Neuroprotective Effects of Tetrahydrocurcumin against Glutamate-Induced Oxidative Stress in Hippocampal HT22 Cells

Ethyl Acetate Fraction of Chestnut Honey Attenuates Scopolamine-Induced Cognitive Impairment in Mice and Glutamate-Induced Neurotoxicity in HT22 Cells

Chestnut honey has various benefits, such as antioxidative, anti-inflammatory, immunomodulatory, antibacterial, and antiviral effects. However, the effects of chestnut honey or the ethyl acetate fraction of chestnut honey (EACH) on neurodegenerative diseases and their related cognitive impairment and neurotoxicity have not yet been established. Therefore, in this study, we investigated the mitigating effect of the EACH on scopolamine (SCO)-injected cognitive decline in mice and glutamate-exposed neurotoxicity in HT22 cells. EACH administration significantly reversed SCO-induced cognitive decline in mice, as demonstrated through the Morris water maze and passive avoidance tests. The EACH treatment showed a significant alleviation effect by recovering more than 80% of the cell viability decrease induced by glutamate exposure in the HT22 neuronal cell model. Furthermore, the EACH significantly reduced reactive oxygen species accumulation, lactate dehydrogenase release, mitochondrial depolarization, and neuronal apoptosis. The EACH regulated the level of apoptosis-related proteins, induced the nuclear translocation of nuclear factor-E2-related factor 2 (Nrf-2) and the expression of related antioxidant proteins, and induced the phosphorylation of tropomyosin-related kinase receptor B (TrkB)/cAMP-calcium response element-binding protein (CREB) and the expression of brain-derived neurotrophic factor. These data indicate that the EACH can prevent neurons from oxidative damage and improve cognitive dysfunction by activating Nrf-2 and TrkB/CREB signaling pathways. Therefore, the EACH demonstrates potential therapeutic value in mitigating oxidative stress-induced neurotoxicity, cognitive decline, and related neurodegenerative diseases.

The role of tetrahydrocurcumin in disease prevention and treatment

In recent decades, natural compounds derived from herbal medicine or dietary sources have played important roles in prevention and treatment of various diseases and have attracted more and more attention. Curcumin, extracted from the Curcumae Longae Rhizoma and widely used as food spice and coloring agent, has been proven to possess high pharmacological value. However, the pharmacological application of curcumin is limited due to its poor systemic bioavailability. As a major active metabolite of curcumin, tetrahydrocurcumin (THC) has higher bioavailability and stability than curcumin. Increasing evidence confirmed that THC had a wide range of biological activities and significant treatment effects on diseases. In this paper, we reviewed the research progress on the biological activities and therapeutic potential of THC on different diseases such as neurological disorders, metabolic syndromes, cancers, and inflammatory diseases. The extensive pharmacological effects of THC involve the modulation of various signaling transduction pathways including MAPK, JAK/STAT, NF-κB, Nrf2, PI3K/Akt/mTOR, AMPK, Wnt/β-catenin. In addition, the pharmacokinetics, drug combination and toxicology of THC were discussed, thus providing scientific basis for the safe application of THC and the development of its dietary supplements and drugs.

Farrerol attenuates glutamate-induced apoptosis in HT22 cells via the Nrf2/heme oxygenase-1 pathway

Farrerol is a flavonoid found in plants with a wide range of pharmacological effects, including protection and enhancement of nerve cell function, as well as antioxidant and antibacterial properties, among others. Neurodegenerative diseases are irreversible neurological disorders resulting from the loss of neuronal cells in the brain and spinal cord. In this experiment, we investigated the neuroprotective and antioxidant effects of farrerol on glutamate-induced HT22 cells. Our results showed that farrerol inhibited reactive oxygen species expression, apoptosis, mitochondrial damage, and the activation of caspases 3 and 9 in HT22 cells induced by glutamate. Additionally, farrerol potentially regulated the Nrf2/heme oxygenase-1 (HO-1) signaling pathway, as it attenuated the nuclear translocation of Nrf2 and promoted the expression of HO-1. These findings suggest that farrerol has potential as a new therapeutic option.

