Fast and Sensitive LC-MS/MS Method for the Quantitation of Saponins in Various Sugar Beet Materials

An LC-MS/MS method was developed for the simultaneous quantitative analysis of the following 11 triterpene saponins within different sugar beet materials and plant compartments: betavulgaroside I (1), betavulgaroside II (2), betavulgaroside III (3), betavulgaroside IV (4), betavulgaroside VIII (5), boussingoside A2 (6), 3-O-[β-d-glucopyranosyl-(1 → 2)-(β-d-xylopyranosyl-(1 → 3))-β-d-glucuronopyranosyl]-28-O-β-d-glucopyranosyl-3β-hydroxyolean-12-en-28-oic acid (7), betavulgaroside V (8), chikusetsusaponin IVa (9), calenduloside E (10), and ginsenoside R0 (11). Our results showed highly varying amounts of saponins within different varieties, roots, and leaves as well as different plant compartments. The amounts for sugar beet roots were in the range of 862 mg/kg to 2 452 mg/kg. They were mostly higher for leaves compared to roots of the same variety with amounts ranging from 907 mg/kg to 5 398 mg/kg. Furthermore, the occurrence of sugar beet saponins within different side streams was examined; in this context, sugar beet fiber contained the highest amounts of saponins for all investigated plant constituents and byproduct streams with a total amount of 12.7 g/kg. Finally, this is the first publication about the occurrence of individual saponins in sugar beets.