Suppressive Effect of Ginsenoside Rg3 against Lipopolysaccharide-Induced Depression-Like Behavior and Neuroinflammation in Mice

Potential effect of herbal antidepressants on cognitive deficit: Pharmacological activity and possible molecular mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

Cognitive symptom is a "core" symptom of major depressive disorder (MDD) patients with clear deficit in memory, social and occupational function, and may persist during the remitting phase. Therefore, the remission of cognitive symptom has been considered as one of the main objectives in the treatment of MDD. Herbal antidepressants have been used to treat MDD, and there has been great advances in the understanding of the ability of these herbs to improve cognitive deficit linked to brain injury and various diseases including depression, Alzheimer disease, diabetes and age-related disorders. This systematic review summarizes the evidence from preclinical studies and clinical trials of herbal antidepressants with positive effects on cognitive deficit. The potential mechanisms by which herbal antidepressants prevent cognitive deficit are also reviewed. This review will facilitate further research and applications.

MATERIALS AND METHODS

We conducted an open-ended, English restricted search of MEDLINE (PubMed), Web of Science and Scopus for all available articles published or online before 31 December 2019, using terms pertaining to medical herb/phytomedicine/phytochemical/Chinese medicine and depression/major depressive disorder/antidepressant and/or cognitive impairment/cognitive deficit/cognitive dysfunction.

RESULTS

7 prescriptions, more than 30 individual herbs and 50 phytochemicals from China, Japan, Korea and India with positive effects on the depressive state and cognitive deficit are reviewed herein. The evidence from preclinical studies and clinical trials proves that these herbal antidepressants exhibit positive effects on one or more aspects of cognitive defect including spatial, episodic, aversive, and short- and long-term memory. The action mode of the improvement of cognitive deficit by these herbal antidepressants is mediated mainly through two pathways. One pathway is to promote hippocampal neurogenesis through activating brain derived neurotrophic factor-tropomyosin-related kinase B signaling. The other pathway is to prevent neuronal apoptosis through the inhibition of neuro-inflammation and neuro-oxidation.

CONCLUSION

These herbal antidepressants, having potential therapy for cognitive deficit, may prevent pathological processes of neurodegenerative diseases. Furthermore, these herbal medicines should provide a treasure trove, which will accelerate the development of new antidepressants that can effectively improve cognitive symptom in MDD. Studies on their molecular mechanisms may provide more potential targets and therapeutic approaches for new drug discovery.

Traditional Chinese Medicine in Depression Treatment: From Molecules to Systems

Depression is a multigenetic or multifactorial syndrome. The central neuron system (CNS)-orientated, single target, and conventional antidepressants are insufficient and far from ideal. Traditional Chinese Medicine (TCM) has historically been used to treat depression up till today, particularly in Asia. Its holistic, multidrug, multitarget nature fits well with the therapeutic idea of systems medicine in depression treatment. Over the past two decades, although efforts have been made to understand TCM herbal antidepressants at the molecular level, many fundamental questions regarding their mechanisms of action remain to be addressed at the systems level in order to better understand the complicated herbal formulations in depression treatment. In this Mini Review, we review and discuss the mechanisms of action of herbal antidepressants and their acting targets in the pathological systems in the brain, such as monoamine neurotransmissions, hypothalamic–pituitary–adrenal (HPA) axis, neurotropic factor brain-derived neurotrophic factor (BDNF) cascade, and glutamate transmission. Some herbal molecules, constituents, and formulas are highlighted as examples to discuss their mechanisms of action and future directions for comprehensive researches at the systems level. Furthermore, we discuss pharmacological approaches to integrate the mechanism of action from the molecular level into the systems level for understanding of systems pharmacology of TCM formulations. Integration of the studies at the molecular level into the systems level not only represents a trend in TCM study but also promotes our understanding of the system-wide mechanism of action of herbal antidepressant formulations.

