Hypericin, a Naphthodianthrone Derivative, Prevents Methylglyoxal-Induced Human Endothelial Cell Dysfunction

Inhibitory effects and mechanisms of phenolic compounds in rapeseed oil on advanced glycation end product formation in chemical and cellular models in vitro

Sinapic acid (SA), canolol (CAO) and canolol dimer (CAO dimer) are the main phenolic compounds in rapeseed oil. However, their possible efficacy against glycation remains unclear. This study aims to explore the impacts of these substances on the formation of advanced glycation end products (AGEs) based on chemical and cellular models in vitro. Based on fluorescence spectroscopy results, three chemical models of BSA-fructose, BSA-methylglyoxal (MGO), and arginine (Arg)-MGO showed that SA/CAO/CAO dimer could effectively reduce AGE formation but with different abilities. After SA/CAO/CAO dimer incubation, effective protection against BSA protein glycation was observed and three different MGO adducts were formed. In MGO-induced HUVEC cell models, only CAO and CAO dimer significantly inhibited oxidative stress and cell apoptosis, accompanied by the regulation of the Nrf2-HO-1 pathway. During the inhibition, 20 and 12 lipid mediators were reversed in the CAO and CAO dimer groups compared to the MGO group.

Effects of Hypericin on Cultured Primary Normal Human Dermal Fibroblasts Under Increased Oxidative Stress

INTRODUCTION

Wound healing is a dynamic process that begins with inflammation, proliferation, and cell migration of a variety of fibroblast cells. As a result, identifying possible compounds that may improve fibroblast cell wound healing capacity is crucial. Hypericin is a natural quinine that has been reported to possess a wide range of pharmacological profiles, including antioxidant and anti-inflammatory, activities. Herein we examined for the first time the effect of hypericin on normal human dermal fibroblasts (NHDFs) under oxidative stress.

METHODS

NHDF were exposed to different concentrations of hypericin (0-20 μg/mL) for 24 h. For the oxidative stress evaluation, H2O2 was used as a stressor factor. Cell viability and proliferation levels were evaluated. Immunohistochemistry and flow cytometry were performed to assess cell apoptosis levels and with confocal microscopy we identified the mitochondrial superoxide production under oxidative stress and after the treatment with hypericin. Scratch assay was performed under oxidative stress to evaluate the efficacy of hypericin in wound closure. To gain an insight into the molecular mechanisms of hypericin bioactivity, we analyzed the relative expression levels of genes involved in oxidative response and in wound healing process.

RESULTS

We found that the exposure of NHDF to hypericin under oxidative stress resulted in an increase in cell viability and ATP levels. We found a decrease in apoptosis and mitochondrial superoxide levels after treatment with hypericin. Moreover, treatment with hypericin reduced wound area and promoted wound closure. The levels of selected genes showed that hypericin upregulated the levels of antioxidants genes. Moreover, treatment with hypericin in wound under oxidative stress downregulated the levels of proinflammatory cytokines, and metalloproteinases; and upregulated transcription factors and extracellular matrix genes.

CONCLUSION

These findings indicated that hypericin possesses significant in vitro antioxidant activity on NHDF and provide new insights into its potential beneficial role in the management of diabetic ulcers.

Effects of Aronia melanocarpa and Hypericum perforatum aqueous extracts on hexavalent chromium induced toxicity in rat's thyrocytes

BACKGROUND

Hexavalent chromium known as oxidizing agent is able to form reactive oxygen species. Aronia melanocarpa and Hypericum perforatum are two plants known for their antioxidant effects. Our study aimed to establish if CrVI induces apoptosis and structural changes in thyrocytes and if its effect can be counteracted by the administration of both extracts.

MATERIALS AND METHODS

Wistar rats divided in five groups: C - distilled water (DW), Cr - 75 mg/L CrVI in DW for 3 months, Cr 2 - 75 mg/L CrVI in DW for 3 months followed by 1 month DW, CrA - 3 months 75 mg/L CrVI in DW and 1 month Aronia 2.5% extract, CrH - 3 months 75 mg/L CrVI in DW and 1 month Hypericum 2.5% extract. Histological assessment and qRT-PCR for evaluation of BAX and Bcl2 protein levels performed on thyroid samples.

