Molecular Signaling Pathway Targeted Therapeutic Potential of Thymoquinone in Alzheimer’s disease

Evaluation of the Effects of Thymoquinone on RAGE/NOX4 Expressions and Brain Tissue Morphometry in Experimental Alzheimer's Disease Induced by Amyloid Beta 1-42 Peptide

The onset of Alzheimer's disease (AD) is attributed to widespread amyloid beta (Aβ) plaque accumulation, tau hyperphosphorylation, oxidative stress, and neuroinflammation. However, the underlying mechanism of AD remains unclear, and no curative treatment currently exists. The aim was to investigate the effect of thymoquinone by suppressing the RAGE/NOX4 pathway in AD. Mice (n = 60) were divided into five groups, and an experimental AD model induced by an Aβ1-42 peptide was established in two groups. We also administered 5 mg/kg thymoquinone (TMQ) to the mice for its properties to slow or treat neurodegeneration in AD. Behavioral tests for memory and emotional states, micro-computed tomography (Micro CT) to assess brain volume, ELISA to measure malondialdehyde (MDA) levels, hematoxylin and eosin staining (H&E) to evaluate neuronal degeneration were used. Immunohistochemical (IHC), Western blot (WB), and real-time polymerase chain reaction (PCR) methods were used to evaluate the inhibitory effect of TMQ on a receptor for advanced glycation end products (RAGE)/nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4) signaling in AD. The results showed that TMQ may have ameliorative effects on memory, spatial learning, learning ability, and anxiety in AD. We showed that TMQ has an antioxidative effect by decreasing MDA levels by the ELSIA method (p < 0.05). There was a marked increase in neuronal degeneration in AD mice compared to other groups (p < 0.05). We concluded that TMQ could ameliorate neuronal degeneration in AD by H&E staining and suppress RAGE/NOX4 signaling by IHC and WB analysis. We concluded that TMQ could be therapeutic in AD by reducing AB expression level by IHC analysis (p < 0.05). Real-time PCR analysis showed that APP (p < 0.05), RAGE, and NOX4 (p < 0.05) gene expressions could be reduced by TMQ. In conclusion, TMQ has a high therapeutic potential in AD and an effective preventive and therapeutic strategy can be developed with more comprehensive studies on TMQ.

A Comprehensive Review of the Antioxidant, Antimicrobial, and Therapeutic Efficacies of Black Cumin (Nigella sativa L.) Seed Oil and Its Thymoquinone

Black cumin (Nigella sativa L.) (family Ranunculaceae) is a largely utilized therapeutic herb worldwide. This comprehensive review discusses the pharmacological benefits of black cumin seed oil, focusing on its bioactive component thymoquinone (TQ). The review is structured as follows: First, we examine the antimicrobial properties of black cumin oil, followed by an analysis of its antioxidant capabilities. Finally, we explore its therapeutic potential, particularly in neurodegenerative diseases and COVID-19. Phytochemicals from N. sativa have exhibited potential for developing novel preventive and therapeutic strategies against jaundice, gastrointestinal disorders, skin diseases, anorexia, conjunctivitis, dyspepsia, intrinsic hemorrhage, amenorrhea, paralysis, anorexia, rheumatism, diabetes, hypertension, fever, influenza, eczema, asthma, cough, bronchitis, and headache. The broader spectrum of application for N. sativa and its essential bioactives have certainly enhanced the commercial value of this seed oil. TQ, a major constituent of black cumin seed oil, has numerous beneficial properties. Researchers have extensively studied black cumin seed oil and its major component, TQ. These studies have revealed a wide range of pharmacological properties, including anticancer, immunomodulatory, analgesic, antimicrobial, antidiabetic, and anti-inflammatory effects. Additionally, TQ has shown neuroprotective, spasmolytic, bronchodilatory, hepatoprotective, renoprotective, gastroprotective, and antioxidant activities.

Behavioral and histological study on the neuroprotective effect of thymoquinone on the cerebellum in AlCl3-induced neurotoxicity in rats through modulation of oxidative stress, apoptosis, and autophagy