Bifidobacteria-Fermented Red Ginseng and Its Constituents Ginsenoside Rd and Protopanaxatriol Alleviate Anxiety/Depression in Mice by the Amelioration of Gut Dysbiosis

Gut dysbiosis is closely connected with the outbreak of psychiatric disorders with colitis. Bifidobacteria-fermented red ginseng (fRG) increases the absorption of ginsenoside Rd and protopanxatriol into the blood in volunteers and mice. fRG and Rd alleviates 2,4,6-trinitrobenzenesulfonic acid-induced colitis in mice. Therefore, to understand the gut microbiota-mediated mechanism of fRG against anxiety/depression, we examined the effects of red ginseng (RG), fRG, ginsenoside Rd, and protopanaxatriol on the occurrence of anxiety/depression, colitis, and gut dysbiosis in mice. Mice with anxiety/depression were prepared by being exposed to two stressors, immobilization stress (IS) or Escherichia coli (EC). Treatment with RG and fRG significantly mitigated the stress-induced anxiety/depression-like behaviors in elevated plus maze, light-dark transition, forced swimming (FST), and tail suspension tasks (TST) and reduced corticosterone levels in the blood. Their treatments also suppressed the stress-induced NF-κB activation and NF-κB+/Iba1+ cell population in the hippocampus, while the brain-derived neurotrophic factor (BDNF) expression and BDNF+/NeuN+ cell population were increased. Furthermore, treatment with RG or fRG suppressed the stress-induced colitis: they suppressed myeloperoxidase activity, NF-κB activation, and NF-κB+/CD11c+ cell population in the colon. In particular, fRG suppressed the EC-induced depression-like behaviors in FST and TST and colitis more strongly than RG. fRG treatment also significantly alleviated the EC-induced NF-κB+/Iba1+ cell population and EC-suppressed BDNF+/NeuN+ cell population in the hippocampus more strongly than RG. RG and fRG alleviated EC-induced gut dysbiosis: they increased Bacteroidetes population and decreased Proteobacteria population. Rd and protopanaxatriol also alleviated EC-induced anxiety/depression and colitis. In conclusion, fRG and its constituents Rd and protopanaxatriol mitigated anxiety/depression and colitis by regulating NF-κB-mediated BDNF expression and gut dysbiosis.

Insights into gastrointestinal microbiota-generated ginsenoside metabolites and their bioactivities

The gastrointestinal microbiota and host co-evolve into a complex 'super-organism,' and this relationship plays a vital role in many physiological processes, such as drug metabolism. Ginseng is an important medicinal resource and the main ingredients are ginsenosides, which are less polar, difficult to absorb, and have low bioavailability. However, studies have shown that the biological activity of ginsenosides such as compound K (CK), ginsenoside Rg3 (Rg3), ginsenoside Rh2 (Rh2), 20(S)-protopanaxatriol (20(S)-PPT), and 20(S)-protopanaxadiol (20(S)-PPD) is closely related to the gastrointestinal microbiota. In this paper, the metabolic pathway of gastrointestinal microbiota-generated ginsenosides and the main pharmacological effects of these metabolites are discussed. Furthermore, our study provides a new insight into the discovery of novel drugs. Specifically, in new drug screening process, candidates with low biological activity and bioavailability should not be excluded. Because their metabolites may exhibit good pharmacological effects due to the involvement of the gastrointestinal microbiota. In addition, in further research studies to develop probiotics, a combination of agents could exert greater efficacy than single agents. Moreover, differences in lifestyle and diet lead to differences in the gastrointestinal microbiota in the human body. Therefore, administration of the same drug dose to different individuals could elicit different therapeutic effects, owing to the involvement of the gastrointestinal microbiota. Thus, treatment accuracy could be achieved by detecting the gastrointestinal microbiota before drug treatment.HighlightsGastrointestinal microbiota plays a decisive role in bioactivities of ginsenosides.The metabolic pathway and main pharmacological effects of ginsenoside metabolites are discussed.It provides new insights into novel drug discovery and further research to find probiotic, combinations to exert greater efficacy.Differences in lifestyle and diet, varies the gastrointestinal microbiota in the human body. However, the same dose of a drug producing different therapeutic effects may involve gastrointestinal microbiota.