RESULTS

The Cr and Cr2 groups were those with altered cytoarchitecture: increase in the diameter of many thyroid follicles, a decrease in their number, a decrease in the height of the follicular cells. The histological examination of the CrH group revealed almost recovery of structural architecture. The BAX gene levels were higher in the Cr and Cr2 groups indicating the apoptotic activity of chromium. In extract receiving groups the BAX gene expressions were significantly lower, but the lowest level presented the CrH group. Bcl2 gene expression levels indicate antiapoptotic activity being elevated in the Cr group, followed by CrA, Cr2, and CrH groups. The BAX/Bcl2 ratio which significantly increased in the case of the Cr and Cr2 group compared to the groups that were administered the two plant extracts.

CONCLUSION

The results obtained in this study confirm that CrVI has toxic effects on thyroid endocrine cells and H. perforatum has stronger antioxidant properties against the action of hexavalent chromium in thyrocytes than A. melanocarpa.

Continuous-Flow Chemistry and Photochemistry for Manufacturing of Active Pharmaceutical Ingredients

An active pharmaceutical ingredient (API) is any substance in a pharmaceutical product that is biologically active. That means the specific molecular entity is capable of achieving a defined biological effect on the target. These ingredients need to meet very strict limits; chemical and optical purity are considered to be the most important ones. A continuous-flow synthetic methodology which utilizes a continuously flowing stream of reactive fluids can be easily combined with photochemistry, which works with the chemical effects of light. These methods can be useful tools to meet these strict limits. Both of these methods are unique and powerful tools for the preparation of natural products or active pharmaceutical ingredients and their precursors with high structural complexity under mild conditions. This review shows some main directions in the field of active pharmaceutical ingredients' preparation using continuous-flow chemistry and photochemistry with numerous examples of industry and laboratory-scale applications.

Hypericum Genus as a Natural Source for Biologically Active Compounds

Hypericum L. genus plants are distributed worldwide, with numerous species identified throughout all continents, except Antarctica. These plant species are currently used in various systems of traditional medicine to treat mild depression, wounds and burns, diarrhea, pain, fevers, and their secondary metabolites previously shown, and the in vitro and/or in vivo cytotoxic, antimicrobial, anti-inflammatory, antioxidant, antihyperglycemic, and hepatoprotective activities, as well as the acetylcholinesterase and monoamine oxidase inhibitory activities. We conducted a systematic bibliographic search according to the Cochrane Collaboration guidelines to answer the question: "What is known about plants of Hypericum genus as a source of natural products with potential clinical biological activity?" We documented 414 different natural products with confirmed in vitro/in vivo biological activities, and 58 different Hypericum plant species as sources for these natural products. Phloroglucinols, acylphloroglucinols, xanthones, and benzophenones were the main chemical classes identified. The selective cytotoxicity against tumor cells, cell protection, anti-inflammatory, antimicrobial, antidepressant, anti-Alzheimer's, and adipogenesis-inhibition biological activities are described. Acylphloroglucinols were the most frequent compounds with anticancer and cell-protection mechanisms. To date, no work has been published with a full descriptive list directly relating secondary metabolites to their species of origin, plant parts used, extraction methodologies, mechanisms of action, and biological activities.

Endophytes, a Potential Source of Bioactive Compounds to Curtail the Formation–Accumulation of Advanced Glycation End Products: A Review

Endophytes, microorganisms that live in the internal tissues and organs of the plants, are known to produce numerous bioactive compounds, including, at times, some phytochemicals of their host plant. For such reason, endophytes have been quoted as a potential source for discovering bioactive compounds, particularly, of medical interest. Currently, many non-communicable diseases are threatening global human health, noticeably: diabetes, neurodegenerative diseases, cancer, and other ailment related to chronic inflammation and ageing. Intriguingly, the pathogenesis and development of these diseases have been linked to an excessive formation and accumulation of advanced glycation end products (AGEs). AGEs are a heterogeneous group of compounds that can alter the conformation, function, and lifetime of proteins. Therefore, compounds that prevent the formation and consequent accumulation of AGEs (AntiAGEs compounds) could be useful to delay the progress of some chronic diseases, and/or harmful effects of undue AGEs accumulation. Despite the remarkable ability of endophytes to produce bioactive compounds, most of the natural antiAGEs compounds reported in the literature are derived from plants. Accordingly, this work covers 26 plant antiAGEs compounds and some derivatives that have been reported as endophytic metabolites, and discusses the importance, possible advantages, and challenges of using endophytes as a potential source of antiAGEs compounds.