Positive Tetrahydrocurcumin-Associated Brain-Related Metabolomic Implications

Tetrahydrocurcumin (THC) is a metabolite of curcumin (CUR). It shares many of CUR's beneficial biological activities in addition to being more water-soluble, chemically stable, and bioavailable compared to CUR. However, its mechanisms of action have not been fully elucidated. This paper addresses the preventive role of THC on various brain dysfunctions as well as its effects on brain redox processes, traumatic brain injury, ischemia-reperfusion injury, Alzheimer's disease, and Parkinson's disease in various animal or cell culture models. In addition to its strong antioxidant properties, the effects of THC on the reduction of amyloid β aggregates are also well documented. The therapeutic potential of THC to treat patterns of mitochondrial brain dysmorphic dysfunction is also addressed and thoroughly reviewed, as is evidence from experimental studies about the mechanism of mitochondrial failure during cerebral ischemia/reperfusion injury. THC treatment also results in a dose-dependent decrease in ERK-mediated phosphorylation of GRASP65, which prevents further compartmentalization of the Golgi apparatus. The PI3K/AKT signaling pathway is possibly the most involved mechanism in the anti-apoptotic effect of THC. Overall, studies in various animal models of different brain disorders suggest that THC can be used as a dietary supplement to protect against traumatic brain injury and even improve brain function in Alzheimer's and Parkinson's diseases. We suggest further preclinical studies be conducted to demonstrate the brain-protective, anti-amyloid, and anti-Parkinson effects of THC. Application of the methods used in the currently reviewed studies would be useful and should help define doses and methods of THC administration in different disease conditions.

Novel pyrrolidine-aminophenyl-1,4-naphthoquinones: structure-related mechanisms of leukemia cell death

Novel derivatives of aminophenyl-1,4-naphthoquinones, in which a pyrrolidine group was added to the naphthoquinone ring, were synthesized and investigated for the mechanisms of leukemic cell killing. The novel compounds, TW-85 and TW-96, differ in the functional (methyl or hydroxyl) group at the para-position of the aminophenyl moiety. TW-85 and TW-96 were found to induce concentration- and time-dependent apoptotic and/or necrotic cell death in human U937 promonocytic leukemia cells but only TW-96 could also kill K562 chronic myeloid leukemia cells and CCRF-CEM lymphoblastic leukemia cells. Normal peripheral blood mononuclear cells were noticeably less responsive to both compounds than leukemia cells. At low micromolar concentrations used, TW-85 killed U937 cells mainly by inducing apoptosis. TW-96 was a weaker apoptotic agent in U937 cells but proved to be cytotoxic and a stronger inducer of necrosis in all three leukemic cell lines tested. Both compounds induced mitochondrial permeability transition pore opening, cytochrome c release, and caspase activation in U937 cells. Cytotoxicity induced by TW-96, but not by TW-85, was associated with the elevation of the cytosolic levels of reactive oxygen species (ROS). The latter was attenuated by diphenyleneiodonium, indicating that NADPH oxidase was likely to be the source of ROS generation. Activation of p38 MAPK by the two agents appeared to prevent necrosis but differentially affected apoptotic cell death in U937 cells. These results further expand our understanding of the structure-activity relationship of aminophenyl-1,4-naphthoquinones as potential anti-leukemic agents with distinct modes of action.

Selaginella tamariscina Inhibits Glutamate-Induced Autophagic Cell Death by Activating the PI3K/AKT/mTOR Signaling Pathways

