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Beta vulgaris L. is an important food crop and a rich source of bioactive triterpene saponins.This study evaluated cultivarand growth-stage-dependent variability of saponins in leaves and roots of three beet cultivars (Round Dark Red, Cylindra, and Snow Ball) and in leaves of Swiss chard (Rhubarb Chard), harvested at seven harvest dates between June and September 2024.Saponins were identified and quantified using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS).A total of 32 triterpene saponins representing oleanane-type, akebonoic acid-, hederagenin-, and gypsogenin-derived aglycones were detected.Pronounced organ-dependent differences were observed.Total saponin content ranged from 386 to 10,414 mg/kg fresh weight (FW) in leaves and from 1,170 to 23,298 mg/kg FW in roots.Two-way analysis of variance confirmed highly significant effects of cultivar, harvest time, and their interaction on total saponin levels in both leaves and roots (all p<0.0001).Roots exhibited a broader content range and a pronounced mid-season maximum, whereas leaf saponin levels generally peaked in the mid-to-late season in a genotype-dependent pattern.Major saponins (Act-UrA--akebonoic acid and betavulgarosides II, III, IV, and VII) predominated in the quantitative profile and exhibited coordinated seasonal variation.Multivariate analyses (principal component analysis and hierarchical cluster analysis) clearly separated samples according to plant organ and further resolved cultivar-and season-related patterns.Overall, saponin accumulation in B. vulgaris is strongly regulated by organ type, genotype, and growth stage, emphasizing the importance of cultivar selection and harvest timing for maximizing bioactive potential.
Tekieli et al. (2026) studied this question.