Phytochemical Characterization and Antimicrobial Properties of a Hydroalcoholic Extract of <em>Trysterix corymbosus</em> (L) Kuijt, a Chilean Mistletoe Species Hosted on <em>Salix babilonica</em> (L)

Background/Objectives: The genus Tristerix comprises at least ten species, found from southern Chile to Colombia in South America. In Chile, several species of these hemiparasitic plants are commonly known as quitral or quintral. Traditionally, quitral, mainly T. corymbosus (syn. T. tetrandus), has been used in alternative medicine for its anti-inflammatory, digestive, hemostatic, hypocholesterolemic, wound-healing, and astringent properties. Due to its wide distribution in central and southern Chile and its frequent collection for ethnopharmacological purposes, this study aimed to investigate the phytochemical composition and antimicrobial properties of T. corymbosus. Methods: A hydroalcoholic extract of T. corymbosus was prepared from powdered leaves and small branches. Subsequently, the addition of methanol produced a precipitation to isolate three different fractions: a methanol-soluble fraction that was rotovaped, a brown powder obtained after filtration, and a tar-like residue that remained at the bottom of the flask. These fractions were resuspended in 70% ethanol or water and tested for antimicrobial activity. Results: All fractions showed activity against Streptococcus pyogenes, but not E. coli, with the brown powder exhibiting the strongest potency against S. pyogenes and other Gram-positive bacteria. Qualitative phytochemical characterization, followed by HPLC-MS analysis, revealed the presence of key compounds, including lipidic compounds with surfactant properties. Conclusions: the abundant lipidic molecules present in the analyzed fraction likely account for the antimicrobial effects through affecting membrane structure of Gram-positive bacteria, some Gram-negative and yeast Candida albicans supporting the traditional wound-healing uses of T. corymbosus in ancestral and alternative medicine.