# Mouse neuronal dendritic complexity and resilience to stress-induced depression in Drosophila melanogaster are enhanced by Withania somnifera alkaloids

## TL;DR

This study shows that alkaloids in ashwagandha can improve brain cell structure and reduce stress effects in fruit flies.

## Contribution

The study identifies alkaloids, not withanolides, as bioactive compounds in ashwagandha with neuroprotective effects.

## Key findings

- Polar fractions of ashwagandha increased dendritic complexity in mouse neurons.
- Alkaloids like acetyltropine were linked to stress resilience in fruit flies.
- Withanolide-rich fractions lacked the observed bioactivity.

## Abstract

Withania somnifera (WS), also known as ashwagandha, is used in traditional Ayurvedic medicine for its rejuvenating properties. While most research has focused on withanolides as primary bioactive constituents, this study highlights the potential role of alkaloids in the biological effects of WS.

To explore compounds responsible for bioactivity of WS on dendritic complexity in mouse primary neurons and on stress-related behaviors in Drosophila melanogaster.

An aqueous extract was prepared from dried root of WS grown in Central Oregon, and fractionated into ethanol insoluble, polar, and non-polar fractions. The preparations were tested for effects on dendritic complexity of mouse primary hippocampal neurons, and on stress-induced behavioral changes in Drosophila melanogaster flies. The composition of WS extract and fractions was examined using liquid chromatography coupled to high-resolution or multiple reaction monitoring mass spectrometry (LC-HRMS/MS or LC-MRM-MS).

WS root aqueous extract and its polar fraction enhanced dendritic complexity in mouse primary hippocampal neurons and significantly improved stress-related behavior in Drosophila, whereas the withanolide-rich, non-polar fraction did not. The bioactive, polar fraction contained alkaloids including acetyltropine, which was then confirmed as a major, bioactive alkaloid in WS root and differentiated from its isomer acetyl exotropine by its LC-MRM-MS retention time and 2D-NMR.

These findings highlight a role for alkaloids, including acetyltropine, as potential active constituents of WS associated with neuroprotective and anti-stress effects traditionally attributed to this plant. Results support continued evaluation of additional WS active compounds beyond withanolides.