5-Lipoxygenase-derived oxylipins from the red alga Rhodymenia pertusa

A one-step method of 10,17-dihydro(pero)xydocosahexa-4Z,7Z,11E,13Z,15E,19Z-enoic acid synthesis by soybean lipoxygenase

“…Importantly, the protons with d z4. 15 (16) H-], but not with the protons at C (13) and C (14) . Therefore, product II a was identified as 17-hydroperoxydocosahexa-4Z,7Z,10Z, 13Z,15E,19Z-enoic acid, with the hydroxyl group at C (17) being in the S configuration (10,12).…”

“…That mechanism is based on an epoxidation reaction of the C (17) hydroperoxy group of 17(S)-HPDHA yielding a compound with the 11E,13E,15Z geometry of the conjugated triene. If the C (17) hydroperoxy group is absent (e.g., is substituted with a hydroxy group), the reaction should not occur because the crucial intermediate, C (16) /C (17) epoxide, cannot be formed. Contrary to this assumption, in our recent experiments (10), we were able to obtain 10, 17(S)-diHDHA from either 17(S)-HPDHA or 17(S)HDHA.…”

“…1, 3, 4). This was not surprising considering the highly symmetrical nature of 10,17(S)-HDHA (Scheme 2), with four pairs of equivalent protons at C (10) / C (17) , C (11) /C (16) , C (12) /C (15) , and C (13) /C (14) . The clear absence of trans,trans vinyl protons was also indicative of a specific (i.e., purely enzymatic) mechanism of formation of the products, as any involvement of a free radical chain reaction similar to those described previously (14,15) would have produced measurable quantities of thermodynamically favorable trans,trans or all-trans isomers of the products, which was not the case in the current experiments.…”

“…Additional evidence that supports the 11E,13Z,15E arrangement of the conjugated triene came from the fact that the methine protons at C (10) and C (17) (d z4.15-4.17 ppm) produced cross-peaks with trans vinyl protons at C (11) and C (16) (d z5.75 ppm). No such cross-peaks with protons of a cis vinyl group (d z5.97 ppm) were observed.…”

Identification of hydroxyeicosatetraenoic acid components of schistosomal hemozoin

“…Chiral purity of biologically derived hydroxylated fatty acids is typically attributed to the lipoxygenase (Lox) family [24][25][26][27][28][29][30][31] with preference usually shown for S-stereoisomer products. In the absence of Lox, however, free-radical mediated peroxidation of AA can yield a racemic mixture of each hydroxylated isomer.…”