Seasonal effect on chemical composition and biological activities of Sonoran propolis

Propolis is widely used as a folk medicine and as a constituent of health foods in many parts of the world. The main purpose of this study was to evaluate the seasonal effect on the chemical composition and biological activities (antiproliferative and antioxidant activities) of Sonoran propolis (Mexico). Propolis was collected during all four seasons of the year and chemical composition, antiproliferative, and free-radical scavenging activities of collected propolis were evaluated by HPLC, MTT, and DPPH assays, respectively. The relative abundance of the main chemical constituents of propolis was similar in all propolis samples analysed. In contrast, significant differences were observed in their antiproliferative activity in the B-cell lymphoma cancer cell line M12.C3.F6. Propolis collected in the spring showed the highest inhibitory effect on the growth of cancer cells. All propolis samples had weak free-radical scavenging activity. Our results indicate that season had a significant effect on the antiproliferative properties of Sonoran propolis.