The Beneficial Effects of Geniposide on Glucose and Lipid Metabolism: A Review

Iridoids modulate inflammation in diabetic kidney disease: A review

In recent years, preclinical research on diabetic kidney disease (DKD) has surged to the forefront of scientific and clinical attention. DKD has become a pervasive complication of type 2 diabetes. Given the complexity of its etiology and pathological mechanisms, current interventions, including drugs, dietary modifications, exercise, hypoglycemic treatments and lipid-lowering methods, often fall short in achieving desired therapeutic outcomes. Iridoids, primarily derived from the potent components of traditional herbs, have been the subject of long-standing research. Preclinical data suggest that iridoids possess notable renal protective properties; however, there has been no summary of the research on their efficacy in the management and treatment of DKD. This article consolidates findings from in vivo and in vitro research on iridoids in the context of DKD and highlights their shared anti-inflammatory activities in treating this condition. Additionally, it explores how certain iridoid components modify their chemical structures through the regulation of intestinal flora, potentially bolstering their therapeutic effects. This review provides a focused examination of the mechanisms through which iridoids may prevent or treat DKD, offering valuable insights for future research endeavors. Please cite this article as: Zhou TY, Tian N, Li L, Yu R. Iridoids modulate inflammation in diabetic kidney disease: A review. J Integr Med. 2024; Epub ahead of print.

Total iridoid glycoside extract of Lamiophlomis rotata (Benth) Kudo accelerates diabetic wound healing by the NRF2/COX2 axis

BACKGROUND

Lamiophlomis rotata (Benth.) Kudo (L. rotata), the oral Traditional Tibetan herbal medicine, is adopted for treating knife and gun wounds for a long time. As previously demonstrated, total iridoid glycoside extract of L. rotata (IGLR) induced polarization of M2 macrophage to speed up wound healing. In diabetic wounds, high levels inflammatory and chemotactic factors are usually related to high reactive oxygen species (ROS) levels. As a ROS target gene, nuclear factor erythroid 2-related factor 2 (NRF2), influences the differentiation of monocytes to M1/M2 macrophages. Fortunately, iridoid glycosides are naturally occurring active compounds that can be used as the oxygen radical scavenger. Nevertheless, the influence of IGLR in diabetic wound healing and its associated mechanism is largely unclear.

MATERIALS AND METHODS

With macrophages and dermal fibroblasts in vitro, as well as a thickness excision model of db/db mouse in vivo, the role of IGLR in diabetic wound healing and the probable mechanism of the action were investigated.

RESULTS

Our results showed that IGLR suppressed oxidative distress and inflammation partly through the NRF2/cyclooxygenase2 (COX2) signaling pathway in vitro. The intercellular communication between macrophages and dermal fibroblasts was investigated by the conditioned medium (CM) of IGLR treatment cells. The CM increased the transcription and translation of collagen I (COL1A1) and alpha smooth muscle actin (α-SMA) within fibroblasts. With diabetic wound mice, the data demonstrated IGLR activated the NRF2/KEAP1 signaling and the downstream targets of the pathway, inhibited COX2/PEG2 signaling and decreased the interaction inflammatory targets of the axis, like interleukin-1beta (IL-1β), interleukin 6 (IL-6), apoptosis-associated speck-like protein (ASC), cysteinyl aspartate specific proteinase1 (caspase1) and NOD-like receptor-containing protein 3 (NLRP3).In addition, the deposition of COL1A1, and the level of α-SMA, and Transforming growth factor-β1 (TGF-β1) obviously elevated, whereas that of pro-inflammatory factors reduced in the diabetic wound tissue with IGLR treatment.

CONCLUSION

IGLR suppressed oxidative distress and inflammation mainly through NRF2/COX2 axis, thus promoting paracrine and accelerating wound healing in diabetes mice.

Geniposide alleviates cholesterol-induced endoplasmic reticulum stress and apoptosis in osteoblasts by mediating the GLP-1R/ABCA1 pathway

BACKGROUND

Cholesterol (CHO) is an essential component of the body. However, high CHO levels in the body can damage bone mass and promote osteoporosis. CHO accumulation can cause osteoblast apoptosis, which has a negative effect on bone formation. The pathogenesis of osteoporosis is a complicate process that includes oxidative stress, endoplasmic reticulum (ER) stress, and inflammation. Geniposide (GEN) is a natural compound with anti-osteoporotic effect. However, the roles of GEN in osteopathogenesis are still unclear. Our previous studies demonstrated that GEN could reduce the accumulation of CHO in osteoblasts and the activation of ER stress in osteoblasts. However, the molecular mechanism of GEN in inhibiting CHO-induced apoptosis in osteoblasts needs to be further investigated.

