HPLC-RID method for oligosaccharide quantification: validation, chemical composition, and cytotoxicity screening in açaí seeds

Açaí seeds represent an abundant Amazonian residue with substantial potential for valorization due to their complex chemical composition. In this study, discarded açaí seeds were comprehensively characterized, revealing a diverse and bioactive-rich matrix. The seeds contained relevant concentrations of organic acids (citric and succinic), mono- and disaccharides (fructose, glucose, maltose), and eighteen phenolic compounds, including catechin, epigallocatechin, epicatechin, procyanidins B1/B2, 3,4-dihydroxybenzoic acid, vanillic acid, and ferulic acid. Amino acids such as alanine, glutamine, and aspartic acid were also detected in high levels, providing additional nutritional and biochemical relevance. Oligosaccharide profiling revealed the presence of inulin, kestose, nystose, fructofuranosylnystose, xylobiose, xylose, and mannose, underscoring the seeds as a source of mannooligosaccharides with prebiotic potential. Simulated gastrointestinal digestion demonstrated high bioaccessibility for compounds such as hesperidin, caffeic acid, caftaric acid, and procyanidin B1, indicating substantial release during digestion. A safety screening using human fibroblast (HFF-1) assays showed no cytotoxic effects even at the highest tested concentrations, confirming the biocompatibility of the seeds for potential food and nutraceutical applications. A validated and sensitive HPLC-RID method supported reliable quantification of oligosaccharides in this complex matrix. Altogether, these findings highlight discarded açaí seeds as a safe, chemically rich, and sustainable raw material with strong potential for developing functional ingredients and bioactive compounds.