Acetylenes from Plants


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


Related Images

Acetylenes from Fatty Acids

Allylic Rearrangement

Origin of C13 and C14-polyacetylenes

Oxidation-Reduction Series

α-Oxidation

α-Oxidation by Decarboxylation

Baeyer-Villiger Type Oxidation

Unusual Allenic Lipid

Phenyl and Thiophene Derivatives

Miscellaneous Polyacetylenes

Additional Acetylenic Compounds

Toxic and Bioactive Acetylenic Compounds

Acetylenic Phytoalexins


Lecture Slides

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.