| Abstract
| - Experiments were carried out to establish the structure of themonosaccharides comprising thecarbohydrate side chain of the tomato glycoalkaloid dehydrotomatine.This was accomplished by(a) isolating dehydrotomatine and α-tomatine from commercialtomatine, (b) derivatizing themonosaccharides formed on acid hydrolysis of commercial tomatine,dehydrotomatine, and α-tomatine to alditol acetates and methylated alditol acetates, and (c)determining the structures ofthe galactose, glucose, and xylose derivatives by gaschromatography−mass spectrometry. Bothdehydrotomatine and α-tomatine have the same tetrasaccharide sidechain. They differ only bythe presence in dehydrotomatine of a double bond at carbon atoms 5 and6 of ring B and its absencein α-tomatine. Dehydrotomatine, ortomatidenol-3β-lycotetraose, appears to represent a newclassof glycoalkaloids in which a lycotetraose carbohydrate side chain isattached to an aglycon containinga double bond. Biosynthetic pathways leading to the formation ofdehydrotomatine and α-tomatineand the significance of the results to host-plant resistance and thediet are discussed. Keywords: Carbohydrate analysis; dehydrotomatine; gas chromatography;glycoalkaloids; HPLC;mass spectrometry; tomatidenol; tomatidine; α-tomatine;tomatoes
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