Chemical Profiles and Bioactive Molecules of Propolis: A Review

Abstract

Propolis is a dark sticky material that bees (indispensable actors in biosphere) harvest from exudates and buds of plants alongside pollinating them, promoting agriculture and protecting the ecosystem. Its chemical composition is highly variable and dependent on the local flora. In search for rapid chemical screening methods which are capable of characterizing propolis samples from various geographic origins, various hyphenated techniques such as HPLC-DAD, HPLC-MS/MS, LC-MS, LC-MS/MS, GC-MS etc., have been used and giving an insight on the regional variation in chemical composition. Various chromatographic techniques (CC, UPLC, HLPC, RP-HPLC, TLC….) are used in obtaining organic bioactive compounds from propolis. The structures of these compounds are characterised using state-of-the-art spectroscopic and spectrometric methods. There is no clear-cut distinction of propolis from different regions but the major chemical compounds can be classified in two main groups as those from temperate propolis and those from tropical propolis. Compounds isolated from propolis from temperate regions are mostly flavones, flavonols, flavanones, flavanonols, chalcones, aurones, pterocarpans, lignans, phenolic acids and their esters, etc. Compounds isolated from propolis from tropical and subtropical regions are mostly terpenoids, steroids and xanthones. Propolis is very rich in structurally diverse molecules which are capable of being isolated. These compounds/potential drugs are usually subjected directly to bioassays or used as starting material for synthesis in view of obtaining their derivatives or synthetic analogues with enhanced biological activities.