Phenolic Profiles, Antioxidant Capacity, and Enzyme Inhibitory Activities of Helichrysum noeanum: A Natural Source of Multifunctional Bioactive Compounds

Natural bioactive compounds with antioxidant properties and associated biological activities are increasingly valued for food and nutraceutical applications. This study investigated the organ-specific phenolic composition, antioxidant capacity, and enzyme inhibitory activities of Helichrysum noeanum to evaluate its potential as a multifunctional source of such compounds. Methanolic extracts from flowers, leaves, stems, and roots were analyzed for total phenolics, flavonoids, and individual compounds using LC–ESI–MS/MS, alongside antioxidant and enzyme inhibitory activities. Leaves showed the highest phenolic content (87.23 mg GAEs/g extract) and strongest antioxidant capacity (RACI = 1.19), dominated by chlorogenic acid. Roots showed the highest concentrations of caffeic and ferulic acids, while stems contained benzoic acid derivatives and quercetin. Leaf extracts exhibited the most potent reducing and radical-scavenging activities, whereas roots and stems were superior in cholinesterase and α-amylase inhibition. Correlation analysis suggested that antioxidant responses were more closely associated with total phenolic content than with total flavonoid content, whereas enzyme inhibitory activities exhibited organ-dependent variation. Overall, H. noeanum represents an organ-specific source of bioactive compounds with potential relevance for nutraceutical and food-related applications.