Saikosaponin-d attenuated lipopolysaccharide-induced depressive-like behaviors via inhibiting microglia activation and neuroinflammation

Saikosaponin-d (SSd), a triterpenoid saponins compound extracted from Radix Bupleuri, has been demonstrated to effectively alleviate chronic mild stress-induced depressive behaviors in rats, but the underlying molecular mechanisms are still uncertain. Increasing evidence indicated that microglia activation and inflammatory responses were involved in the pathogenesis of depression. Thus, we desired to induce inflammation-related depressive-like behaviors in mice by injecting lipopolysaccharide (LPS) to investigate whether the antidepressant effect of SSd is related to inhibiting inflammation. The results of behavioral tests showed that SSd administration ameliorated LPS-induced depressive-like behaviors, as shown by increased sucrose consumption in the sucrose preference test and decreased immobility time in the tail suspension test and forced swimming test. Furthermore, immunostaining results showed that SSd pretreatment inhibited LPS-induced microglia activation in the hippocampus of mice and primary microglia cells. Enzyme-linked immunosorbent assay (ELISA) results showed that SSd pretreatment suppressed LPS-induced overexpression of inflammatory factors such as interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α both in vivo and in vitro. Immunostaining and western blot analysis results demonstrated that SSd pretreatment also inhibited LPS-induced HMGB1 translocation from nuclear to extracellular and decreased the protein levels of TLR4, p-IκB-α, NF-κBp65. These results suggested that SSd effectively improved LPS-induced inflammation-related depressive-like behaviors by inhibiting LPS-induced microglia activation and neuroinflammation, and the possible mechanism might associate with the regulation of the HMGB1/TLR4/NF-κB signaling pathway.

MiRNA-532-5p Regulates CUMS-Induced Depression-Like Behaviors and Modulates LPS-Induced Proinflammatory Cytokine Signaling by Targeting STAT3

BACKGROUND

It is known that miR-532-5p is critical for neuronal differentiation. However, the role of miR-532-5p in depression remains unknown. This study aimed to investigate the role and mechanism of miR-532-5p in major depressive disorder (MDD).

METHODS

The depression mice model was established by chronic unpredictable mild stress (CUMS) and confirmed by forced swimming test (FST) and sucrose preference test (SPT). The role of miR-532-5p in MDD was detected by tail suspension test (TST), FST, SPT and SIT. QRT-PCR was used to detect the expression of miR-139-5p in hippocampus and BV-2 microglia of mice. ELISA and Western blotting were used to detect the expression of the nitric oxide synthase (NOS), proinflammatory cytokines (IL-6, IL-1β, TNF-α, and MCP-1) and transcriptional activator 3 (STAT3). Luciferase reporter assay was used to verify the downstream target genes of miR-532-5p.

RESULTS

MiR-532-5p was significantly reduced in the hippocampus of mice treated with CUMS. Overexpression of miR-532-5p significantly reduced CUMS-induced depression-like behaviors and suppressed the expression of IL-6, IL-1β, TNF-α and MCP-1. MiR-532-5p directly targeted signal transducers and STAT3 in BV2 cells. In addition, overexpression of miR-532-5p restrained the raise of inducible NOS and IL-6, IL-1 β, TNF-α and MCP-1 in LPS-exposed BV2 cells.

CONCLUSION

This study indicates that miR-532-5p plays an important role in CUMS-induced depression-like behaviors by targeting STAT3, and miR-532-5p may be a potential target for MDD therapy.

Korean Red Ginseng reduces chronic social defeat stress-induced mood disorders via N-methyl-D-aspartate receptor modulation in mice

Background

A chronic social defeat stress (CSDS) model has been proposed as relevant to stress-induced behavioral change in humans. In this study, we examined the effect of Korean Red Ginseng (KRG) on CSDS-induced mood disorders and protein expression in an animal model.

