Studies on phenolic compounds in Sambucus nigra L. fruits

Introduction. Among species of the Viburnaceae Raf. family, Sambucus nigra L. has a centuries-old history of use in folk medicine. Numerous studies substantiated that fruits and flowers of S. nigra are sources of flavonols, anthocyanins, phenolic acids, and other bioactive compounds. The aim of this study was to determine the levels of phenolic compounds in fruits of S. nigra cultivars and wild clones. Materials and methods. Three elderberry cultivars, ‘Haschberg’, ‘Dana’, and ‘Sambo 5’ as well as two wild clones, SN1 and SN2, were selected from the genetic resource collection of the Botanical Garden at Vytautas Magnus University. The samples were stored in plastic bags in a freezer at −28 °C, lyophilised, ground into powder, and stored in containers under dry and dark conditions. All results were expressed on a dry weight basis. Lyophilised S. nigra fruit powder (2.5 g) was extracted with 40 mL of 70% ethanol using ultrasound-assisted extraction for 10 minutes. The obtained extracts were centrifuged, filtered, and stored at 4 °C until analysis. All the spectrophotometric measurements were carried out with an i3 UV/VIS spectrophotometer. Results and discussion. In our study, the total phenolic content (TPC) in the fruits of various S. nigra cultivars ranged from 14.71 ± 1.39 to 38.69 ± 3.27 mg GAE/g DW, with the highest TPC found in the fruits of the 'Sambo 5' and 'Dana' cultivars. The total flavonoid content (TFC) in the fruits of S. nigra cultivars ranged from 3.75 ± 0.35 to 11.59 ± 0.34 mg RE/g DW, with the highest TFC observed in the ‘Haschberg’ cultivar. The total monomeric anthocyanin content (TAC) varied from 0,51 ± 0.10 to 2.01 ± 0.31 mg EE/g DW, with the highest values detected in the fruits of the ‘Sambo 5’ and ‘Dana’ cultivars. Antioxidant activity varied among cultivars, with ‘Sambo 5’ showing the highest CUPRAC values (2328 ± 102.8 µmol TE/g DW) and ‘Dana’ the highest ABTS•+ values (2574 ± 34.5 µmol TE/g DW). Overall, ‘Dana’ and ‘Sambo 5’ exhibited the strongest antioxidant activity. UHPLC-ESI-MS/MS analysis identified twenty phenolic compounds - phenolic acids, flavonols, flavones, flavan-3-ols, and one flavanone. Chlorogenic acid and rutin were the predominant compounds, especially in the fruits of the cultivar ‘Haschberg’. Flavonoids luteolin, naringenin, procyanidins, and (-)-epicatechin were present in small amounts. Conclusions. This study highlights the biochemical diversity of S. nigra fruits and the variability among cultivars and wild populations. Assessment of antioxidant and anticancer activities confirms their biological significance. The genotypes studied differed significantly in the amounts of phenolic compounds. This research provides valuable insights that support the expanded use of S. nigra fruits in functional foods, pharmaceuticals, and nutraceuticals.