C6-Aldehyde Formation by Fatty Acid Hydroperoxide Lyase in the Brown Alga Laminaria angustata

Abstract

Some marine algae can form volatile aldehydes such as n-hexanal, hexenals, and nonenals. In higher plants it is well established that these short-chain aldehydes are formed from C18 fatty acids via actions of lipoxygenase and fatty acid hydroperoxide lyase, however, the biosynthetic pathway in marine algae has not been fully established yet. A brown alga, Laminaria angustata, forms relatively higher amounts of C6- and C9-aldehydes. When linoleic acid was added to a homogenate prepared from the fronds of this algae, formation of n-hexanal was observed. When glutathione peroxidase was added to the reaction mixture concomitant with glutathione, the formation of n-hexanal from linoleic acid was inhibited, and oxygenated fatty acids accumulated. By chemical analyses one of the major oxygenated fatty acids was shown to be (S)-13-hydroxy-(Z, E)-9, 11-octadecadienoic acid. Therefore, it is assumed that n-hexanal is formed from linoleic acid via a sequential action of lipoxygenase and fatty acid hydroperoxide lyase (HPL), by an almost similar pathway as the counterpart found in higher plants. HPL partially purified from the fronds has a rather strict substrate specificity, and only 13-hydroperoxide of linoleic acid, and 15-hydroperoxide of arachidonic acid are the essentially suitable substrates for the enzyme. By surveying various species of marine algae including Phaeophyta, Rhodophyta and Chlorophyta it was shown that almost all the marine algae have HPL activity. Thus, a wide distribution of the enzyme is expected.

Biosynthesis and function of polyacetylenes and allied natural products

“…Intrachain oxidation yields hydroperoxide derivatives capable of cleavage to short chain aldehydes. Hydroperoxide lyase has also been solubilized from brown algae, which cleaves (9Z,11E,12S)-12-hydroperoxy-9,11-octadecadienoic acid to hexanal, in a manner analogous to higher plant wounding and pest responses [157,158]. Cell lysates from the green alga U. conglobata produce midchain (9R)-hydroperoxides from 2C and 2P [159], but cleave arachidonic acid via a (11R)-hydroperoxy intermediate to (2E,4Z) and (2E,4E)-decadienal [160].…”

“…Cell lysates from the green alga U. conglobata produce midchain (9R)-hydroperoxides from 2C and 2P [159], but cleave arachidonic acid via a (11R)-hydroperoxy intermediate to (2E,4Z) and (2E,4E)-decadienal [160]. Control of the cleavage reactions is exerted by strict substrate specificity, as shown by the action of partially purified Laminaria angustata hydroperoxide lyase on (13S)-hydroperoxy and (15S)-hydroperoxides of linoleate and arachidonate, respectively [157]. Other activities, such as a heme-c containing protein, may be involved in the production of racemic 9-and 13-hydroperoxides in certain algae [161].…”

Formation of Aldehyde Flavor (n-hexanal, 3Z-nonenal and 2E-nonenal) in the Brown Alga, Laminaria Angustata

“…The marine algae are major components of the earth's biomass, responsible for significant carbon fixation, and occupy an extreme diversity of climatic Minor pathway Major pathway A. was reported by Boonprab et al (2003a) B. was reported by Boonprab et al (2003b) niches. Further studies would provide insight into the physiology or regulation of these pathways, which may be involved in growth development, chemical defense, oxidative stress or other mtabolic functions in algae.…”

“…HPL partially purified from the fronds has a rather strict substrate specificity, and only 13-hydroperoxide of linoleic acid, and 15-hydroperoxide of arachidonic acid are the essentially suitable substrates for the enzyme. (Boonprab et al, 2003a) Biosynthesis of C6 aldehyde (n-hexanal) and C9 aldehydes (n-hexanal, 3Z-nonenal and 2E-nonenal) from arachidonic acid In higher plants, C6 and C9 aldehydes are formed from C18 fatty acids, such as linoleic acid or linolenic acid, through the formation of 13-and 9-hydroperoxides, followed by their stereospecific cleavage by fatty acid hydroperoxide lyases. Some marine algae can also form C6 and C9 aldehydes, but the precise biosynthetic pathway has not been fully elucidated.…”

Diversity and evolution of cytochromes P450 in stramenopiles

“…Now both genomic and metabolomic data are available for Ectocarpus siliculosus, and genome and metabolome data are available for two species pairs from the same genus in two other stramenopiles. Genome data from S. japonica can be compared to metabolome data from S. angustata (Boonprab et al 2003b;Boonprab et al 2003a), whereas genome data from T. pseudonana can be related with metabolic data from T. rotula (Barofsky and Pohnert 2007;D'Ippolito et al 2006). It is not yet possible to assign all P450 paralogs to a specific enzymatic activity, but our data already provide some clarifications.…”