Genipin

Genipin is a cell permeable inhibitor of uncoupling protein 2 (UCP2).

In Vitro:Genipin stimulats glucose uptake in a time- and dose-dependent manner. The maximal effect is achieved at 2 h with a concentration of 10 μM. In myotubes, genipin promotes glucose transporter 4 (GLUT4) translocation to the cell surface, which increases the phosphorylation of insulin receptor substrate-1 (IRS-1), AKT, and GSK3β. Meanwhile, genipin increases ATP levels, closed KATP channels, and then increases the concentration of calcium in the cytoplasm in C2C12 myotubes. Genipin-stimulated glucose uptake could be blocked by both the PI3-K inhibitor wortmannin and calcium chelator EGTA. Moreover, genipin increases the level of reactive oxygen species and ATP in C2C12 myotubes[1]. Genipin increases mitochondrial membrane potential, which then increases ATP levels and closes KATP channels, thereby stimulating insulin secretion in pancreatic β-cells. Genipin activates glucose-excited POMC neurons[2]. Cytochrome c content increases significantly in the cytosol of genipin-treated FaO cells. Activation of caspase-3 and caspase-7 is ultimately responsible for genipin-induced apoptotic process in hepatoma cells. ROS level notably increases in Hep3B cells treated with 200 μM genipin[3].

References:
[1]. Ma C, et al. Genipin stimulates glucose transport in C2C12 myotubes via IRS-1 and calcium- dependent mechanism. J Endocrinol. 2012 Dec 20. [2]. Parton LE, et al. Glucose sensing by POMC neurons regulates glucose homeostasis and is impaired in obesity. Nature. 2007 Sep 13;449(7159):228-32. [3]. Kim BC, et al. Genipin-induced apoptosis in hepatoma cells is mediated by reactive oxygen species/c-Jun NH2-terminal kinase-dependent activation of mitochondrial pathway. Biochem Pharmacol. 2005 Nov 1;70(9):1398-407. [4]. Ye D, et al. Genipin normalizes depression-like behavior induced by prenatal stress through inhibiting DNMT1. Epigenetics. 2018 Mar 9:1-22.

Antithrombotic effect of geniposide and genipin in the mouse thrombosis model.[Pubmed:11745015]

Planta Med. 2001 Dec;67(9):807-10.

Geniposide is one of the constituents of Gardenia fruit (Gardenia jasminoides Ellis, Rubiaceae), which has been used in traditional medicine. Although its anti-inflammatory and antithrombotic effects have been reported, the way it acts is still unclear. We have investigated the effects of geniposide and its metabolite Genipin on thrombogenesis and platelet aggregation. In an in vivo model, geniposide and Genipin significantly (P < 0.05) prolonged the time required for thrombotic occlusion induced by photochemical reaction in the mouse femoral artery. In an in vitro study, both geniposide and Genipin inhibited collagen-induced, but did not inhibit arachidonate-induced, mouse platelet aggregation. However aspirin, a cyclooxygenase inhibitor, inhibited arachidonate-induced platelet aggregation but only partially inhibited the collagen-induced one. We also showed, by measuring PLA(2)-catalyzed arachidonic acid release, that geniposide inhibited phospholipase A(2) (PLA(2)) activity. We conclude that geniposide showed an antithrombotic effect in vivo due to the suppression of platelet aggregation. PLA(2) inhibition by geniposide is one possible anti-platelet mechanism.

Genipin as a novel chemical activator of EBV lytic cycle.[Pubmed:25626372]

J Microbiol. 2015 Feb;53(2):155-65.

Epstein-Barr virus (EBV) is a ubiquitous gammaherpesvirus that causes acute infection and establishes life-long latency. EBV causes several human cancers, including Burkitt's lymphoma, nasopharyngeal and gastric carcinoma. Antiviral agents can be categorized as virucides, antiviral chemotherapeutic agents, and immunomodulators. Most antiviral agents affect actively replicating viruses, but not their latent forms. Novel antiviral agents must be active on both the replicating and the latent forms of the virus. Gardenia jasminoides is an evergreen flowering plant belonging to the Rubiaceae family and is most commonly found growing wild in Vietnam, Southern China, Taiwan, Japan, Myanmar, and India. Genipin is an aglycone derived from an iridoid glycoside called geniposide, which is present in large quantities in the fruit of G. jasminoides. In this study, Genipin was evaluated for its role as an antitumor and antiviral agent that produces inhibitory effects against EBV and EBV associated gastric carcinoma (EBVaGC). In SNU719 cells, one of EBVaGCs, Genipin caused significant cytotoxicity (70 muM), induced methylation on EBV C promoter and tumor suppressor gene BCL7A, arrested cell-cycle progress (S phases), upregulated EBV latent/lytic genes in a dose-dependent manner, stimulated EBV progeny production, activated EBV F promoter for EBV lytic activation, and suppressed EBV infection. These results indicated that Genipin could be a promising candidate for antiviral and antitumor agents against EBV and EBVaGC.

