Reduction of Lewy Body Pathology by Oral Cinnamon

Cinnamon and cognitive function: a systematic review of preclinical and clinical studies

Cinnamon is the inner bark of trees named Cinnamomum. Studies have shown that cinnamon and its bioactive compounds can influence brain function and affect behavioral characteristics. This study aimed to systematically review studies about the relationship between cinnamon and its key components in memory and learning. Two thousand six hundred five studies were collected from different databases (PubMed, Scopus, Google Scholar, and Web of Science) in September 2021 and went under investigation for eligibility. As a result, 40 studies met our criteria and were included in this systematic review. Among the included studies, 33 were In vivo studies, five were In vitro, and two clinical studies were also accomplished. The main outcome of most studies (n = 40) proved that cinnamon significantly improves cognitive function (memory and learning). In vivo studies showed that using cinnamon or its components, such as eugenol, cinnamaldehyde, and cinnamic acid, could positively alter cognitive function. In vitro studies also showed that adding cinnamon or cinnamaldehyde to a cell medium can reduce tau aggregation, Amyloid β and increase cell viability. For clinical studies, one study showed positive effects, and another reported no changes in cognitive function. Most studies reported that cinnamon might be useful for preventing and reducing cognitive function impairment. It can be used as an adjuvant in the treatment of related diseases. However, more studies need to be done on this subject.

Analysis of bioactive compounds in cinnamon leaves and preparation of nanoemulsion and byproducts for improving Parkinson's disease in rats

Introduction

Cinnamomum osmophloeum Kanehira (C. osmophloeum), a broad-leaved tree species of Taiwan, contains phenolic acids, flavonoids, and phenylpropanoids such as cinnamaldehyde and cinnamic acid in leaves. Many reports have shown that the cinnamon leaf extract possesses anti-inflammatory, hypoglycemic, hypolipidemic and neuroprotective functions. This study aims to analyze bioactive compounds in C. osmophloeum (cinnamon leaves) by UPLC-MS/MS and prepare hydrosol, cinnamon leaf extract and cinnamon leaf nanoemulsion for comparison in improving Parkinson's disease (PD) in rats.

Methods

After extraction and determination of total phenolic and total flavonoid contents, cinnamaldehyde and the other bioactive compounds were analyzed in cinnamon leaves and hydrosol by UPLC-MS/MS. Cinnamon leaf nanoemulsion was prepared by mixing a suitable proportion of cinnamon leaf extract, soybean oil, lecithin, Tween 80 and deionized water, followed by characterization of particle size and polydispersity index by dynamic light scattering analyzer, particle size and shape by transmission electron microscope, encapsulation efficiency, as well as storage and heating stability. Fifty-six male Sprague-Dawley rats aged 8 weeks were divided into seven groups with group 1 as control (sunflower oil) and group 2 as induction (2 mg/kg bw rotenone in sunflower oil plus 10 mL/kg bw saline), while the other groups including rotenone injection (2 mg/kg bw) followed by high-dose of 60 mg/kg bw (group 3) or low-dose of 20 mg/kg bw (group 4) for tube feeding of cinnamon leaf extract or cinnamon leaf nanoemulsion at the same doses (groups 5 and 6) every day for 5 weeks as well as group 7 with rotenone plus hydrosol containing 0.5 g cinnamon leaf powder at a dose of 10 mL/kg bw. Biochemical analysis of brain tissue (striatum and midbrain) was done to determine dopamine, α-synuclein, tyrosine hydroxylase, superoxide dismutase, catalase, glutathione peroxidase and malondialdehyde contents by using commercial kits, while catalepsy performed by bar test.

Results and discussion

An extraction solvent of 80% ethanol was found to be the most optimal with a high yield of 15 bioactive compounds being obtained following UPLC analysis. A triple quadrupole tandem mass spectrometer with electrospray ionization mode was used for identification and quantitation, with cinnamaldehyde present at the highest amount (17985.2 µg/g). The cinnamon leaf nanoemulsion was successfully prepared with the mean particle size, zeta potential, polydispersity index and encapsulation efficiency being 30.1 nm, -43.1 mV, 0.149 and 91.6%, respectively. A high stability of cinnamon leaf nanoemulsion was shown over a 90-day storage period at 4 and heating at 100 for 2 h. Animal experiments revealed that the treatments of cinnamon leaf extract, nanoemulsion and hydrosol increased the dopamine contents from 17.08% to 49.39% and tyrosine hydroxylase levels from 17.07% to 25.59%, while reduced the α-synuclein levels from 17.56% to 15.95% in the striatum of rats. Additionally, in the midbrain of rats, an elevation of activities of superoxide dismutase (6.69-16.82%), catalase (8.56-16.94%), and glutathione peroxidase (2.09-16.94%) was shown, while the malondialdehyde content declined by 15.47-22.47%. Comparatively, the high-dose nanoemulsion exerted the most pronounced effect in improving PD in rats and may be a promising candidate for the development of health food or botanic drug.

