Identifying the mechanism underlying antidepressant-like effects of loganin by network pharmacology in combination with experimental validation

Amelioration of gap junction dysfunction in a depression model by loganin: Involvement of GSK-3β/β-catenin signaling

ETHNOPHARMACOLOGICAL RELEVANCE

Cornus officinalis Sieb. et Zucc has significant neuroprotective activity and has been widely studied for its potential to improve cognitive function. Our team's previous research has found that loganin isolated from Cornus officinalis has an antidepressant effect. Depression is a mental disorder accompanied by dysfunction of Connexin43 (Cx43)-formed astrocytic gap junctions. However, the precise mechanisms of loganin involved remain uncertain.

AIM OF THE STUDY

We aimed to examine the mechanism by which loganin produces its antidepressant properties.

MATERIALS AND METHODS

Using a chronic unpredictable stress (CUS) model of depression in rats, the study evaluated the behavioral responses to treatment with loganin, fluoxetine, and their combination. Biochemical analyses were conducted to measure the expression and phosphorylation status of Cx43, β-catenin, GSK-3β in the brain. In vitro experiments were also performed how loganin protects the gap junctions in astrocytes that have been exposed to corticosterone.

RESULTS

After four weeks of loganin treatment, rats exposed to CUS showed a decrease in depressive-like behaviors. When combined with fluoxetine, the antidepressant-like effects were observed faster than with either treatment alone. Loganin significantly increased Cx43 expression in the prefrontal cortex and ventral hippocampus, reversed Cx43 mimetic peptide Gap26-induced depressive-like behaviors, decreased Cx43 phosphorylation at Ser368, increased β-catenin levels, and promoted GSK-3β phosphorylation at Ser9. In vitro, loganin prevented corticosterone-induced damage to gap junctions between astrocytes, an effect that was negated by XAV-939 (β-catenin inhibitor).

CONCLUSION

These results implied that loganin could exert antidepressant-like effects by improving the gap junctions of astrocytes in the prefrontal cortex and hippocampus, acting through the GSK-3β/β-catenin signaling pathway. The combination of loganin with fluoxetine may provide a faster onset of antidepressant action compared to either treatment alone, highlighting the potential of loganin as a natural adjunct therapy for depression.

Investigating the possible mechanism of Cornus officinalis in the therapy of ischemic stroke by UHPLC-Q-TOF-MS, network pharmacology, molecular docking, and experimental verification

ETHNOPHARMACOLOGICAL RELEVANCE

Cornus officinalis is a conventional Chinese medicine for tonifying liver and kidney in ancient China. The active ingredients from Cornus officinalis can delay the progression of cerebral aneurysms, alleviate experimental autoimmune encephalomyelitis, and show a good intervention effect on brain diseases. Loganin, the active ingredient of Cornus officinalis, has a neuroprotective effect on cerebral ischemia-reperfusion injury in mice. It is yet unknown, nevertheless, how Cornus officinalis works to treat ischemic stroke.

AIM OF THE STUDY

Based on ultra-high performance liquid chromatography-quadrupole/time-of-flight mass spectrometry (UHPLC-Q-TOF-MS), network pharmacology and molecular docking, Cornus officinalis's mechanism of intervention in ischemic stroke is explored and verified by experiments.

MATERIALS AND METHODS

To examine the chemical components of Cornus officinalis, UHPLC-Q-TOF-MS was used. The network pharmacology was used to construct the "active ingredient-core target-main pathway" network of Cornus officinalis. Then, the link between the main active components and the key protein targets, as determined by network pharmacology, was verified through the application of molecular docking. The middle cerebral artery occlusion/reperfusion (MCAO/R) rat model used in this study was created using the suture technique. The pharmacological effects of Cornus officinalis were explored by neurological function score, behavior, TTC staining, ultrasound and flow cytometry. Western blot and qPCR were used to confirm the core target.

