Biosynthetic intermediates and stereochemical aspects of aldehyde biosynthesis in the marine diatom Thalassiosira rotula

• Published in: Phytochemistry (Oxford) Vol. 67; no. 3; pp. 314 - 322
• Main Authors: d’Ippolito, Giuliana, Cutignano, Adele, Tucci, Sara, Romano, Giovanna, Cimino, Guido, Fontana, Angelo
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.02.2006; Elsevier
• Subjects: Aldehyde; Aldehydes - chemistry; Aldehydes - metabolism; Alkenes - chemistry; Biological and medical sciences; Diatoms - chemistry; Diatoms - enzymology; Eicosapentaenoic Acid - analogs & derivatives; Eicosapentaenoic Acid - chemistry; Eicosapentaenoic Acid - metabolism; Fatty Acids - chemistry; Fatty Acids - metabolism; Fundamental and applied biological sciences. Psychology; Hydroperoxide; Hydroperoxide lyase; Lipoxygenase - chemistry; Lipoxygenase - metabolism; Metabolism; Metabolism. Physicochemical requirements; Models, Biological; Molecular Conformation; Nuclear Magnetic Resonance, Biomolecular; Oxygenase; Oxylipins; Plant physiology and development; Stereoisomerism; Thalassiosira rotula; Thalassiosira rotula; GC–MS; HPL; Hydroperoxide lyase; Hydroperoxide; CET-TPP; 9 S-HHTrE; Aldehyde; Oxylipins; Oxygenase; NMR; CET; HTA; LOX; 11-HEPE; EPA; HTrA; 9-HPHTrE; PUA; Biosynthetic intermediate; Algae; Biosynthesis; Heterokontophyta; Bacillariophyta; Biosynthesis precursor; EC 1.13.11.12; Thallophyta
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/j.phytochem.2005.11.012

First direct evidence for lipoxygenase-mediated origin of antiproliferative and apoptotic aldehydes in marine diatoms is given. Intermediates of the aldehyde biosynthesis in Thalassiosira rotula are investigated. Use of labeled precursors and cell preparations proves production of 2 E,4 Z-octadienal ( 1a) from 6 Z,9 Z,12 Z-hexadecatrienoic acid (C16:3 ω − 4) through the lipoxygenase-dependent intermediate (9 S)-9-hydroperoxyhexadeca-6,10,12-trienoic acid. On the contrary, synthesis of 2 E,4 Z,7 Z-decatrienal ( 2a) involves mainly EPA (C20:5 ω − 3) by a 11 R-lipoxygenase, as suggested by identification of chiral 11 R-HEPE (12% e.e.) in the diatom extracts. Consistently with the necessity to have a rapid transport and metabolization of the intermediate hydroperoxides, we show that lipoxygenase and lyase activities are both found in the same subcellular fraction of the microalga.