Methods

To evaluate the effect of KRG on social defeat stress, test mice were exposed in the resident aggressor's home cage compartment for 14 days beginning 1 h after KRG treatment (10, 20, and 40 mg/kg, per oral (p.o.)). After the exposure, behavioral tests to measure anxiety, social interaction, and depression-like behavior were performed. To investigate the underlying mechanism, N-methyl-D-aspartate receptor expression levels in CSDS-induced mice were evaluated using Western blot analysis.

Results

CSDS induced anxiety-like behaviors by decreasing central activity in the open-field test and open-arm approach in the elevated plus maze test and led to social avoidance behavior in the social interaction test. CSDS mice showed upregulated NR1, NR2A, and NR2B expression in the hippocampus. KRG 20 and 40 mg/kg ameliorated anxiety-like activities and KRG 20 mg/kg alleviated social avoidance by decreasing time in the corner zone. KRG treatment recovered CSDS-induced NR1, NR2A, and NR2B protein levels in the hippocampus.

Conclusion

These results indicate that KRG has a therapeutic effect on CSDS-induced mood disorder by alleviating N-methyl-D-aspartate receptor overexpression in the hippocampus.

Mechanisms of Panax ginseng action as an antidepressant

OBJECTIVES

Panax ginseng, a well-known traditional Chinese medicine with multiple pharmacological activities, plays a crucial role in modulating mood disorders. Several recent studies have identified an underlying role of Panax ginseng in the prevention and treatment of depression. However, the cellular and molecular mechanisms remain unclear.

MATERIALS AND METHODS

In this review, we summarized the recent progress of antidepressant effects and underlying mechanisms of Panax ginseng and its representative herbal formulae.

RESULTS

The molecular and cellular mechanisms of Panax ginseng and its herbal formulae include modulating monoamine neurotransmitter system, upregulating the expression of neurotrophic factors, regulating the function of HPA axis, and anti-inflammatory action.

CONCLUSIONS

Therefore, this review may provide theoretical bases and clinical applications for the treatment of depression by Panax ginseng and its representative herbal formulae.

Linking What We Eat to Our Mood: A Review of Diet, Dietary Antioxidants, and Depression

Studies have shown that diet and nutrition play significant roles in the prevention of depression and its clinical treatment. The present review aims to provide a clear understanding of the associations between diet patterns, specific foods, nutrients such as antioxidants, and depression. As a result, balanced dietary patterns such as the Mediterranean diet and certain foods such as fish, fresh vegetables, and fruits have been associated with a lower risk of depression or depressive symptoms, while high-fat Western diets and sugar-sweetened beverages have been associated with higher risk of depression or depressive symptoms. Dietary antioxidants such as green tea polyphenols or isoflavonoid intake have been negatively associated with depression or depressive symptoms. It is concluded that diet patterns, specific foods, and antioxidants play important roles in the prevention and clinical treatment of depression.

Suppressive effects of the supercritical-carbon dioxide fluid extract of Chrysanthemum indicum on chronic unpredictable mild stress-induced depressive-like behavior in mice

