Excerpt from Kay, Mazza and Holub (2005)
The parent anthocyanins represented only 32.0% [120.63 2.85 (nmol h)/L] of the total anthocyanins detected with 68.0% [256.02 5.23 (nmol h) identified as conjugated metabolites. Additionally, the total urinary excretion of anthocyanins over 24 h was 1071.54 375.46 g, reaching a maximal rate of excretion (Rmax 202.74 85.06 g/h) at 3.72 0.83 h. Parallel to the serum data, only 32.5% (347.85 60.61 g) of the anthocyanins excreted in the urine (total 24 h) were the parent compounds with 67.5% (723.69 92.59 g) occurring as conjugated metabolites.
Does this imply the conversion rate of total anthocyanins to secondary metabolites is 68%?
correct, that is their conclusion. just a note on terminology, conjugated metabolites are not secondary metabolites but rather phase II metabolites which is different. secondary metabolites refers to metabolism non-essential to plants such as many of the phenolics including anthocyanins
cheers,
K
I meant to add that since the 2005 article, Colin Kay and his collaborators have done 13C-labeled studies showing a larger percentage yet of metabolites are accounted for by low molecular weight degradants such as protocatechuic acid, vanillic acid, and benzoic acid species. See his more recent articles - Czank et al 2013 am j clin nutr, warner et al 2017 mol nutr food res, de ferrars et al 2014 brit j pharmacology
Hi Kenneth,
Thanks for your answers.
Would PCA, PGA, vanillic acid, chlorogenic acid be termed secondary metabolites or conjugated metabolites?
Terun
Would you be able to provide definitions for secondary, conjugated and phase II metabolites?
PCA pga vanillic and chlorogenic are all secondary metabolites. Only chlorogenic is a conjugate, in its case conjugation of caffeic acid to quinic acid because all the compounds we are speaking of are phenolics and quinic acid is similar to sugars
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