METHODS

MC3T3-E1 cells were treated with osteogenic induction medium (OIM). Ethanol-solubilized cholesterol (100 µM) was used as a stimulator, and 10 µM and 25 µM geniposide was added for treatment. The alterations of protein expression were detected by western blot, and the cell apoptosis was analyzed by a flow cytometer.

RESULTS

CHO promoted osteoblast apoptosis by activating ER stress in osteoblasts, while GEN alleviated the activation of ER stress and reduced osteoblast apoptosis by activating the GLP-1R/ABCA1 pathway. Inhibition of ABCA1 or GLP-1R could eliminate the protective activity of GEN against CHO-induced ER stress and osteoblast apoptosis.

CONCLUSION

GEN alleviated CHO-induced ER stress and apoptosis in osteoblasts by mediating the GLP-1R/ABCA1 pathway.

Bidirectional effects of geniposide in liver injury: Preclinical evidence construction based on meta-analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Gardenia jasminoides J.Ellis is widely used to treat liver diseases in traditional Chinese medicine. Geniposide, a major active constituent of Gardenia jasminoides J.Ellis, exerts therapeutic effects against liver injury, however, it also induces hepatotoxicity.

AIM OF THE STUDY

This meta-analysis was designed to determine the mechanisms of both the hepatoprotective and hepatotoxic effects of geniposide.

MATERIALS AND METHODS

The articles analysed in this meta-analysis were primarily obtained from five databases. The 10-item SYRCLE risk-of-bias tool was used to evaluate the quality of the included articles. STATA (version 15.1) was used to evaluate the total effect or toxicity sizes. In addition, three-dimensional (3D) dose/time-effect and mechanistic analyses were performed to assess the therapeutic and toxic effects of geniposide.

RESULTS

A total of 25 studies involving 479 animals were included. Meta-analysis revealed that geniposide not only significantly (P < 0.001) increased liver injury indices including ALT and AST levels but also improved liver function by decreasing the levels of ALT, AST and inflammatory factors in animal models of liver injury. The 3D dose/time-effect analysis revealed that geniposide administered at a dose of 20-150 mg/kg for 5-28 days effectively protected the liver without inducing toxicity. Mechanistically, geniposide exerts protective or toxic effects by regulating the TNF-α/NF-κB pathway to control oxidative stress and inflammatory responses.

CONCLUSION

Geniposide exhibits dual pharmacological activity in liver injury. It exerts potent hepatoprotective effects when administered at a dose of 20-150 mg/kg for 5-28 days.

Therapeutic potentials of iridoids derived from Rubiaceae against in vitro and in vivo inflammation: A scoping review

Acute inflammation may develop into chronic, life-threatening inflammation-related diseases if left untreated or if there are persistent triggering factors. Cancer, diabetes mellitus, stroke, cardiovascular diseases, and neurodegenerative disorders are some of the inflammation-related diseases affecting millions of people worldwide. Despite that, conventional medical therapy such as non-steroidal anti-inflammatory drugs (NSAIDs) is associated with serious adverse effects; hence, there is an urgent need for a newer and safer therapeutic alternative from natural sources. Iridoids are naturally occurring heterocyclic monoterpenoids commonly found in Rubiaceae plants. Plant extracts from the Rubiaceae family were demonstrated to have medicinal benefits against neurodegeneration, inflammation, oxidative stress, hyperglycaemia, and cancer. However, the therapeutic effects of natural iridoids derived from Rubiaceae as well as their prospective impacts on inflammation in vitro and in vivo have not been thoroughly explored. The databases of PubMed, Scopus, and Web of Science were searched for pertinent articles in accordance with PRISMA-ScR guidelines. A total of 31 pertinent articles from in vitro and in vivo studies on the anti-inflammatory potentials of iridoids from Rubiaceae were identified. According to current research, genipin, geniposide, and monotropein are the most researched iridoids from Rubiaceae that reduce inflammation. These iridoids primarily act by attenuating inflammatory cytokines and mediators via inhibition of the NF-κB signalling pathway in various disease models. A comprehensive overview of the current research on the anti-inflammatory properties of iridoids from the Rubiaceae family is presented in this review, highlighting the characteristics of the experimental models used as well as the mechanisms of action of these iridoids. To develop an alternative therapeutic agent from iridoids, more studies are needed to elucidate the effects and mechanism of action of iridoids in a wide variety of experimental models as well as in clinical studies pertaining to inflammation-related diseases.