Glutamate-induced neural toxicity in autophagic neuron death is partially mediated by increased oxidative stress. Therefore, reducing oxidative stress in the brain is critical for treating or preventing neurodegenerative diseases. Selaginella tamariscina is a traditional medicinal plant for treating gastrointestinal bleeding, hematuria, leucorrhea, inflammation, chronic hepatitis, gout, and hyperuricemia. We investigate the inhibitory effects of Selaginella tamariscina ethanol extract (STE) on neurotoxicity and autophagic cell death in glutamate-exposed HT22 mouse hippocampal cells. STE significantly increased cell viability and mitochondrial membrane potential and decreased the expression of reactive oxygen species, lactate dehydrogenase release, and cell apoptosis in glutamate-exposed HT22 cells. In addition, while glutamate induced the excessive activation of mitophagy, STE attenuated glutamate-induced light chain (LC) 3 II and Beclin-1 expression and increased p62 expression. Furthermore, STE strongly enhanced the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) phosphorylation activation. STE strongly inhibited glutamate-induced autophagy by activating the PI3K/Akt/mTOR signaling pathway. In contrast, the addition of LY294002, a PI3K/Akt inhibitor, remarkably suppressed cell viability and p-Akt and p62 expression, while markedly increasing the expression of LC3 II and Beclin-1. Our findings indicate that autophagy inhibition by activating PI3K/Akt/mTOR phosphorylation levels could be responsible for the neuroprotective effects of STE on glutamate neuronal damage.

Tetrahydrocurcumin improves lipopolysaccharide-induced myocardial dysfunction by inhibiting oxidative stress and inflammation via JNK/ERK signaling pathway regulation

BACKGROUND

Acute myocardial dysfunction in patients with sepsis is attributed to oxidative stress, inflammation, and cardiomyocyte loss; however, specific drugs for its prevention are still lacking. Tetrahydrocurcumin (THC) has been proven to contribute to the prevention of various cardiovascular diseases by decreasing oxidative stress and inflammation. This study was performed to investigate the functions and mechanism of action of THC in septic cardiomyopathy.

METHODS

After the oral administration of THC (120 mg/kg) for 5 consecutive days, a mouse model of sepsis was established via intraperitoneal lipopolysaccharide (LPS, 10 mg/kg) injection. Following this, cardiac function was assessed, pathological section staining was performed, and inflammatory markers were detected.

RESULTS

Myocardial systolic function was severely compromised in parallel with the accumulation of reactive oxygen species and enhanced cardiomyocyte apoptosis in mice with sepsis. These adverse changes were markedly reversed in response to THC treatment in septic mice as well as in LPS-treated H9c2 cells. Mechanistically, THC inhibited the release of pro-inflammatory cytokines, including tumor necrosis factor alpha, interleukin (IL)-1β, and IL-6, by upregulating mitogen-activated protein kinase phosphatase 1, to block the phosphorylation of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated protein kinase (ERK). Additionally, THC enhanced the levels of antioxidant proteins, including nuclear factor-erythroid 2-related factor 2, superoxide dismutase 2, and NAD(P)H quinone oxidoreductase 1, while decreasing gp91^phox expression. Furthermore, upon THC treatment, Bcl-2 expression was significantly increased, along with a decline in Bax and cleaved caspase-3 expression, which reduced cardiomyocyte loss.

CONCLUSION

Our findings indicate that THC exhibited protective potential against septic cardiomyopathy by reducing oxidative stress and inflammation through the regulation of JNK/ERK signaling. The findings of this study provide a basis for the further evaluation of THC as a therapeutic agent against septic cardiomyopathy.

Six new polyoxygenated xanthones from Garcinia cowa and their neuroprotective effects on glutamate-mediated hippocampal neuronal HT22 cell death

Six new polyoxygenated xanthones, garcicowanones F-H (1-3), norcowanol A-B (4-5), and garcinone F (6) along with twelve known compounds 7-18 were obtained from the latex of Garcinia cowa Roxb. ex Choisy. All new compounds have a 1,3,7-trioxygenated or 1,3,6,7-tetraoxygenated xanthone nucleus and differ from majority of xanthones from G. cowa by hydrated side chains. Compounds 1, 7, 8 and 18 exhibited significant neuroprotective effects on glutamate-mediated hippocampal neuronal HT22 cell death. In particular, compound 1 exhibited the most potent neuroprotective effect with >80% cell viability in the concentration range of 2.9-115 µM. Further studies on compound 1 showed that it decreased cellular Ca2+ influx and inhibits cellular reactive oxygen species generation in HT22 cells. A Western blot analysis showed that MAPK phosphorylation, Bax, and AIF translocation dramatically increased upon treatment with 5 mM glutamate and decreased upon a co-treatment with compound 1.

