Mechanism of isoflavone aglycone’s effect on cognitive performance of senescence-accelerated mice

Genistein antagonizes inflammatory damage induced by β-amyloid peptide in microglia through TLR4 and NF-κB

OBJECTIVES

Microglia activation and neuroinflammation have been associated with the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD). Toll-like receptor 4 (TLR4) and nuclear factor (NF)-κB-mediated signal pathways exert key modulating roles in the inflammatory processes. The aim of the present study was to investigate whether genistein (Gen) has a neuroprotective effect against inflammatory damage induced by β-amyloid peptide25-35 (Aβ25-35) through the TLR4 and NF-κB-mediated signal pathways.

METHODS

BV-2 microglia cells were preincubated with Gen for 2 h and then treated with 25 μM Aβ25-35 for another 24 h. The expression of inflammatory mediators, TLR4 and NF-κB and the activity of NF-κB were measured.

RESULTS

The results showed that Gen could attenuate the cytotoxicity and inflammatory damage induced by Aβ25-35. Gen also significantly reversed Aβ25-35-induced up-regulation of TLR4 and NF-κB expression and the DNA binding and transcriptional activities of NF-κB.

CONCLUSION

These results indicated that Gen could alleviate the inflammation caused by Aβ25-35 treatment, which might be associated with the regulation of the TLR4/NF-κB signal pathway.

Total isoflavones from soybean and tempeh reversed scopolamine-induced amnesia, improved cholinergic activities and reduced neuroinflammation in brain

The present study was undertaken to compare the neuroprotective effects between total isoflavones from soybean and tempeh against scopolamine-induced cognitive dysfunction. Total isoflavones (10, 20 and 40mg/kg) from soybean (SI) and tempeh (TI) were administered orally to different groups of rats (n=6) for 15days. Piracetam (400mg/kg, p.o.) was used as a standard drug while scopolamine (1mg/kg, i.p.) was used to induce amnesia in the animals. Radial arm and elevated plus mazes served as exteroceptive behavioural models to measure memory. Brain cholinergic activities (acetylcholine and acetylcholinesterase) and neuroinflammatory activities (COX-1, COX-2, IL-1β and IL10) were also assessed. Treatment with SI and TI significantly reversed the scopolamine effect and improved memory with TI group at 40mg/kg, p.o. exhibiting the best improvement (p<0.001) in rats. The TI (10, 20 and 40mg/kg, p.o.) significantly increased (p<0.001) acetylcholine and reduced acetylcholinesterase levels. Meanwhile, only a high dose (40mg/kg, p.o.) of SI showed significant improvement (p<0.05) in the cholinergic activities. Neuroinflammation study also showed that TI (40mg/kg, p.o.) was able to reduce inflammation better than SI. The TI ameliorates scopolamine-induced memory in rats through the cholinergic neuronal pathway and by prevention of neuroinflammation.

Preparation, drug releasing property and pharmacodynamics of soy isoflavone-loaded chitosan microspheres

Soybean isoflavone (SIF) has anti-aging properties and many other biological functions; however, SIF is difficult to reach higher blood concentration due to its rapid metabolism. Therefore, it is of great value to design and produce a sustained-release formulation that is able to maintain a stable level of plasma concentrations. In this paper, soybean isoflavone sustained-release microsphere from chitosan and sodium alginate was prepared successfully. The important factors that determined the quality of the microspheres were the sodium alginate concentration in solution B, the ratio of soybean isoflavone to chitosan and the mixing speed. The relative yield, encapsulation efficiency and drug loading capability of SIF were much higher than the existing commercial formulations. In real gastrointestinal conditions, compared with the non-sustained release group, the release rate of SIF slowed down and the reaction time was prolonged. Animal experiments showed that sustained-release microspheres intensified the anti-aging potentials of SIF. Compared with the Non-sustained release (NSR) group mice, oral SIF/CHI microsphere treated mice were better in the Morris Water Maze Test (MWMT), the MDA level in the both plasma and brain of the sustained release (SR) group mice decreased, and SOD content was remarkably improved.