Study On The Cytotoxicity And Immune Activity Of Soyasaponin Ab In Vitro

Soyasaponins are important components in soybean and other legume. They belong to pentacyclic triterpenoid oleanane saponins. Soyasaponins show a variety of physiological activity and have broad prospects in medicine, health care products. Soyasaponin Ab is the main component separated and purified from soyasaponin complex. Up to now, most bioactivity studies were focused on the soyasaponin complex and less monomer were reported.In this paper, we purified soyasaponin Ab from from soy germ powder, studied its cytotoxicity, immune activity on RAW264.7 cells in vitro and explored the relevant molecular signaling mechanism.Hemolytic experiment results showed that the hemolytic effect of soyasaponin Ab is very weak compared with quillaja bark saponins. Soyasaponin Ab of 10 mg/mL showed no hemolytic effect and at the concentration of 20 mg/mL its hemolytic effect was only about 7%. The quillaja bark saponins as the control group showed strong hemolysis as at the concentration of 20 μg/mL it showed almost complete hemolysis. Furthermore, MTT experiment results showed that, soyasaponin Ab showed little cytotoxicity on RAW264.7 cells compared with quillaja bark saponins. These results suggested that the cytotoxicity of soyasaponin Ab is extremely low in vitro.ELISA results showed that soyasaponin Ab(0~200 μg/mL) promoted the the RAW264.7 cells to release cytokines TNF-α and IL-1β in a dose-independent manner; dual-luciferase experiment results showed that soyasaponin Ab could activate NF-κB transcription factor. These results indicated that soy saponins showed some immune activity.Western blot experiment results showed that TLR4 si RNA transfected to RAW264.7 cells effectively inhibited the expression of TLR4 for its inhibition efficiency greater than 60%, while the release of TNF-α, IL-1β levels were significantly lower than non-transfected TLR4 siRNA group and the activity of NF-κB transcription factor was also significantly lower than untransfected TLR4 si RNA group. These results indicated that, TLR4 might play an important role in the release of TNF-α and IL-1β and the NF-κB signaling transduction pathway of RAW264.7 cells induced by soyasaponin Ab.