Abstract
Peganum harmala L. is rich in β-carboline and quinazoline alkaloids, but the organ-specific distribution of their polar glycosides remains poorly characterized. Fruits, roots, stems, and leaves of wild, fruiting P. harmala plants collected from the western desert of Egypt were profiled by LC–ESI–TIMS–MS/MS. In a preliminary acid–base work-up, 76–100% of the summed signal area of the detected alkaloid hexosides, and part of that of harmol, was found in the residual aqueous phase; direct acidic extraction, which avoids basification and organic-solvent partitioning, was therefore used for organ profiling. Sixteen alkaloids and two flavonoids were detected or tentatively annotated; seven alkaloids were identified using authentic standards. Four alkaloid hexosides were detected, including vasicinol hexoside and pegaharmine J hexoside, which are proposed here as new tentative annotations. The hexosides exhibited distinct organ-specific distribution patterns: vasicine hexoside and vasicine dihexoside were detected mainly in fruits, vasicinol hexoside in leaves, and pegaharmine J hexoside, together with its aglycone, in stems. Roots showed the highest mean levels of harmol, vasicine, and deoxypeganine and, together with fruits, of harmine and harmalol, whereas fruits were enriched in harmaline, the vasicine hexosides, and deoxyvasicinone; all annotated compounds differed significantly among organs. An exploratory interpretation based on experimental and predicted pKa and logP values suggests that ionization state and glycosylation, which markedly reduces logP, contribute to organ-specific accumulation; the vasicine hexosides are proposed as candidate sink-associated metabolites. This study provides an organ-resolved LC–MS profile of Egyptian P. harmala, shows that direct acidic extraction retains polar-alkaloid glycosides in the analyzed extract, and generates testable hypotheses regarding their biosynthesis, transport, and storage.