Nutrikinetics and bioavailability of Promunel®, a standardized poplar-type propolis phenolic extract: a...

Brown poplar-type propolis has been recognized and used for centuries to help prevent upper respiratory tract infections (URTIs). However, the scarce, incomplete information in humans on the nutrikinetics and bioavailability of its phenolic constituents, combined with a lack of standardization in its phenolic content and profile pose major challenges to develop bioactive ingredients. Thus, the aim of this study was to establish the nutrikinetics and total bioavailability (NKBA) parameters of brown poplar-type propolis phenolics in humans using the Standardized Propolis Extract (SPE) Promunel®. To achieve this, a 48 h NBKA study was conducted following a double blinded, randomized, placebo-controlled, cross-over design in healthy humans (n = 10) with two doses of SPE (1X = 400 mg or 4X = 1600 mg). Phenolic compounds were detected, identified and quantified in the extract, plasma and urine through different LC-MS/UV technologies. The SPE used is a rich (304.44 ± 15.61 µmol mg^-1) and diverse source of phenolic compounds (5 sub-families). A total of 63 and 85 phenolic metabolites were identified and quantified in plasma and urine, mostly in the form of glucuronides and sulfates. In plasma, phenolic metabolites reached C_max (1.22 ± 0.20 for 1X and 4.80 ± 0.48 µM for 4X) after 1 h of SPE intake, while urinary excretion occurred mostly during the first 3 h after. The total net bioavailability of SPE phenolic compounds at 48 h was 57.16 ± 5.71% for 1X and 43.82 ± 6.77% for 4X. Generally, the data between SPE 1X and 4X were proportional, indicating that a higher dose does not substantially modulate total net bioavailability. Overall, our data shows that brown poplar-type SPE phenolic compounds are highly bioavailable in the form of cinnamic acid and flavonoid conjugates, and that these compounds are rapidly absorbed and eliminated through the urine. Our results suggest that, for a sustained presence in circulation, brown poplar-type propolis supplements should be consumed more than once a day.