Acetylenes in plants -- three main types: C-18 FA's, metabolized FA's, and miscellaneous types
C-18 FA's are often components of triglycerides. There are often triple bonds in the same places that one predicts double bonds
this type of acetylenic compound is found in seeds of some members of the Asteraceae (Compositae), but are commonly accumulated in the Santalaceae, Loranthaceae, Viscaceae, Olacaceae, and Opiliaceae.
Metabolized compounds are found in the Asteraceae, Apiaceae (Umbelliferae), Araliaceae, Pittosporaceae, and Campanulaceae.
Crepenynic acid is the first acetylenic acid in the series ... and a key intermediate
Allylic oxidation and rearrangement
"crepenynic acid rearrangement"
β- and α-oxidation
there are at least two types of α-cleavages (see below)
Oxidation and reduction series
-CH3 ----> -CH2OH ----> -CHO ----> -CO2H (and vice versa)
"Baeyer-Villiger" type oxidation
cleavage in the middle of chains
Aromatic compounds
compounds with three triple bonds often cyclize to benzene rings - the mechanism for how this happens is not clear
Sulfur compounds
"sulfur" adds across conjugated triple bonds to form thiophenes and related compounds
many acetylenes are toxic
phytoalexins
Allenic fatty acids
These compounds are sporadically distributed. Laballenic acid is found in Lamium species (Lamiaceae), as well as in an unusual triglyceride in Sapium sebiferum (Euphorbiaceae).
Plants with Acetylenic Compounds
Origin of C13 and C14-polyacetylenes
α-Oxidation by Decarboxylation
Baeyer-Villiger Type Oxidation
Phenyl and Thiophene Derivatives
Additional Acetylenic Compounds
Toxic and Bioactive Acetylenic Compounds
Plants with Acetylenic Compounds
© David S. Seigler, Integrative Biology 425, Plant Secondary Metabolism, Department of Plant
Biology, 265 Morrill Hall, 505 S. Goodwin Ave., University of Illinois, Urbana, Illinois 61801, USA.
217-333-7577. seigler@life.uiuc.edu.
