In the early part of the nineteenth century, carotenoids were found in paprika (1817), saffron (1818), annatto (1825), carrots (1831), and autumn leaves (1837). In 1906, Zwet succeeded in the separation of carotene, xanthophyll and chlorophyll from green leaves using column chromatography. In the 1930s, Karrer and Khun elucidated the structures of
β-carotene and lycopene. Furthermore, they found that
β-carotene was a precursor of vitamin A. They won the Nobel Prize in chemistry for this work. Subsequently, structures of lutein, zeaxanthin, and astaxanthin were revealed by their groups. These structural studies were based on the oxidative degradation of carotenoids with KMnO
4, and structures were analyzed using elemental analysis. In the 1950s, the Zechmeister group studied
E/
Z (
cis–
trans) isomerization of carotenoids. In the 1960s, the Weedon group and Liaaen-Jensen group elucidated the structure of fucoxanthin and peridinin, respectively, using NMR and MS spectrometry [
3]. Since the first structural elucidation of
β-carotene by Kuhn and Karrer in 1928–1930, about 750 naturally occurring carotenoids had been reported up until 2004 [
1]. Improvements of analytical instruments such as NMR, MS, and HPLC have made it possible to perform the structural elucidation of very minor carotenoids in nature [
2]. Annually, several new structures of carotenoids are being reported. Our research group has performed the structural elucidation and analysis of naturally occurring carotenoids using NMR, MS, MS/MS, and LC/MS [
2] over the last decade. About 100 kinds of natural carotenoids were reported from 2004 to 2018 [
2]. Synthetic studies of carotenoids revealed the stereochemistry of several complex structures of natural carotenoids such as peridinin, fucoxanthin, crassostreaxanthin B, and cucurbitaxanthin A [
4].