The chemical composition of propolis from Bulgaria, Turkey, Greece and Alge
ria was investigated by GC-MS. All of them contained mainly flavonoids and
esters of caffeic and ferulic acids, which indicated that their main source
are buds of poplars of the taxonomic section Aegieros. Some Turkish sample
s contained a low percent of diterpenic acids, while in Algerian samples si
gnificant amounts of a hydroxyditerpenic acid (M=322, its structure not det
ermined by its MS) were found. All samples showed significant antibacterial
and weak to moderate antifungal activity.