Metal Complexes with Hydroxyflavones: A Study of Anticancer and Antimicrobial Activities

Metal chelation to bioactive small molecules is a well-established strategy to enhance the biological activity of the resulting complexes. Among the widely explored structural motifs, the combination of prominent metal centers with naturally inspired derivatives has attracted considerable attention. One such promising platform is the flavone scaffold, derived from flavonoids and studied since ancient times. Flavones are plant-derived compounds known for their diverse biological activities and health benefits. They exhibit significant structural variability, primarily through backbone modifications such as hydroxylation. Importantly, coordination of metal ions to hydroxylated flavone cores often improves their natural bioactivities, including anticancer and antimicrobial effects. In this review, we summarize transition metal complexes incorporating hydroxyflavone (OH–F) ligands reported over the past 15 years. We provide a concise overview of synthetic approaches and structural characterization, with a particular emphasis on coordination modes (e.g., maltol-type, acetylacetonate-type, catechol-type, and others). Furthermore, we discuss biological evaluation results, especially anticancer and antimicrobial studies, to highlight the therapeutic potential of these complexes. Finally, we suggest directions for the future development of metal-based agents bearing hydroxyflavone moieties through several critical points in terms of the accuracy, reproducibility, and relevance of biological studies involving metal-based compounds.