Abstract
Stereoisomeric neoxanthins A-H were isolated from spinach leaves and Chlorella ellipsoidea and some members of the neoxanthin set were recognized as genuine components in nature. Extraction with acetone or methanol, treatment with 12% KOH in methanol, chromatographic resolution on a lime column developed with 10% acetone in benzene, and fractional crystallization gave crystals of neoxanthins A, C, D, and E. Considering the ultraviolet, infrared, nuclear magnetic resonance, and mass spectrometric characteristics and other features, neoxanthin E could well represent an all-trans form while a peripheral unhindered mono-cis configuration was assigned to neoxanthin A, C or D. Neoxanthin G or H, possibly an artefact produced during isolation, would possess a next-to-central unhindered cis form.
