Human serum determination and in vitro anti-inflammatory activity of the vitamin E metabolite α-(13'-hydroxy)-6-hydroxychroman

Cytochrome P450-derived long-chain metabolites are gaining increasing interest as bioactive intermediates of vitamin E. In this study we first report on the HPLC-ECD and GC–MS analysis in human serum of the earliest metabolite of this vitamin, namely α-(13'-hydroxy)-6-hydroxychroman (α-13'-OH). The two chromatographic procedure are sensitive enough (LOQ of 10nM) to measure α-13'-OH after hexane extraction of 1ml of sample obtained from healthy volunteers supplemented for 1-week with 1000 IU/d (671mg/d) RRR-α-tocopherol. The observed concentrations ranged between 15 and 50nM, with minor differences between fasting and 4-hr post-meal state. Baseline (non-supplemented state) levels of 7.2±1.6nM were observed extracting higher volumes of serum. Biological effects of α-13'-OH investigated for the first time in RAW264.7 murine macrophages involved transcriptional control of inflammatory cytokines, and transcriptional and functional regulation of COX2 and iNOS enzymes in response to lipopolysaccharides. In conclusion, here we present the first quantitative evaluation of serum α-13'-OH also providing early evidence of the anti-inflammatory potential of this metabolite that is worth of further investigation in the area of functional and nutraceutical implications of vitamin E metabolism. •An original HPLC and GC-MS procedure to measure serum α-13-OH, the earliest metabolite ofvitamin E, is proposed.•Baseline levels of α-13-OH (gt; 10 nM) steadily increase by 2 to 7 times after 1-week supplementation with high doses of RRR-α-tocopherol.•This metabolite modulates key inflammatory pathways in macrophages in vitro.