The aim of the present study was to explore whether the supercritical-carbon dioxide fluid extract from flowers and buds of Chrysanthemum indicum (SEC) exhibits antidepressant-like effects in a chronic unpredictable mild stress (CUMS)-induced mice model. Firstly, SEC was found to reverse a CUMS-induced decrease in the body weight gain in mice. Next, SEC was found to alleviate CUMS-induced depressive-like behavior, evidenced by the reversal of the decrease in the sucrose consumption in the sucrose preference test (SPT), the increase in the locomotor activity in the open field test (OPF), and the alleviation of immobility duration in both the forced swimming test (FST), and tail-suspension test (TST). SEC also attenuated CUMS-induced hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis by decreasing the levels of serum corticosterone and (CORT) and adrenocorticotropic hormone (ACTH), and hypothalamus corticotrophin-releasing hormone (CRH). In addition, SEC was found to suppress the expression of pro-inflammatory cytokines, including the tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 in the hippocampal of CUMS mice. Interestingly, further investigations demonstrated that SEC inhibited CUMS-induced activation of the nuclear factor kappa B (NF-κB) and NOD-like receptor protein 3 (NLRP3) inflammasomes pathways but upregulated brain-derived neurotrophic factor (BDNF) expression and promoted phosphorylation of extracellular signal-regulated kinase (ERK) and cAMP-response element-binding protein (CREB) in hippocampal. In summary, SEC was able to alleviate depressive-like behavior in a CUMS-induced mice model, accompanied by inhibitory roles in the hyperactivity of the HPA axis and pro-inflammatory cytokine expression. Modulating the NF-κB/NLRP3 and BDNF/CREB/ERK pathways contributed to SEC-mediated antidepressant-like effects.

Four Novel Dammarane-Type Triterpenoids from Pearl Knots of Panax ginseng Meyer cv. Silvatica

Panax ginseng Meyer cv. Silvatica (PGS), which is also known as "Lin-Xia-Shan-Shen" or "Zi-Hai" in China, is grown in forests and mountains by broadcasting the seeds of ginseng and is harvested at the cultivation age of 15⁻20 years. In this study, four new dammarane-type triterpenoids, ginsengenin-S1 (1), ginsengenin-S2 (2), ginsenoside-S3 (3), ginsenoside-S4 (4), along with one known compound were isolated from pearl knots of PGS. Ginsengenin-S2 significantly alleviated oxidative damage when A549 cells were exposed to cigarette smoke (CS) extract. In addition, ginsengenin-S2 could inhibit the CS-induced inflammatory reaction in A549 cells. Protective effects of ginsengenin-S2 against CS-mediated oxidative stress and the inflammatory response in A549 cells may involve the Nrf2 and HDAC2 pathways.

Study on Antidepressant Activity of Pseudo-Ginsenoside HQ on Depression-Like Behavior in Mice

Suppressive effects of ginsenoside Rh₂ (Rh₂), (24R)-pseudo-ginsenoside HQ (R-PHQ), and (24S)-pseudo-ginsenoside HQ (S-PHQ) against lipopolysaccharide (LPS)-induced depression-like behavior were evaluated using the forced swimming test (FST) and tail suspension test (TST) in mice. Pretreatment with Rh₂, R-PHQ, and S-PHQ significantly decreased immobility time in FST and TST with clear dose-dependence, and significantly downregulated levels of serum tumor necrosis factor-α and interleukin-6, and upregulated superoxide dismutase activity in the hippocampus of LPS-challenged mice. Furthermore, R-PHQ and S-PHQ significantly increased the expression of the brain-derived neurotrophic factor (BDNF), tropomyosin-related kinase B (TrkB), sirtuin type 1 (Sirt1), and nuclear-related factor 2, and inhibited the phosphorylation of inhibitor of κB-α and nuclear factor-κB (NF-κB) in the hippocampus of LPS-challenged mice. Additionally, the antidepressant-like effect of R-PHQ was found related to the dopaminergic (DA), γ-aminobutyric acid (GABA)ergic, and noradrenaline systems, while the antidepressive effect of S-PHQ was involved in the DA and GABAergic systems. Taken together, these results suggested that Rh₂, R-PHQ, and S-PHQ produced significant antidepressant-like effects, which may be related to the BDNF/TrkB and Sirt1/NF-κB signaling pathways.

