Cis3Hexenal

Cis-3-hexenal, also known as (Z)-3-hexenal, is a volatile aldehyde with the formula C6H10O. It is a major component of the green leaf volatile blend released by many plants and is responsible for the characteristic fresh, grassy aroma associated with damaged vegetation.

Biosynthesis and metabolism: Cis-3-hexenal is produced in plants through the lipoxygenase pathway from polyunsaturated fatty acids such as linolenic acid. After initial lipoxygenase action creates hydroperoxides, hydroperoxide lyase cleaves these intermediates to yield cis-3-hexenal and other products. In plants, cis-3-hexenal is rapidly metabolized to less volatile compounds such as cis-3-hexenol and cis-3-hexenyl acetates by alcohol dehydrogenases and acetyltransferases, contributing to a complex bouquet of volatiles.

Ecological role: Emission of cis-3-hexenal occurs promptly upon tissue damage or herbivory. As a signaling cue, it can prime defense responses in neighboring plants, attract natural enemies of herbivores, and participate in plant-plant communication. Some evidence also suggests antimicrobial effects at higher concentrations, contributing to defense at the interface between plant tissues and the environment.

Chemical properties and applications: As a reactive, volatile aldehyde, cis-3-hexenal can undergo oxidation and isomerization, occasionally converting to trans-2-hexenal under certain conditions, which alters odor characteristics. Beyond ecological roles, green leaf volatiles including cis-3-hexenal are used in flavor and fragrance contexts and are studied for their roles in induced resistance and pest-management strategies.