Anti-inflammatory effect of soyasaponins through suppressing nitric oxide production in LPS-stimulated RAW 264.7 cells by attenuation of NF-κB-mediated nitric oxide synthase expression.

The anti-inflammatory properties of soyasaponins (especially soyasaponins with different chemical structures) have scarcely been investigated. We investigated the inhibitory effects of five structural types of soyasaponins (soyasaponin A(1), A(2), I and soyasapogenol A, B) on the induction of nitric oxide (NO) and inducible NO synthase (iNOS) in murine RAW 264.7 cells activated with lipopolysaccharide (LPS). Soyasaponin A(1), A(2) and I (25-200 µg/mL) dose-dependently inhibited the production of NO and tumor necrosis factor α (TNF-α) in LPS-activated macrophages, whereas soyasapogenol A and B did not. Furthermore, soyasaponin A(1), A(2) and I suppressed the iNOS enzyme activity and down-regulated the iNOS mRNA expression both in a dose-dependent manner. The reporter gene assay revealed that soyasaponin A(1), A(2) and I decreased LPS-induced nuclear factor kappa B (NF-κB) activity. Soyasaponin A(1), A(2) and I exhibit anti-inflammatory properties by suppressing NO production in LPS-stimulated RAW 264.7 cells through attenuation of NF-κB-mediated iNOS expression. It is proposed that the sugar chains present in the structures of soyasaponins are important for their anti-inflammatory activities. These results have important implication for using selected soyasaponins towards the development of effective chemopreventive and anti-inflammatory agents.

[Differentiation of neonatal rat striatal neural stem cells induced by all-trans retinoic acid].

OBJECTIVE: To investigate the role of all-trans retinoic acid (atRA) in inducing differentiation of neonatal rat striatal neural stem cells (NSCs). METHODS: Neonatal rat striatal NSCs were obtained by mechanical isolation and serum-free culture. The roles of atRA at different concentrations in inducing the differentiation of NSCs were observed by immunofluorescent cytochemical staining, and the expression of retinoic acid receptor (RAR) gene was determined by semi-quantitative RT-PCR. RESULTS: atRA could dose-dependently accelerate the differentiation of NSCs into neuron-like cells, and the physiological concentration of atRA was optimal for inducing NSC differentiation. atRA could induce the expression of RARbeta mRNA in a dose- and time-dependent manner. CONCLUSION: atRA can accelerate differentiation of NSCs into neuron-likes cells and up-regulate the expression of RAR-beta mRNA in neonatal rat striatal NSCs.

[Establishment and assessment of Caco-2 cell in vitro absorption model].

OBJECTIVE: To establish and assess the Caco-2 cell in vitro absorption model. METHODS: Caco-2 cells were cultured on the millipore filters fixed in Snapwell transport chamber. The cell morphology, transepithelial electrical resistance, mannitol efflux rate and alkaline phosphatase activities were monitored during culture. RESULTS: After 21 days of in vitro culture, formation of tight junction was observed between the cells. The transepithelial electrical resistance reach a relatively stable value of 620-/+47 Omega.cm(2), the mannitol efflux rate was lower than 0.3%.h(-1).cm(-2), and the alkaline phosphatase activity in the apical side was significantly higher than that in the basolateral side. CONCLUSION: The established Caco-2 cell model shows similar morphology to intestinal epithelial cells with formation of polarity, and can be used as an in vitro model for absorption studies.