| Abstract [eng] |
Industrial hemp traditionally is grown for the production of textile fiber, pressing oil from the seeds and in foods. More recently, interest in cannabis has increased due to the specific phytochemicals in their leaves. The main bioactive compounds which are found in hemp leaves are essential oil (EO) and non-psychotropic phytocannabinoids. They attracted an increasing interest of researchers and medics due to their health benefits. The aim of this study is to develop and evaluate the technologies of fractionation of industrial hemp bioactive compounds using traditional and high pressure methods and to determine the influence of different extraction methods on the composition of various properties compounds. The target compounds were isolated using Clevenger hydrodistillation (HD) and supercritical CO2 extraction (SFE-CO2). The possibilities of fractionating hemp extracts after SFE-CO2 were tested by using two separators operating at different pressure and temperature in order to separate waxes from other (mostly volatile) compounds. Pure CO2 and its mixture with a co-solvent ethanol (5 % EtOH) were tested at the same separation parameters. In the second part of this study hemp material, extracts and residues after HD and SFE-CO2 were used for evaluating their antioxidant activities in different in vitro assays (TPC, ABTS•+ and ORAC). For the reason to investigate the possibility of using plant extracts and extraction residues as a source of various functional ingredients. The yield of EOs after HD varied from 0.07 to 0.15 % depending on the cultivar, while depending on the vegetation period – from 0.01 to 0.24 %. The predominant EOs components determined by GC-FID and GC-TOF/MS were α-pinene, myrcene, E-caryophyllene, α-humulene, caryophyllene oxide and CBD. After HD the antioxidant activity of water extract recoveries were almost equal to that found in the plant material, that indicates a very high extraction efficiency. The maximum amount of phytocannabinoids Δ9-THC and Δ9-THCA determined by HPLC-UV/Vis in raw material were investigated in 'Grandi' (0.23 and 0.22 %), while CBD and CBDA – in 'Sidrabi' (0.94 and 0.97 %) hemp cultivar leaves. After SFE-CO2 fractionation without organic solvent (0 % EtOH) and with 5 % ethanol (5 % EtOH) depending on different cooling temperature (-30–0 ℃), it was observed that the most efficient extraction was obtained using 5 % EtOH at -10 ℃. As a result, using these parameters the highest yield of volatile (3.15 %) and the lowest yield of wax fraction (1.38 %) was obtained. The highest recoveries of the main cannabinoids, namely CBD and CBDA, determined in volatile fraction by HPLC-UV/Vis after SFE-CO2 were obtained at -10 °C with 5% EtOH, 0.29 and 0.53 g/100 g DW, respectively. Besides, the recovery of ORAC values was remarkably higher at -10 ℃ when 5 % EtOH was applied, 27.50 vs 3.06 mg TE/g DW, respectively. |
