dione

DescriptionMonocrotaline (MCT) is a toxic 11-membered macrocyclic pyrrolizidine alkaloid (PA) derived from the seeds of the Crotalaria spectabilis plant. It poisons livestock and humans through the ingestion of contaminated grains and other foods. Pyrrolizidine alkaloid is activated by cytochrome P450 to the reactive pyrrole metabolite dehydromonocrotaline (MCTP) in the liver. The alkaloid causes pulmonary artery hypertension, right ventricular hypertrophy, and pathological changes in the pulmonary vasculature. Monocrotaline is produced for research use. It is used in rat model to investigate human pulmonary hypertension as it offers technical simplicity, reproducibility, and low cost compared with other models of pulmonary hypertension.

DescriptionA hepatotoxic alkaloid of the pyrrolizidine group obtained from Crotalaria retusa and C. spectabilis, the base is laevorotatory with [α]26D - 55.7° (CHCI3). It may be characterized as the hydrochloride, m.p. 184°C ldec.); [α]28D - 38.4° (H20) and the methiodide which crystallizes from MeOH with 3 moles of solvent, m.p. 205°C (dry, dec.); [α]28D + 23.4° (MeOH). Hydrolysis with boiling Ba(OHh furnishes retronecine and monocrotic acid, C7H120 3, b.p. 145-6°C/ 18 mm which is optically inactive. This acid yields a methyl ester, b.p. 94-6°Cj 18 mm, a p-bromophenacyl ester, m.p. 78°C and a 2:4-dinitrophenylhydrazone, m.p. 95-6°C. Hydrogenation in the presence of Pt02 as catalyst yields retro_x0002_necanol and monocrotalic acid, CSH120S' m.p. 181-2°C; [α]28D - 5.33° (H20) which gives a methyl ester, m.p. 79-800 C; [α]30D - 16.2° (EtOH) and a pbromophenacyl ester, m.p. 162-3°C.

HistoryIn 1935, W.M. Neil and L.L. Russoff isolated monocrotaline from Crotalaria sessiliflora L.Monocrotaline showed anticancer activity invivo, especially for treating squamous cell carcinoma, cervical cancer, and leukemia. However, since many pyrrolizidine alkaloid compounds have hepatotoxicity, further development of these compounds is restricted.China began the research of monocrotaline, as early as 1943. Crotalaria sessiliflora L. was also recorded in the 1977 edition of the Pharmacopoeia of the People’s Republic of China. But monocrotaline was reported for its liver toxicity; teratogenic, allergic reactions; and other side effects, limiting its further clinical applications. In 1992, the Ministry of Health stopped the clinical application of monocrotaline injection. Further pharmacology study is essential for monocrotaline .