Activation of PPARα Exhibits Therapeutic Efficacy in a Mouse Model of Juvenile Neuronal Ceroid Lipofuscinosis

Juvenile neuronal ceroid lipofuscinosis (JNCL) is a fatal inherited neurodegenerative disease of children that occurs because of defective function of the lysosomal membrane glycoprotein CLN3. JNCL features glial activation and accumulation of autofluorescent storage material containing subunit c of mitochondrial ATP synthase (SCMAS), ultimately resulting into neuronal loss. Until now, no effective therapy is available for JNCL. This study underlines the possible therapeutic importance of gemfibrozil, an activator of peroxisome proliferator-activated receptor α (PPARα) and a lipid-lowering drug approved by the Food and Drug Administration in an animal model of JNCL. Oral gemfibrozil treatment reduced microglial and astroglial activation, attenuated neuroinflammation, restored the level of transcription factor EB (TFEB; the master regulator of lysosomal biogenesis), and decreased the accumulation of storage material SCMAS in somatosensory barrel field (SBF) cortex of Cln3Δex7/8 (Cln3ΔJNCL) mice of both sexes. Accordingly, gemfibrozil treatment also improved locomotor activities of Cln3ΔJNCL mice. While investigating the mechanism, we found marked loss of PPARα in the SBF cortex of Cln3ΔJNCL mice, which increased after gemfibrozil treatment. Oral gemfibrozil also stimulated the recruitment of PPARα to the Tfeb gene promoter in vivo in the SBF cortex of Cln3ΔJNCL mice, indicating increased transcription of Tfeb in the CNS by gemfibrozil treatment via PPARα. Moreover, disease pathologies aggravated in Cln3ΔJNCL mice lacking PPARα (Cln3ΔJNCLΔPPARα) and gemfibrozil remained unable to decrease SCMAS accumulation, reduce glial activation, and improve locomotor performance of Cln3ΔJNCLΔPPARα mice. These results suggest that activation of PPARα may be beneficial for JNCL and that gemfibrozil may be repurposed for the treatment of this incurable disease.SIGNIFICANCE STATEMENT Despite intense investigations, no effective therapy is available for JNCL, an incurable inherited lysosomal storage disorder. Here, we delineate that oral administration of gemfibrozil, a lipid-lowering drug, decreases glial inflammation, normalizes and/or upregulates TFEB, and reduces accumulation of autofluorescent storage material in SBF cortex to improve locomotor activities in Cln3Δex7/8 (Cln3ΔJNCL) mice. Aggravation of disease pathology in Cln3ΔJNCL mice lacking PPARα (Cln3ΔJNCLΔPPARα) and inability of gemfibrozil to decrease SCMAS accumulation, reduce glial activation, and improve locomotor performance of Cln3ΔJNCLΔPPARα mice delineates an important role of PPARα in this process. These studies highlight a new property of gemfibrozil and indicate its possible therapeutic use in JNCL patients.

Treadmill workout activates PPARα in the hippocampus to upregulate ADAM10, decrease plaques and improve cognitive functions in 5XFAD mouse model of Alzheimer's disease

Although liver is rich in peroxisome proliferator-activated receptor α (PPARα), recently we have described the presence of PPARα in hippocampus where it is involved in non-amyloidogenic metabolism of amyloid precursor protein (APP) via ADAM10, decreasing amyloid plaques and improving memory and learning. However, mechanisms to upregulate PPARα in vivo in the hippocampus are poorly understood. Regular exercise has multiple beneficial effects on human health and here, we describe the importance of regular mild treadmill exercise in upregulating PPARα in vivo in the hippocampus of 5XFAD mouse model of Alzheimer's disease. We also demonstrate that treadmill exercise remained unable to stimulate ADAM10, reduce plaque pathology and improve cognitive functions in 5XFADΔPPARα mice (5XFAD mice lacking PPARα). On the other hand, treadmill workout increased ADAM10, decreased plaque pathology and protected memory and learning in 5XFADΔPPARβ mice (5XFAD mice lacking PPARβ). Moreover, the other PPAR (PPARγ) also did not play any role in the transcription of ADAM10 in vivo in the hippocampus of treadmill exercised 5XFAD mice. These results underline an important role of PPARα in which treadmill exercise remains unable to exhibit neuroprotection in the hippocampus in the absence of PPARα.

