FRIEDELIN, THE MAJOR COMPONENT OF GRAPEFRUIT EPICUTICULAR WAX

Marsh grapefruit (Citrus paradisi Macf.) fruit epicuticular wax was fr actionated into various lipid classes by thin-layer chromatography and quantified by gas chromatography, and structures were verified by mas s spectroscopy and H-1 and C-13 magnetic resonance spectroscopy. Fried elin was shown for the first time to be the major component of grapefr uit epicuticular wax. Other triterpenes were also present in lesser qu antities. Triterpene structures verified were beta-amyrin, beta-amyron e, beta-amyrin acetate, alpha-amyrin, alpha-amyrone, alpha-amyrin acet ate, and 24-methylenecycloartanol. Further analyses revealed friedelin levels to be 5-45% of the wax in 8 of 14 other fruits and vegetables and from 9% to 18% in the leaves of 3 citrus cultivars.