Flavonoid-Rich Profiles across Different Populations of Six Iranian Achillea Species

Achillea L. (Asteraceae) is a medicinally important genus with a long history of use in traditional and folk medicine for the treatment of various ailments. The genus is characterized by a diverse and rich phytochemical composition, particularly phenolic compounds and flavonoids, which have been widely investigated for their antioxidant, anti-inflammatory, and antimicrobial properties. Among these constituents, luteolin, apigenin, and their derivatives are of particular interest because of their documented pharmacological properties. The present study aimed to characterize individual phenolic and flavonoid compounds in six Iranian Achillea species and their populations using high-performance liquid chromatography (HPLC). Considerable interspecific and population-level variation was observed in the accumulation of individual metabolites. For example, luteolin 6,8-di-C-glucoside was found to reach its highest content (14.55 mg g⁻¹ dry weight) in A. kellalensis, while vicenin-2, an apigenin C-glycoside, exhibited 7.09 mg g⁻¹ dry weight in A. wilhelmsii. Several A. wilhelmsii populations showed particularly high levels of apigenin-derived flavonoids, including vicenin-2, vitexin, and apigenin-7-O-glucoside. In contrast, compounds such as luteolin, quercetin, and kaempferol exhibited varied distribution patterns among the evaluated species. The observed diversity in flavonoid profiles underscores the potential of Iranian Achillea as a source of pharmacologically relevant compounds. Consequently, the chemically enriched species and populations identified may serve as promising plant material for targeted compound isolation, bioactivity-guided screening, and further pharmacological and pharmaceutical research.