Therapeutic potential of plant iridoids in depression: a review

Valtrate alleviates inflammation by targeting USP9X to enhance NLRP3 degradation

BACKGROUND

The NLRP3 inflammasome is a key regulator of innate immunity and plays a critical role in the pathogenesis of various inflammatory diseases. Regulating NLRP3 has emerged as a promising strategy for the development of anti-inflammatory therapies. Valtrate (Val), a natural compound derived from Valeriana officinalis Jones, has demonstrated significant anti-inflammatory activity. However, its precise mechanism of action remains unclear.

PURPOSE

This study elucidates the molecular mechanisms of Val suppressing NLRP3 inflammasome activation.

METHODS

We screened 100 natural compounds for anti-pyroptotic in lipopolysaccharide (LPS)/nigericin-stimulated THP-1 cells and bone marrow-derived macrophages (BMDMs) using lactate dehydrogenase (LDH) release assays. Val's effect on NLRP3 were assessed via immunoblotting and ELISA. Target identification employed DARTS, proteomics, thermal shift assay (TSA), microscale thermophoresis (MST), and molecular dynamics (MD) simulations. In vivo efficacy was evaluated in acetaminophen (APAP)- and LPS-induced liver injury models.

RESULTS

Val potently inhibited pyroptosis (99.20 % LDH reduction) and selectively degraded NLRP3 via post-translation mechanisms (PTMs) without altering its mRNA. DARTS and CETSA confirmed that Val directly interacts with the C2 fragment of USP9X without inhibiting its enzymatic activity, while RMSD, RMSF, and Gibbs energy landscape analyses supported its stable binding to USP9X, which was further confirmed by MST. Mechanistically, Val downregulated USP9X protein expression and promoted K48- and K63-linked ubiquitination and proteasomal degradation of NLRP3. In vivo, Val exhibited therapeutic potential in murine models of acute liver injury induced by APAP and LPS. Val reduced serum ALT and AST levels, inflammatory cytokines, and liver injury (histopathological analysis (H&E) and TUNEL).

CONCLUSION

This study uncovers an unrecognized mechanism by which Val attenuates NLRP3 inflammasome activation by disrupting the USP9X-NLRP3 axis, thereby promoting NLRP3 ubiquitination and proteasomal degradation. Notably, Val down-regulates USP9X protein levels without impairing its catalytic activity, representing a distinct mechanism from existing USP9X inhibitors. These findings not only deepen our understanding of Val's anti-inflammatory action but also underscore its promise as a lead compound for the development of novel therapeutics targeting NLRP3-driven inflammatory diseases.

Modification of iridoids in focus: Bridging structural complexity with biological innovation

Iridoids, a class of oxygenated monoterpene compounds with a methylcyclopentan-[c]-pyran skeletal, widely exist in plants and microorganisms. Iridoids are mainly classified into cyclopentane iridoids and secoiridoids. The unique structure makes it exhibit varieties of biological activities, such as neuroprotective, anti-tumor, anti-viral, anti-oxidant and anti-inflammatory effects. In order to take a deep dive into the structural properties of iridoid derivatives, as well as to facilitate the development of them, we recapitulate the modification strategies of representative iridoids and biological activities of iridoid derivatives, especially discuss their structure-activity relationship in this review. This article will provide the latest overview and offer insights for structural modification of iridoids in future.

Neuroinflammation and Natural Antidepressants: Balancing Fire with Flora

Background/Objectives: Major depressive disorder (MDD) is a major global health concern that is intimately linked to neuroinflammation, oxidative stress, mitochondrial dysfunction, and complicated metabolic abnormalities. Traditional antidepressants frequently fall short, highlighting the urgent need for new, safer, and more acceptable therapeutic techniques. Phytochemicals, i.e., natural antidepressants derived from plants, are emerging as powerful plant-based therapies capable of targeting many pathogenic pathways at the same time. Summary: This narrative review synthesizes evidence from preclinical and clinical studies on the efficacy of phytochemicals such as curcumin, polyphenols, flavonoids, and alkaloids in lowering depressed symptoms. Consistent data show that these substances have neuroprotective, anti-inflammatory, and antioxidant properties, altering neuroimmune interactions, reducing oxidative damage, and improving mitochondrial resilience. Particularly, polyphenols and flavonoids have great therapeutic potential because of their capacity to penetrate the blood-brain barrier, inhibit cytokine activity, and encourage neuroplasticity mediated by brain-derived neurotrophic factor (BDNF). Despite promising results, the heterogeneity in study designs, phytochemical formulations, and patient demographics highlights the importance of thorough, standardized clinical studies. Conclusions: This review identifies phytochemicals as compelling adjuvant or independent therapies in depression treatment, providing multimodal mechanisms and enhanced tolerability. Additional research into improved dosage, pharmacokinetics, long-term safety, and integrative therapy approaches is essential. Using phytotherapeutics could considerably improve holistic and customized depression care, encouraging new research routes in integrative neuroscience and clinical psychiatry.

