Chemical composition, antiradical activity and botanical sources of Maltese propolis

Abstract

Propolis is a honeybee product which bees produce by collecting resins from various botanical sources. The chemical composition of propolis is dependent on the availability of resinous plant materials in different geographic regions. This study was undertaken to determine the chemical profile of Maltese propolis, evaluate the resinous plant sources used to produce Maltese propolis and assess the antioxidant activity of Maltese propolis. Nineteen Maltese propolis samples from Malta, Gozo and Comino were studied by Gas Chromatography-Mass Spectrometry (GC~·MS) after silylation. They exhibited the typical Mediterranean chemical profile, rich in diterpene compounds (19 - 93% of total ion chromatogram, TIC, GC-MS). Thirty-three diterpene compounds were identified; four of which were new to Maltese propolis; 2,3-dchydroferruginol, 3-hydroxyferruginol, dihydroxyferruginol and 7-hydroxytotarol. The resin of Cupressaceae species was identified as the major plant source contributing the characteristic diterpene profile of Maltese propolis. Three other newly identified terpene compounds in Maltese propolis were sesquiterpenes of the carotane class; teferidin, ferutidin and jaeschkeanadiol. The origin of these terpenes was identified to be Ferula communis. This study proposes a characteristic chemical profile to identify F communis resin in propolis. Two other newly identified compounds in Maltese propolis were the flavonoid 2',4'-dihydroxychalcone and the aromatic acid, ferulic acid. Overall, three new compounds which had not been previously characterised in any propolis sample have been identified in this study; ferutidin, teferidin and 7-hydroxytotarol.