Composition and Colors of Propolis from Vale do Jequitinhonha (Brazil): A Pilot Study Based on Untargeted Metabolomics

Abstract

Propolis exhibits marked chemical diversity driven by botanical sources and environmental conditions, which challenges its classification based solely on geographic origin or color. In this study, 54 propolis samples collected from different microregions of Vale do Jequitinhonha (Minas Gerais, Brazil) were analyzed using an untargeted metabolomics approach by liquid chromatography-mass spectrometry, combined with visible spectroscopy measurements and correlation-based statistical analyses. Multivariate analysis revealed pronounced chemical variability across the dataset, with partial differentiation observed for samples from the Diamantina microregion, while other microregions showed substantial overlap. Visible spectroscopy allowed objective classification of the extracts into green (19 samples), red (5 samples), and other (30 samples), with green samples showing absorption bands mainly around 670 nm and red samples around 495 nm. A total of 77 molecular features were tentatively annotated, predominantly corresponding to phenolic acids, flavonoids, dihydrochalcones, and related phenolic subclasses. Compounds commonly reported as markers of Brazilian green and red propolis, such as artepillin C, caffeoylquinic acid derivatives, liquiritigenin, vestitol, and formononetin, were detected, including samples outside their classical regions of occurrence. Correlation-based integration of metabolomics and spectroscopic data indicated that propolis color arises from the combined contributions of multiple phenolic compounds rather than from a single pigment molecule.

Keywords:
chemical profile; phenolic compounds; Minas Gerais; PCA; statistical total correlation spectroscopy; mass spectrometry