Detection of oxylipin route controlled by 16(S)-lipoxygenase and allene oxide synthase in cucumber and flax leaves

  • Phytochemistry. 2025 Oct:238:114555. doi: 10.1016/j.phytochem.2025.114555.
Natalia V Lantsova  1 ,  Svetlana S Gorina  1 ,  Tatiana M Iljina  1 ,  Yana Y Toporkova  2 ,  Alexander N Grechkin  3
Affiliations
  • 1. Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, P.O. Box 30, 420111, Kazan, Russia.
  • 2. Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, P.O. Box 30, 420111, Kazan, Russia. Electronic address: [email protected].
  • 3. Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, P.O. Box 30, 420111, Kazan, Russia. Electronic address: [email protected].
PMID: 40404039 DOI: 10.1016/j.phytochem.2025.114555
Abstract

GC-MS profiling of oxylipins (Me/TMS) in cucumber and flax leaves revealed the presence of 13(S)- and 16(S)-lipoxygenase products. Analyses of hydrogenated products (Me/TMS) revealed the presence of 13-hydroxystearic and 16-hydroxystearic acids at a ratio of CA. 1:1 in flax leaves and 1:2 in cucumber leaves. Furthermore, the allene oxide synthase (AOS) products 12-oxo-10,15-phytodienoic acid and α-ketols were detected in the leaves. Alongside the ketols biosynthesized from 13-hydroperoxides of linoleic and α-linolenic acids via the corresponding allene oxides, a novel product, the α-ketol 15-oxo-16-hydroxy-9,12-octadecadienoic acid was detected. Its identification was approved by mass spectral data, hydrogenation, as well as the 1H-NMR, 1H-1H-COSY, and 1H-1H-TOCSY spectra. Vic-diols, for instance, 12,13- and 15,16-diols, were detected along with ketols. These vic-diols were apparently formed by the enzymatic reduction of ketols. To verify the enzymatic origin of 15,16-ketol, three recombinant Enzymes, namely cucumber (CsAOS, CYP74A1_CS), tomato (LeAOS3, CYP74C3), and maize (ZmAOS1, CYP74A19) AOSs, were incubated with α-linolenic acid 16(S)-hydroperoxide. All three Enzymes were active towards the α-linolenic acid 16(S)-hydroperoxide (albeit less than towards 13-hydroperoxides) and converted it into 15-oxo-16-hydroxy-9,12-octadecadienoic acid. The detection of the 16-LOX/16-AOS route in the leaves of cucumber and flax Plants expands our knowledge of the plant LOX pathway.

Keywords
16(S)-Lipoxygenase; Allene oxide synthase; Cucumis sativus L.; Linum usitatissimum L.; α-ketol; α-linolenic acid 16(S)-hydroperoxide.
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