Low-Thujone A. absinthium L. (Wormwood) Essential Oils and Extracts with Potential Antioxidative/Prooxidant Activity

Nowadays, the global demand for medicinal plants, including A. absinthium L. (wormwood), has increased considerably, leading to significant pressure on their wild populations and the biodiversity of ecosystems. Consequently, the rates of exploitation may exceed those of natural regeneration. This destructive process can be reduced by cultivating plants with the desired secondary metabolites by transferring them from their natural habitats. The present study investigates phytochemistry and the potential antioxidative/prooxidant activity of low-thujone A. absinthium plants. The chemical composition of wormwood extracts and essential oils (EOs) was determined by HPLC/DAD/TOF and GC/MS techniques, respectively. Trans-Sabinyl acetate (59.6 ± 10.1%) predominated in the wormwood EOs, while the content of toxic trans-thujone was negligible (1.2 ± 0.5%). Eighteen acids, such as fumaric, ascorbic, succinic, quinic, malic, gallic, benzoic, (neo/iso)chlorogenic, (di)ferulic, caffeic, etc., were found in 50% methanolic wormwood extracts. Additionally, (epi)catechin, astragalin, diosmetin, piceatannol-3'-O-glucoside, quercetin-3-O-glucoside, quercetin-3-O-rhamnoside-7-O-glucoside, hesperidin, apigenin-7-O-glucoside, baicalin, 5,7,3'-trihydroxy-3,6,4',5'-tetramethoxyflavone and rutin were tentatively identified in the extracts. Total phenolic content was found 412.82 ± 11.10 mg/L (of gallic acid equivalent) in A. absinthium methanolic extracts. Using conventional spectroscopic methods, the antioxidant activity (DPPH radicals scavenging) was determined to be 0.83 ± 0.06 mmol/L (TROLOX equivalent) in the wormwood essential oil. ABTS^●+ and DPPH^● scavenging activity means, 3.485 ± 0.07 (TROLOX, mmol/L) and 6.48 ± 0.25 (TROLOX, mmol/L) were revealed for A. absinthium methanolic extracts. Less commonly used methods, electrochemical tests showed the presence of oxidizable compounds with characteristic E_pa values of 0.38 and 0.61 V. Moreover, hydrogen peroxide scavenging tests were performed. The largest quantity of peroxide (31.86 ± 0.1 μmol/L) was formed in the wormwood boiling infusions (at pH = 7.2). As the presence of toxic and neurotoxic thujone isomers is undesirable, therefore, the search for low- or thujone-free plants from natural populations that exhibit biological activity (i.e., antioxidant/prooxidant) is of great importance.