RESULTS

The outcomes of the investigation demonstrated that Cornus officinalis had a potent anti-ischemic stroke effect. UHPLC-Q-TOF-MS method was used to determine 24 chemical constituents in Cornus officinalis, of which 22 components had a close relationship with protein targets relevant to ischemic stroke. The 27 protein targets screened by "active ingredient-core target-main pathway" may be the possible targets of Cornus officinalis in the therapy of ischemic stroke. Most of the 27 protein targets had to do with the inflammatory response, apoptosis and energy metabolism. KEGG enrichment analysis showed that AGE/RAGE ranked high and was closely related to inflammatory response. Molecular docking predicted that the top 10 components in the network diagram had good binding with inflammatory factors IL6, IL-1β and TNF-α protein targets. Western blot research outcomes stated that Cornus officinalis could firmly impede the production of AGE, RAGE, and P-NFκB P65. Cornus officinalis had the potential to prevent ischemic stroke by drastically inhibiting the production of TNF-α, IL-1β, and IL-6, according to the results of qPCR study.

CONCLUSION

This study found that Cornus officinalis can improve the brain injury, motor ability and blood flow velocity of MCAO/R rats and suppress the inflammatory reaction through the AGE/RAGE/NFκB pathway to exert the therapeutic effect on ischemic stroke.

Regulation of the microglial polarization for alleviating neuroinflammation in the pathogenesis and therapeutics of major depressive disorder

Major depressive disorder (MDD), as a multimodal neuropsychiatric and neurodegenerative illness with high prevalence and disability rates, has become a burden to world health and the economy that affects millions of individuals worldwide. Neuroinflammation, an atypical immune response occurring in the brain, is currently gaining more attention due to its association with MDD. Microglia, as immune sentinels, have a vital function in regulating neuroinflammatory reactions in the immune system of the central nervous system. From the perspective of steady-state branching states, they can transition phenotypes between two extremes, namely, M1 and M2 phenotypes are pro-inflammatory and anti-inflammatory, respectively. It has an intermediate transition state characterized by different transcriptional features and the release of inflammatory mediators. The timing regulation of inflammatory cytokine release is crucial for damage control and guiding microglia back to a steady state. The dysregulation can lead to exorbitant tissue injury and neuronal mortality, and targeting the cellular signaling pathway that serves as the regulatory basis for microglia is considered an essential pathway for treating MDD. However, the specific intervention targets and mechanisms of microglial activation pathways in neuroinflammation are still unclear. Therefore, the present review summarized and discussed various signaling pathways and effective intervention targets that trigger the activation of microglia from its branching state and emphasizes the mechanism of microglia-mediated neuroinflammation associated with MDD.

20 (S)-Protopanaxadiol Alleviates DRP1-Mediated Mitochondrial Dysfunction in a Depressive Model In Vitro and In Vivo via the SIRT1/PGC-1α Signaling Pathway

Depression is a complex and common mental illness affecting physical and psychological health. Panax ginseng C. A. Mey is a traditional Chinese medicine with abundant pharmacological activity and applications in regulating mood disorders. 20 (S)-Protopanaxadiol is the major intestinal metabolite of ginsenoside and one of the active components in ginseng. In this study, we aimed to investigate the therapeutic effects of 20 (S)-Protopanaxadiol on neuronal damage and depression, which may involve mitochondrial dynamics. However, the mechanism underlying the antidepressant effects of 20 (S)-Protopanaxadiol is unelucidated. In the present study, we investigated the potential mechanisms underlying the antidepressant activity of 20 (S)-Protopanaxadiol by employing a corticosterone-induced HT22 cellular model and a chronic unpredicted mild stress (CUMS)-induced animal model in combination with a network pharmacology approach. In vitro, the results showed that 20 (S)-Protopanaxadiol ameliorated the corticosterone (CORT)-induced decrease in HT22 cell viability, decrease in 5-hydroxytryptamine (5-HT) levels, and increase in nitric oxide (NO) and malondialdehyde (MDA) levels. Furthermore, 20 (S)-Protopanaxadiol exerted improvement effects on the CORT-induced increase in HT22 cell mitochondrial reactive oxygen species, loss of mitochondrial membrane potential, and apoptosis. In vivo, the results showed that 20 (S)-Protopanaxadiol ameliorated depressive symptoms and hippocampal neuronal damage in CUMS mice, and sirtuin1 (SIRT1) and peroxisome proliferator-activated receptor-1-Alpha (PGC-1α) activity were activated in the hippocampus of mice, thereby alleviating mitochondrial dysfunction and promoting the clearance of damaged mitochondria. In both in vivo and in vitro models, after inhibiting SIRT1 expression, the protective effect of 20 (S)-Protopanaxadiol on mitochondria was significantly weakened, and dynamin-related protein 1 (DRP1)-mediated mitochondrial division was significantly reduced. These findings suggest that 20 (S)-Protopanaxadiol may exert neuroprotective and antidepressant effects by attenuating DRP1-mediated mitochondrial dysfunction and apoptosis by modulating the SIRT1/PGC-1α signaling pathway.

