Dietary Phenolic Compounds Interfere with the Fate of Hydrogen Peroxide in Human Adipose Tissue but Do Not Directly Inhibit Primary Amine Oxidase Activity

Figure 2

Inhibition of tyramine-induced hydrogen peroxide production in human subcutaneous adipose tissue homogenates by reference MAO and SSAO inhibitors and by phenolic compounds. Fluorescence readouts after 30 min incubation were substracted from corresponding values at t0 and net increase was set at 100% for 1 mM tyramine without any inhibitor. (a) The MAO (pargyline, dark squares) or SSAO inhibitor (semicarbazide, open squares) was present during the 15 min preincubation and the 30 min incubation at 0.001–1 mM or at 0.01 μM–1 mM, respectively. The addition of pargyline 1 mM + semicarbazide 1 mM (P + S, black triangle) was used to abolish all amine oxidase activity. Mean ± SEM of 6 to 22 homogenates. When invisible, SEM bars lie within the symbols. (b) The phenolic compounds were tested at the indicated final doses during preincubation and incubation: resveratrol (dark circles), pterostilbene (dark squares), caffeic acid (black triangles), or quercetin (open squares). Mean ± SEM of 7 to 10 homogenates.

(a)

(b)