A novel honey-based product enriched with coumarin from Melilotus flowers

Coumarin is a plant secondary metabolite responsible for the health-promoting properties of the Melilotus officinalis herb used in traditional medicine in the treatment of lymphedema and chronic venous diseases. The aim of this study was to analyze the possibility of honey enrichment with coumarin derived from sweet clover (Melilotus) in two different ways: herb honey and herb-infused honey production. Herb honey was obtained by feeding bees with sugar syrup enriched with a M. officinalis herb water infusion, whereas herbal macerates in multifloral honey were prepared with crushed flowers (fresh and dried) of M. officinalis and Melilotus albus at 20 degrees C in dark place for 6 months. Melilotus albus nectar honey (n = 14) was used as control. Using HPLC analysis, the highest content of coumarin (from 41.33 to 137.89 mg/kg) and its precursor o-coumaric acid (from 6.57 to 25.15 mg/kg) in M. officinalis flowers-infused honey were found. Herb honey contains 4.48 mg/kg coumarin and for the first time, this compound was determined in nectar honey from Polish M. albus honey (0.05 to 0.88 mg/kg). The addition of Melilotus flowers enhanced antioxidant activity (measured by FRAP, DPPH and PCL methods) of infused-honey in comparison to multifloral honey (control) and herb honey. The coumarin and o-coumaric acid were weakly correlated with antioxidant activity. It was found that only herb-infused honey can be proposed as the natural safe remedy for venous diseases prevention.