Characterisation of the variation of total saponin content in the <i>Medicago</i> species using an optimised extraction technique

Medicago sativa is an important worldwide forage species containing characteristic secondary metabolites such as saponin which are reported to be biologically active. The objective of this study was to determine the dynamics of total saponin content in M. sativa among different cuttings throughout a year and the variation of total saponin content in 28 accessions in genera Medicago using an optimised ultrasonic-assisted technique. Under field conditions, seasonal changes of total saponin content in M. sativa showed an increase from March (spring) (4.0 mg g−1 dry matter [DM]) towards a peak in late June (early summer) (9.5 mg g−1 DM), and subsequent a decrease in September (fall) (7.0 mg g−1 DM). The maximum total saponin content in M. sativa (range: 6.5−9.4 mg g−1 DM) was obtained at the 3rd harvest. A significant variation of total saponin content was observed both among different annual (range: 6.3–8.8 mg g−1 DM) and perennial (range: 6.1–11.2 mg g−1 DM) Medicago species. Flower of Medicago species showed the highest saponin content compared to other plant parts. The present study would serve a valuable reference for the selection of germplasm with different levels of saponin compounds for various application purposes and thus contribute to Medicago breeding programmes.</p