Methylglyoxal induces p53 activation and inhibits mTORC1 in human umbilical vein endothelial cells

Methylglyoxal (MGO), a precursor of advanced glycation end products (AGEs), is regarded as a pivotal mediator of vascular damage in patients with diabetes. We have previously reported that MGO induces transcriptional changes compatible with p53 activation in cultured human endothelial cells. To further substantiate this finding and to explore the underlying mechanisms and possible consequences of p53 activation, we aimed (1) to provide direct evidence for p53 activation in MGO-treated human umbilical vein endothelial cells (HUVECs), (2) to assess putative mechanisms by which this occurs, (3) to analyze down-stream effects on mTOR and autophagy pathways, and (4) to assess the potential benefit of carnosine herein. Exposure of HUVECs to 800 µM of MGO for 5 h induced p53 phosphorylation. This was paralleled by an increase in TUNEL and γ-H2AX positive cells, indicative for DNA damage. Compatible with p53 activation, MGO treatment resulted in cell cycle arrest, inhibition of mTORC1 and induction of autophagy. Carnosine co-treatment did not counteract MGO-driven effects. In conclusion, our results demonstrate that MGO elicits DNA damage and p53 activation in HUVECs, resulting in modulation of downstream pathways, e.g. mTORC1.

Hypericin Induces Apoptosis in AGS Cell Line with No Significant Effect on Normal Cells

It is of great importance to find an effective approach that not only eliminates gastric cancer cells but also do exhibits significant side effect to normal cells. Some studies have shown the effectiveness of hypericin against cancer cells. In this study, we evaluated the anti-cancer effect of Hypericin in the treatment of gastric cancer. In this study, the AGS cell line was exposed to different concentrations of hypericin for 24 and 48 h. Evaluation of cell death was done by MTT assay. The rate of apoptosis was measured by flow cytometry assay using Annexin V/ Propidium Iodide. The expression rate of Bcl2, p53 and Bax genes was evaluated by Real-time PCR test, and immunocytochemistry (ICC) analysis and western blotting was used for further evaluation of p53. MTT assay test showed that hyepricin induces 50% cell death in the concentration of 1 (µg/mL) and 0.5 (µg/mL) at 24 h and 48 h post-treatment, respectively, however no similar effect seen on fibroblast cells. Annexin/PI test revealed that cell apoptosis after exposure to hypericin for 24 h was 74%. Real-time PCR showed that expression level of Bax, p53 and Bax genes increases and Bcl2 gene decreases in AGS cell lines after treatment by hypericin. ICC analysis and western blotting for p53 confirmed these data. The results of this study indicated that hypericin has the potential to be introduced as an effective treatment for gastric cancer. Therefore, it seems that this substance has potential to be utilized as anti-cancer drug.

Hypericin-mediated photodynamic therapy for the treatment of cancer: a review

OBJECTIVES

Hypericin is a polycyclic aromatic naphthodianthrone that occurs naturally. It is also an active ingredient in some species of the genus Hypericum. Emerging evidence suggests that hypericin has attracted great attention as a potential anticancer drug and exhibits remarkable antiproliferative effect upon irradiation on various tumour cells. This paper aims to summarise the anticancer effect and molecular mechanisms modulated by hypericin-medicated photodynamic therapy and its potential role in the cancer treatment.

KEY FINDINGS

Hypericin-medicated photodynamic therapy could inhibit the proliferation of various tumour cells including bladder, colon, breast, cervical, glioma, leukaemia, hepatic, melanoma, lymphoma and lung cancers. The effect is primarily mediated by p38 mitogen-activated protein kinase (MAPK), JNK, PI3K, CCAAT-enhancer-binding protein homologous protein (CHOP)/TRIB3/Akt/mTOR, TRAIL/TRAIL-receptor, c-Met and Ephrin-Eph, the mitochondria and extrinsic signalling pathways. Furthermore, hypericin-medicated photodynamic therapy in conjunction with chemotherapeutic agents or targeted therapies is more effective in inhibiting the growth of tumour cells.