Connection between Systemic Inflammation and Neuroinflammation Underlies Neuroprotective Mechanism of Several Phytochemicals in Neurodegenerative Diseases

Oxidative damage, mitochondrial dysfunction, and neuroinflammation are strongly implicated in the pathogenesis of neurodegenerative diseases including Alzheimer's disease (AD) and Parkinson's disease (PD), and a substantial portion of elderly population at risk of these diseases requires nutritional intervention to benefit health due to lack of clinically relevant drugs. To this end, anti-inflammatory mechanisms of several phytochemicals such as curcumin, resveratrol, propolis, polyunsaturated fatty acids (PUFAs), and ginsenosides have been extensively studied. However, correlation of the phytochemicals with neuroinflammation or brain nutrition is not fully considered, especially in their therapeutic mechanism for neuronal damage or dysfunction. In this article, we review the advance in antioxidative and anti-inflammatory effects of phytochemicals and discuss the potential communication with brain microenvironment by improved gastrointestinal function, enhanced systemic immunity, and neuroprotective outcomes. These data show that phytochemicals may modulate and suppress neuroinflammation of the brain by several approaches: (1) reducing systemic inflammation and infiltration via the blood-brain barrier (BBB), (2) direct permeation into the brain parenchyma leading to neuroprotection, (3) enhancing integrity of disrupted BBB, and (4) vagal reflex-mediated nutrition and protection by gastrointestinal function signaling to the brain. Therefore, many phytochemicals have multiple potential neuroprotective approaches contributing to therapeutic benefit for pathogenesis of neurodegenerative diseases, and development of strategies for preventing these diseases represents a considerable public health concern and socioeconomic burden.

Pancreatic Cancer-Associated Depression: A Case Report and Review of the Literature

The prevalence of major depressive disorder (MDD) in pancreatic cancer (PC) has been reported up to 7 times higher than the general population. Despite repeated studies that show worse quality of life, survival outcomes, and treatment compliance in cancer patients with depression, baseline antidepressant use ranges from 15% to 27%. A meta-analysis of 6 prospective trials specific to PC estimates that 43% of patients with PC experience depression after diagnosis. This is especially alarming in patients with PC, who may experience a prodrome of symptoms including depression and loss of drive. In fact, this prodrome of symptoms may very well be due to an overexpression of indoleamine 2,3-dioxgenase, an enzyme in the kynurenine pathway that leads to serotonin depletion and the buildup of cytotoxic metabolites in the brain. In this literature review, we outline all previous studies pertinent to PC and depression, as well as the molecular underpinnings that may contribute to states of depression, and report on previous randomized control trials in cancer populations that investigate the use of antidepressants to treat depressive symptoms and improve quality of life both prophylactically and after the onset of major depressive disorder. In addition, we detail a case report outlining the precipitous decline in health in 1 patient with PC and depression.

Ginsenosides: the need to move forward from bench to clinical trials

Panax ginseng, known as Koran ginseng, one of the most commonly used traditional plants, has been demonstrated to show a wide range of pharmacological applications. Ginsenosides are the major active ingredients found in ginseng and are responsible for the biological and pharmacological activities, such as antioxidation, antiinflammation, vasorelaxation, and anticancer actions. Existing studies have mostly focused on identifying and purifying single ginsenosides and investigating pharmacological activities and molecular mechanisms in cells and animal models. However, ginsenoside studies based on clinical trials have been very limited. Therefore, this review aimed to discuss the currently available clinical trials on ginsenosides and provide insights and future directions for developing ginsenosides as efficacious and safe drugs for human disease.

Antidepressant-Like Effects of Cistanche tubulosa Extract on Chronic Unpredictable Stress Rats Through Restoration of Gut Microbiota Homeostasis

