Soyasaponin Ab has anti-inflammatory effects, it can inhibit colon shortening, myeloperoxidase activity, the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS), and activation of the transcription factor nuclear factor-κB (NF-κB); soyasaponin Ab (1, 2, 5, and 10 μM) can inhibit the production of NO (IC50 = 1.6 ± 0.1 uM) and prosta.Soyasaponin Aa and Ab can markedly inhibit adipocyte differentiation and expression of various adipogenic marker genes through the downregulation of the adipogenesis-related transcription factors PPARγ and C/EBPα in 3T3-L1 adipocytes. Soyasaponins Ab and Bb can prevent scopolamine-induced memory impairment in mice without the inhibition of acetylcholinesterase, exhibit memory-enhancing effects. Soyasaponin Ab may represent a viable candidate for effective vaccine adjuvant, TLR4 receptor dependent pathway may be involved in immune stimulatory effects of soyasaponin Ab.