Isolation of allene carotenoids from mamey

The fruit of red mamey (Pouteria sapota) contains a wide variety of carotenoids, generally in high concentration, which makes possible even the isolation of minor components in measurable amounts. Carotenoids were extracted from red mamey with acetone, subsequent saponification resulted a crude extract, which was submitted to column chromatography using aluminium oxide (Al2O3) as adsorbent. By using consecutive chromatographic steps and crystallization allene carotenoids, such as neoxanthin, (9'Z)-neoxanthin and capsoneoxanthin, were isolated from the most polar fractions in milligram amounts and in high purity. The amount of capsoneoxanthin was found sufficient for the complete analysis of this rare carotenoid 15 years after its first isolation. The complete H-1-and C-13 NMR assignments of neoxanthin and (9'Z)-neoxanthin using 2D techniques were achieved for the first time, as well. Electronic Circular Dichroism (ECD) spectra for the neoxanthin isomers were in good accordance with literature data, whereas the spectrum of capsoneoxanthin suggested aggregate formation in n-hexane solution.