SUMMARY

During the past few decades, the anticancer properties of photoactivated hypericin have been extensively investigated. Hypericin-medicated photodynamic therapy can modulate a variety of proteins and genes and exhibit a great potential to be used as a therapeutic agent for various types of cancer.

Glyoxal and Methylglyoxal as E-cigarette Vapor Ingredients-Induced Pro-Inflammatory Cytokine and Mucins Expression in Human Nasal Epithelial Cells

BACKGROUND

Glyoxal (GO), and methylglyoxal (MGO) are among the most toxic compounds emitted by electronic cigarette (E-cig) and regular tobacco cigarette smoke. Airway diseases presented mucus over production as their major pathophysiologic feature. However, the effects of GO and MGO on pro-inflammatory cytokines and mucin expression in human nasal epithelial cells, as well as the underlying signaling pathway, have not yet been studied.

OBJECTIVE

This study is to determine whether GO and MGO induce pro-inflammatory cytokines, and MUC5AC/5B expression via mitogen-activated protein kinase (MAPK)s and nuclear factor-kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathways.

METHODS

The effect of GO, and MGO on pro-inflammatory cytokines, mucins expression and the signalling pathway of GO and MGO were investigated using water-soluble tetrazolium salt-1, enzyme immunoassays, and immunoblot analysis with specific inhibitors and small interfering RNA.

RESULTS

GO and MGO did not affect cell viability up to 2 mM in human nasal epithelial cells. GO and MGO increased production of pro-inflammatory such as interleukin (IL)-1β and IL-6) and MUC5AC/5B. Additionally, GO and MGO significantly activated extracellular signal-regulated kinase 1/2 (ERK1/2), p38 MAPK, and NF-κB. Whether ERK1/2, p38 MAPK, and NF-κB signaling pathway were involved in GO and MGO-induced production of pro-inflammatory cytokines (IL-1β and IL-6) and MUC5AC/5B, we used specific inhibitors and siRNA transfection. These significantly repressed GO- and MGO-induced expression of pro-inflammatory cytokines (IL-1β and IL-6) and MUC5AC/5B.

CONCLUSIONS

GO and MGO induced pro-inflammatory cytokines and MUC5AC/5B expression via ERK1/2, p38 MAPK, and NF-κB in human nasal epithelial cells. These results suggested that GO and MGO may be involved in mucus hypersecretion-related airway diseases.

Isosamidin from Peucedanum japonicum Roots Prevents Methylglyoxal-Induced Glucotoxicity in Human Umbilical Vein Endothelial Cells via Suppression of ROS-Mediated Bax/Bcl-2

Methylglyoxal (MGO) is a highly reactive metabolite of glucose. Elevated levels of MGO induce the generation of reactive oxygen species (ROS) and cause cell death in endothelial cells. Vascular endothelial cell damage by ROS has been implicated in the progression of diabetic vascular complications, cardiovascular diseases, and atherosclerosis. In this study, the protective effect of isosamidin, isolated from Peucedanum japonicum roots, on MGO-induced apoptosis was investigated using human umbilical vein endothelial cells (HUVECs). Among the 20 compounds isolated from P. japonicum, isosamidin showed the highest effectiveness in inhibiting MGO-induced apoptosis of HUVECs. Pretreatment of HUVECs with isosamidin significantly prevented the generation of ROS and cell death induced by MGO. Isosamidin prevented MGO-induced apoptosis in HUVECs by downregulating the expression of Bax and upregulating the expression of Bcl-2. MGO treatment activated mitogen-activated protein kinases (MAPKs), such as p38, c-Jun N terminal kinase (JNK), and extracellular signal-regulated kinase (ERK). In contrast, pretreatment with isosamidin strongly inhibited the activation of p38 and JNK. Furthermore, isosamidin caused the breakdown of the crosslinks of the MGO-derived advanced glycation end products (AGEs). These findings suggest that isosamidin from P. japonicum may be used as a preventive agent against MGO-mediated endothelial dysfunction in diabetes. However, further study of the therapeutic potential of isosamidin on endothelial dysfunction needs to explored in vivo models.

