Phytochemical characterization and evaluation of anti-inflammatory and anticancer activities of Cistus laurifolius originated propolis

Determination of the botanical origin of plant-originated bee products like propolis is a highly crucial task especially for the standardization of the extract and prediction of its health benefits. While there are various propolis types across globe, the existence of two main propolis types originating from black poplar and Eurasian aspen poplar have been revealed in Türkiye up to date. This study focused on the chemical characterization and bioactivities of unique propolis samples which showed a distinct chemical profile from the known types of propolis. Accordingly, the botanical origin of this new type of propolis was determined by comparative analysis of hydroalcoholic extracts of propolis with that of Cistus laurifolius extract by HPTLC. Marker compounds such as luteolin, apigenin, quercetin, and 3-O-methylquercetin were detected in both extracts along with an unknown compound. Moreover, this unidentified compound was purified by successive chromatographic methods and its chemical structure was elucidated as 3,7-O-dimethylquercetin by NMR and MS analyses. Besides, LC-MS/MS was used for the quantification of the compounds. The results of bioactivity studies showed that standardized hydroalcoholic propolis extract led to a decrease in nitrite release from LPS-activated RAW264.7 cells at 10 µg/mL indicating its remarkable anti-inflammatory activity. Additionally, propolis extract showed potent anticancer activity against pancreatic cancer cell lines MIA PaCa-2 in both 2D and 3D models in a concentration-dependent manner. The strongest effect on spheroid size change was observed at the concentration of 1 mg/mL.