Abstract
Circaea lutetiana (Onagraceae) is a perennial medicinal species widely distributed across temperate forest ecosystems of Europe, Asia, and North America. This mini-review integrates current knowledge on the botanical characteristics, ecological distribution, phytochemical composition, and biological properties of Circaea lutetiana, with particular emphasis on its dominant polyphenolic constituents. Available studies demonstrate that the species is rich in flavonoids, phenolic acids, ellagic acid derivatives, and ellagitannins, among which oenothein B represents a characteristic and major constituent. Beyond polyphenols, structurally characterized glycosides, lipophilic metabolites, phytosterols, triterpenoids, fatty acids, tocopherols, and mineral elements contribute to the chemical complexity of the species. The reported biological activities of Circaea lutetiana, including antioxidant, anti-inflammatory, antihypertensive, and antimicrobial effects, are discussed in relation to the phytochemical profile of the plant and the biological significance of its major constituents. Recent research in green nanotechnology has additionally highlighted the potential of Circaea lutetiana extracts, particularly in the biosynthesis of silver nanoparticles, where plant metabolites act as reducing and stabilizing agents and may contribute to improved antimicrobial performance.