Antioxidant, Enzyme Inhibitory, and Protective Effect of Amelanchier lamarckii Extract

Abstract

The present study aimed to investigate the chemical content of Romanian juneberries (Amelanchier lamarckii), their effect on antioxidant and enzyme inhibition activities, and their bioaccessibility after simulated in-vitro digestion. In Amelanchier lamarckii extract (AME), 16 polyphenolic compounds were identified by LC-ESI+-MS analysis. The most representative compounds found in the extract were cyanidin-galactoside, 3,4-dihydroxy-5-methoxybenzoic acid, feruloylquinic acid, and kaempferol, all belonging to the anthocyanins, phenolic acids, and flavonols subclasses. The polyphenols of AME exert quenching abilities of harmful reactive oxygen species, as the CUPRAC antioxidant assay value was 323.99 µmol Trolox/g fruit (FW), whereas the FRAP antioxidant value was 4.10 μmol Fe²⁺/g fruit (FW). Enzyme inhibition assays targeting tyrosinase (IC50 = 8.843 mg/mL), α-glucosidase (IC50 = 14.03 mg/mL), and acetylcholinesterase (IC50 = 49.55 mg/mL) were used for a screening of AME's inhibitory potential against these key enzymes as a common approach for the discovery of potential antidiabetic, skin pigmentation, and neurodegenerative effects. The screening for the potential antidiabetic effects due to the α-glucosidase inhibition was performed in glucose-induced disease conditions in a human retinal pigmented epithelial cell experimental model, proving that AME could have protective potential. In conclusion, AME is a valuable source of phenolic compounds with promising antioxidant potential and metabolic disease-protective effects, warranting further investigation for its use in the nutraceutical and health industries.

Keywords: Amelanchier lamarckii; antioxidant; bioaccessibility; enzyme inhibition; juneberries; phenolics; retina.

Figure 1

Inhibition of tyrosinase (tyr), α-glucosidase (glu), and acetylcholinesterase (ache) after 15 min of incubation with Amelanchier lamarckii extract (AME). The plots represent the normalized logarithmic concentrations versus percentages of inhibition.

Figure 2

Influence of AME (µg/mL) on human pigmented epithelial D407 cells’ proliferation in basal glucose (5 mM) conditions (a). The effect of AME (µg/mL) on D407 cells in different glucose-concentration environments (5, 30, and 60 mM). Results are presented as the mean ± SD of 5 measurements, one-way ANOVA, and multiple comparison Dunnett’s test (b). The data were compared using the one-way ANOVA test. **** means p < 0.0001, and *** means p < 0.001, ** means p < 0.01, * means p < 0.01, indicating highly significant differences between the sets of data.