Effects of sarsasapogenin derivatives on amyloid fibrils and cell viability

Authors: Barbora Spodniaková 1    Zuzana Bednáriková 1    Rui Wang 2    Miroslav Gančár 1    Zuzana Gažová 1   
1 Ústav experimentálnej fyziky, Oddelenie biofyziky,SAV, Košice, Slovenká republika    2 School of Pharmacy, East China University of Science and Technology, Shanghai, China   
Year: 2020
Section: Biophysics, mathematical modeling, biostatistics
Abstract No.: 1942
ISBN: 978-80-972360-6-9

Formation and accumulation of protein amyloid aggregates is associated with pathologies of many currently untreatable amyloid-related disorders including Alzheimer's disease (AD) [1]. Anemarrhenae asphodeloides is a Chinese herb used in traditional Chinese medicine as an antidepressant and anti-diabetic agent. Recently, the neuroprotective effect of  sarsasapogenin,  the extract of A. asphodeloides, has been reported. Mainly its ability to improve the memory deficit caused by presence of amyloid-β aggregates in brain [2]. In this study we have examined the in vitro anti-amyloidogenic and neurotrophic potential of sarsasapogenin (ML1) and its derivatives (ML4, ML9, ML13).

The destroying activity of sarsasapogenin and three its derivatives was studied by means of ThT fluorescence spectroscopy and atomic force microscopy. Among studied compounds, ML1 and ML4 displayed significant destroying activity towards Aβ42 amyloid fibrils. At 100 µM concentration, the most potential derivative ML4 reduced ThT fluorescence intensity up to 36 % compared to untreated amyloid fibrils, corresponding to 64% destroying activity.  The capacity to destroy Aβ42 fibrils increased with increasing concentration of the compound. Contrary, ML9 and ML13 displayed no Aβ42 fibrils destroying activity. We have studied the effect of studied compounds on SH-SY5Y neuroblastoma cells survival. Our results showed that none of the studied compounds had a significant effect on SH-SY5Y proliferation. We have also tested the effect of compounds on Aβ42 fibrils-induced cytotoxicity using colorimetric WST-1 assay. Interestingly, compounds ML9 and ML13, with no fibrils destructive activity, decreased the metabolic activity of the cells. Contrary, the activity of compounds ML1 and ML4 led to destruction of preformed Aβ42 amyloid fibrils however did not form highly toxic intermediates. Thus the cell proliferation was not decreased. The ability of compounds to induce the neuritic outgrowth and building new interneuronal connections would be of a great advantage in treatment of AD. From the studied compounds, ML4 was able to effectively induce neuritic outgrowth of the neuroblastoma cells.

The present work is a step towards understanding the relationship between the structure, anti-amyloid and neurotrophic potential of sarsasapogenin and sarsasapogenin derivatives. Based on this study, ML4 compound is an effective anti-amyloid compound with ability to induce neuritic outgrowth in neuroblastoma cells. Even though it is structurally very similar to its mother molecule (sarsasapogenin ML1), the additional aromatic ring caused significantly higher anti-amyloid and neurotrophic efficiency. ML4 compound has a great potential to become blueprint for design of new effective sarsasapogenin derivatives with potential to treat amyloidosis. 

This work was supported by grants VEGA 2/0145/17, APVV 18-0284, ITMS project 313011T553 (DIAGNAD). Studied compounds were synthesized and kindly provided by Lei Ma, Bu-Bing Zeng (East China University of Science and Technology, Shanghai, China).
[1] Kashyap, P., Muthusamy, K., Niranjan, M., Trikha, S., & Kumar, S. (2019). Sarsasapogenin: A steroidal saponin from Asparagus racemosus as multi target directed ligand in Alzheimer’s Disease. Steroids, 108529. doi:10.1016/j.steroids.2019.108529. 
[2] Yu, L., Huang, C., Dong, D., Huang, Y., Ma, L., & Wang, R. (2019). Neuroprotective effects of sarsasapogenin-AA13 via autophagy and MAPK pathway. Int J Clin Exp Med12(5), 4920-4927.