Detection of a Pathway From Linoleate to a Novel Cyclopentenone: cis‐12‐Oxo‐10‐Phytoenoic Acid in Sunflower Roots

  title={Detection of a Pathway From Linoleate to a Novel Cyclopentenone: cis‐12‐Oxo‐10‐Phytoenoic Acid in Sunflower Roots},
  author={Alexander N Grechkin and Anna V. Ogorodnikova and Oleg I. Gnezdilov and Lucia S. Mukhtarova},
The lipoxygenase pathway in sunflower roots was studied in vitro. A preliminary incubation of linoleic acid with 15 000 g supernatant of homogenate of sunflower roots (1.5–6 days after germination) revealed the predominant activity of 13‐lipoxygenase. The exogenously added linoleic acid 13‐hydroperoxide is further utilized through two competing pathways. One of them is directed towards formation of the ketodiene (9Z,11E)‐13‐oxooctadeca‐9,11‐dienoic acid. The second pathway, which is controlled… 

Novel Allene Oxide Synthase Products Formed via Favorskii‐Type Rearrangement: Mechanistic Implications for 12‐Oxo‐10,15‐phytodienoic Acid Biosynthesis

In vitro incubations of AOSs with α‐linolenic acid 13(S)‐hydroperoxide reliably afforded 1 along with 12‐oxo‐PDA and α‐ketol demonstrated that cyclopropanones are short‐lived AOS products along with allene oxides.

Tomato CYP74C3 is a Multifunctional Enzyme not only Synthesizing Allene Oxide but also Catalyzing its Hydrolysis and Cyclization

The results indicate that in contrast to the ordinary allene oxide synthases, LeAOS3 (CYP74C subfamily) is a multifunctional enzyme, catalyzing not only the synthesis, but also the hydrolysis and cyclization of allenes oxide.

Allene Oxide Synthase Pathway in Cereal Roots: Detection of Novel Oxylipin Graminoxins

Young roots of wheat, barley, and sorghum, as well as methyl jasmonate pretreated rice seedlings, undergo an unprecedented allene oxide synthase pathway targeted to previously unknown oxylipins 1–3, indicating that conversion of the allenes oxide into the cyclopropanone is controlled by soluble cyclase.

Stereospecific biosynthesis of (9S,13S)-10-oxo-phytoenoic acid in young maize roots.

Biosynthesis of Jasmonates from Linoleic Acid by the Fungus Fusarium oxysporum. Evidence for a Novel Allene Oxide Cyclase.

The presence of AOS and the biosynthesis of the allene oxide 12,13(S)-epoxy-9,11-octadecadienoic acid confirms the conclusion that the fungal AOC is distinct from the corresponding plant enzyme.



Identification of a Jasmonate-regulated Allene Oxide Synthase That Metabolizes 9-Hydroperoxides of Linoleic and Linolenic Acids*

The molecular cloning and characterization of a novel AOS-encoding cDNA from Lycopersicon esculentum suggest that LeAOS3 plays a role in the metabolism of 9-lipoxygenase-derived hydroperoxides in roots, and that this branch of oxylipin biosynthesis is regulated by the jasmonate signaling cascade.

On the specificity of allene oxide cyclase

A number of oxygenated fatty acids having structural features in common with the natural allene oxides were tested as inhibitors of allene oxide cyclase and fatty acid hydroperoxides with a double bond at n−3 and with the hydroperoxide function at n −6 exhibit the highest affinity but the slowest reaction velocity.

New cyclopentenone fatty acids formed from linoleic and linolenic acids in potato

Quantitative determination of 10-oxo-11-phytoenoic acid in linoleic acid-supplied homogenates of different parts of the potato plant showed high levels in roots and stolons, lower levels in developing tubers, and no detectable levels in leaves.

The lipoxygenase pathway in tulip (Tulipa gesneriana): detection of the ketol route.

Tulip bulbs possess abundant allene oxide cyclase activity, the substrate for which is linolenate 13(S)-hydroperoxide, even though 13( S)-lipoxygenase products were not detectable in the bulbs.

Substrate specificity for the synthesis of cyclic Fatty acids by a flaxseed extract.

Substrate specificity studies showed that n-3,6,9 unsaturation was an absolute requirement for conversion of polyunsaturated fatty acids into analogous products containing a cyclopentenone ring.

A pathway for biosynthesis of divinyl ether fatty acids in green leaves

Incubations of isomeric hydroperoxides derived from α-linolenic and linoleic acids with the enzyme preparation from R. acris showed that 13(S)-hydroperoxy-9(Z), 11(E)-octadecadienoic acid was transformed into the divinyl ether 12-[1′(Z)-hexenyloxy]-9-Z, 11-E-dodecadienOic acid.