4‐Demethylsterols and triterpene alcohols from two Vanilla bean species: Vanilla fragrans and V. tahitensis

Abstract

Abstract4‐Demethylsterol and triterpene alcohol compositions of two Vanilla bean species (V. fragrans and V. tahitensis) were investigated. From retention times and gas chromatography‐mass spectrometry, nine 4‐demethylsterols were identified in V. fragrans and seven in V. tahitensis. The 4‐demethylsterol fraction of V. fragrans was characterized by a high content of 24‐methylene cholesterol (27–40%) and of β‐sitosterol (35–46%). The 4‐demethylsterol fraction of V. tahitensis was characterized by a high content of stigmasterol (27%) and of β‐sitosterol (57.5%), and a lower amount of 24‐methylene cholesterol (5%). Vanilla tahitensis was also characterized by the presence of ergosta‐5,25‐dien‐3β‐ol (2%) and the absence of campesterol, stigmasta‐5,22,25‐trien‐3β‐ol, and ergosta‐7,24(28)‐dien‐3β‐ol. The beans’ age modified the ratio 24‐methylene cholesterol/β‐sitosterol in V. fragrans. Combining liquid chromatography and gas chromatography allowed the identification of four other demethylsterols in V. fragrans (brassicasterol, 0.02%; stigmasta‐5,23‐dien‐3β‐ol, 1.43%; stigmasten‐22‐ol, 0.1%; and fucosterol, 0.5%) from the 4‐demethylsterol fraction. 24‐Methylene cholesterol and β‐sitosterol were isolated, and their structures were confirmed by 1H and 13C nuclear magnetic resonance. Four triterpene alcohols were identified in V. fragrans, including cycloartenol (0.9–1.6%) from the triterpene alcohol fraction, 24‐dihydrotirucallol (17–23%) from the triterpene alcohol fraction, tirucall‐7‐en‐3β‐ol (6–7.5%) from the triterpene alcohol fraction, and in a higher content cyclosadol (66–69%) from the triterpene alcohol fraction. The content ranges were studied as a function of the beans’ age. Demethylsterol and triterpene alcohols profile could be used for origin differentiation.