Simultaneous Determination of Thirteen Iridoid Glycosides in Crude and Processed Fructus Corni from Different Areas by UPLC-MS/MS Method

Fructus Corni (F. Corni) is the dried mature pulp of Cornus officinalis Sieb. et Zucc.(Cornaceae), which is rich in iridoids. In this study, a simple, sensitive and rapid UPLC-MS/MS method was developed for the simultaneous determination of 13 iridoid glycosides of F. Corni from different areas. Specifically, we included five new compounds (cornusdiridoid C, cornusdiridoid E, cornusdiridoid F, 3'',5''-dehydroxycornuside and 2'-O-p-coumaroyl-kingiside) and isomers (2'-O-p-E-coumaroylloganin and 2'-O-p-Z-coumaroylloganin) for the first time in the quality markers of F. Corni. A total of 13 compounds and two pairs of isomers were well isolated and tested within just 14 min. All calibration curves showed good linear regression (r2 ≥ 0.99) within the tested concentration ranges. The limit of detection and limit of quantification were in the range of 0.19-1.90 and 0.38-3.76 ng/mL, respectively. The intra-day and inter-day precision were <3.21% and 12.49%, the RSD values of repeatability did not exceed 6.81% and the average recoveries were 90.95-113.59% for the analytes. All iridoid glycosides stabilized within 12 h (RSD < 10.99%). This method has been successfully applied to the quality evaluation of crude and processed F. Corni from different areas. The determination of characteristic iridoid glycosides and isomers will provide a more reliable and comprehensive method for the evaluation of F. Corni.

Quality evaluation of Lonicerae Japonicae Flos from different origins based on high-performance liquid chromatography (HPLC) fingerprinting and multicomponent quantitative analysis combined with chemical pattern recognition

INTRODUCTION

Lonicerae Japonicae Flos (LJF) is widely used in food and traditional Chinese medicine. To meet demand, Lonicera japonica Thunb. is widely cultivated in many provinces of China. However, reported studies on the quality evaluation of LJF only used a single or a few active components as indicators, which could not fully reflect the quality of LJF.

OBJECTIVES

In the present study, we aimed to develop a methodology for comprehensively evaluating the quality of LJF from different origins based on high-performance liquid chromatography (HPLC) fingerprinting and multicomponent quantitative analysis combined with chemical pattern recognition.

MATERIALS AND METHODS

The HPLC method was developed for fingerprint analysis and was used to determine the contents of 19 components of LJF. To distinguish between samples and identify differential components, similarity analysis, hierarchical cluster analysis, principal component analysis, and orthogonal partial least squares discriminant analysis were performed.

RESULTS

The HPLC fingerprint was established. Using the developed method, the contents of 19 components recognized in the fingerprint analysis were determined. Samples from different origins could be effectively distinguished.

CONCLUSIONS

HPLC fingerprinting and multicomponent quantitative analysis combined with chemical pattern recognition is an efficient method for evaluating LJF.