Nanocrystalline cellulose-geniposide complex enhances gut-brain axis modulation for depression treatment

Depression, a major global health issue, is closely associated with imbalances in gut microbiota and altered intestinal functions. This study investigates the antidepressant potential of a composite of Geniposide (GP) and Nanocrystalline Cellulose (NCC), focusing on its effects on the gut-brain axis. Utilizing network pharmacology, GP was identified as a key compound targeting the BCL2 gene in depression management. Experimental approaches, including a chronic unpredictable mild stress (CUMS) model in mice, cellular assays, and fecal microbiota transplantation (FMT), were used to evaluate the composite's effectiveness. Results indicate that GP activates the adenosine monophosphate-activated protein kinase (AMPK) pathway by upregulating BCL2, enhancing intestinal barrier integrity, and balancing gut flora. These mechanisms contribute to its positive effects on hippocampal function and depressive-like behaviors in mice, suggesting that the GP-NCC composite could be a promising avenue for developing depression therapies that target gut health.

Renal Health Through Medicine-Food Homology: A Comprehensive Review of Botanical Micronutrients and Their Mechanisms

BACKGROUND

As an ancient concept and practice, "food as medicine" or "medicine-food homology" is receiving more and more attention these days. It is a tradition in many regions to intake medicinal herbal food for potential health benefits to various organs and systems including the kidney. Kidney diseases usually lack targeted therapy and face irreversible loss of function, leading to dialysis dependence. As the most important organ for endogenous metabolite and exogenous nutrient excretion, the status of the kidney could be closely related to daily diet. Therefore, medicinal herbal food rich in antioxidative, anti-inflammation micronutrients are ideal supplements for kidney protection. Recent studies have also discovered its impact on the "gut-kidney" axis.

METHODS

Here, we review and highlight the kidney-protective effects of botanicals with medicine-food homology including the most frequently used Astragalus membranaceus and Angelica sinensis (Oliv.) Diels, concerning their micronutrients and mechanism, offering a basis and perspective for utilizing and exploring the key substances in medicinal herbal food to protect the kidney.

RESULTS

The index for medicine-food homology in China contains mostly botanicals while many of them are also consumed by people in other regions. Micronutrients including flavonoids, polysaccharides and others present powerful activities towards renal diseases.

CONCLUSIONS

Botanicals with medicine-food homology are widely speeded over multiple regions and incorporating these natural compounds into dietary habits or as supplements shows promising future for renal health.

A Future Avenue of Treatment Ulcerative Colitis Targeting Macrophage Polarization: A Phytochemical Application

Background

Ulcerative colitis (UC) is a prevalent inflammatory bowel disease primarily impacting the mucosa of the colon. It is characterized by recurring and incurable symptoms and causes immense suffering and significant economic burden due to limited treatment options. Typical symptoms of UC include diarrhea, alterations in bowel patterns, bleeding from the rectum, rectal pain or urgency, anemia, and tiredness. Therefore, developing novel and effective treatment strategies for UC is imperative.

Purpose

This review aimed to explain how macrophage polarization contributes to UC development and compiled information on natural compounds with promising therapeutic potential that can target the macrophage phenotype and shed light on its potential mode of action.

