Double hydroperoxidation of α-linolenic acid by potato tuber lipoxygenase

Characterization and biological effects of di-hydroxylated compounds deriving from the lipoxygenation of ALA

“…Further studies presented by Sok and Kim ( 23,24 ) reported four isomers, but again their characterization was not fully established, especially that of the all trans isomers. In 1991 Grechkin et al ( 25 ) showed that potato tuber lipoxygenase (LOX) generated mainly 9(S)-hydroperoxy-octadeca-10 E ,12 Z ,15 Z -trienoic acid [9(S)-HpOTE] which is different from the sLOX which produces mainly 13(S)-hydroperoxy-9 Z ,11 E, 15 Zoctadecatrienoic acid [13(S)-HpOTE]. Also, two compounds after reduction by NaBH 4 were characterized as 9,16-di-HOTE (10 E ,12 Z ,14 E ) except for the stereochemistry of the carbon 16 which remains undetermined and trans isomers were not detected.…”

The lipoxygenase pathway in garlic (Allium sativum L.) bulbs: detection of the novel divinyl ether oxylipins

“…. Potato tuber lipoxygenase preparation was obtained as described previously [7]. Garlic (Allium sativum L.) bulbs were purchased from the local market.…”

“…[1-14C]9-HPOD and [1-14C]9-HPOT were obtained by incubations of linoleate and linolenate, respectively, with potato tuber lipoxygenase as described in [7,9]. …”

“…The extracted products were methylated with ethereal diazomethane. Radio-HPLC analyses were performed in main details as described previously [7][8][9]. The obtained methyl esters were separated by the reversed-phase radio-HPLC on the OctadecylDaltosil 100 (5/lm, 4.6 × 250 mm; Serva Feinbiochemica, Heidelberg, Germany) column using linear gradient from 60 : 40 to 96 : 4 (v/v) in the solvent mixture methanol/water for 55 min, then 25 min more in isocratic conditions, flow rate 0.4 ml/min.…”

Secretion of two novel enzymes, manganese 9S-lipoxygenase and epoxy alcohol synthase, by the rice pathogen Magnaporthe salvinii

“…The 18:1n-9, 18:1n-6, and the methyl ester derivative of 18:2n-6 were not oxidized by 9 S-MnLOX to a signifi cant degree. consistent with 9,16-DiHOTrE, likely formed by double dioxygenation, or by hydrolysis of an allylic epoxide, 9,10-epoxy-11 E ,13 E ,15 Z -octadecatrienoic acid ( 45,46 ). LC-MS/MS analysis suggested the latter mechanism, as the 9-hydroperoxy-16-hydroxy-octadecatrienoic acid was detected ( m/z 325 → 307 → full scan with signals, inter alia , at m/z 249 (307-58; loss of HCO-CH 2 -CH 3 )), whereas 9,16-dihydroperoxyoctadecatrienoic acid was not detected.…”