The metabolism of the plant lignans matairesinol, secoisolariciresinol, pinoresinol, syringaresinol, arctigenin, 7-hydroxymatairesinol, isolariciresinol, and lariciresinol by human fecal microflora was investigated to study their properties as mammalian lignan precursors. The quantitative analyses of lignan precursors and the mammalian lignans enterolactone and enterodiol were performed by HPLC with coulometric electrode array detector. The metabolic products, including mammalian lignans, were characterized as trimethylsilyl derivatives by gas chromatography-mass spectrometry. Matairesinol, secoisolariciresinol, lariciresinol, and pinoresinol were converted to mammalian lignans only. Several metabolites were isolated and tentatively identified as for syringaresinol and arctigenin in addition to the mammalian lignans. Metabolites of 7-hydroxymatairesinol were characterized as enterolactone and 7-hydroxyenterolactone by comparison with authentic reference compounds. A metabolic scheme describing the conversion of the most abundant new mammalian lignan precursors, pinoresinol and lariciresinol, is presented.

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Postprandial insulin responses to grain products are determined by the form of food and botanical structure rather than by the amount of fiber or the type of cereal in the food. These effects may be mediated through GIP and GLP-1.

Studies on the yeasts Cmdda oleophila, Candida utilis, Lipomyces starkeyi, Rhodosporidium toruloides and Saccharomyces cerevisiae revealed the existence of three different temperature adaptation responses involving changes in fatty acid composition. These conclusions were drawn by determining the growth rates, total cellular fatty acid content, fatty acid composition, degree of unsaturation, and the mean chain length of fatty acids over a range of growth temperatures. Within temperatures permitting growth, there were no changes in the major fatty acids of any of the yeasts, but the absolute amounts and relative compositions of the fatty acids did alter. In S. cerevisiae there were temperature-induced changes in the mean fatty acid chain length, whereas in R. toruloides there were changes in the degree of unsaturation. C. oleophila, C. utilis and L. starkeyi showed both responses, depending on whether the growth temperature was above or below 20-26 "C. Below 20-26 "C temperaturedependent changes were observed in the mean chain length whereas above 20-26 "C there were changes in the degree of unsaturation.