Growing evidence shows that neuropsychiatric disorders, such as depression, are linked with gut microbiome through the gut–brain axis. Cistanches Herba is well known for the treatment of “kidney-yang” deficiency in traditional Chinese medicine (TCM), and has been used for treatment of neurodegenerative diseases in recent years. In this study, chronic unpredictable stress (CUS)-induced depression model was established to explore the impact of Cistanche tubulosa extract (CTE) on behavioral tests, monoamine neurotransmitters and neurotrophic factors in hippocampus and colon, gut microbiota composition, and short-chain fatty acids (SCFAs) production. Moreover, correlation analysis was used to evaluate the functional relationship between altered gut microbiota, changed neurotransmitters and neurotrophins in hippocampus and colon, and disturbed concentration of SCFAs. CTE significantly improved depression-like behaviors in rats under CUS. Brain level of 5-hydroxytryptamine (5-HT) and brain-derived neurotrophic factor (BDNF) expression in CUS rats were restored by CTE. The relative abundance of gut microbiota and the concentrations of acetate and hexanoic acid could also be modulated by CTE treatment. We further showed that the application of CTE in CUS rats led to strong correlation among disrupted gut microbiota composition, hippocampus neurotransmitter levels, and production of neuroactive metabolite SCFAs. Altogether, these results identify CTE as a potential treatment for depressive symptoms by restoring homeostasis of gut microbiota for microbiota–gut–brain axis disorders, opening new avenues in the field of neuropsychopharmacology.

The anxiolytic-like effects of ginsenoside Rg3 on chronic unpredictable stress in rats

The present study is to evaluate the anxiolytic-like activities underlying ginsenoside Rg3 (GRg3). The anxiolytic-like activities were induced by GRg3 (20 and 40 mg/kg, i.g), evidenced by blocking the decreased time and entries in the open arms in elevated plus maze test and by reversing the increased latency to feed in novelty-suppressed feeding test. In addition, the decreased levels on progesterone, allopregnanolone, serotonin (5-HT) in the prefrontal cortex and hippocampus of chronic unpredictable stress (CUS) were blocked by GRg3 (20 and 40 mg/kg, i.g). Furthermore, the increased corticotropin releasing hormone, corticosterone and adrenocorticotropic hormone were blocked by GRg3 (20 and 40 mg/kg, i.g). Collectively, the anxiolytic-like effects produced by GRg3 were associated with the normalization of neurosteroids biosynthesis, serotonergic system as well as HPA axis dysfunction.

Panax Notoginseng Saponins: A Review of Its Mechanisms of Antidepressant or Anxiolytic Effects and Network Analysis on Phytochemistry and Pharmacology

Panax notoginseng (Burk) F. H. Chen, as traditional Chinese medicine, has a long history of high clinical value, such as anti-inflammatory, anti-oxidation, inhibition of platelet aggregation, regulation of blood glucose and blood pressure, inhibition of neuronal apoptosis, and neuronal protection, and its main ingredients are Panax notoginseng saponins (PNS). Currently, Panax notoginseng (Burk) F. H. Chen may improve mental function, have anti-insomnia and anti-depression effects, alleviate anxiety, and decrease neural network excitation. However, the underlying effects and the mechanisms of Panax notoginseng (Burk) F. H. Chen and its containing chemical constituents (PNS) on these depression-related or anxiety-related diseases has not been completely established. This review summarized the antidepressant or anxiolytic effects and mechanisms of PNS and analyzed network targets of antidepressant or anxiolytic actions with network pharmacology tools to provide directions and references for further pharmacological studies and new ideas for clinical treatment of nervous system diseases and drug studies and development. The review showed PNS and its components may exert these effects through regulating neurotransmitter mechanism (5-HT, DA, NE), modulation of the gamma-amino butyric acid (GABA) neurotransmission, glutamatergic system, hypo-thalamus-pituitary-adrenal (HPA) axis, brain-derived neurotrophic factor (BDNF), and its intracellular signaling pathways in the central nervous system; and produce neuronal protection by anti-inflammatory, anti-oxidation, or inhibition of neuronal apoptosis, or platelet aggregation and its intracellular signaling pathways. Network target analysis indicated PNS and its components also may have anti-inflammatory and anti-apoptotic effects, which leads to the preservation of brain nerves, and regulate the activity and secretion of nerve cells, exerting anti-depression and anxiolytic effects, which may provide new directions for further in-depth researches of related mechanisms.