Results

The phenotypic alteration of macrophages profoundly affects the development of UC, and these cells are essential for preserving intestinal immunological homeostasis. Evidence from research suggests that one effective method for UC prevention and therapy is to guide macrophage polarization toward the M2 phenotype. Phytochemicals, which are compounds extracted from plants, possess a wide array of biological activities. For example: Ginsenoside Rg1 emerges as a crucial regulator of macrophage polarization, promoting the M2 phenotype while inhibiting the M1 phenotype. Notably, their low toxicity and high effectiveness render them promising candidates for therapeutic interventions. These compounds have demonstrated encouraging protective effects against inflammation in the colon.

Conclusions

Exploring phytochemicals as a therapeutic avenue targeting macrophage polarization presents an innovative approach to treating UC.

To elucidate the bioactive components of Lamiophlomis herba in the treatment of liver fibrosis via plasma pharmacochemistry and network pharmacology

Lamiophlomis Herba (LH) is a traditional Chinese and Tibetan dual-use herb with hemostatic and analgesic effects, and is widely used in the clinical treatment of traumatic bleeding and pain. In recent years, LH has been proven to treat liver fibrosis (LF), but the chemical components related to the pharmacological properties of LH in the treatment of LF are still unclear. Based on the theory of plasma pharmachemistry, the characteristic components in water extract and drug-containing plasma samples of LH were qualitatively analyzed by UPLC-Q-TOF-MS. The chemical components in plasma were screened and the targets were predicted by network pharmacology. Then, the predicted components and targets were verified in vitro by Elisa and qRT-PCR technology. Finally, the pharmacological effects of LH and its monomeric components were determined by hematoxylin-eosin staining of rat liver. A total of 50 chemical constituents were identified in LH, of which 12 were blood prototypes and 9 were metabolites. In vitro experiments showed that LH and its monomeric components luteolin, shanzhiside methyl ester, loganic acid, loganin, 8-O-acetyl shanzhiside methyl ester could increase the expression of antioxidant genes (NQO-1, HO-1) and decrease the expression of inflammatory genes (IL-6, IL-18), thereby reducing the expression of extracellular matrix-related genes and proteins (COL1A1, COL3A1, LN, α-sma, PC-III, Col-IV). In vivo experiments showed that LH could reduce the area of LF in rats in a dose-dependent manner, and shanzhiside methyl ester and 8-O-acetyl shanzhiside methyl ester may be the main components in pharmacodynamics. These effects may be mediated by LH-mediated Nrf2/NF-κB pathway. This study explored the potential pharmacodynamic components of LH in the treatment of LF, and confirmed that shanzhiside methyl ester and 8-O-acetyl shanzhiside methyl ester play a key role in the treatment of LF with LH.

A Transcriptomic and Metabolomic Study on the Biosynthesis of Iridoids in Phlomoides rotata from the Qinghai-Tibet Plateau

Phlomoides rotata is a traditional Chinese herbal medicine that grows in the Qinghai-Tibet Plateau region at a 3100-5000 m altitude. Iridoid compounds are the main active compounds of the P. rotata used as medical ingredients and display anti-inflammatory, analgesic, and hepatoprotective properties. To better understand the biological mechanisms of iridoid compounds in this species, we performed a comprehensive analysis of the transcriptome and metabolome of P. rotata leaves from four different regions (3540-4270 m). Global metabolome profiling detected 575 metabolites, and 455 differentially accumulated metabolites (DAMs) were detected in P. rotata leaves from the four regions. Eight major DAMs related to iridoid metabolism in P. rotata leaves were investigated: shanzhiside methyl ester, 8-epideoxyloganic acid, barlerin, shanzhiside, geniposide, agnuside, feretoside, and catalpin. In addition, five soil physical and chemical indicators in P. rotata rhizosphere soils were analyzed. Four significant positive correlations were observed between alkaline nitrogen and geniposide, exchangeable calcium and geniposide, available potassium and shanzhiside, and available phosphorus and shanzhiside methyl ester. The transcriptome data showed 12 P. rotata cDNA libraries with 74.46 Gb of clean data, which formed 29,833 unigenes. Moreover, 78.91% of the unigenes were annotated using the eight public databases. Forty-one candidate genes representing 23 enzymes involved in the biosynthesis of iridoid compounds were identified in P. rotata leaves. Moreover, the DXS1, IDI1, 8-HGO1, and G10H2 genes associated with iridoid biosynthesis were specifically expressed in P. rotata. The integration of transcriptome and metabolome analyses highlights the crucial role of soil physical and chemical indicators and major gene expression related to iridoid metabolism pathways in P. rotata from different areas. Our findings provide a theoretical foundation for exploring the molecular mechanisms underlying iridoid compound accumulation in P. rotata.