Cinnamomum verum J. Presl Bark Contains High Contents of Nicotinamide Mononucleotide

The global population is aging, and intervention strategies for anti-aging and the prevention of aging-related diseases have become a topic actively explored today. Nicotinamide adenine dinucleotide (NAD⁺) is an important molecule in the metabolic process, and its content in tissues and cells decreases with age. The supplementation of nicotinamide mononucleotide (NMN), an important intermediate and precursor of NAD⁺, has increased NAD⁺ levels, and its safety has been demonstrated in rodents and human studies. However, the high content of NMN in natural plants has not been fully explored as herbal medicines for drug development. Here, we identified that the leaf of Cinnamomum verum J. Presl (C. verum) was the highest NMN content among the Plant Extract Library (PEL) with food experience, using ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS). To validate this result, the extraction and quantitative analysis of bark, leaf, root, and stem of fresh C. verum was conducted. The results revealed that the bark had the highest NMN content in C. verum (0.471 mg/100 g). Our study shed light on the prospects of developing natural plants in the context of NMN as drugs for anti-aging and prevention of aging-related diseases. The future should focus on the development and application of C. verum pharmaceutical formulations.

Treadmill exercise reduces α-synuclein spreading via PPARα

This study underlines the importance of treadmill exercise in reducing α-synuclein (α-syn) spreading in the A53T brain and protecting nigral dopaminergic neurons. Preformed α-syn fibril (PFF) seeding in the internal capsule of young A53T α-syn mice leads to increased spreading of α-syn to substantia nigra and motor cortex and concomitant loss of nigral dopaminergic neurons. However, regular treadmill exercise decreases α-syn spreading in the brain and protects nigral dopaminergic neurons in PFF-seeded mice. Accordingly, treadmill exercise also mitigates α-synucleinopathy in aged A53T mice. While investigating this mechanism, we have observed that treadmill exercise induces the activation of peroxisome proliferator-activated receptor α (PPARα) in the brain to stimulate lysosomal biogenesis via TFEB. Accordingly, treadmill exercise remains unable to stimulate TFEB and reduce α-synucleinopathy in A53T mice lacking PPARα, and fenofibrate, a prototype PPARα agonist, reduces α-synucleinopathy. These results delineate a beneficial function of treadmill exercise in reducing α-syn spreading in the brain via PPARα.

Dutta et al. demonstrate that regular treadmill exercise is capable of decreasing α-synuclein spreading in the brain and protecting nigral dopaminergic neurons in mice. However, treadmill running does not reduce α-synucleinopathy in mice lacking peroxisome proliferator-activated receptor α (PPARα), highlighting a role of PPARα in the beneficial effect of treadmill running.

Protection of dopaminergic neurons in hemiparkinsonian monkeys by flavouring ingredient glyceryl tribenzoate

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease and this study underlines the significance of a small molecule glyceryl tribenzoate (GTB), a FDA approved food additive, in preventing parkinsonian pathologies in MPTP-induced animal models. The study conducted in MPTP-induced mice demonstrated dose-dependent protection of nigral tyrosine hydroxylase (TH) and striatal dopamine level by GTB oral treatment and the optimum dose was found to be 50 mg/kg/d. In the next phase, the study was carried out in MPTP-injected hemiparkinsonian monkeys, which recapitulate better clinical parkinsonian syndromes. GTB inhibited MPTP-driven induction of glial inflammation, which was evidenced by reduced level of GTP-p21Ras and phospho-p65 in SN of monkeys. It led to decreased expression of inflammatory markers such as IL-1β and iNOS. Simultaneously, GTB oral treatment protected nigral TH cells, striatal dopamine, and improved motor behaviour of hemiparkinsonian monkeys. Presence of sodium benzoate, a GTB metabolite and a FDA-approved drug for urea cycle disorders and glycine encephalopathy, in the brain suggests that the neuroprotective effect imparted by GTB might be mediated by sodium benzoate. Although the mechanism of action of GTB is poorly understood, the study sheds light on the therapeutic possibility of a food additive GTB in PD.

