The chemical complexity of natural products, such as Eugenia punicifolia (Kunth) DC. plant, presents a challenge when extracting and identifying bioactive compounds. This study investigates the impact of different extraction systems and seasonal variations on the chemical profile and pharmacological potential of E. punicifolia leaves using NMR spectroscopy for chemical analysis and canonical correlation analysis (CCA) for bioactivity correlation. Extracts obtained with methanol (M), ethanol (E), methanol/ethanol (1:1, ME), and methanol/ethanol/water (3:1:1, MEW) were analyzed for antioxidant, antiglycation, and antiviral activities. Quantitative ¹H NMR, combined with the PULCON method, was used to quantify phenolic compounds such as quercetin, myricetin, catechin, and gallic acid. The results showed that the MEW extract obtained in the rainy season exhibited the highest antioxidant and antiglycation activities, with a greater than 93% of advanced-glycation end-products (AGEs) inhibition capacity. Furthermore, our results showed that all the extracts were able to inhibit over 94% of the Zika virus (ZIKV) infection in Vero E6 cells. The CCA established strong correlations between the phenolic compounds and bioactivities, identifying gallic acid, catechin, quercetin, and myricetin as key chemical markers. This study demonstrates the importance of selecting appropriate extraction systems and considering seasonality to optimize the pharmacological potential of E. punicifolia leaves and highlights the efficacy of NMR in linking chemical composition with bioactivities.

The influence of extraction solvents on the recovery of phenolic constituents from Eugenia protenta McVaugh leaves was investigated using solvent selection criteria based on the Snyder triangle and the linear solvation energy relationships (LSER) solvatochromic parameters (hydrogen‑bond donor acidity (α), hydrogen-bond acceptor basicity (β) and dipolarity/polarizability (π*)). Extracts obtained with methanol, ethanol, isopropanol, acetone, and ethyl acetate were evaluated in terms of extraction yield, gallic acid content, and antioxidant and antiglycation activities. Gallic acid was identified by nuclear magnetic resonance (1H NMR) and quantified by quantitative nuclear magnetic resonance (qNMR) using the pulse length-based concentration determination (PULCON) method as a marker of the phenolic fraction. Methanol provided the highest extraction yield (30.6 ± 4.0 mg g-1) and gallic acid content (36.8 ± 0.2 mg g-1 dry extract), while alcoholic extracts showed the best overall antioxidant and antiglycation performance. The results indicate that extraction efficiency depends not only on solvent polarity, but also on specific solute-solvent interactions related to hydrogen bonding and dipolarity/polarizability, supporting the use of protic solvents to recover phenolic‑rich bioactive extracts.

The chemical complexity of natural products such as Eugenia punicifolia (Kunth) DC. plant, presents a challenge when extracting and identifying bioactive compounds. This study investigates the impact of different extraction systems and seasonal variations on the chemical profile and pharmacological potential of E. punicifolia leaves using NMR spectroscopy for chemical analysis and canonical correlation analysis (CCA) for bioactivity correlation. Extracts obtained with methanol (M), ethanol (E), methanol:ethanol [1:1 (ME)], and methanol:ethanol:water [3:1:1 (MEW)] were analyzed for antioxidant, antiglycation and antiviral activities. Quantitative ¹H NMR, combined with the PULCON method, was used to quantify phenolic compounds such as quercetin, myricetin, catechin and gallic acid. The results showed that the MEW extract obtained in the rainy season exhibited the highest antioxidant and antiglycation activities, with an AGE inhibition capacity greater than 93%. Furthermore, our results showed that all the extracts were able to inhibit over 94% of the Zika virus (ZIKV) infection in Vero E6 cells. The CCA established strong correlations between the phenolic compounds and bioactivities, identifying gallic acid, catechin, quercetin and myricetin as key chemical markers. This study demonstrates the importance of selecting appropriate extraction systems and considering seasonality to optimize the pharmacological potential of E. punicifolia leaves and highlights the efficacy of NMR in linking chemical composition with bioactivities.