Exploring the transformative impact of traditional Chinese medicine on depression: Insights from animal models

Depression, a prevalent and complex mental health condition, presents a significant global health burden. Depression is one of the most frequent mental disorders; deaths from it account for 14.3% of people worldwide. In recent years, the integration of complementary and alternative medicine, including traditional Chinese medicine (TCM), has gained attention as a potential avenue for addressing depression. This comprehensive review critically assesses the efficacy of TCM interventions in alleviating depressive symptoms. An in-depth look at different research studies, clinical trials, and meta-analyses is used in this review to look into how TCM practices like herbal formulations, acupuncture, and mind-body practices work. The review looks at the quality of the evidence, the rigor of the methods, and any possible flaws in the current studies. This gives us an idea of where TCM stands right now in terms of treating depression. This comprehensive review aims to assess the efficacy of TCM interventions in alleviating depressive symptoms. In order to learn more about their possible healing effects, the study also looks into how different types of TCM work, such as herbal formulas, acupuncture, and mind-body practices.

Study on the Neuroprotective Effects of Eight Iridoid Components Using Cell Metabolomics

Iridoid components have been reported to have significant neuroprotective effects. However, it is not yet clear whether the efficacy and mechanisms of iridoid components with similar structures are also similar. This study aimed to compare the neuroprotective effects and mechanisms of eight iridoid components (catalpol (CAT), genipin (GE), geniposide (GEN), geniposidic acid (GPA), aucubin (AU), ajugol (AJU), rehmannioside C (RC), and rehmannioside D (RD)) based on corticosterone (CORT)-induced injury in PC12 cells. PC12 cells were randomly divided into a normal control group (NC), model group (M), positive drug group (FLX), and eight iridoid administration groups. Firstly, PC12 cells were induced with CORT to simulate neuronal injury. Then, the MTT method and flow cytometry were applied to evaluate the protective effects of eight iridoid components on PC12 cell damage. Thirdly, a cell metabolomics study based on ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-Q/TOF-MS) was performed to explore changes in relevant biomarkers and metabolic pathways following the intervention of administration. The MTT assay and flow cytometry analysis showed that the eight iridoid components can improve cell viability, inhibit cell apoptosis, reduce intracellular ROS levels, and elevate MMP levels. In the PCA score plots, the sample points of the treatment groups showed a trend towards approaching the NC group. Among them, AU, AJU, and RC had a weaker effect. There were 38 metabolites (19 metabolites each in positive and negative ion modes, respectively) identified as potential biomarkers during the experiment, among which 23 metabolites were common biomarkers of the eight iridoid groups. Pathway enrichment analysis revealed that the eight iridoid components regulated the metabolism mainly in relation to D-glutamine and D-glutamate metabolism, arginine biosynthesis, the TCA cycle, purine metabolism, and glutathione metabolism. In conclusion, the eight iridoid components could reverse an imbalanced metabolic state by regulating amino acid neurotransmitters, interfering with amino acid metabolism and energy metabolism, and harmonizing the level of oxidized substances to exhibit neuroprotective effects.

Phytochemicals against Osteoarthritis by Inhibiting Apoptosis

Osteoarthritis (OA) is a chronic joint disease that causes pathological changes in articular cartilage, synovial membrane, or subchondral bone. Conventional treatments for OA include surgical and non-surgical methods. Surgical treatment is suitable for patients in the terminal stage of OA. It is often the last choice because of the associated risks and high cost. Medication of OA mainly includes non-steroidal anti-inflammatory drugs, analgesics, hyaluronic acid, and cortico-steroid anti-inflammatory drugs. However, these drugs often have severe side effects and cannot meet the needs of patients. Therefore, safe and clinically appropriate long-term treatments for OA are urgently needed. Apoptosis is programmed cell death, which is a kind of physiologic cell suicide determined by heredity and conserved by evolution. Inhibition of apoptosis-related pathways has been found to prevent and treat a variety of diseases. Excessive apoptosis can destroy cartilage homeostasis and aggravate the pathological process of OA. Therefore, inhibition of apoptosis-related factors or signaling pathways has become an effective means to treat OA. Phytochemicals are active ingredients from plants, and it has been found that phytochemicals can play an important role in the prevention and treatment of OA by inhibiting apoptosis. We summarize preclinical and clinical studies of phytochemicals for the treatment of OA by inhibiting apoptosis. The results show that phytochemicals can treat OA by targeting apoptosis-related pathways. On the basis of improving some phytochemicals with low bioavailability, poor water solubility, and high toxicity by nanotechnology-based drug delivery systems, and at the same time undergoing strict clinical and pharmacological tests, phytochemicals can be used as a potential therapeutic drug for OA and may be applied in clinical settings.

