Synthetic and analytical strategies for the quantification of phenyl-γ-valerolactone conjugated metabolites in human urine

Abstract

This work opens the door to better studying the bioavailability of flavan-3-ols and the real exposition to flavan-3-ol sources, as well as to define the bioactivity of these colonic metabolites in cell assays.

Flavonoid‐Derived Human Phenyl‐γ‐Valerolactone Metabolites Selectively Detoxify Amyloid‐β Oligomers and Prevent Memory Impairment in a Mouse Model of Alzheimer's Disease

“…Chemicals: PVL metabolites #1, #2, and #3 (see Table S1, Supporting Information) were produced by asymmetric synthesis, [54] while compounds #4, #5, #6, and #7 were synthesized by functionalization of the corresponding aglycones. [55] PVLs were dissolved in DMSO as 20 mm stock solutions. Details for other compounds used in this manuscript can be found in Supporting Information.…”

Full 1H and 13C NMR spectral assignment of conjugated valerolactone metabolites isolated from urine of black tea consumers by means of SPE‐prepLC–MS–LC–MS‐NMR

“…The collected fractions were concentrated by SPE and further separated using an orthogonal analytical column where MS guides the separation of conjugated valerolactones. 1D 1 H and 2D homoand heteronuclear NMR experiments were used for the assignment of 1 H and 13 C NMR resonances of the isolated fractions. The PULCON principle was used for quantification.…”

“…An overview of the identified compounds is given in Table 2. For each identified compound, the respective coupling constants, 1 H chemical shifts and 13 C chemical shifts (from HSQC experiments) are given in Table 3. These spectral assignments correspond well with those from spectral predictions on the basis of quantum mechanical principles.…”

“…Although these isolated metabolite aliquots allowed for use as authentic standards for quantification of tea polyphenol metabolites by LC–MS, they were of insufficient amounts to be used for in vitro testing of bioactivity. For this purpose a minimal amount of ≈10 μg of purified metabolites is required, which can currently only be obtained by de novo synthesis . Although synthetic routes will yield ample material, they involve significant investments in time and money.…”

“…For this purpose a minimal amount of ≈10 μg of purified metabolites is required, [4] which can currently only be obtained by de novo synthesis. [13][14][15] Although synthetic routes will yield ample material, they involve significant investments in time and money.…”