Tropolone alkaloids

The tropolone alkaloid of Liliaceae species, colchicine, is transformed by acetylation, alkaline cyclization, and dehydration into the tetracyclic pyrrolotropone acetyl anhydrocolchicine [77TL2977 83AX(C)1709]. When the dicarboxylic acid anhydride groups of puberulonic and stipitatonic acids (metabolites of Penicillium species) condense with o-phenylenediamine, another tetracyclic pyrrolotropone structure is formed (51JCS1139 59JCS2847). 

New Tropolonic Alkaloids and Related Compounds from Colchicum Species... 

Extensive tracer experiments show that tropolone alkaloids of the species Colchicum are derived from the I-phenethylisoquinoline system (73) by way of the dienone O-methylandrocymbine (16) (56). These findings, when combined with results of the earlier work (57), support the sequence shown. 

Reviews on the photoisomerisation of tropolone alkaloids and on the photoreactions of hydroxamic acids ° have been published. 

There is no uniform classification for the A. In the literature divisions according to origin (examples Aconitum, Amaryllidaceae, Aspidosperma, cactus, Catharanthus, Cephalotaxus, Cinchona, coca, Corydalis, curare, Dendrobates, ergot, Erythrina, Iboga, Lycopodium, Maytenus, opium, Rauvol-fia, Senecio, Strychnos, tobacco, Vinca alkaloids, salamander, Solanum, Veratrum steroid alkaloids) in addition to divisions according to chemical structure (examples aporphine, benzylisoquinoline, bis-benzylisoquinoline, berberine, carboline, diterpene, inudazole, indole, indolizidine, isoquinoline, lupinane, macrocyclic, morphine, peptide, / -phenyl-ethylamine, piperidine, purine, pyridine, pyrrolidine, pyrrolizidine, quinoline, quinolizidine, quinucli-dine, spermine, spermidine, steroid, terpene, tro-pane, tropolone alkaloids) are used. 

The amide nitrogen of colchicine is not basic, and some have argued that colchicine is not a true alkaloid. However, as the precursors and the pathway leading to this compound are typical for those of alkaloids, colchicine is considered an alkaloid for present purposes. Although this compound is the best known of the group, more than 30 other tropolonic alkaloids occur in Colchicum autumnale and related plants (Capraro and Brossi, 1984). The physical constants and spectral data of colchicine and related alkaloids have been tabulated (Tojo, 1989). 

The formation of tropolone alkaloids is characteristic of the subfamily Wurmbaeoideae (Lfiiaceae family). The best known alkaloid... 

Boye O and Brossi A (1992) Tropolonic Colchicum alkaloids and alio congeners. The Alkaloids, Chemistry and Pharmacology (ed Brossi A and Cordell GA) Vol 41. Academic, San Diego, pp 125-176. 

Extraction of dried plant materials from Colchicum species with methanol afforded, after separation into neutral and basic fractions and chromatography on silica, several tropolonic and alio congener alkaloids (listed in Table I and II). 

---