Profiling Hydrophilic Cucurbita pepo Seed Extracts: A Study of European Cultivar Variability

Cucurbita pepo (CP) seeds are traditionally used to alleviate lower urinary tract symptoms associated with benign prostatic hyperplasia and overactive bladder. While these effects are often attributed to lipophilic constituents, recent studies have highlighted the therapeutic potential of oil-free hydroethanolic extracts. However, their composition remains insufficiently characterized, considering the species’ significant phenotypic and phytochemical variability. This study aimed to characterize the phytochemical profile of hydrophilic hydroethanolic seed extracts from ten CP cultivars originating from different European regions, with a focus on compositional variability. The elemental composition, along with primary and secondary metabolites, was analyzed using established spectroscopic and chromatographic methods. The extracts showed considerable variation in protein (45.39 to 114.58 mg/g dw) and free amino acid content (46.51 to 111.10 mg/g dw), as well as differences in elemental composition. Principal component analysis revealed distinct clustering patterns, with several samples displaying metabolite profiles comparable to the Cucurbita pepo var. styriaca variety currently recommended by the European Pharmacopoeia (Ph. Eur.) and the Committee on Herbal Medicinal Products (HMPC). These findings open the possibility of using other CP varieties as alternative sources for extract preparation and offer novel insights into the composition of less explored hydrophilic extracts derived from CP seeds.