Unsaponifiable lipid constituents of some underutilized tropical seed oils

Sterols, triterpene alcohols, and hydrocarbons present in the unsaponifiable fraction of some underutilized tropical seed oils have been examined. The seeds include Telfairia occidentalis (TLO), Andenopus breviflorus (ADB), Cucumeropsis edulis (CME), Antiaris africana (ATF), and Monodora tenuifolia (MNT). The oil content of the seeds was high (34.7-68.8%), whereas triacylglycerols comprised the dominant lipid group in the oils (65.4-73.9%). The percentage of unsaponifiables ranged from 1.1 to 7.9%. Ten sterols were identified in the fractions. In the Cucurbitaceae oils (TLO, CME, and ADB), Delta(7)-sterols constituted the dominant sterols. These include 24-ethylcholesta-7,-22E,25-trienol (7), 24-ethylcholesta-7,25-dienol (9), 24Z-ethylidenecholes-7-enol (10), and 24-ethylcholesta-7,24-dienol (11). However Delta(5)-sterols (1-5) occurred at the highest concentration in the other two samples (ATF and MNT). Fifteeen triterpene alcohols were detected in the fractions. Olean-12-enol (16), isomultiflorenol (8), and lupeol (23) were the dominant alcohols in the Cucurbitaceae family, whereas alpha-amyrin (urs-12-enol) (20) was the dominant triterpene alcohol in ATF and MNT. A mixture of C-18-C-34 n-alkanes, squalene, and some monoterpenes was detected in the hydrocarbon fraction.