Unravelling Egyptian blue Lily (Nymphaea nouchali) organs’ metabolome via UHPLC/PDA/ESI-QTOF-MS and in relation to their antioxidant and anti-cholinesterase effects

Abstract Nymphaea nouchali is a prevalent water lily well recognized for its dietary and traditional medicinal purposes, attributed to its diverse phytochemical composition. This study is the first to provide a comprehensive metabolite profiling of Egyptian Nymphaea organs viz., flower, leaf, and stem using UHPLC/PDA/ESI-QTOF-MS high-resolution ultra-performance liquid chromatography Electrospray ionization/ photo diode array detector/ Quadrupole time-of-flight mass spectrometry. Alongside the in-vitro antioxidant activities employing different methods viz., DPPH, ATBS, NO scavenging, hydrogen peroxide scavenging, and cholinesterase inhibitory (AChE) activity were investigated. A total of 185 secondary metabolites were annotated belonging to 10 chemical classes viz., phenolic acids, ellagitannins, flavonoids, anthocyanins, alkaloids, amino acids and vitamins, organic acids, fatty acids & amides, lipids and sugars/sugar derivatives. Among them, 72 are newly reported viz., ellagic acid, corilagin, patuletin glycosides, naringenin, eriodictyol glycosides, spermidine alkaloids, and 33 lipids in Egyptian Nymphaea. Flowers recorded the highest antioxidant activities with IC 50 values (45.15 µg/ml) for DPPH, (5.02 µg/ml) for ABTS + , (54.07 µg/ml) for NO, (55.04 µg/ml) for H 2 O 2 assays and (1.85 µg/ml) for AChE inhibition. Flowers demonstrated potential antioxidant activities in correlation to their flavonoids, anthocyanins and alkaloids. Multivariate analysis (MVA), including unsupervised tools like principal component analysis (PCA) & hierarchical cluster analysis (HCA), and supervised orthogonal projections to latent structures discriminant analysis (OPLS-DA) are likewise employed. This research is designed to deal in depth with the chemical profile of the Egyptian water lily and tried to correlate such profile with their corresponding neuroprotective effect. Furthermore, in-vivo biological studies are planned to confirm the active agent post isolation from the active organs following results based on chemometric analysis. As future work, it is highlighted to target the isolation of novel entities.