Blackcurrant (Ribes nigrum L.) Matrices: Polyphenol Release, Antioxidant Capacity and Enzyme Inhibitory Potential

Blackcurrant (Ribes nigrum L.) fruits and their by-products represent valuable sources of bioactive compounds. This study compared fruits, juice, seeds, oil, and leaves with respect to their content of selected bioactive components, potential intestinal availability of polyphenols estimated by dialysis, and in vitro biological activities. Blackcurrant leaves contained several-fold higher levels of polyphenols in the dialyzable fraction (651.3 mg/100 g) than fruits (255.1 mg/100 g) and juice (261.4 mg/100 g). Seeds exhibited the strongest antioxidant activity among all matrices, reaching 13.3, 10.9 and 11.4 mmol Trolox/100 g in the ABTS, FRAP and ORAC assays, respectively. Hydrophilic fractions of juice and seeds showed notably stronger α-amylase inhibition (IC₅₀ < 0.01 mg/mL) than the antidiabetic drug acarbose (IC₅₀ = 0.35 mg/mL). Juice also demonstrated higher pancreatic lipase inhibition (IC₅₀ = 0.01 mg/mL) compared with Orlistat (IC₅₀ = 0.15 mg/mL) and effectively inhibited acetylcholinesterase, butyrylcholinesterase, and 15-lipoxygenase (IC₅₀ = 0.11, 0.03, and 0.02 mg/mL, respectively). These results indicate that various blackcurrant matrices possess strong biological activity and may serve as promising functional food ingredients or sources of health-promoting compounds.