Biosynthesis of R‐(+)‐octane‐1’3‐diol. Crucial role of β‐oxidation in the enantioselective generation of 1’3‐diols in stored apples

Abstract

The biosynthesis of R-octane-1,3-diol and R-5(Z)-octene-1,3-diol, two natural antimicrobial agents in apples and pears, was investigated in stored apples after application of [9,10,12,13-3H]linoleic acid, [9,10,12,13,15,16-3H]linolenic acid, [1-14C]linoleic acid, [U-14C]oleic acid, lipoxygenase-derived metabolites of [9,10,12,13-3H]linoleic acid, 13C18-labeled linoleic acid hydroperoxides, and 2H-labeled octanol derivatives. Analysis of the products and quantification of incorporation and labeling pattern were achieved by high-performance liquid chromatography-radiodetection, capillary gas chromatography (GC)-isotope ratio mass spectrometry, and GC-mass spectrometry analysis. Almost all the applied precursors were partly transformed into R-octane-1,3-diol. Linoleic acid derivatives, still containing the 12,13 cis double bond, and octanol derivatives oxy-functionalized at carbon 3 were the most efficient precursors of the 1,3-diol. The data imply that R-octane-1,3-diol is generated in stored apples in the course of the beta-oxidation from R-3-hydroxy-octanoyl-SCoA originating from 2-cis-octenoyl-SCoA by enoyl-CoA hydratase. In an analogous fashion, R-5(Z)-octene-1,3-diol is formed from the unsaturated intermediate.

Pear Fruit Volatiles

“…Jennings and Tressl (1974) proposed a possible~-oxidation pathway for the biogenesis of mono-, di-, and tri-unsaturated esters specific to 'Bartlett' pear from unsaturated fatty acids (Fig. This pathway has also been reported to operate in other fruits such as apple (Paillard 1979;Bartley et al 1985;Beuerle and Schwab 1999), banana, and strawberry (Tressl and Albrecht 1986). Oleic and linoleic acid are metabolized to various shorter chain-length acyl-CoAs by losing two carbons during each oxidation cycle.…”

Metabolic diversity in apple germplasm

“…These β‐glycols play an important role in some cider apple varieties as aroma precursors and exhibit antimicrobial activity at concentrations harmless for humans and animals (Dietrich et al. , Beuerle and Schwab ). This is an example that loss of functional alleles not only may lead to a strong reduction in desired metabolites, but also to an increase in desired metabolites, in this case an approximately 20 times higher concentration of β‐glycols, in some progeny compared with both parents.…”

HS–SPME–GC–MS profiling and sensory analyses of juices from red-fleshed ‘Weirouge’ apples made with innovative and conventional dejuicing systems

“…1,3-Diols may represent intermediates of the fatty acid metabolism, possibly involving catabolic β-oxidation or lipoxygenase reaction [59] and anabolic de novo synthesis [53]. Beuerle and Schwab [60] have investigated the biosynthesis of (R)-1,3-diols in stored apples during β-oxidation of linoleic acid. As a stereoselective step, enoyl-CoA hydratase catalyzes the hydroxylation of 2-(Z)octenyl-SCoA, resulting in (R)-3-hydroxyoctanoyl-SCoA.…”

“…The latter may be converted into a corresponding ester or the reduction of the (R)-3-hydroxy octanoic acid intermediate may result in (R)-1,3-octanediol. In an analogous pathway, linolenic acid was transformed into its unsaturated analogue (R)-5(Z)-octene-1,3-diol [60].…”