Therapeutic implications and clinical manifestations of thymoquinone

Thymoquinone (TQ), a natural phytochemical predominantly found in Nigella sativa, has been investigated for its numerous health benefits. TQ showed anti-cancer, anti-oxidant, and anti-inflammatory properties, validated in various disease models. The anti-cancer potential of TQ is goverened by anti-proliferation, cell cycle arrest, apoptosis induction, ROS production, anti-metastasis and anti-angiogenesis, inhibition of cell migration and invasion action. Additionally, TQ exhibited antitumor activity via the modulation of multiple pathways and molecular targets, including Akt, ERK1/2, STAT3, and NF-κB. The present review highlighted the anticancer potential of TQ . We summarize the anti-cancer, anti-oxidant, and anti-inflammatory properties of TQ, focusing on its molecular targets and its promising action in cancer therapy. We further described the molecular mechanisms by which TQ prevents signaling pathways that mediate cancer progression, invasion, and metastasis.

Explore the Multitarget Mechanism of Tetrahydrocurcumin preventing on UV-Induced Photoaging mouse skin

UV induced photoaging is the main external factor of skin aging. In this study, we tested the protective effects of tetrahydrocurcumin on UV-induced skin photoaging of KM mice and researched the multi-target mechanism through RNA sequencing technology. Mouse experiments show that tetrahydrocurcumin strongly changed in skin appearance, epidermal thickness, and wrinkle-related parameters in UV-irradiated mice. RNA-seq result show that we found 29 differentially expressed mRNA transcripts in UV mice relative to Ctrl rats (18 up-regulated and 11 down-regulated) and 7 significantly dysregulated mRNAs were obtained in the THC group compared to the UV group (1 up-regulated and 6 down-regulated), respectively. Spink7, Edn3, Stab2 may be the key target genes of tetrahydrocurcumin in preventing aging. Bioinformatics analysis shows that the response to muscle contraction and melanin biosynthetic GO term and Inflammation related pathway such as PPAR, MAPK would involve in effects of tetrahydrocurcumin. The results of this study indicated that tetrahydrocurcumin can improve the appearance through anti-inflammatory, improving extracellular matrix and inhibiting melanin production. It could be suggested as a protective measure in the prevention of UV-induced photoaging.

Curcumin can improve Parkinson's disease via activating BDNF/PI3k/Akt signaling pathways

Parkinson's disease is a common progressive neurodegenerative disease, and presently has no curative agent. Curcumin, as one of the natural polyphenols, has great potential in neurodegenerative diseases and other different pathological settings. The brain-derived neurotrophic factor (BDNF) and phosphatidylinositol 3 kinase (PI3k)/protein kinase B (Akt) signaling pathways are significantly involved nerve regeneration and anti-apoptotic activities. Currently, relevant studies have confirmed that curcumin has an optimistic impact on neuroprotection via regulating BDNF and PI3k/Akt signaling pathways in neurodegenerative disease. Here, we summarized the relationship between BDNF and PI3k/Akt signaling pathway, the main biological functions and neuroprotective effects of curcumin via activating BDNF and PI3k/Akt signaling pathways in Parkinson's disease. This paper illustrates that curcumin, as a neuroprotective agent, can delay the progression of Parkinson's disease by protecting nerve cells.

Biochemical, structural and physical changes in aging human skin, and their relationship

Skin is the largest organ of the human body, having the purpose of regulating temperature, protecting us from microbes or mechanical shocks, and allowing the sensations from touch. It is generally accepted that aging induces profound changes in the skin's biochemical, structural and physical properties, which can lead to impaired biological functions and/or diverse diseases. So far, the effects of aging on these skin properties have been well documented. However, very few studies have focused exclusively on the relationship among these critical properties in the aging process, which is this review's primary focus. Many in vivo, ex vivo, and in vitro techniques have been previously used to characterize these properties of the skin. This review aims to provide a comprehensive overview on the effects of aging on the changes in biochemical, structural, and physical properties, and explore the potential mechanisms of skin with the relation between these properties. First, we review different or contradictory results of aging-related changes in representative parameters of each property, including the interpretations of the findings. Next, we discuss the need for a standardized method to characterize aging-related changes in these properties, to improve the way of defining age-property relationship. Moreover, potential mechanisms based on the previous results are explored by linking the biochemical, structural, and physical properties. Finally, the need to study changes of various functional properties in the separate skin layers is addressed. This review can help understand the underlying mechanism of aging-related alterations, to improve the evaluation of the aging process and guide effective treatment strategies for aging-related diseases.

