Bioprospecting of Labdane-Type Diterpenes From Austroeupatorium laetevirens: Molecular Networking, Structural Elucidation, and Biological Activity Evaluation.

Labdane-type diterpenes are the main specialized metabolites in the Austroeupatorium genus, known for diverse biological activities. This study employed molecular networking to facilitate the identification of labdanes in Austroeupatorium laetevirens, alongside isolation, structural elucidation, and evaluation of anti-Mycobacterium tuberculosis and antiproliferative activities. Ultra-high performance liquid chromatography coupled with high-resolution tandem mass spectrometry was used for dereplication, with data processed through the Global Natural Products Social Molecular Networking platform and visualized in Cytoscape. Structural elucidation was based on nuclear magnetic resonance spectroscopy, vibrational circular dichroism spectroscopy, and density functional theory calculations. Dereplication analysis led to the putative annotation of nine labdanes, two of which were isolated, including one new compound. Seven known compounds were also isolated, with eupatorin and eupafolin showing moderate antimycobacterial activity. Additionally, 25 compounds were putatively identified through dereplication. These findings reinforce the relevance of labdane-type diterpenes within the Austroeupatorium genus.