Phytochemical and Antioxidant Characterization of Centaurea macrocephala Willd.: With Notes on Chemotaxonomic Relevance

Centaurea macrocephala Willd. (Asteraceae) is a perennial herbaceous plant that has been relatively understudied in terms of its phytochemical composition and chemotaxonomic classification. Various Centaurea species are widely recognized for their medicinal properties. However, the phenolic composition, antioxidant activity, and volatile profile of C. macrocephala remain largely unexplored. This study aims to comprehensively evaluate the phytochemical profile and antioxidant properties of C. macrocephala, focusing on its flowers, leaves, and stems. The phenolic composition was determined using High-Performance Liquid Chromatography (HPLC), while antioxidant activity was assessed through Ferric Reducing Antioxidant Power (FRAP) and Copper Reducing Antioxidant Capacity (CUPRAC) assays. Additionally, volatile compounds were analyzed using Gas Chromatography-Mass Spectrometry coupled with Solid-Phase Microextraction (GC-MS-SPME). The leaves showed the highest levels of total phenolic and flavonoid compounds, which may explain the stronger antioxidant responses observed in FRAP and CUPRAC results. HPLC analysis identified chlorogenic acid, rutin, and quercetin derivatives as the dominant phenolic compounds. GC-MS-SPME analysis revealed that the volatile composition of C. macrocephala is predominantly characterized by aldehydes and ketones, distinguishing it from other Centaurea species, which are typically rich in sesquiterpenes.