**4. Conclusions**

The possible binding of HpzA with HSA was explored by utilizing molecular docking, MD simulation, PCA, and FEL analyses. Docking results indicated that the binding of HpzA with HSA showed an appreciable binding affinity and many intermolecular interactions. MD trajectory analyses (i.e., RMSD, RMSF, *Rg*, SASA, and hydrogen bonding) suggested that the HSA–HpzA docked complex was quite stable with minimal conformational alterations. Moreover, PCA and FEL analyses of HSA and HSA–HpzA confirmed that both the systems were stable without any significant change. However, a minor change in the shape and position of the global minima of HSA when bound to HpzA indicated that the HpzA might alter the conformational shape of the binding site of HSA. Fluorescence-based binding ascertained the actual binding affinity between HpzA and HSA, suggesting that HpzA binds to HSA with a significant affinity, validating the in silico observations. Overall, this study reinforces the idea that HSA–HpzA interactions can be explored in AD. The results contribute in many ways to our knowledge and provide a base for setting up an experimental platform of HpzA interactions with HSA to explore them in AD management.

**Supplementary Materials:** The following supporting information can be downloaded online. Figure S1: Molecular structure of Huperzine A: (A) 2D, (B) 3D stick, and (C) 3D ball and stick model of Huperzine A. Figure S2: Different docked conformations of HpzA with HSA. Figure S3: Energy table of different docked conformations of HpzA with HSA.

**Author Contributions:** Conceptualization, A.S. and D.K.Y.; methodology, A.S., M.S.K., M.S. and F.A.A.; software, S.A.A., W.A.A. and A.S.; validation; A.S., M.S.K., M.S. and D.K.Y.; formal analysis, A.S., F.A.A., B.A. and S.A.A.; writing—original draft and preparation; A.S., M.S.K., M.S. and F.A.A.; writing—review and editing; D.K.Y. and A.S.; visualization, A.S. and M.S.; project administration, A.S., M.S.K. and M.S.; Funding acquisition, A.S. and D.K.Y. All authors have read and agreed to the published version of the manuscript.

**Funding:** M.S.K. acknowledges the generous support from the Research Supporting Project (RSP-2021/352) by King Saud University, Riyadh, Saudi Arabia.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are contained within the article and Supplementary Materials.

**Conflicts of Interest:** The authors declare no conflict of interest.

**Sample Availability:** Not applicable.
