LAUSR

ETHNOPHARMACOLOGICAL RELEVANCE Propolis is a bee-derived product used since antiquity for its general health-giving properties and is especially noted for its anti-bacterial activity. In more recent times, propolis has been employed against more specific targets such as antiproliferative effects vs cancer cells, wound healing and type-2 diabetes. AIM OF THE STUDY European (poplar)-type propolis from New Zealand contains a number of hydroxy cinnamic acid esters and a set of aglycone flavonoid compounds, mainly chrysin, galangin, pinocembrin and pinobanksin. Propolis is usually taken orally and propolis metabolites quickly appear in the plasma of the ingestee. In this work we aimed to identify the major flavonoid plasma metabolites by direct analysis of the plasma. MATERIALS AND METHODS After consumption of a large dose of propolis in a single sitting, blood samples were taken and analysed using LCMS/MS. The major flavonoid metabolites identified were also synthesised using chemical (sulfates) or enzymatic methods (glucuronides). RESULTS Both the sulfate and glucuronide conjugates of the four major propolis flavonoids are readily detected in human plasma after propolis ingestion. Preparation of the sulfates and glucuronides of the four major flavonoids allowed the relative proportions of the various metabolites to be determined. Although the sulfates are seen as large peaks in the LCMS/MS, the glucuronides are the dominant conjugate species. CONCLUSIONS This study shows most of the flavonoids in the plasma are present as 7-O-glucuronides with only galangin showing some di-glucuronidation (3,7-O-diglucuronide). No evidence was found for hydroxy cinnamic acid type metabolites in the plasma samples.