Alzheimer disease (AD) is a neurodegenerative condition. Thymoquinone (TQ) is a natural compound that possesses beneficial biological effects on the brain. The present study evaluates the protective impact of TQ on the cerebellum in rats with AlCl3-induced Alzheimer's disease. Four groups were utilized. Control: 20 rats that were subdivided into two subgroups. Ia: received distilled water for 4 weeks. Ib: received corn oil via oral gavage (1 ml/kg daily) for 4 weeks. TQ group: 10 rats received TQ in corn oil via oral gavage (20 mg/kg daily) for 4 weeks. AD group:10 rats received AlCl3 in distilled water via oral gavage (300 mg/kg daily) for 4 weeks. AD & TQ group: 10 rats received both AlCl3 & TQ for 4 weeks. The grip period in the rotarod test decreased, escape latency in first three days and the entry latency period to the quadrant with the removed escape platform in the Morris water maze test increased in AD group, but when TQ was administered concurrently, there was a noteworthy improvement. Meanwhile, when compared to AD group, the addition of TQ showed a significant decrease (P < 0.05) in levels of malondialdehyde (MDA) and nitric oxide (NO), associated with a significant increase (P < 0.05) in reduced glutathione (GSH) level. Furthermore, AD & TQ group exhibited substantial preservation of the cerebellum's histological structure, the Purkinje cells number and transverse diameter showed a high significant increase (P < 0.001) and a significant increase (P < 0.05), respectively in comparison to the AD group. Using TQ showed improvement in behavioral tests, biochemical and histological findings. Thus, TQ might have therapeutic effects on Alzheimer's disease.

Evaluating the Protective Effects of Thymoquinone on Methamphetamine-induced Toxicity in an In Vitro Model Based on Differentiated PC12 Cells

Methamphetamine (Meth) is a highly addictive stimulant. Its potential neurotoxic effects are mediated through various mechanisms, including oxidative stress and the initiation of the apoptotic process. Thymoquinone (TQ), obtained from Nigella sativa seed oil, has extensive antioxidant and anti-apoptotic properties. This study aimed to investigate the potential protective effects of TQ against Meth-induced toxicity by using an in vitro model based on nerve growth factor-differentiated PC12 cells. Cell differentiation was assessed by detecting the presence of a neuronal marker with flow cytometry. The effects of Meth exposure were evaluated in the in vitro neuronal cell-based model via the determination of cell viability (in an MTT assay) and apoptosis (by annexin/propidium iodide staining). The generation of reactive oxygen species (ROS), as well as the levels of glutathione (GSH) and dopamine, were also determined. The model was used to determine the protective effects of 0.5, 1 and 2 μM TQ against Meth-induced toxicity (at 1 mM). The results showed that TQ reduced Meth-induced neurotoxicity, possibly through the inhibition of ROS generation and apoptosis, and by helping to maintain GSH and dopamine levels. Thus, the impact of TQ treatment on Meth-induced neurotoxicity could warrant further investigation.

Anti-Neuroinflammatory Potential of Natural Products in the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is an age-related chronic progressive neurodegenerative disease, which is the main cause of dementia in the elderly. Much evidence shows that the onset and late symptoms of AD are caused by multiple factors. Among them, aging is the main factor in the pathogenesis of AD, and the most important risk factor for AD is neuroinflammation. So far, there is no cure for AD, but the relationship between neuroinflammation and AD may provide a new strategy for the treatment of AD. We herein discussed the main etiology hypothesis of AD and the role of neuroinflammation in AD, as well as anti-inflammatory natural products with the potential to prevent and alleviate AD symptoms, including alkaloids, steroids, terpenoids, flavonoids and polyphenols, which are available with great potential for the development of anti-AD drugs.

From kitchen to clinic: Pharmacotherapeutic potential of common spices in Indian cooking in age-related neurological disorders

Aging is described as an advanced time-related collection of changes that may negatively affect with the risk of several diseases or death. Aging is a main factor of several age-related neurological disorders, including neurodegenerative diseases (Alzheimer’s disease, Parkinson’s disease, and dementia), stroke, neuroinflammation, neurotoxicity, brain tumors, oxidative stress, and reactive oxygen species (ROS). Currently available medications for age-related neurological disorders may lead to several side effects, such as headache, diarrhea, nausea, gastrointestinal (GI) diseases, dyskinesia, and hallucinosis. These days, studies on plant efficacy in traditional medicine are being conducted because herbal medicine is affordable, safe, and culturally acceptable and easily accessible. The Indian traditional medicine system called Ayurveda uses several herbs and medicinal plants to treat various disorders including neurological disorders. This review aims to summarize the data on the neuroprotective potential of the following common Indian spices widely used in Ayurveda: cumin (Cuminum cyminum (L.), Apiaceae), black cumin (Nigella sativa (L.), Ranunculaceae), black pepper (Piper nigrum (L.), Piperaceae), curry leaf tree (Murraya koenigii (L.), Spreng Rutaceae), fenugreek (Trigonella foenum-graecum (L.), Fabaceae), fennel (Foeniculum vulgare Mill, Apiaceae), cardamom (Elettaria cardamomum (L.) Maton, Zingiberaceae), cloves (Syzygium aromaticum (L.) Merr. & L.M.Perry, Myrtaceae), and coriander (Coriandrum sativum (L.), Apiaceae) in age-related neurological disorders.