Effects of <i>Syzygium cumini</i> Seed Extract on the Memory Loss of Alzheimer’s Disease Model Rats

Alzheimer’s disease (AD) is the most prominent dementia-related disease and characterized by the presence of insoluble amyloid beta peptide (Aβ) fibers in or around the brain neurons of the affected person. Therefore, agent(s) capable of inhibiting brain amyloid deposition might delay the occurrence or retard the progress forwards of AD and related neurobehavioral symptoms. Here, we report whether, chronic oral administration of Syzygium cumini (locally known as Jam)-seed extract exerts protection against the progressive cognitive decline in the Aβ1-40-infused AD model rats. After 12 weeks of feeding with S. cumini seed extract (at 300 mg/kg BW), we evaluated the learning-related memory of the rats by 8-arm radial maze task, where we determined two types of memory errors, namely reference memory errors (RMEs) and working memory errors (WMEs). After completion of memory tests, rats were sacrificed and the levels of lipid peroxide (LPO), the Aβ1-40-burden, Aβ1-40-oligomers, proinflammatory TNFα, brain derived neurotrophic factor (BDNF), Tyrosine-kinase B (TrkB), postsynaptic-density protein 95 (PSD-95) and Synapse-associated protein (SNAP-25) were determined in the corticohippocampal tissues of the brain. In addition, in vitro antioxidative effects of S. cumini seed extract were evaluated. The oral administration of S. cumini extract significantly increased the memory-related learning ability of the AD model rats, concomitantly with reductions in the levels of corticohippocampal Aβ1-40-burden and Aβ1-40-oligomers. Furthermore, the extract suppressed the levels of TNFα and LPO in the corticohippocampal tissues of the AD rats and also the later in the plasma, suggesting an anti-oxidative and anti-inflammatory activities of the S. cumini extract in the brains of AD model rats. S. cumini extract also increased the levels of brain cognition and memory-related proteins, including BDNF, TrKB, PSD-95 and SNAP-25. We thus suggest that S. cumini-seed extract could be used in neurobehavioral deficits and associated pathogenesis of Alzheimer’s disease.