Untargeted phytochemical profiling and biological activity of small yellow onion (Allium flavum L.) from different regions of Romania

•Allium flavum was investigated for its nutraceutical profile and bioactive properties.•A. flavum flowers collected from Făget (AFFF) was the best source of polyphenols.•All the tested extracts exhibited α-glucosidase inhibition potential.•Carotenoids and sulfur compounds correlated with lipase inhibitory activity.•AFFF extracts strongly inhibited radical-induced membrane damage in erythrocytes. This study examined the phytochemical profiles (mainly phenolics, carotenoids, and organosulfur compounds) and biological effects of hydroalcoholic extracts of Allium flavum (AF), a species of the Allium genus commonly known as small yellow onion. Unsupervised and supervised statistical approaches revealed clear differences between extracts prepared with samples collected from different areas of Romania. Overall, the AFFF (AF flowers collected from Făget) extract was the best source of polyphenols, also showing the highest antioxidant capacity evaluated through both in vitro DPPH, FRAP, and TEAC anti-radical scavenging assays and cell-based OxHLIA and TBARS assays. All the tested extracts exhibited α-glucosidase inhibition potential, while only the AFFF extract exhibited anti-lipase inhibitory activity. The phenolic subclasses annotated were positively correlated with the assessed antioxidant and enzyme inhibitory activities. Our findings suggested that A. flavum has bioactive properties worth exploring further, being a potential edible flower with health-promoting implications.