Bioactive responses of Hep-G2 cells to soyasaponin extracts differs with respect to extraction conditions

Soyasaponins are bioactive oleanane triterpenoids found in soy and other legumes. The effect of two methanolic extractions of soy flour, room temperature (RT) and reflux (RE) extractions on composition and bioactive properties in hepatocarcinoma cells (Hep-G2) were investigated. A greater amount of 2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP) conjugated soyasaponins βg was measured in RT and a greater amount of the structurally related non-DDMP soyasaponins I and III were detected in RE. MTT cell viability yielded an LC50 of 0.926 ± 0.08 mg/mL for RT and 0.546 ± 0.06 mg/mL for RE. ViaCount viability assay showed similar results for RE as the MTT assay however, RT treatment produced no difference compared with the control. Analysis using TUNEL and cell cycle analysis revealed that RE treatment induced apoptosis and flow cytometry forward side scatter and morphological assessment of RT showed evidence of Hep-G2 differentiation after 72 h. Differences in the bioactivities may be attributed to the different concentration of DDMP conjugated soyasaponin βg recovered in RT and RE extracts.