Zebrafish as an Emerging Model for Bioassay-Guided Natural Product Drug Discovery for Neurological Disorders

Most neurodegenerative diseases are currently incurable, with large social and economic impacts. Recently, there has been renewed interest in investigating natural products in the modern drug discovery paradigm as novel, bioactive small molecules. Moreover, the discovery of potential therapies for neurological disorders is challenging and involves developing optimized animal models for drug screening. In contemporary biomedicine, the growing need to develop experimental models to obtain a detailed understanding of malady conditions and to portray pioneering treatments has resulted in the application of zebrafish to close the gap between in vitro and in vivo assays. Zebrafish in pharmacogenetics and neuropharmacology are rapidly becoming a widely used organism. Brain function, dysfunction, genetic, and pharmacological modulation considerations are enhanced by both larval and adult zebrafish. Bioassay-guided identification of natural products using zebrafish presents as an attractive strategy for generating new lead compounds. Here, we see evidence that the zebrafish’s central nervous system is suitable for modeling human neurological disease and we review and evaluate natural product research using zebrafish as a vertebrate model platform to systematically identify bioactive natural products. Finally, we review recently developed zebrafish models of neurological disorders that have the potential to be applied in this field of research

HPLC-PDA isolation and LC-MS/MS detection of an acetylcholinesterase inhibitory flavonoid from <i>Tephrosia purpurea</i> (L.) Pers. in zebrafish brain

104-111Separation of bioactive compounds or therapeutic small molecules from medicinal herbs is challenging due to the complexity of the phytochemicals. Tephrosia purpurea (L.) Pers. (Fam. Fabaceae) is rich in therapeutic compounds, used forisolation of an acetylcholinesterase inhibitor by HPLC coupled with Photo diode array (PDA) and mass spectrometric techniques. The separation was achieved through analytical HPLC by development of gradient mobile phase using methanol and acetonitrile along with 0.1 M ammonium acetate in Milli-Q water by two modes of mobile phase separations to yield the maximum purity, 99.13%. Based on the above-developed strategies, the preparative isolation of the acetylcholinesterase inhibitory flavonoid was purified at 269 nm with a retention time of 13. 9 min. The isolated compound from T. purpurea was confirmed as a flavonoid by phytochemical screening tests. The molecular mass was identified as 366.1467 Da by UPLC/Q-ToF-MS for the purified flavonoid.. Further, the molecular formula was found to be C22H22O5 by HR-MS/MS fragmentation pattern analysis through ChemSpider database search. The fragmentation pattern favoured the purified compound for similarity to Cyqualon. The isolated compound showed acetylcholinesterase (AchE) inhibition with the IC50 value of 54 µM in the zebrafish brain. However, the comparative study on the commercial cyqualon compound and the isolated compound showed different UV spectrum with the values at 269 nm and 257.5 nm, respectively. These findings concluded that the compound might be a novel flavonoid from Tephrosia purpurea which could be used as a therapeutic compound for neurodegenerative diseases after structural characterization

Molecular interaction of human acetylcholinesterase with trans-tephrostachin and derivatives for Alzheimer's disease

Alzheimer's disease (AD), a neurodegenerative disorder affects more than 35 million people globally. Acetylcholinesterase suppression is the common approach to enhance the well-being of AD patients by increasing the duration of acetylcholine in the cholinergic synapses. Generally, herbal secondary metabolites are reported to be a major resource for acetylcholinesterase inhibitors (AChEIs). Trans-tephrostachin was reported from Tephrosia purpurea for AChE inhibition. Here, we report on the design, synthesis, and assessment of human acetylcholinesterase inhibitory activity from trans-tephrostachin derivatives or analogs as anti-AD agents. The five newly synthesized compounds 4a. 4b, 4c, 4d and 4e displayed potent inhibitory activities with IC50 values of 35.0, 35.6, 10.6, 10.3, and 28.1 μM respectively. AChE enzyme kinetic study was performed for the five derived compounds using the Ellman's method. The Lineweaver-Burk and the secondary plots revealed the mixed inhibition for 4a, 4c and 4d whereas 4b and 4e demonstrated competitive inhibition. Molecular docking and molecular dynamics simulations showed the derivatives or analogs of trans-tephrostachin attained a high binding affinity and efficacy than the standard drug. In conclusion, trans-tephrostachin and its derivative compounds could become effective agents for further drug development to treat AD.Published versio