Aqueous Extracts of Bay Leaf (Laurus nobilis) and Rosemary (Rosmarinus officinalis) Inhibit Iron-Induced Lipid Peroxidation and Key-Enzymes Implicated in Alzheimer’s Disease in Rat Brain-in Vitro

Abstract

Neurological disorders remain a global health challenge, with Alzheimer’s Disease (AD) as the most famous cause of dementia in old people. Nevertheless, culinary spices and herbs have shown promising potentials in the management of neurological diseases. This study aimed at investigating the neuroprotective property of aqueous extracts of bay leaf (Laurus nobilis) and rosemary (Rosmarinus officinalis) by assessing the antioxidant activity of the extracts and the effects on key-enzymes implicated in AD: Acetylcholinesterase (AChE) and Butyrylcholinesterase (BChE) and lipid peroxidation in vitro. Bioactive constituents of the samples were characterized using GC-MS and the interaction of the identified compounds with AChE and BChE was determined through molecular docking. Both extracts exhibited remarkable inhibitory activities against AChE and BChE, with no significant (p>0.05) difference in their inhibitory activities. Similarly, aqueous extracts of both samples inhibited iron-induced lipid peroxidation in rat brain with L. nobilis extract exhibiting significantly (p<0.05) higher inhibitory activity (IC50: 67.83±13.53 µg/mL) than R. officinalis (IC50: 96.96±15.63 µg/mL). Also, L. nobilis extract displayed a better radical scavenging ability and Ferric Reducing Antioxidant Power (FRAP). However, no significant difference (p>0.05) in their iron-chelating abilities as reflected in the IC50 values (L. nobilis: 10.93±0.42 µg/mL; R. officinalis: 10.12±0.40 µg/mL). Furthermore, GC-MS analysis confirmed the presence of 39 phenolic compounds in both samples, with chlorogenic acid, rosmarinic acid, rosmanol, rutin, hesperetin 7-O-rutinoside and luteolin predicted to be stronger cholinesterase inhibitors compared to galantamine in an in silico study. Hence, L. nobilis and R. officinalis may be considered promising sources of nutraceuticals in the management of AD. Future research would consider in vivo studies on the neuroactive properties of the extracts and the potent cholinesterase inhibitors identified in silico.