Potential Role of Curcumin for the Treatment of Major Depressive Disorder

Curcumin is the major biologically active polyphenolic constituent in the turmeric plant (Curcuma longa) that has been shown to have antioxidant, anti-inflammatory, neuroprotective, anticancer, antimicrobial, and cardioprotective effects. Interest in curcumin as a treatment for mental health conditions has increased and there is an expanding body of preclinical and clinical research examining its antidepressant and anxiolytic effects. In this narrative review, human trials investigating the effects of curcumin for the treatment of depression or depressive symptoms are summarised. Using findings from in vitro, animal, and human trials, possible biological mechanisms associated with the antidepressant effects of curcumin are also explored. To increase the understanding of curcumin for the treatment of depression, directions for future research are proposed.

The potential role of dexmedetomidine on neuroprotection and its possible mechanisms: Evidence from in vitro and in vivo studies

Neurological disorders following brain injuries and neurodegeneration are on the rise worldwide and cause disability and suffering in patients. It is crucial to explore novel neuroprotectants. Dexmedetomidine, a selective α2-adrenoceptor agonist, is commonly used for anxiolysis, sedation and analgesia in clinical anaesthesia and critical care. Recent studies have shown that dexmedetomidine exerts protective effects on multiple organs. This review summarized and discussed the current neuroprotective effects of dexmedetomidine, as well as the underlying mechanisms. In preclinical studies, dexmedetomidine reduced neuronal injury and improved functional outcomes in several models, including hypoxia-induced neuronal injury, ischaemic-reperfusion injury, intracerebral haemorrhage, post-traumatic brain injury, anaesthetic-induced neuronal injury, substance-induced neuronal injury, neuroinflammation, epilepsy and neurodegeneration. Several mechanisms are associated with the neuroprotective function of dexmedetomidine, including neurotransmitter regulation, inflammatory response, oxidative stress, apoptotic pathway, autophagy, mitochondrial function and other cell signalling pathways. In summary, dexmedetomidine has the potential to be a novel neuroprotective agent for a wide range of neurological disorders.

Experimental and clinical reports on anti-inflammatory, antioxidant, and immunomodulatory effects of Curcuma longa and curcumin, an updated and comprehensive review

Curcuma longa (C. longa) or turmeric is a plant with a long history of use in traditional medicine, especially for treating inflammatory conditions C. longa and its main constituent, curcumin (CUR), showed various pharmacological effects such as antioxidant and anti-microbial properties. The updated knowledge of anti-inflammatory, antioxidant, and immunomodulatory effects of C. longa and CUR is provided in this review article. Pharmacological effects of C. longa, and CUR, including anti-inflammatory, antioxidant, and immunomodulatory properties, were searched using various databases and appropriate keywords until September 2020. Various studies showed anti-inflammatory effects of C. longa and CUR, including decreased white blood cell, neutrophil, and eosinophil numbers, and its protective effects on serum levels of inflammatory mediators such as phospholipase A2 and total protein in different inflammatory disorders. The antioxidant effects of C. longa and CUR were also reported in several studies. The plant extracts and CUR decreased malondialdehyde and nitric oxide levels but increased thiol, superoxide dismutase, and catalase levels in oxidative stress conditions. Treatment with C. longa and CUR also improved immunoglobulin E (Ig)E, pro-inflammatory cytokine interleukin 4 (IL)-4, transforming growth factor-beta, IL-17, interferon-gamma levels, and type 1/type 2 helper cells (Th1)/(Th2) ratio in conditions with disturbance in the immune system. Therefore C. longa and CUR showed anti-inflammatory, antioxidant, and immunomodulatory effects, indicating a potential therapeutic effect of the plant and its constituent, CUR, for treating of inflammatory, oxidative, and immune dysregulation disorders.

