How Seasonality May Shape Key Phenolic Compounds of <i>Eugenia punicifolia</i>: A Study Driven by NMR Metabolomics

<i>Eugenia punicifolia</i> DC., a medicinal plant rich in bioactive phenolics, has shown promising results regarding its potential in the prevention of type 2 diabetes. This study investigated the seasonal influence on the chemical profile of leaf extracts (methanol:ethanol:water, 3:1:1) using ¹H NMR spectroscopy and multivariate analysis. Principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) revealed distinct metabolic patterns associated with rainy (Feb-May), dry (Sep-Nov), and transitional (Jan, Jun, Jul, and Dec) periods. The PLS-DA model showed high predictive power (<i>R</i> ² > 0.85, <i>Q</i> ² > 0.85), identifying quercetin, myricetin, gallic acid, catechin, and epigallocatechin as seasonal markers. Significant correlations were found between metabolite levels and environmental variables, such as temperature, rainfall, and sunlight exposure. These results demonstrate that abiotic factors regulate the biosynthesis of phenolic compounds, reflecting the plant's adaptive responses. The study offers a scientific basis for optimizing harvest timing and enhances understanding of the ecological and pharmacological potential of <i>E. punicifolia</i>, providing valuable insights into the development of standardized herbal medicines and phytoproducts.