Sodium Benzoate, a Metabolite of Cinnamon and a Food Additive, Improves Cognitive Functions in Mice after Controlled Cortical Impact Injury

Traumatic brain injury (TBI) is a major health concern, sometimes leading to long-term neurological disability, especially in children, young adults and war veterans. Although research investigators and clinicians have applied different treatment strategies or neurosurgical procedures to solve this health issue, we are still in need of an effective therapy to halt the pathogenesis of brain injury. Earlier, we reported that sodium benzoate (NaB), a metabolite of cinnamon and a Food and Drug Administration-approved drug against urea cycle disorders and glycine encephalopathy, protects neurons in animal models of Parkinson's disease and Alzheimer's disease. This study was undertaken to examine the therapeutic efficacy of NaB in a controlled cortical impact (CCI)-induced preclinical mouse model of TBI. Oral treatment with NaB, but not sodium formate (NaFO), was found to decrease the activation of microglia and astrocytes and to inhibit the expression of inducible nitric oxide synthase (iNOS) in the hippocampus and cortex of CCI-insulted mice. Further, administration of NaB also reduced the vascular damage and decreased the size of the lesion cavity in the brain of CCI-induced mice. Importantly, NaB-treated mice showed significant improvements in memory and locomotor functions as well as displaying a substantial reduction in depression-like behaviors. These results delineate a novel neuroprotective property of NaB, highlighting its possible therapeutic importance in TBI.

Glyceryl tribenzoate: A food additive with unique properties to be a substitute for cinnamon

Cinnamon is a regularly used natural seasoning and flavoring material throughout the world for eras. Recent laboratory studies have demonstrated that oral cinnamon may be beneficial for different neuroinflammatory and neurodegenerative disorders such as multiple sclerosis (MS), Parkinson's disease (PD), Alzheimer's disease (AD), and Lewy body diseases (LBD). However, cinnamon's certain limitations (e.g. unavailability of true Ceylon cinnamon throughout the world, impurities in ground cinnamon, etc.) have initiated an interest among researchers to find an alternate of cinnamon that can potentially deliver the same efficacy in the diseases mentioned above. Glyceryl tribenzoate (GTB) is a U.S. Food and Drug Administration (FDA)-approved flavoring ingredient that is used in food and food packaging industries. It has been found that similar to cinnamon, oral GTB is capable of upregulating regulatory T cells and suppressing the autoimmune disease process of experimental autoimmune encephalomyelitis, an animal model of MS. Moreover, both GTB and cinnamon metabolite sodium benzoate (NaB) have the potency to attenuate neurodegenerative pathology in a mouse model of Huntington disease (HD). Here, we have also demonstrated anti-inflammatory property of GTB in astrocytes and macrophages, a property that is also seen with cinnamon and its metabolite sodium benzoate (NaB). Therefore, here, we have made a sincere attempt to discuss the similarities and dissimilarities between cinnamon and GTB with a focus whether GTB has the potential to be considered as a substitute of cinnamon for neuroinflammatory and neurodegenerative disorders.

Alleviation of Huntington pathology in mice by oral administration of food additive glyceryl tribenzoate

Huntington's disease (HD) is a neurodegenerative disorder characterized by accumulation of mutant huntingtin protein and significant loss of neurons in striatum and cortex. Along with motor difficulties, the HD patients also manifest anxiety and loss of cognition. Unfortunately, the clinically approved drugs only offer symptomatic relief and are not free from side effects. This study underlines the importance of glyceryl tribenzoate (GTB), an FDA-approved food flavoring ingredient, in alleviating HD pathology in transgenic N171-82Q mouse model. Oral administration of GTB significantly reduced mutant huntingtin level in striatum, motor cortex as well as hippocampus and increased the integrity of viable neurons. Furthermore, we found the presence of sodium benzoate (NaB), a FDA-approved drug for urea cycle disorders and glycine encephalopathy, in the brain of GTB-fed HD mice. Accordingly, NaB administration also markedly decreased huntingtin level in striatum and cortex. Glial activation is found to coincide with neuronal death in affected regions of HD brains. Interestingly, both GTB and NaB treatment suppressed activation of glial cells and inflammation in the brain. Finally, neuroprotective effect of GTB and NaB resulted in improved motor performance of HD mice. Collectively, these results suggest that GTB and NaB may be repurposed for HD.