Wenyang-Tianjing-Jieyu Decoction Improves Depression Rats of Kidney Yang Deficiency Pattern by Regulating T Cell Homeostasis and Inflammation Level

PURPOSE

Chronic inflammation is one of the key mechanisms of depression. Wenyang-Tianjin-Jie Decoction (WTJD) is an effective antidepressant found in the course of diagnosis and treatment, but the mechanism of therapeutic effect is not clear. The study aimed to evaluate the efficacy of WTJD in the kidney yang deficiency (KYD) type of depression rats and reveal its mechanisms.

MATERIALS AND METHODS

We selected forty 6-week-old male Sprague-Dawley rats for the study. We established a KYD [Phellodendron amurense Rupr (Huangbai) solution oral gavage and 4°C environments; 8 weeks] type of depression (chronic unpredictable mild stimulus; 6 weeks) rat model first. After successful modeling, we used WTJD or fluoxetine on rats for 3 weeks. Then we evaluated the depression and KYD behavior. Finally, we observed the expression of key inflammatory factors and proteins in peripheral blood and hippocampus, and further investigated the immune balance of Th17/Treg and Th1/Th2 cells and the activity of their main regulatory pathways JAK2/STAT3 and TLR4/TRAF6/NF-κB.

RESULTS

The imbalance of Th17/Treg and Th1/Th2 cells in rats were related to KYD and depressive symptoms. Through this study, we found that WTJD can inhibit the activity of JAK2/STAT3 and TLR4/TRAF6/NF-κB pathways, balance Th17/Treg and Th1/Th2 cell homeostasis, regulate the levels of inflammatory factors in the hippocampus and peripheral blood, and reverse KYD and depression.

CONCLUSION

This study confirmed that WTJD had a reliable effect on depression rats with KYD, and its mechanism was to regulate the immune homeostasis of hippocampal T cells and related inflammatory factors to improve KYD and depression symptoms in rats.

The efficacy and safety of acupoint catgut embedding therapy for depression: a protocol for systematic review and meta-analysis

Background

Depression is a common public health problem, characterized by persistent low mood, lack of pleasure and exhaustion. Conventional treatments such as antidepressants and psychotherapy have some limitations, including variable efficacy, adverse side effects and high costs. Acupoint catgut embedding (ACE) therapy, as a subtype of acupuncture, has gained increasing clinical application due to its long-term effects, higher patient compliance, and cost-effectiveness. This study aims to conduct a meta-analysis to evaluate the efficacy and safety of ACE for depression.

Methods

Electronic searches will be conducted in 12 databases (both in English and Chinese databases), encompassing from inception to April 2022, without language restrictions. Randomized controlled trials (RCTs) that involve ACE for treating depression will be included. The primary outcome measures will include the response rate, Hamilton Depression Rating Scale (HAMD), Beck Depression Inventory (BDI), and Traditional Chinese Medicine Symptom Scale (TCMSSS). The secondary outcome measure will include Quality of Life scale score (QoL) and the incidence of adverse events. Results will be presented as risk ratios for dichotomous data and mean differences for continuous data. Two reviewers will independently conduct study selection, data extraction, and quality assessment. The methodological quality of eligible studies will be evaluated according to the criteria specified by the Cochrane Handbook for Systematic Reviews of Interventions (Version 5.1.0). Meta-analysis will be performed by RevMan 5.3 software.