The Roles of Superoxide on At-Level Spinal Cord Injury Pain in Rats

Background: In the present study, we examined superoxide-mediated excitatory nociceptive transmission on at-level neuropathic pain following spinal thoracic 10 contusion injury (SCI) in male Sprague Dawley rats. Methods: Mechanical sensitivity at body trunk, neuronal firing activity, and expression of superoxide marker/ionotropic glutamate receptors (iGluRs)/CamKII were measured in the T7/8 dorsal horn, respectively. Results: Topical treatment of superoxide donor t-BOOH (0.4 mg/kg) increased neuronal firing rates and pCamKII expression in the naïve group, whereas superoxide scavenger Tempol (1 mg/kg) and non-specific ROS scavenger PBN (3 mg/kg) decreased firing rates in the SCI group (* p < 0.05). SCI showed increases of iGluRs-mediated neuronal firing rates and pCamKII expression (* p < 0.05); however, t-BOOH treatment did not show significant changes in the naïve group. The mechanical sensitivity at the body trunk in the SCI group (6.2 ± 0.5) was attenuated by CamKII inhibitor KN-93 (50 μg, 3.9 ± 0.4) or Tempol (1 mg, 4 ± 0.4) treatment (* p < 0.05). In addition, the level of superoxide marker Dhet showed significant increase in SCI rats compared to the sham group (11.7 ± 1.7 vs. 6.6 ± 1.5, * p < 0.05). Conclusions: Superoxide and the pCamKII pathway contribute to chronic at-level neuropathic pain without involvement of iGluRs following SCI.

1-Methoxylespeflorin G11 Protects HT22 Cells from Glutamate-Induced Cell Death through Inhibition of ROS Production and Apoptosis

This study aimed to investigate the neuroprotective effects of 1-methoxylespeflorin G11 (MLG), a pterocarpan, against glutamate-induced neurotoxicity in neuronal HT22 hippocampal cells. The protective effects of MLG were evaluated using MTT assay and microscopic analysis. The extent of apoptosis was studied using flow cytometric analysis performed on the damaged cells probed with annexin V/propidium iodide. Moreover, mitochondrial reactive oxygen species (ROS) were assessed using flow cytometry through MitoSOXTM Red staining. To determine mitochondrial membrane potential, staining with tetramethylrhodamine and JC-1 was performed followed by flow cytometry. The results demonstrated that MLG attenuates glutamate-induced apoptosis in HT22 cells by inhibiting intracellular ROS generation and mitochondrial dysfunction. Additionally, MLG prevented glutamate-induced apoptotic pathway in HT22 cells through upregulation of Bcl-2 and downregulation of cleaved PARP-1, AIF, and phosphorylated MAPK cascades. In addition, MLG treatment induced HO-1 expression in HT22 cells. These results suggested that MLG exhibits neuroprotective effects against glutamate-induced neurotoxicity in neuronal HT22 cells by inhibiting oxidative stress and apoptosis.

Comparative Study of Curcumin and Its Hydrogenated Metabolites, Tetrahydrocurcumin, Hexahydrocurcumin, and Octahydrocurcumin, on Melanogenesis in B16F10 and MNT-1 Cells

