Valorization of European Cranberry Bush ( Viburnum opulus L.) Berry Pomace Extracts Isolated with Pressurized Ethanol and Water by Assessing Their Phytochemical Composition, Antioxidant, and Antiproliferative Activities

Defatted by supercritical CO₂, Viburnum opulus berry pomace (VOP) was subjected to consecutive extraction with pressurized ethanol (E) and water (W) and yielded 23% of VOP-E and 8% of VOP-W, respectively. The major phytochemical groups covering 42 identified and quantified constituents in VOP extracts were organic and phenolic acids, iridoids, quercetin and (epi)catechin derivatives, flavalignans, procyanidins, and anthocyanins. The on-line HPLC-DPPH^•-scavenging assay revealed the presence of numerous antioxidants. VOP-E had a higher total phenolic content, was a stronger antioxidant (equivalent to 0.77, 0.42, and 0.17 g trolox/g in oxygen radical absorbance capacity (ORAC), ABTS, and DPPH assays, respectively), and recovered the major part of phenolics from the pomace; however, both extracts demonstrated similar antioxidant activity in the cellular assay. VOP-E inhibited HT29 cancer cells at non-cytotoxic concentrations. The results of this study revealed that VOP contains valuable phytochemicals possessing antioxidant and antiproliferative activities. Consequently, extracts from VOP substances may be of interest in developing functional ingredients for healthy foods, nutraceuticals, and cosmeceuticals.

Keywords: antioxidant capacity; antiproliferative activity; flavonoids; guelder rose berries; pomace; pressurized liquid extraction.