Folates deconjugation

Folates are generally present in low concentration in foods thus, any method of analysis requires isolation and sensitive detection (Vahteristo et. al., 1996). The method described here uses extraction of the folic acid (Fig. 9.13) with rapid microwave heating and enzymatic deconjugation with hog-kidney con-jugase and chicken pancreatic enzymes. The extracts are purified with strong anion-exchange SPE. The final analysis is with HPLC. 

It is reasonable to expect that deconjugation is required for absorption of folate because pteroheptaglutamaite is a large and strongly electronegative molecule that would not diffuse easily across biological mem-... 

The hypothesis that contraceptive steroids might interfere with folate deconjugation in the small intestine was examined by Stephens et al. (S19). Homogenized human jejunal mucosa obtained by peroral biopsy and lysosomal preparations from guinea pig jejunum were utilized. Estradiol, estrone, and progesterone were found not to inhibit folate conjugase in these systems, or to inhibit transport of folate conjugase across lysosomal membranes. 

FIG. 2. Schematic diagram of whole-body folate metabolism. Dietary forms of polyglutamyl folates are deconjugated in the jejunum (vertical rectangle on left) by mucosal and, to a lesser extent, pancreatic hydrolases. Secretion of folate in bite accounts for an enterohepatic circulation that has not been incorporated into modeling. Tissues behave, at least superficially, as a large, kinetically slow, pool. 

Deconjugation of folates. Enzymatic reaction to convert polyglutamate vitamers of folates to the respective monoglutamates. 

Monch, S., and Rychlik, M., 2012. Improved Folate Extraction and Tracing Deconjugation Efficiency by Dual Label Isotope Dilution Assays in Foods. Journal of Agricultural and Food Chemistry. 60 1363-1372. 

In this chapter chromatographic folate methods for various applications are presented. Sample treatments including extraction, cleanup, and deconjugation steps are also discussed. 

R Engelhardt, IF Gregory. Adequacy of enzymatic deconjugation in quantification of folate in foods. J Agric Food Chem 38 154—158, 1990. 

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