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GC-MS and LC-MS profiles of the supercritical fluid extracts of black poplar (Populus nigra L.) buds

The buds of black poplar (Populus nigra L.) are used in traditional medicine due to their antibacterial, antifungal, anti-inflammatory and antioxidant activities. These activities are attributed to both volatile and non-volatile compounds, so it is important to use adequate method to extract these component groups. The method that could allow an efficient extraction of compounds without leaving traces of toxic solvents is SC-CO2 resulting in an extract that can be used for medical purposes. Therefore, the black poplar buds were extracted using supercritical CO2 (SC-CO2) under various conditions (pressure and temperature) and optimized based on the sum of the major, relevant volatile and non-volatile compounds. The best extraction conditions at which the highest amount of both volatile and non-volatile components was extracted were 300 bar and 60 °C. The composition of the obtained extracts was determined by GC-MS and UHPLC-DAD-QqTOF-MS. The volatile profile of SC-CO2 extracts was compared with composition of essential oil (EO) obtained by hydrodistillation. The percentages of the major volatile compounds in the optimized SC-CO2 extracts were: pinostrobin chalcone (20.8 %), β-eudesmol (9.5 %), α-eudesmol (9.2 %), 2-methyl-2-butenyl p-coumarate (7.9 %), tricosane (6.3 %), pentyl-p-coumarate (6.1 %), γ-eudesmol (4.9 %), benzyl salicylate (4.7 %), 3-methyl-2-butenyl-benzoate (4.0%). In contrast, β-Eudesmol (10.9 %), α-eudesmol (10.4 %), guaiol (5.7 %), 3-methyl-2-butenyl-benzoate (5.5 %), γ-eudesmol (5.5 %), γ-curcumene (4.7 %) and bulnesol (4.4 %) dominated in the EO, but providing much lower yield. The major compounds identified in the UHPLC profile of the optimized SC-CO2 extracts were pinostrobin, pinocembrin, 3-O-pinobanksin acetate and methyl-butenyl p-coumarate (751.7 ; 485.6 ; 290.2 and 144.9 mg/100g of buds, respectively). The SC-CO2 extraction under the optimized conditions was found to be useful for efficient and simultaneous extraction of both volatile and non-volatile, bioactive compounds of poplar buds.

Populus nigra L., sesquiterpenes, phenolics, supercritical CO2 extraction, phytochemical profiles

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