Development and validation of a simple and rapid UPLC-MS/MS method for loganin and its application in pharmacokinetic and tissue distribution studies

ETHNOPHARMACOLOGICAL RELEVANCE

Cornus officinalis Sieb. et Zucc. is a medicinal and edible homolog in traditional Chinese medicine. Loganin, an iridoid glycoside, is one of the main active components of Cornus officinalis Sieb. et Zucc. Loganin has been demonstrated to improve depression-like behavior and may be a potential antidepressant candidate. However, the pharmacokinetic characteristics and tissue distribution of loganin, especially in the brain region, are still unclear.

AIM OF THE STUDY

This study aims to investigate the pharmacokinetic characteristics and tissue distribution after oral administration of loganin in rats.

MATERIALS AND METHODS

A simple, rapid and reproducible UPLC-MS/MS method was developed and validated for the determination of loganin in rat plasma and tissues. The samples were prepared by acetonitrile precipitation with chloramphenicol as internal standard (IS). Loganin was separated by gradient elution on ACQUITY UPLC®BEH C18 (2.1 × 50 mm, 1.7 μm) using multiple reactions monitoring (MRM) mode. Concentration-time data was subjected to pharmacokinetic analysis. The pharmacokinetic parameters of loganin in rat plasma were analyzed by compartment model using DAS 2.0 software.

RESULTS

The established UPLC-MS/MS method was accurate and reliable with a good linearity (R2 > 0.99) in the respective concentration range, satisfying the quantitative requirements. This method was successfully used to study the pharmacokinetics and tissue distribution after oral administration of loganin in rats. The peak time (Tmax) of oral administration was about 40 min, and the half-life (t1/2) was about 50 min, indicating that loganin was quickly absorbed and eliminated in rats. Oral bioavailability was 5.50%. The dose correlation results showed that AUC had a poor correlation with dose, while Cmax had a good correlation with dose. In tissues, loganin (35 mg/kg) was highly distributed in the stomach, small intestine, kidney, liver and lung. When the dose was 70 mg/kg, loganin had significant distribution in the cortex.

CONCLUSION

In this study, a simple and sensitive UPLC-MS/MS method was developed and validated for the determination of loganin in rat plasma and tissues. Loganin was absorbed quickly, eliminated quickly, and had low bioavailability. The distribution of loganin in the cortex was higher than that in the hippocampus. We hope that our results can provide a reference for loganin to become a new antidepressant.

Loganin attenuates neuroinflammation after ischemic stroke and fracture by regulating α7nAChR-mediated microglial polarization

Fracture in acute stage of ischemic stroke can increase inflammatory response and enhance stroke injury. Loganin alleviates the symptoms of many inflammatory diseases through its anti-inflammatory effect, but its role in ischemic stroke and fracture remains to be explored. Here, mice were handled with permanent middle cerebral artery occlusion (pMCAO) followed by tibial fracture 1 day later to establish a pMCAO+fracture model. Loganin or Methyllycaconitine (MLA, a specific a7nAchR inhibitor) were intragastrically administered 2 or 0.5 h before pMCAO, respectively. And mouse motor function and infarct volume were evaluated 3 days after pMCAO. We found that loganin alleviated the neurological deficit, cerebral infarction volume, and neuronal apoptosis (NeuN⁺ TUNEL⁺ ) in mice with pMCAO+fracture. And loganin suppressed pMCAO+fracture-induced neuroinflammation by promoting M2 microglia polarization (Iba1⁺ CD206⁺ ) and inhibiting M1 microglia polarization (Iba1⁺ CD11b⁺ ). While administration with MLA reversed the protective effect of loganin on pMCAO+fracture-induced neurological deficit and neuroinflammation. Next, LPS was used to stimulate BV2 microglia to simulate pMCAO+fracture-induced inflammatory microenvironment in vitro. Loganin facilitated the transformation of LPS-stimulated BV2 cells from M1 pro-inflammatory state (CD11b⁺ ) to M2 anti-inflammatory state (CD206⁺ ), which was antagonized by treatment with MLA. And loganin induced autophagy activation in LPS-stimulated BV2 cells by activating a7nAchR. Moreover, treatment with rapamycin (an autophagy activator) neutralized the inhibitory effect of MLA on loganin induced transformation of BV2 cells to M2 phenotype. Furthermore, BV2 cells were treated with LPS, LPS + loganin, LPS + loganin+MLA, or LPS + loganin+MLA+ rapamycin to obtain conditioned medium (CM) for stimulating primary neurons. Loganin reduced the damage of primary neurons caused by LPS-stimulated BV2 microglia through activating a7nAchR and inducing autophagy activation. In conclusion, loganin played anti-inflammatory and neuroprotective roles in pMCAO + fracture mice by activating a7nAchR, enhancing autophagy and promoting M2 polarization of microglia.

