Polyphenol composition of fresh and dried Quillaja saponaria leaf extracts by UHPLC/MS

Quillaja saponaria Molina is an endemic Chilean tree valued for its saponin-rich bark and biomass. However, overexploitation and drought have endangered natural populations, highlighting the need for sustainable alternatives such as the use of leaves. In this study, we analyzed the polyphenolic profile of water extracts obtained from fresh and dried Q. saponaria leaves using UHPLC/MS. Although the extraction was optimized for saponin recovery, several polyphenolic compounds remained detectable. The analysis revealed a diverse composition, including phenolic acids and flavonoids, with piscidic acid dominating (82.65–82.96 % of total quantified polyphenols), followed by p-coumaric acid derivatives identified as Quillajasides A and B and their isomers (4.81–5.34 %), and quercetin derivatives (3.7–4.15 %). These findings suggest that polyphenols, though secondary in saponin-rich water extracts, may influence extract properties relevant to industrial and food applications. This comprehensive analysis contributes to sustainable plant resource management and provides insights into Q. saponaria leaves as a source of bioactive compounds.