Neuroprotective effects of Isodon ramosissimus (Hook.f.) Codd (Lamiaceae) aqueous extract against scopolamine-induced Alzheimer-like phenotype.

ETHNOPHARMACOLOGICAL RELEVANCE: Isodon ramosissimus is traditionally used in folk medicine for the management of neurological disorders. However, its neuroprotective properties against scopolamine-induced cognitive impairments have not yet been scientifically investigated.

AIM OF THE STUDY: This study investigated the anti-amnesic and neuroprotective effects of the aqueous extract of Isodon ramosissimus (IrAE) in a scopolamine-induced Alzheimer's-like phenotype in rats.

MATERIALS AND

METHODS

Liquid chromatography-mass spectrometry (LC-MS) and quantitative phytochemical analyses were performed to tentatively identify IrAE bioactive compounds. Forty-eight male Wistar rats were randomly assigned to six groups receiving saline, scopolamine (1 mg/kg), scopolamine plus donepezil (5 mg/kg), or scopolamine plus IrAE (75, 150, or 300 mg/kg) for 14 consecutive days. Learning and memory were evaluated using the novel object recognition and Morris water maze tests. Cholinesterase activity, oxidative stress biomarkers, and histopathological changes in the prefrontal cortex and hippocampus were also assessed.

RESULTS

Scopolamine induced significant cognitive deficits (p < 0.01), increased Acetylcholinesterase activity and oxidative stress (p < 0.01), and caused substantial neuronal damage. IrAE treatment significantly reversed learning and memory deficits (p < 0.01), attenuated acetylcholinesterase activity and oxidative stress (p < 0.01), and preserved cortical and hippocampal neurons from scopolamine's neurotoxic effects. LC-MS analysis tentatively identified oridonin, stigmasterol, chrysoeriol, ferruginol, and corosolic acid, compounds with reported cognitive-enhancing, antioxidant, anti-inflammatory, anticholinesterase, and neuroprotective activities.

CONCLUSION

IrAE exerts marked anti-amnesic and neuroprotective effects, associated with cholinergic and antioxidant modulation. These findings provide preliminary pharmacological support for the traditional use of IrAE, warranting further preclinical investigation of its potential in the management of cognitive disorders.