Current challenges in polyphenol analytical chemistry

Agrimonolide and Desmethylagrimonolide Induced HO-1 Expression in HepG2 Cells through Nrf2-Transduction and p38 Inactivation

“…1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical inhibition assay was completed by following our previous study (Gleichenhagen and Schieber, 2016). A volume of 10 μL of sample was added to 190 μL solution of 0.4 mM DPPH dispersed in 95% ethanol.…”

“…Owing to the complexity of polyphenols, various experimental approaches are employed to examine the characterization of the bioactive polyphenol components from herbs. Furthermore, the interactions between polyphenols and other food ingredients, such as protein, fatty acid, and dietary fiber, are investigated as it might affect the bio-accessibility of polyphenols during digestion, absorption, and metabolism in human (Gleichenhagen and Schieber, 2016). The application of polyphenols is recommended to restrict the occurrence of lipoper oxidation and maintain human health (Brenes et al, 2016).…”

Development and Validation of Methods for the Determination of Anthocyanins in Physiological Fluids via UHPLC-MSn

“…In human intervention studies, urine samples are often collected to monitor the metabolism and the excretion of polyphenolic compounds. The enzymatic release of the phase II metabolites by sulfatases and glucuronidases should be interpreted with caution because of the well-known disadvantages [33]. However, enzymatic hydrolysis is often needed to increase the concentration of the aglycones and to ensure their accurate quantification, as anthocyanidin reference compounds are commercially available in contrast to their phase II metabolites [34].…”

Polyphenol Phase‐II Metabolites are Detectable in Human Plasma after Ingestion of 13C Labeled Spinach—a Pilot Intervention Trial in Young Healthy Adults

“…Most of the human intervention studies with controlled polyphenol intake monitored plasma appearance of free and already known conjugates only; further information with respect to the quantity and the structure of degradation products are scarce. The combination of different in vitro or in vivo approaches with new analytical techniques now create the opportunity for a more targeted analysis to improve our understanding of the absorption and metabolism of polyphenolic compounds . One of the encouraging novel technologies is the use of compounds to be supplied in human intervention studies labeled with the stable isotope 13 C; the chemical synthesis of single 13 C labeled polyphenols is, however, demanding, time consuming, and also cost intensive .…”

“…The combination of different in vitro or in vivo approaches with new analytical techniques now create the opportunity for a more targeted analysis to improve our understanding of the absorption and metabolism of polyphenolic compounds. [15] One of the encouraging novel technologies is the use of compounds to be supplied in human intervention studies labeled with the stable isotope 13 C; the chemical synthesis of single 13 C labeled polyphenols is, however, demanding, time consuming, and also cost intensive. [16] Alternatively, secondary plant compounds can be labeled intrinsically with 13 CO 2 to provide fully labeled polyphenols, which can be used in human intervention trials and facilitates the analysis of labeled metabolites with UHPLC-MS n in biological samples.…”