Curcumin, a bioactive from Curcuma longa, has been shown to possess anti-melanogenic activity previously; however, the effects of its hydrogenated metabolites (HMs)—Tetrahydrocurcumin (THC), Hexahydrocurcumin (HHC), and Octahydrocurcumin (OHC)—on melanogenesis have not been sufficiently explored. We have studied and compared three HMs (THC, HHC, and OHC) with the parent compound, curcumin (PC), on melanin synthesis in B16F10 mouse and MNT-1 human melanoma cells. Our results demonstrated that all the HMs were nontoxic over the concentration range 5–40 µM, while PC was nontoxic at 5 µM but induced toxicity at 20 and 40 µM in B16F10 cells. All three HMs enhanced melanin synthesis, while PC (5 µM) inhibited it. THC (40 µM) significantly stimulated melanin synthesis to a greater degree than HHC and OHC in both B16F10 and MNT-1 cells; the order of melanogenesis stimulation was THC = OHC > HHC in B16F10 mouse cells, while it was THC > HHC > OHC in MNT-1 cells. HMs stimulated melanogenesis by pathways not involving tyrosinase, as neither the intracellular tyrosinase activity nor the protein levels of tyrosinase were affected. In addition, mushroom tyrosinase activity, using L-Dihydroxyphenylalanine (L-DOPA) as the substrate, showed no direct effects of HMs. In summary, our results demonstrate that the HMs enhanced melanogenesis, which establishes that the hydrogenation of the heptadiene moiety of curcumin leads to a loss of its anti-melanogenic activity and instead results in the stimulation of melanogenesis. This stimulation is not further enhanced upon hydrogenation of the β-diketone, which was noted in MNT-1 cells, although the correlation to the number of keto groups differed in B16F10 cells where HHC was the weakest stimulator of melanogenesis. Collectively, THC with both keto groups intact is the best stimulator. Moreover, our results also validate that the electrophilicity of curcumin is necessary for its anti-melanogenic activity, as the non-electrophilic HMs did not inhibit melanogenesis. Furthermore, our results suggest that THC might hold promise as a stimulator of melanogenesis for treatment of hypopigmentation disorders and anti-graying therapies. Future studies to probe the molecular signaling mechanisms and test whether the pro-melanogenic activity of HMs is retained in primary human melanocytes are warranted.

PSA mimetic 5-nonyloxytryptamine protects cerebellar neurons against glutamate induced excitotoxicity: An in vitro perspective

PSA-NCAM is a molecule of therapeutic interest for its key role in promoting neuritogenesis and synaptic plasticity. The current study was aimed to investigate the neuroregenerative potential of 5-nonyloxytryptamine (5-NOT) as PSA mimetic compound against glutamate induced excitotoxicity. 2D and 3D cultures of cerebellar neurons challenged with glutamate were used to ascertain the effect of 5-NOT on neurite outgrowth, migration and expression of neuronal plasticity markers. Glutamate excitotoxicity is one of the major underlying pathological factor responsible for neurodegeneration in various neurological disorders such as trauma, stroke, ischemia, epilepsy and neurodegenerative diseases.5-NOT treatment was observed to promote axonal growth and defasiculation in glutamate challenged neurons as well as promoted the migration of cerebellar neurons in both wound scratched area and cerebellar explant cultures. Further, 5-NOT treatment upregulated the expression of synaptic plasticity and cell survival pathway proteins which showed reduced expression after glutamate induced excitotoxicity. Thus, this preliminary data reveals thatPSA-mimetic,5-NOT may prove to be a potential neuroprotective candidate for neurodegenerative diseases.

Neuroprotective Effect of Carotenoid-Rich Enteromorpha prolifera Extract via TrkB/Akt Pathway against Oxidative Stress in Hippocampal Neuronal Cells

In this study, we found that E. prolifera extract (EAEP) exhibits neuroprotective effects in oxidative stress-induced neuronal cells. EAEP improved cell viability as well as attenuated the formation of intracellular reactive oxygen species (ROS) and apoptotic bodies in glutamate-treated hippocampal neuronal cells (HT-22). Furthermore, EAEP improved the expression of brain-derived neurotrophic factor (BDNF) and antioxidant enzymes such as heme oxygenase-1 (HO-1), NAD(P)H quinine oxidoreductase-1 (NQO-1), and glutamate-cysteine ligase catalytic subunit (GCLC) via the tropomyosin-related kinase receptor B/ protein kinase B (TrkB/Akt) signaling pathway. In contrast, the pre-incubation of K252a, a TrkB inhibitor, or MK-2206, an Akt-selective inhibitor, ameliorated the neuroprotective effects of EAEP in oxidative stress-induced neuronal cells. These results suggest that EAEP protects neuronal cells against oxidative stress-induced apoptosis by upregulating the expression of BDNF and antioxidant enzymes via the activation of the TrkB/Akt pathway. In conclusion, such an effect of EAEP, which is rich in carotenoid-derived compounds, may justify its application as a food supplement in the prevention and treatment of neurodegenerative disorders.