Genipin inhibits UCP2-mediated proton leak and acutely reverses obesity- and high glucose-induced beta cell dysfunction in isolated pancreatic islets.[Pubmed:16753577]

Cell Metab. 2006 Jun;3(6):417-27.

Uncoupling protein 2 (UCP2) negatively regulates insulin secretion. UCP2 deficiency (by means of gene knockout) improves obesity- and high glucose-induced beta cell dysfunction and consequently improves type 2 diabetes in mice. In the present study, we have discovered that the small molecule, Genipin, rapidly inhibits UCP2-mediated proton leak. In isolated mitochondria, Genipin inhibits UCP2-mediated proton leak. In pancreatic islet cells, Genipin increases mitochondrial membrane potential, increases ATP levels, closes K(ATP) channels, and stimulates insulin secretion. These actions of Genipin occur in a UCP2-dependent manner. Importantly, acute addition of Genipin to isolated islets reverses high glucose- and obesity-induced beta cell dysfunction. Thus, Genipin and/or chemically modified variants of Genipin are useful research tools for studying biological processes thought to be controlled by UCP2. In addition, these agents represent lead compounds that comprise a starting point for the development of therapies aimed at treating beta cell dysfunction.

Genipin induces cyclooxygenase-2 expression via NADPH oxidase, MAPKs, AP-1, and NF-kappaB in RAW 264.7 cells.[Pubmed:24296130]

Food Chem Toxicol. 2014 Feb;64:126-34.

Genipin is a compound found in gardenia fruit extract with diverse pharmacological activities. However, the mechanism underlying Genipin-induced cyclooxygenase-2 (COX-2) expression remains unknown. In this study, we investigated the effects of Genipin on COX-2 expression and determined that exposure to Genipin dose-dependently enhanced the production of prostaglandin E2 (PGE2), a major COX-2 metabolite, in RAW 264.7 cells. These effects were mediated by Genipin-induced activation of the COX-2 promoter, as well as AP-1 and NF-kappaB luciferase constructs. Phosphatidylinositol-3-kinase/Akt and MAPKs were also significantly activated by Genipin, and Akt and MAPKs inhibitors (PD98059, SB20358, SP600125, and LY294002) inhibited Genipin-induced COX-2 expression. Moreover, Genipin increased production of the ROS and the ROS-producing NAPDH-oxidase (NOX) family oxidases, NOX2 and NOX3. Inhibition of NADPH with diphenyleneiodonium attenuated ROS production, COX-2 expression and NF-kappaB and AP-1 activation. These results suggest that the molecular mechanism mediating ROS-dependent COX-2 up-regulation and PGE2 production by Genipin involves activation of Akt, MAPKs and AP-1/NF-kappaB.

Genipin cross-linked nanocomposite films for the immobilization of antimicrobial agent.[Pubmed:25140839]

ACS Appl Mater Interfaces. 2014 Sep 10;6(17):15232-42.

Cellulose nanocrystal (CNC) reinforced chitosan based antimicrobial films were prepared by immobilizing nisin on the surface of the films. Nanocomposite films containing 18.65 mug/cm(2) of nisin reduced the count of L. monocytogenes by 6.73 log CFU/g, compared to the control meat samples (8.54 log CFU/g) during storage at 4 degrees C in a Ready-To-Eat (RTE) meat system. Film formulations containing 9.33 mug/cm(2) of nisin increased the lag phase of L. monocytogenes on meat by more than 21 days, whereas formulations with 18.65 mug/cm(2) completely inhibited the growth of L. monocytogenes during storage. Genipin was used to cross-link and protect the activity of nisin during storage. Nanocomposite films cross-linked with 0.05% w/v Genipin exhibited the highest bioactivity (10.89 mug/cm(2)) during the storage experiment, as compared to that of the un-cross-linked films (7.23 mug/cm(2)). Genipin cross-linked films were able to reduce the growth rate of L. monocytogenes on ham samples by 21% as compared to the un-cross-linked films. Spectroscopic analysis confirmed the formation of Genipin-nisin-chitosan heterocyclic cross-linked network. Genipin cross-linked films also improved the swelling, water solubility, and mechanical properties of the nanocomposite films.

Genipin inhibits MMP-1 and MMP-3 release from TNF-a-stimulated human periodontal ligament cells.[Pubmed:25457105]

Biochimie. 2014 Dec;107 Pt B:391-5.

