Untargeted metabolomics reveals chemical variation and antimicrobial biomarkers in Dodonaea viscosa var. angustifolia (L.f.) Benth

Dodonaea viscosa var. angustifolia (L.f.) Benth is a widely used medicinal plant with reported biological activities, however few studies have identified marker compounds for quality control of the plant and interspecies chemical variation. The aim of this study was to investigate chemical variation in the non-volatile constituents of D. viscosa var. angustifolia collected from different locations, using high-performance thin layer chromatography (HPTLC) and untargeted ultra-performance liquid chromatography–mass spectrometry (UPLC–MS) metabolomics, and to identify chemo-biomarkers for quality control through biochemometrics analysis. Fifty leaves samples of D. viscosa var. angustifolia collected from the Western Cape Province of South Africa were chemically profiled using HPTLC and UPLC–MS. Antimicrobial activity of the leaves extracts was evaluated against five pathogens: Acinetobacter baumannii, Bacillus cereus, Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus . Multivariate data analysis was applied to the UPLC–MS data to assess chemical variation, while biochemometrics was used to correlate chemical profiles with antimicrobial activity and identify potential antimicrobial biomarkers. Untargeted UPLC–MS metabolomics analysis revealed inter- and intra-population variation, identifying three chemotypes that differed quantitatively in their marker compounds. Dodonaea viscosa var. angustifolia exhibited varied antimicrobial activity with MIC values ranging from 0.50 to 8.00 mg/mL against the tested pathogens. 2β-Hydroxyhardwickiic acid, viscosine, and santin were identified as potential bioactive markers in chemometric models of three out of the five pathogens. Integrating untargeted metabolomics and biochemometrics contributes to the standardisation of medicinal plant raw materials and the identification of markers associated with quality and biological activity.