Cornuside, by regulating the AGEs-RAGE-IκBα-ERK1/2 signaling pathway, ameliorates cognitive impairment associated with brain aging

Anti-Alzheimer's disease (AD) drugs can only change the symptoms of cognitive impairment in a short time but cannot prevent or completely cure AD. Thus, a more effective drug is urgently needed. Cornuside is extracted from Corni Fructus, a traditional Chinese medicine that plays an important role in treating dementia and other age-related diseases. Thus, the study aimed to explore the effects and mechanisms of Cornuside on the D-galactose (D-Gal) induced aging mice accompanied by cognitive decline. Initially, we found that Cornuside improved the learning and memory abilities of D-Gal-treated mice in behavioral experiments. Pharmacological experiments indicated that Cornuside acted on anti-oxidant and anti-inflammatory effects. Cornuside also reversed acetylcholin esterase (AChE) activity. Meanwhile, pathology tests showed that Cornuside had a protective effect on neuron damage. Cornuside increased the expression of brain-derived neurotrophic factor (BDNF), and down-regulated the expression of receptor for advanced glycosylation end products (RAGE), ionized calcium binding adapter molecule 1 (Iba1), and glial fibrillary acidic protein (GFAP) respectively. Further studies claimed that Cornuside had important effects on the expression of IκBα and extracellular signal-regulated kinases 1/2 (ERK1/2). These effects might be achieved through regulating the AGEs-RAGE-IκBα-ERK1/2 signaling pathway, among which, ERK1/2 might be the key protein. The study provides direct preclinical evidence for the research of Cornuside, which may become an excellent candidate drug for the treatment of aging-related AD.

Characterization and identification of chemical constituents in Corni Fructus and effect of storage using UHPLC-LTQ-Orbitrap-MS

Corni Fructus (CF) has been widely used as both traditional medicine and food; however, systematic studies on its chemical profile and the impact of storage periods on the indicative components are lacking. In this study, UHPLC-LTQ-Orbitrap-MS was used to investigate the fragmentation behaviors of multiple compounds from CF and the content variety of its indicative components for different storage periods. The major basic components of CF were determined to be iridoid glucosides, pentacyclic triterpenoids, phenolic acids, tannins and flavonoids. The characteristic cleavage pathways of the iridoid glucosides, pentacyclic triterpenoids, phenolic acids, tannins and flavonoids were further investigated and elaborated, which could assist in identifying the structures of similar components of other Chinese herbal medicines. Using accurate mass measurements for each precursor ion and the subsequent fragmented ions, and then comparing with standards and literature data, a total of 130 components, including 69 iridoid glucosides, 9 pentacyclic triterpenoids, 16 phenolic acids, 20 tannins and 16 flavonoids, 47 of which are potentially new compounds, were identified. The storage period studies indicated that the contents of 19 indicative components in CF changed differently with the prolongation of the storage period. Among them, morroniside, loganin, sweroside, cornuside, gallic acid, oleanolic acid and ursolic acid were the most important. These results provide abundant information for the identification and improved understanding of the chemical constituents in CF to clarify the content variety of its indicative components for different storage periods.