Discussion

Due to the limitations, a safer, high-efficacy and non-pharmacological intervention with minimal side effects is required for treating depression. ACE has the advantages of longer-lasting effects, improved patient compliance, and reduced treatment costs. This protocol represents a meta-analysis and systematic review, aiming to present the current evidence regarding the efficacy and safety of ACE for depression. It seeks to provide clinicians with a theoretical basis and valuable references for complementary and alternative medicine therapies in their treatment approaches.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/#recordDetails, Identifier CRD42022325966.

Geniposide improves depression by promoting the expression of synapse-related proteins through the Creb1/Six3os1 axis

The present study aims to investigate the mechanism of Geniposide in the treatment of depression. By screening the effective components and targets of Zhi-zi-chi decoction, 140 candidate targets related to depression were identified. Further transcriptome sequencing was conducted to screen differentially expressed mRNAs and lncRNAs; 7 candidate Geniposide treatment targets for depression were obtained. KEGG/GO enrichment analysis and molecular docking were performed to select the optimal drug target, revealing that Creb1 is an important target. Additionally, Six3os1 is the lncRNA with the smallest P-value among the differentially expressed lncRNAs, and the JASPAR database revealed a binding site between Creb1 and the Six3os1 promoter. The intersection of Synapse-related genes obtained from the GeneCards database and differentially expressed mRNAs produced 6 synaptic-related genes. RNA-protein interaction prediction revealed that Six3os1 interacts with the protein encoded by these genes. Geniposide upregulates the expression of Creb1 and Six3os1. Creb1 can transcriptionally activate Six3os1, thereby upregulating the expression of the synaptic-related proteins Htr3a and Htr2a, improving depression.

Metabolomics Analysis of Different Tissues of Lonicera japonica Thunb. Based on Liquid Chromatography with Mass Spectrometry

Lonicera japonica Thunb. (LJT) has been widely used as medicines or food additives in Asian countries for thousands of years. The flower buds are often medicinally used, and the other tissues are ignored. However, flowers, leaves and stems have also been reported to have antimicrobial, anti-inflammatory and antioxidant effects. In the current study, un-targeted metabolomics analysis was performed to investigate the metabolic difference among different tissues (flowers, flower buds, stems and leaves) of LJT based on liquid chromatography with mass spectrometry. A total of 171 metabolites were identified, including 28 flavonoids, 35 phenolic acids, 43 iridoids, 9 amino acids, 6 nucleotides, 16 fatty acids, 22 lipids and 12 others. Four new secondary metabolites were discovered. Some flavonoids and iridoids were not detected in leaves and stems. Principal component analysis showed significant differences among four different tissues. Some 27, 81, 113 differential metabolites were found between flowers/flower buds, leaves/flower buds, stems/flower buds, respectively. Primary metabolites showed a higher content in the flowers and flower buds. For the flavonoids, flavones were mainly accumulated in the leaves, flavonols were mainly accumulated in the flower buds, and acylated flavonol glucosides were mainly accumulated in the flowers. Most phenolic acids showed a higher content in the flowers or flower buds, while phenolic acid-glucosides showed significantly higher content in the flower buds. The most abundant iridoids in the LJT also showed a higher content in the flowers and flower buds. These results can provide new insights into the understanding of the metabolites changes in different tissues, and lay a theoretical foundation for the comprehensive utilization of LJT.

A potential therapeutic approach for ulcerative colitis: targeted regulation of macrophage polarization through phytochemicals

Ulcerative colitis (UC), a type of inflammatory bowel disease characterized by recurring and incurable symptoms, causes immense suffering and economic burden for patients due to the limited treatment options available. Therefore, it is imperative to develop novel and promising strategies, as well as safe and effective drugs, for the clinical management of UC. Macrophages play a critical role as the initial line of defense in maintaining intestinal immune homeostasis, and their phenotypic transformation significantly influences the progression of UC. Scientific studies have demonstrated that directing macrophage polarization toward the M2 phenotype is an effective strategy for the prevention and treatment of UC. Phytochemicals derived from botanical sources have garnered the interest of the scientific community owing to their distinct bioactivity and nutritional value, which have been shown to confer beneficial protective effects against colonic inflammation. In this review, we explicated the influence of macrophage polarization on the development of UC and collated data on the significant potential of natural substances that can target the macrophage phenotype and elucidate the possible mechanism of action for its treatment. These findings may provide novel directions and references for the clinical management of UC.