Comparing and phylogenetic analysis chloroplast genome of three Achyranthes species

In this study, the chloroplast genome sequencing of the Achyranthes longifolia, Achyranthes bidentata and Achyranthes aspera were performed by Next-generation sequencing technology. The results revealed that there were a length of 151,520 bp (A. longifolia), 151,284 bp (A. bidentata), 151,486 bp (A. aspera), respectively. These chloroplast genome have a highly conserved structure with a pair of inverted repeat (IR) regions (25,150 bp; 25,145 bp; 25,150 bp), a large single copy (LSC) regions (83,732 bp; 83,933 bp; 83,966 bp) and a small single copy (SSC) regions (17,252 bp; 17,263 bp; 17,254 bp) in A. bidentate, A. aspera and A. longifolia. There were 127 genes were annotated, which including 8 rRNA genes, 37 tRNA genes and 82 functional genes. The phylogenetic analysis strongly revealed that Achyranthes is monophyletic, and A. bidentata was the closest relationship with A. aspera and A. longifolia. A. bidentata and A. longifolia were clustered together, the three Achyranthes species had the same origin, then the gunes of Achyranthes is the closest relative to Alternanthera, and that forms a group with Alternanthera philoxeroides. The research laid a foundation and provided relevant basis for the identification of germplasm resources in the future.

Dexmedetomidine Attenuates Glutamate-Induced Cytotoxicity by Inhibiting the Mitochondrial-Mediated Apoptotic Pathway

Background

Glutamate (GLU) is the most excitatory amino acid in the central nervous system and plays an important role in maintaining the normal function of the nervous system. During cerebral ischemia, massive release of GLU leads to neuronal necrosis and apoptosis. It has been reported that dexmedetomidine (DEX) possesses anti-oxidant and anti-apoptotic properties. The objective of this study was to investigate the effects of DEX on GLU-induced neurotoxicity in PC12 cells.

Material/Methods

PC12 cells were treated with 20 mM GLU to establish an ischemia-induced injury model. Cell viability was accessed by MTT assay. MDA content and SOD activity were analyzed by assay kits. Apoptosis rate, ROS production, intracellular Ca²⁺ concentration, and MMP were evaluated by flow cytometry. Western blot analysis was performed to analyze expressions of caspase-3, caspase-9, cyt-c, bax, and bcl-2.

Results

PC12 cells treated with GLU exhibited reduced cell viability and increased apoptosis rates, which were ameliorated by pretreatment with DEX. DEX significantly increased SOD activity, reduced content of MDA, and decreased production of ROS in PC12 cells. In addition, DEX clearly reduced the level of intracellular Ca²⁺ and attenuated the decline of MMP. Moreover, DEX notably reduced expressions of caspase-3, caspase-9, cyt-c, and bax and increased expression of bcl-2.

Conclusions

Our findings suggest that DEX can protect PC12 cells against GLU-induced cytotoxicity, which may be attributed to its anti-oxidative property and reduction of intracellular calcium overload, as well as its ability to inhibit the mitochondria-mediated apoptotic pathway.

Mutual Two-Way Interactions of Curcumin and Gut Microbiota

Curcumin, an herbal naturally occurring polyphenol, has recently been proposed for the treatment of neurodegenerative, neurological and cancer diseases due to its pleiotropic effect. Recent studies indicated that dysbiosis is associated with the abovementioned and other diseases, and gut microflora may be a new potential therapeutic target. The new working hypothesis that could explain the curative role of curcumin, despite its limited availability, is that curcumin acts indirectly on the brain, affecting the “gut–brain–microflora axis”, a complex two-way system in which the gut microbiome and its composition, are factors that preserve and determine brain health. It is therefore suspected that curcumin and its metabolites have a direct regulatory effect on gut microflora and vice versa, which may explain the paradox between curcumin’s poor bioavailability and its commonly reported therapeutic effects. Curcumin and its metabolites can have health benefits by eliminating intestinal microflora dysbiosis. In addition, curcumin undergoes enzymatic modifications by bacteria, forming pharmacologically more active metabolites than their parent, curcumin. In this review, we summarize a number of studies that highlight the interaction between curcumin and gut microbiota and vice versa, and we consider the possibility of microbiome-targeted therapies using curcumin, particularly in disease entities currently without causal treatment.