Subcritical water extraction as a cutting edge technology for the extraction of bioactive compounds from chamomile: Influence of pressure on chemical composition and bioactivity of extracts

The study was designed to determine the relationship between chemical structure, bioactivity and pressure during the subcritical water extraction (SCW) of chamomile. Extraction was carried out at isothermal conditions (100 °C) at five different pressures (10, 30, 45, 60 and 90 bar). Twenty three polyphenolic compounds were identified in the extracts, whereby apigenin was found to be the dominant compound (61.53-1344.99 mg/kg). Results suggest that the lowest applied pressure has negligible effect on phenolic recovery from chamomile, but also the use of pressures above than 45 bar was proven as needlessly. By using in vitro assays, influence of pressure on antioxidant, cytotoxic and enzyme-inhibitory activities of the extracts was evaluated. Extracts obtained at 30, 45 and 60 bar exhibited stronger bioactivities than at 10 and 90 bar. It was concluded that pressure exert a significant influence on chemical composition of extracts, and thus on biological activity of chamomile extracts.