Acute and subacute hepatotoxicity of genipin in mice and its potential mechanism

Gardenia, as a medicinal and edible herb, has the pharmacological activity of protecting the liver and cholagogue, but the hepatotoxicity induced by the chemical component genipin (GP) limits its application. The aim of this study was to evaluate the acute and subacute hepatotoxicity of genipin in normal mice and mice with α-naphthalene isothiocyanate (ANIT)-induced liver injury. The results of the acute study showed that the LD50 of genipin was 510 mg/kg. Genipin exhibited hepatotoxicity in normal and jaundiced mice at doses of 125 mg/kg, 250 mg/kg, and 500 mg/kg, which increased with dose. In a 28-day subacute study, the 50 mg/kg and 100 mg/kg dose groups showed some pharmacodynamic effects at 7 days but exhibited hepatotoxicity that increased with time and improved after drug withdrawal. In addition, based on proteomics, the mechanism of liver injury induced by genipin may be related to the disruption of the UDP-glucuronosyltransferase system and cytochrome P450 enzyme activity. In conclusion, this study showed that genipin hepatotoxicity was time- and dose dependent, but it is worth mentioning that hepatotoxicity was reversible. It is hoped that this study will provide a scientific basis for circumventing the adverse effects of genipin.

Geniposide stimulates autophagy by activating the GLP-1R/AMPK/mTOR signaling in osteoarthritis chondrocytes

Osteoarthritis (OA) is a chronic joint disease characterized by cartilage degeneration. Autophagy is associated with chondrocyte homeostasis and exhibits a role in protecting against OA pathogenesis. Geniposide (GEN), an iridoid glycoside extracted from Eucommia ulmoides Oliv, acts as an activator of GLP-1R, which can stimulate autophagy. The AMPK/mTOR signaling pathway participates in the mediation of autophagy, and GLP-1R may act as an upstream factor of AMPK. However, whether GEN mediates the autophagic responses by activating the GLP-1R/AMPK/mTOR signaling pathway in OA chondrocytes is still unclear. In the current study, attenuated autophagy in MIA-induced rat OA models was observed, as shown by up-regulated expression of p62 and down-regulated expression of Beclin-1 and LC3-II/I. GEN stimulated autophagy and protected OA cartilage by up-regulating GLP-1R expression. In addition, GEN could enhance AMPK phosphorylation and down-regulate mTOR expression in IL-1β-treated C28/I2 cells. Inhibition of AMPK or activation of mTOR could reverse the stimulatory effects of GEN on autophagy. Furthermore, a GLP-1R inhibitor Exendin 9-39 could eliminate the chondroprotective effects of GEN by suppressing the AMPK/mTOR signaling pathway. Conclusively, Geniposide exhibits protective effects against osteoarthritis development by stimulating autophagy via activating the GLP-1R/AMPK/mTOR signaling pathway.

Changes in metabolites in raw and wine processed Corni Fructus combination metabolomics with network analysis focusing on potential hypoglycemic effects

Introduction: Corni Fructus (CF) is a Chinese herbal medicine used for medicinal and dietary purposes. It is available commercially in two main forms: raw CF (unprocessed CF) and wine-processed CF. Clinical observations have indicated that wine-processed CF exhibits superior hypoglycemic activity compared to its raw counterpart. However, the mechanisms responsible for this improvement are not well understood. Methods: To address this gap in knowledge, we conducted metabolomics analysis using ultra-performance liquid chromatography-quadrupole/time-of-flight mass spectrometry (UPLC-QTOF-MS) to compare the chemical composition of raw CF and wine-processed CF. Subsequently, network analysis, along with immunofluorescence assays, was employed to elucidate the potential targets and mechanisms underlying the hypoglycemic effects of metabolites in CF. Results: Our results revealed significant compositional differences between raw CF and wine-processed CF, identifying 34 potential markers for distinguishing between the two forms of CF. Notably, wine processing led to a marked decrease in iridoid glycosides and flavonoid glycosides, which are abundant in raw CF. Network analysis predictions provided clues that eight compounds might serve as hypoglycemic metabolites of CF, and glucokinase (GCK) and adenylate cyclase (ADCYs) were speculated as possible key targets responsible for the hypoglycemic effects of CF. Immunofluorescence assays confirmed that oleanolic acid and ursolic acid, two bioactive compounds present in CF, significantly upregulated the expression of GCK and ADCYs in the HepG2 cell model. Discussion: These findings support the notion that CF exerted hypoglycemic activity via multiple components and targets, shedding light on the impact of processing methods on the chemical composition and hypoglycemic activity of Chinese herbal medicine.

