Stimulating Effect of W. somnifera Extracts Encapsulated into Chitosan Nanoparticles

Abstract Objective: Age-related neuronal loss in the brain is a natural process that causes gradual memory decline and may lead to neurodegenerative diseases. Neurodegenerative disorders, including Alzheimer’s and Parkinson’s diseases, are characterized by gradual but irreversible neuronal death. The search for preventive therapies for neurodegeneration remains an important area of research aimed at delaying age-related brain aging. The aim of this study was to analyze orally administered agents capable of preventing or slowing neurodegenerative processes. Polyphenol-rich extracts of Withania somnifera (WS), also known as ashwagandha, which are known to possess neuroprotective properties, were investigated. Methods: Extracts were obtained by maceration of WS root powder in 70% aqueous ethanol or dimethyl sulfoxide and subsequently separated into four fractions (I–IV) by high-performance liquid chromatography (HPLC). The effects of the HPLC fractions were evaluated by assessing cell proliferation, including proliferation of neural cell lines. The original extract was encapsulated into chitosan nano-/microparticles composed of hexanoyl-modified chitosan or N-(4-tetradecyloxybenzyl)chitosan. Results and Discussion: Active compounds in these fractions were identified by mass spectrometry. In total, 43 molecules were identified, with the major signal (65%) corresponding to three molecules with molecular masses of 415 (10.3%), 471 (39.1%), and 485 (50.6%) Da. Molecules with masses of 415 and 471 Da were identified as β-sitosterol and a group of withanolides (withanolides A, B, D, and G; vitasomniferanolide; vitasomnilide; vitasomniferol C; withaferin A; and withanone), respectively. The molecule with a mass of 485 Da was not identified. Isomeric withanolides were detected in fractions I, III, and IV, whereas molecules with masses of 415 and 485 Da were present in fractions I and IV. Fractions I, III, and IV stimulated the proliferation of neural cells over a broad concentration range. The chitosan-encapsulated WS extract also stimulated neural cell proliferation. Conclusions: Encapsulation of the extract into chitosan particles may protect biologically active compounds from degradation in the gastrointestinal tract and improve their bioavailability following oral administration, thereby enabling the future development of effective agents for the prevention of neurodegeneration.