Chemical composition of Polish propolis and its antiproliferative effect in combination with Bacopa monnieri on glioblastoma cell lines

Propolis and Bacopa monnieri (L.) Wettst. (Brahmi) are natural products that contain many active substances and possess anticancer properties. The aim of this study was to investigate the chemical composition of Polish propolis extract (PPE) by gas chromatography-mass spectrometry (GC–MS), B. monnieri extracts (BcH, BcS) by high performance liquid chromatography with diode array detector and mass spectrometry coupled with electrospray ionization (LC–ESI–MS) and finally determine its anti-proliferative potential combined with BcH and BcS in glioblastoma cell lines (T98G, LN-18, U87MG). The antiproliferative activity of PPE, BcH, BcS and their combination (PPE + BcH) was determined by a cytotoxicity test, and DNA binding was determined by [(3)H]-thymidine incorporation. Flavonoids and phenylpropenoids were the main components of PPE. BcH and BcS samples were also successfully analyzed. Their main constituents were saponins such as bacoside A3, bacopaside II, X and bacopasaponin C and its isomer. The inhibitory effects on the viability and proliferation of the tested glioma cells observed after incubation with the combination of PPE and BcH were significantly stronger than the effects of these two extracts separately. These findings suggest that propolis in combination with B. monnieri shows promising anticancer activity for the treatment of glioblastoma. However, further studies are still required.