Biorefining of Bergenia crassifolia L. roots and leaves by high pressure extraction methods and evaluation of antioxidant properties and main phytochemicals in extracts and plant material

• Pressurised liquid and supercritical fluid extraction applied to Bergenia crassifolia.
• Consecutive extraction with increasing polarity solvents produced several fractions.
• Root and leaf extracts isolated with polar solvents were strong antioxidants in vitro.
• Main phytochemicals were quantified in extracts and plant material by UPLC–MS/MS.
• The content of bergenin was many times higher in roots than in leaves.

Various extraction schemes, methods and solvents, including supercritical fluid extraction with carbon dioxide (SFE–CO2) and pressurised liquid extraction (PLE) were studied for valorising Bergenia crassifolia roots and leaves as a source of natural antioxidants. It was shown that application of SFE–CO2 and PLE schemes with different solvents and process parameters may provide several fractions, in total constituting >66% of soluble substances from the roots and >48 from the leaves. Total phenolic content (TPC), trolox equivalent antioxidant capacity (TEAC) in scavenging ABTS+ and oxygen radical absorbance capacity (ORAC) activities of extracts and solid plant materials were determined. Consecutive extractions with increasing polarity solvents enabled to isolate different amounts of antioxidants. Generally, in case of roots higher antioxidant capacity values were obtained with acetone, while in case of leaves hydroethanolic solvent gave higher values. Considering that protic solvents were applied for re-extracting the residues they were proved as effective solvents for exhaustive processing of plant material. The extracts inhibited oxidation of rape seed oil and its emulsion at 120 °C as measured by the Oxipres and Rancimat methods. The major phytochemicals, namely bergenin, catechin gallate, ellagic acid and quercetin 3–β–D glucoside were quantified in B. crassifolia leaf and root extracts by UPLC/ESI–QTOF–MS; the roots contained several times higher concentrations of these compounds than the leaves, except for ellagic acid, which was not detected in the roots. The results obtained are expected in assisting to increase the prospects of expanding the cultivation of B. crassifolia as a promising industrial crop for developing various specialty natural products.