Biosynthesis of dihydroergot alkaloids

✍ Scribed by Kevin D. Barrow; Peter G. Mantle; Francoise R. Quigley

• Publisher: Elsevier Science
• Year: 1974
• Tongue: French
• Weight: 165 KB
• Volume: 15
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)93135-1

✦ Synopsis

The biosynthesis of polypeptide ergot alkaloids (Ia) involves the intermediate lysergic acid (Ib).' The role of 6-methyleqol-G-ene-B-carboxylic acid (II)2 Is less clear and the mlgration of the double bond fras the 8.9 to the 9.10 position is also poorly understood.' Sam years ago one of us isolated dihydroergosine (III) from cultures of the fungus sphocecic ~oJL&." This is the only naturally occurring polypeptide dihydroergot alkaloid known so far although dihydroclavine alkaloids are more widely distributed and have been isolated from nlll*rous mlcroorganisms.s These dihydroclavine alkaloids are censldered to be formed by reduction of the corresponding clavine alkaloids.c Possible pathways to dihydroergosine could be analogy involve reduction of the 9.10 double bond of ergasine or a precursor of ergosine or involve the roductlon of an alkaloid containing an 8.9 double bond. It is kwmn that the clavine alkaloids incorporate the 5-pro-R hydrogen fra me*alomk acid aed that thls hydrogen Is located at position 10 in the ergoline ring system.' The S-=-S hydrogen is lost in the cyclisation of ring C.