Profiling bioactive compounds and enzyme inhibitory potential of industrial horticultural by-products associated with metabolic and neurological disorders

The growing availability of horticultural by-products presents an opportunity for their sustainable use as sources of bioactive compounds with potential health benefits. In this study, the phytochemical composition (including polyphenols, terpenoids, and sulfur-containing compounds) and in vitro biological activities of 9 by-products from citrus, pomegranate, broccoli, tomato, and carrot were quantitatively assessed. Pomegranate peels—particularly from the 'Wonderful' cultivar—showed the highest antioxidant capacity (ABTS + : 1297.2 mmol Trolox/kg dw) and strongest inhibitory activity against α-glucosidase (IC 50 : 0.1 mg/mL), α-amylase (17.3 mg/mL), and pancreatic lipase (0.3 mg/mL), associated with high levels of punicalagins and ellagic acid derivatives. Broccoli by-products, notably florets and leaves, were richer in sulforaphane and glucosinolates and showed relevant inhibitory effects on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), with IC 50 values as low as 103.3 mg/mL and 54.1 mg/mL, respectively. Pearson correlation and regression analyses revealed enzyme-specific phytochemical signatures: α-glucosidase inhibition was strongly associated with punicalagins and ellagic acid (r > 0.95), lipase inhibition with total polyphenols, and cholinesterase inhibition with sulforaphane and glucosinolates. These findings demonstrate the functional potential of selected horticultural by-products for targeted nutraceutical applications, particularly in the prevention of metabolic and neurodegenerative disorders. • Polyphenols and sulfur compounds were linked to biological functionality. • Enzyme inhibition varied according to by-product and compound profile. • Pomegranate peel showed strong antioxidant and antidiabetic enzyme activity. • Broccoli by-products had notable neuroprotective enzyme inhibitory effects. • Findings support using by-products in nutraceuticals and functional foods.