Identification of chondrillasterol in twoCucurbitaceae seed oils by proton nuclear magnetic resonance spectroscopy

The absolute configuration at C-24 of C-24 epimeric 24-ethyl-5α-cholesta-7,E-22-dien-3β-ols I–IV previously isolated from tea seed oil, shea fat, and gourd and sponge cucumber seed oils, respectively, was studied by proton nuclear magnetic resonance spectroscopy. The results showed that the sterols I and II are identical with spinasterol (24S/α-ethyl group), whereas the sterols III and IV are identified as its 24R/β-epimer, chondrillasterol. This study has thus for the first time properly documented the presence in tracheophytes of a 24β-ethylsterol in which Δ25(27)-bond is reduced.