Separation of geometric isomers of native lutein diesters in marigold (Tagetes erecta L.) by high-performance liquid chromatography–mass spectrometry

Lutein is found in many foods; the richest and purest plant source is marigold flower (Tagetes erecta L.). In this plant, lutein is in the form of saturated fatty acid diesters. By using a binary mobile phase consisting of ethyl acetate and acetonitrile–methanol (9:1), improved separation was achieved on a C18-bonded phase. The unique absorption of lutein cis isomers at 330 nm was used in combination with MS to identify the novel cis-lutein isomeric dimyristate, myristate-palmitate, dipalmitate, and palmitate-stearate diesters, as well as the rare combinations of both trans- and cis-lutein laurate-palmitate and trans- and cis-lutein myristate-stearate. The presence of the all-trans-lutein laurate-myristate, dimyristate, myristate-palmitate, palmitate-stearate, and distearate diesters, reported by others, was also confirmed.