title: Interference of flavonoids with enzymatic assays for the determination of free fatty acid and triglyceride levels.
abstract: Flavonoids are bioactive food compounds with potential lipid-lowering effects. Commercially available enzymatic assays are widely used to determine free fatty acid (FFA) and triglyceride (TG) levels both in vivo in plasma or serum and in vitro in cell culture medium or cell lysate. However, we have observed that various flavonoids interfere with peroxidases used in these enzymatic assays, resulting in incorrect lower FFA and TG levels than actually present. Furthermore, addition of isorhamnetin or the major metabolite of the flavonoid quercetin in human and rat plasma, quercetin-3-O-glucuronide, to murine serum also resulted in a significant reduction of the detected TG levels, while a trend was seen for FFA levels. It is concluded that when applying these assays, vigilance is needed and alternative analytical methods, directly assessing FFA or TG levels, should be used for studying the biological effects of flavonoids on FFA and TG levels.
authors: Division of Toxicology, Wageningen University, Tuinlaan 5, 6703 HE Wageningen, The Netherlands. elise.hoek@wur.nl
authors: Elise F
authors: EF
authors: Hoek-van den Hil
authors: Karsten
authors: K
authors: Beekmann
authors: Jaap
authors: J
authors: Keijer
authors: Peter C H
authors: PC
authors: Hollman
authors: Ivonne M C M
authors: IM
authors: Rietjens
authors: Evert M
authors: EM
authors: van Schothorst
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001671:Biochemistry / Q000379:methods; D003470:Culture Media / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood* / Q000378:metabolism*; D005419:Flavonoids / Q000097:blood / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010544:Peroxidases / Q000378:metabolism*; D011794:Quercetin / Q000031:analogs & derivatives / Q000097:blood; D051381:Rats; D014280:Triglycerides / Q000097:blood* / Q000378:metabolism*
chemical_list: D003470:Culture Media; D005230:Fatty Acids, Nonesterified; D005419:Flavonoids; D014280:Triglycerides; C443401:quercetin 3-O-glucuronide; C047368:3-methylquercetin; D011794:Quercetin; D010544:Peroxidases