[Alkaloids from Bulbocodium vernum L. Content material of Liliaceae-Wurmbaeoidaea]

Reviewing Colchicaceae alkaloids - perspectives of evolution on medicinal chemistry

The subject of chemosystematics has provided insight to both botanical classification and drug development. However, degrees of subjectivity in botanical classifications and limited understanding of the evolution of chemical characters and their biosynthetic pathways has often hampered such studies. In this review an approach of taking phylogenetic classification into account in evaluating colchicine and related phenethylisoquinoline alkaloids from the family Colchicaceae will be applied. Following on the trends of utilizing evolutionary reasoning in inferring mechanisms in eg. drug resistance in cancer and infections, this will exemplify how thinking about evolution can influence selection of plant material in drug lead discovery, and how knowledge about phylogenetic relationships may be used to evaluate predicted biosynthetic pathways.

The photochemical behavior of colchicone and thiocolchicone

The irradiation of colchicone 5 led to the formation of lumicolchicone 7. The same reaction cannot be obtained by using thiocolchicone 6 as substrate. Transient absorption spectroscopy of colchicone and beta-lumicolchicone showed that probably the photoisomerization occurred on colchicone in its first excited singlet state. The spectroscopic data are in agreement with the hypothesis that lumicolchicone was generated in the ground state from the S1 state of colchicone without the presence of any intermediate. Semiempirical calculations on colchicone and thiocolchicone showed that the highest single occupied molecular orbital and the lowest unoccupied molecular orbital of the singlet excited colchicone can give a disrotatory ring closure to 7, while thiocolchicone cannot give the same type of process.