Neoxanthin is a carotenoid and xanthophyll. In plants, it is an intermediate in the biosynthesis of the plant hormone abscisic acid. It is often present in two forms: all-trans and 9-cis isomers. It is produced from violaxanthin, but a suspected neoxanthin synthase[1] is still to be confirmed. Two different genes were confirmed to be implied in violaxanthin conversion to neoxanthin in Arabidopsis and tomato.[2][3] It has a specific role in protection against photooxidative stress.[4] It is a major xanthophyll found in green leafy vegetables such as spinach.
^Neuman, Hadar; Galpaz, Navot; Cunningham Jr, Francis X.; Zamir, Dani; Hirschberg, Joseph (2014). "The tomato mutation nxd1 reveals a gene necessary for neoxanthin biosynthesis and demonstrates that violaxanthin is a sufficient precursor for abscisic acid biosynthesis". Plant Journal. 78 (1): 80–93. doi:10.1111/tpj.12451. PMID24506237.