Biosynthesis of thiophenes in Tagetes patula

The biosynthesis of 5-(3-buten-1-ynyl)-2,2'-bithiophene was studied in root cultures of Tagetes patula. Organ cultures were grown with [U-13C(6)]glucose or [1-13C]glucose. The bithiopene and amino acids from cell protein were isolated and analysed by quantitative NMR spectroscopy. Retrobiosynthetic analysis establish acetyl-CoA or a closely related compound (e.g. malonyl-CoA) as building blocks and their orientations in the bithiophene. The data confirm a previously suggested biosynthetic route via long-chain fatty acids and polyacetylenes. However, a polyketide-like biosynthesis via a carbocyclic intermediate cannot be excluded.