Genipin, the aglycon of geniposide found in gardenia fruit has long been considered for treatment of inflammatory diseases in traditional oriental medicine. Genipin has recently been reported to have some pharmacological functions, such as antimicrobial, antitumor, and anti-inflammatory effects. The aim of this study was to examine whether Genipin could modify matrix metalloproteinase (MMP)-1 and MMP-3, which are related to the destruction of periodontal tissues in periodontal lesion, expression in tumor necrosis factor (TNF)-alpha-stimulated human periodontal ligament cells (HPDLCs). Genipin prevented TNF-alpha-mediated MMP-1 and MMP-3 productions in HPDLCs. Moreover, Genipin could suppress not only extracellular signal-regulated kinase (ERK) and Jun-N-terminal kinase (JNK) phosphorylations but also AMP-activated protein kinase (AMPK) phosphorylation in TNF-alpha-stimulated HPDLCs. Inhibitors of ERK and AMPK could inhibit both MMP-1 and MMP-3 productions. Moreover, we revealed the ERK inhibitor suppressed AMPK phosphorylation in TNF-alpha-stimulated HPDLCs. These data provide a new mechanism through which Genipin could be used for the treatment of periodontal disease to prevent MMPs expression in periodontal lesion.

Genipin, a cross-linking agent, promotes odontogenic differentiation of human dental pulp cells.[Pubmed:25637194]

J Endod. 2015 Apr;41(4):501-7.

INTRODUCTION: The aim of this study was to investigate the effects of Genipin, a natural collagen cross-linking agent, on odontogenic differentiation of human dental pulp cells (hDPCs) because the mechanical properties of collagen allow it to serve as a scaffold for engineering of pulp-dentin complex. Furthermore, the role of extracellular signal-regulated kinase (ERK) was investigated as a mediator of the differentiation. METHODS: The odontogenic differentiation was analyzed by alkaline phosphatase activity, real time-polymerase chain reaction, Western blotting, and alizarin red S staining. The morphologic features of hDPCs cultured in Genipin-treated collagen were evaluated by scanning electron microscopy. For the assessment of mechanical properties of collagen treated with Genipin, the surface roughness and compressive strength were measured. RESULTS: Alkaline phosphatase activity, the expression of odontogenic markers, and mineralized nodule formation increased in the Genipin-treated group. Genipin also activated ERK, and treatment with ERK inhibitor blocked the expression of the markers. The cells cultured in Genipin-treated collagen spread across the substrate and attached in close proximity to one another. The proliferation and differentiation of hDPCs cultured in Genipin-treated collagen were facilitated. The mechanical properties of collagen, such as surface roughness and compressive strength, were increased by treatment with Genipin. CONCLUSIONS: Our results show that Genipin promotes odontogenic differentiation of hDPCs via the ERK signaling pathway. Furthermore, the enhanced mechanical properties of the collagen scaffold induced by Genipin may play important roles in cell fate. Consequently, the application of Genipin might be a new strategy for dentin-pulp complex regeneration.

Induction of angiogenesis using VEGF releasing genipin-crosslinked electrospun gelatin mats.[Pubmed:23863451]

Biomaterials. 2013 Oct;34(31):7754-65.

Rapid and controlled vascularization of engineered tissues remains one of the key limitations in tissue engineering applications. This study investigates the possible use of natural extracellular matrix-like scaffolds made of gelatin loaded with human vascular endothelial growth factor (VEGF), as a bioresorbable platform for long-term release and consequent angiogenic boosting. For this aim, gelatin was firstly electrospun and then cross-linked at two different concentrations (0.1% and 0.5% w/v) by using Genipin, a low toxic agent, in order to fabricate a suitable substrate to be loaded with VEGF. Collected fibers were homogeneous and free of beads, the fibrous structure was retained after cross-linking. Mechanical properties were deeply affected by the chemical treatment showing a different behavior, depending on the testing conditions (i.e., dry or wet state). VEGF release was assessed by means of ELISA assay: a cumulative release of about 90% (0.1% w/v) and 60% (0.5% w/v) at 28 days was measured. Both VEGF loaded mats induced cell viability, endothelial differentiation and showed chemoattractive properties when tested on human mesenchymal stromal cells (hMSCs). In vitro and in vivo angiogenic assays demonstrated that the VEGF loaded mats induced an angiogenic potential in stimulating new vessel formation similar, if not superior, to fresh VEGF. VEGF retains bioactive and pro-angiogenic potential for up to 14 days. The results demonstrated that Genipin cross-linked electrospun gelatin mats loaded with VEGF could be part of a useful strategy to stimulate and induce angiogenesis in tissue engineered applications.