Molecular mechanism analysis and network pharmacology of capsaicin in Alzheimer’s and Parkinson’s diseases: an in silico study

Aim: Parkinson’s disease (PD) and Alzheimer’s disease (AD) represent critical neurological disorders that have emerged as significant health concerns in the 21st century. The pharmacological interventions currently employed to manage these diseases demonstrate limited efficacy and some adverse side effects. Historically, natural products have been used to develop therapeutic agents targeting neurodegenerative disorders. This study aimed to apply in silico techniques to investigate the pharmacological mechanisms of capsaicin as a possible alternative treatment or coadjutant phytotherapy for PD and AD. Methods: We obtained target genes for capsaicin, PD, and AD from the HERB database, the Swiss Target Prediction database, the Comparative Toxicogenomics Database, and the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform, and matched them. Subsequently, we constructed a protein-protein interaction network and performed enrichment analysis of the common targets. Then, the interactions of capsaicin with the proteins with the highest degree were tested using molecular docking. The stability of the complexes was verified using molecular dynamics techniques. Results: A total of 25 targets were found in common from the databases for capsaicin, AD, and PD. The enrichment analysis revealed that proteins from these targets influenced integrin activity in the IGF1-IGF1R complex, cholinesterase activity, and dopamine neurotransmitter receptor activity, all of which are coupled via protein Gi/Go, among other cellular processes. From the protein-protein interaction network, we identified the hub proteins IL6, GSK3B, CASP, BCL2, ESR1, SIRT1, NGF, IGF1, and HMOX1. Furthermore, molecular docking studies between hub proteins and capsaicin showed strong binding affinity. Finally, molecular dynamics simulations support a stable interaction between capsaicin and SIRT1, ESR1, HMOX1, and NGF. Conclusions: This work contributes to understanding the neuroprotective activity of capsaicin in PD and AD. However, these bioinformatic predictions require further experimental validation.