Network Pharmacology and Experimental Verification to Unveil the Mechanism of N-Methyl-D-Aspartic Acid Rescue Humantenirine-Induced Excitotoxicity

Gelsemium is a medicinal plant that has been used to treat various diseases, but it is also well-known for its high toxicity. Complex alkaloids are considered the main poisonous components in Gelsemium. However, the toxic mechanism of Gelsemium remains ambiguous. In this work, network pharmacology and experimental verification were combined to systematically explore the specific mechanism of Gelsemium toxicity. The alkaloid compounds and candidate targets of Gelsemium, as well as related targets of excitotoxicity, were collected from public databases. The crucial targets were determined by constructing a protein-protein interaction (PPI) network. Subsequently, Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to explore the bioprocesses and signaling pathways involved in the excitotoxicity corresponding to alkaloids in Gelsemium. Then, the binding affinity between the main poisonous alkaloids and key targets was verified by molecular docking. Finally, animal experiments were conducted to further evaluate the potential mechanisms of Gelsemium toxicity. A total of 85 alkaloids in Gelsemium associated with 214 excitotoxicity-related targets were predicted by network pharmacology. Functional analysis showed that the toxicity of Gelsemium was mainly related to the protein phosphorylation reaction and plasma membrane function. There were also 164 pathways involved in the toxic mechanism, such as the calcium signaling pathway and MAPK signaling pathway. Molecular docking showed that alkaloids have high affinity with core targets, including MAPK3, SRC, MAPK1, NMDAR_2B and NMDAR_2A. In addition, the difference of binding affinity may be the basis of toxicity differences among different alkaloids. Humantenirine showed significant sex differences, and the LD₅₀ values of female and male mice were 0.071 mg·kg^-1 and 0.149 mg·kg^-1, respectively. Furthermore, we found that N-methyl-D-aspartic acid (NMDA), a specific NMDA receptor agonist, could significantly increase the survival rate of acute humantenirine-poisoned mice. The results also show that humantenirine could upregulate the phosphorylation level of MAPK3/1 and decrease ATP content and mitochondrial membrane potential in hippocampal tissue, while NMDA could rescue humantenirine-induced excitotoxicity by restoring the function of mitochondria. This study revealed the toxic components and potential toxic mechanism of Gelsemium. These findings provide a theoretical basis for further study of the toxic mechanism of Gelsemium and potential therapeutic strategies for Gelsemium poisoning.

Therapeutic potential of plant iridoids in depression: a review

CONTEXT

Depression is a mental disorder characterized by low mood, reduced interest, impaired cognitive function, and vegetative symptoms such as sleep disturbances or poor appetite. Iridoids are the active constituents in several Chinese classical antidepressant formulae such as Yueju Pill, Zhi-Zi-Hou-Po Decoction, Zhi-Zi-Chi Decoction, and Baihe Dihuang Decoction. Parallel to their wide usages, iridoids are considered potential lead compounds for the treatment of neurological diseases.

OBJECTIVE

The review summarizes the therapeutic potential and molecular mechanisms of iridoids in the prevention or treatment of depression and contributes to identifying research gaps in iridoids as potential antidepressant medication.

METHODS

The following key phrases were sought in PubMed, Google Scholar, Web of Science, and China National Knowledge Internet (CNKI) without time limitation to search all relevant articles with in vivo or in vitro experimental studies as comprehensively as possible: ('iridoid' or 'seciridoid' or 'depression'). This review extracted the experimental data on the therapeutic potential and molecular mechanism of plant-derived iridoids for depression.

RESULTS

Plant iridoids (i.e., catalpol, geniposide, loganin), and secoiridoids (i.e., morroniside, gentiopicroside, oleuropein, swertiamarin), all showed significant improvement effects on depression.

DISCUSSION AND CONCLUSIONS

Iridoids exert antidepressant effects by elevating monoamine neurotransmitters, reducing pro-inflammatory factors, inhibiting hypothalamic-pituitary-adrenal (HPA) axis hyperactivity, increasing brain-derived neurotrophic factor (BDNF) and its receptors, and elevating intestinal microbial abundance. Further detailed studies on the pharmacokinetics, bioavailability, and key molecular targets of iridoids are also required in future research, ultimately to provide improvements to current antidepressant medications.