One-Pot Synthesis of Ginsenoside Rh2 and Bioactive Unnatural Ginsenoside by Coupling Promiscuous Glycosyltransferase from Bacillus subtilis 168 to Sucrose Synthase

Ginsenosides, the major effective ingredients of Panax ginseng, exhibit various biological properties. UDP-glycosyltransferase (UGT)-mediated glycosylation is the last biosynthetic step of ginsenosides and contributes to their immense structural and functional diversity. In this study, UGT Bs-YjiC from Bacillus subtilis 168 was demonstrated to transfer a glucosyl moiety to the free C3-OH and C12-OH of protopanaxadiol (PPD) and PPD-type ginsenosides to synthesize natural and unnatural ginsenosides. In vitro assays showed that unnatural ginsenoside F12 (3- O-β-d-glucopyranosyl-12- O-β-d-glucopyranosyl-20( S)-protopanaxadiol) exhibited remarkable activity against diverse human cancer cell lines. A one-pot reaction by coupling Bs-YjiC to sucrose synthase (SuSy) was performed to regenerate UDP-glucose from sucrose and UDP. With PPD as the aglycon, an unprecedented high yield of ginsenosides F12 (3.98 g L^-1) and Rh2 (0.20 g L^-1) was obtained by optimizing the conversion conditions. This study provides an efficient approach for the biosynthesis of ginsenosides using a UGT-SuSy cascade reaction.

Curcumin Prevents Acute Neuroinflammation and Long-Term Memory Impairment Induced by Systemic Lipopolysaccharide in Mice

Systemic lipopolysaccharide (LPS) induces an acute inflammatory response in the central nervous system (CNS) (“neuroinflammation”) characterized by altered functions of microglial cells, the major resident immune cells of the CNS, and an increased inflammatory profile that can result in long-term neuronal cell damage and severe behavioral and cognitive consequences. Curcumin, a natural compound, exerts CNS anti-inflammatory and neuroprotective functions mainly after chronic treatment. However, its effect after acute treatment has not been well investigated. In the present study, we provide evidence that 50 mg/kg of curcumin, orally administered for 2 consecutive days before a single intraperitoneal injection of a high dose of LPS (5 mg/kg) in young adult mice prevents the CNS immune response. Curcumin, able to enter brain tissue in biologically relevant concentrations, reduced acute and transient microglia activation, pro-inflammatory mediator production, and the behavioral symptoms of sickness. In addition, short-term treatment with curcumin, administered at the time of LPS challenge, anticipated the recovery from memory impairments observed 1 month after the inflammatory stimulus, when mice had completely recovered from the acute neuroinflammation. Together, these results suggest that the preventive effect of curcumin in inhibiting the acute effects of neuroinflammation could be of value in reducing the long-term consequences of brain inflammation, including cognitive deficits such as memory dysfunction.

Use of a Promiscuous Glycosyltransferase from Bacillus subtilis 168 for the Enzymatic Synthesis of Novel Protopanaxatriol-Type Ginsenosides

Ginsenosides are the principal bioactive ingredients of Panax ginseng and possess diverse notable pharmacological activities. UDP-glycosyltransferase (UGT)-mediated glycosylation of the C6-OH and C20-OH of protopanaxatriol (PPT) is the prominent biological modification that contributes to the immense structural and functional diversity of PPT-type ginsenosides. In this study, the glycosylation of PPT and PPT-type ginsenosides was achieved using a promiscuous glycosyltransferase (Bs-YjiC) from Bacillus subtilis 168. PPT was selected as the probe for the in vitro glycodiversification of PPT-type ginsenosides using diverse UDP-sugars as sugar donors. Structural analysis of the newly biosynthesized products demonstrated that Bs-YjiC can transfer a glucosyl moiety to the free C3-OH, C6-OH, and C12-OH of PPT. Five PPT-type ginsenosides were biosynthesized, including ginsenoside Rh1 and four unnatural ginsenosides. The present study suggests flexible microbial UGTs play an important role in the enzymatic synthesis of novel ginsenosides.