Phenolic Compounds of Propolis from the Boreal Coniferous Zone
The profile of phenolic compounds in 19 propolis samples from different provinces in Finland were analysed for the first time using HPLC-DAD. Nine individual flavonoids (comprising 26% of the identified phenolics), eleven cinnamic acid derivatives (36%), two caffeic acid derivatives (14%), three chlorogenic acid derivatives (14%), and three other phenolic acids (10%) were found in the propolis samples. The compounds found in the largest quantities were methyl-naringenin and caffeic acid phenethyl ester (CAPE). The phenolic profiles of Finnish propolis show marked differences when compared with P. nigra and P. tremuloides propolis of Central European and Canadian origins. The phenolic compounds found in propolis samples are commonly found in the tree species growing in Finland. Non-metric multidimensional scaling showed that samples were scattered and they did not form clear groups according to the geographical origin or age of the sample.