Comparative NMR-based profiling of polyphenols in Fragaria× ananassa cv. Marisol and Festival strawberry leaves

The polyphenol profiles of strawberry leaves (Fragaria × ananassa cvs. Marisol and Festival), cultivated in the tropical highlands of Costa Rica, were analyzed using high-field (750 MHz) and benchtop (60 MHz) Nuclear Magnetic Resonance (NMR) spectroscopy. Soluble and insoluble fractions were examined, revealing differences in the aromatic (6.0–8.0 ppm) and sugar (3.0–5.5 ppm) regions. High-field NMR provided sharper, more resolved signals, allowing for the identification of glycosylated polyphenols, flavonoids, and phenolic acids. Marisol exhibited a higher diversity and intensity of glycosylated polyphenols compared to Festival. In the insoluble fractions, both cultivars showed a unique peak at 2.0 ppm, absent in the soluble fractions, likely corresponding to lipids or matrix-bound compounds. The benchtop NMR spectra, though lower in resolution, confirmed key spectral patterns and cultivar differences. This study demonstrates the complementary use of high- and low-field NMR for polyphenol profiling and highlights the potential of strawberry leaves as a valuable source of bioactive compounds, contributing to the understanding of underutilized plant materials and their applications in health-related fields.