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.

Elucidation of Geniposide and Crocin Accumulation and Their Biosysnthsis-Related Key Enzymes during Gardenia jasminoides Fruit Growth

Gardenia jasminoides fruits are extensively grown worldwide, with a large harvest, and its major medicinal ingredients are geniposide and crocins. Research on their accumulation and biosynthsis-related enzymes is rare. In this study, the accumulation of geniposide and crocin of G. jasminoides fruits at different developmental stages were clarified by HPLC. The highest cumulative amount of geniposide was 2.035% during the unripe-fruit period, and the highest content of crocin was 1.098% during the mature-fruit period. Furthermore, transcriptome sequencing was performed. A total of 50 unigenes encoding 4 key enzymes related in geniposide biosynthsis pathways were screened, and 41 unigenes encoding 7 key enzymes in the pathways of crocin were elucidated. It was found that the expression levels of differentially expressed genes of DN67890_c0_g1_i2-encoding GGPS, which is highly related to geniposide biosynthesis, and DN81253_c0_g1_i1-encoding lcyB, DN79477_c0_g1_i2-encoding lcyE, and DN84975_c1_g7_i11-encoding CCD, which are highly related to crocin biosynthesis, were consistent with the accumulation of geniposide and crocin content, respectively. The qRT-PCR results showed that the trends of relative expression were consistent with transcribed genes. This study provides insights for understanding the geniposide and crocin accumulation and biosynthsis during fruit development in G. jasminoides.

Effective Therapeutic Verification of Crocin I, Geniposide, and Gardenia (Gardenia jasminoides Ellis) on Type 2 Diabetes Mellitus In Vivo and In Vitro

For many centuries, Gardenia (Gardenia jasminoides Ellis) was highly valued as a food homologous Chinese herbal medicine with various bioactive compounds, including crocin I and geniposide. However, the functional mechanism underlying the hypoglycemic effect of gardenia is absent in the literature. To evaluate the effect of gardenia and its different extracts on type 2 diabetes mellitus (T2DM) in in vivo and in vitro experiments, the dried gardenia powder was extracted using 60% ethanol and eluted at different ethanol concentrations to obtain the corresponding purified fragments. After that, the active chemical compositions of the different purified gardenia fragments were analyzed using HPLC. Then, the hypoglycemic effects of the different purified gardenia fragments were compared using in vitro and in vivo experiments. Finally, the different extracts were characterized using UPLC-ESI-QTOF-MS/MS and the mass spectrometric fragmentation pathway of the two main compounds, geniposide and crocin I, were identified. The experimental results indicated that the inhibitory effect of the 40% EGJ (crocin I) on the α-glucosidase was better than the 20% EGJ (geniposide) in vitro. However, the inhibitory effect of geniposide on T2DM was better than crocin I in the animal experiments. The different results in vivo and in vitro presumed potentially different mechanisms between crocin I and geniposide on T2DM. This research demonstrated that the mechanism of hypoglycemia in vivo from geniposide is not only one target of the α-glucosidase but provides the experimental background for crocin I and the geniposide deep processing and utilization.

Effects of Ferroptosis on Cardiovascular Diseases

Ferroptosis is a novel form of programmed cell death characterized by the accumulation of iron-dependent lipid peroxides, which causes membrane injury. Under the catalysis of iron ions, cells deficient in glutathione peroxidase (GPX4) cannot preserve the balance in lipid oxidative metabolism, and the buildup of reactive oxygen species on the membrane lipids leads to cell death. An increasing body of evidence suggests that ferroptosis plays a significant role in the development and occurrence of cardiovascular diseases. In this paper, we mainly elaborated on the molecular mechanisms regulating ferroptosis and its impact on cardiovascular disease to lay the groundwork for future studies on the prophylaxis and treatment of this patient population.