Protective effects of hypericin against infectious bronchitis virus induced apoptosis and reactive oxygen species in chicken embryo kidney cells

Avian infectious bronchitis virus (IBV), a coronavirus, causes infectious bronchitis leading to enormous economic loss in the poultry industry worldwide. Hypericin (HY) is an excellent compound that has been investigated in antiviral, antineoplastic, and antidepressant. To investigate the inhibition effect of HY on IBV infection in chicken embryo kidney (CEK) cells, 3 different experimental designs: pre-treatment of cells prior to IBV infection, direct treatment of IBV-infected cells, and pre-treatment of IBV prior to cell infection were used. Quantitative real-time PCR (qRT-PCR), immunofluorescence assay (IFA), flow cytometry, and fluorescence microscopy were performed and virus titer was determined by TCID50. The results revealed that HY had a good anti-IBV effect when HY directly treated the IBV-infected cells, and virus infectivity decreased in a dose-dependent manner. Furthermore, HY inhibited IBV-induced apoptosis in CEK cells, and significantly reduced the mRNA expression levels of Fas, FasL, JNK, Bax, Caspase 3, and Caspase 8, and significantly increased Bcl-2 mRNA expression level in CEK cells. In addition, HY treatment could decrease IBV-induced reactive oxygen species (ROS) generation in CEK cells. These results suggested that HY showed potential antiviral activities against IBV infection involving the inhibition of apoptosis and ROS generation in CEK cells.

Effect of Cysteine on Methylglyoxal-Induced Renal Damage in Mesangial Cells

Methylglyoxal (MGO), a highly reactive dicarbonyl compound, is a key precursor of the formation of advanced glycation end products (AGEs). MGO and MGO-AGEs were reportedly increased in patients with diabetic dysfunction, including diabetic nephropathy. The activation of glyoxalase-I (GLO-I) increases MGO and MGO-AGE detoxification. MGO-mediated glucotoxicity can also be ameliorated by MGO scavengers such as N-acetylcysteine (NAC), aminoguanidine (AG), and metformin. In this study, we noted that l-cysteine demonstrated protective effects against MGO-induced glucotoxicity in renal mesangial cells. l-cysteine prevented MGO-induced apoptosis and necrosis, together with a reduction of reactive oxygen species (ROS) production in MES13 cells. Interestingly, l-cysteine significantly reduced MGO-AGE formation and also acted as an MGO-AGE crosslink breaker. Furthermore, l-cysteine treatment accelerated MGO catabolism to D-lactate via the upregulation of GLO-I. The reduction of AGE formation and induction of AGE breakdown, following l-cysteine treatment, further supports the potential use of l-cysteine as an alternative for the therapeutic control of MGO-induced renal complications in diabetes, especially against diabetic nephropathy.

Protective effect of resveratrol on methylglyoxal-induced endothelial dysfunction in aged rats

BACKGROUND

The cardiovascular benefits of resveratrol (RSV) have been well established by previous experimental and clinical studies. The aim of this study was to investigate the effectiveness of RSV administration on the impaired endothelial function induced by methylglyoxal (MGO), and to elucidate the role of endothelial nitric oxide synthase (eNOS) on its protective effect.

METHODS

Aged Wistar rats (80 weeks old, n = 15) were used in this study. The thoracic aorta was isolated and cut into rings for organ culture. Aortic segments of rats were incubated with MGO (420 µM) in the presence or absence of RSV (30 µM) for 4 h (short-term) or 24 h (long-term). Isometric tension studies were performed by an isolated organ bath in response to acetylcholine (ACh, an endothelium-dependent vasodilator) and sodium nitroprusside (SNP, an endothelium-independent vasodilator). Beside, expressions of eNOS and phospho-eNOS (p-eNOS) (Ser 1177) in thoracic aorta rings were evaluated by immunohistochemistry.

RESULTS

Both short-term and long-term MGO incubation significantly inhibited the relaxation response induced by ACh, while the relaxation to SNP was not significantly altered. In addition, eNOS and p-eNOS expressions decreased significantly in arteries incubated with MGO. The impaired endothelial reactivity as well as decreased expressions of eNOS and p-eNOS in MGO-incubated vessels were significantly improved by RSV treatment.

CONCLUSIONS

Endothelium-dependent vasodilatation of the thoracic aorta was significantly inhibited by MGO administration, and RSV may improve vascular endothelial function. The protective effect of RSV against MGO-induced endothelial dysfunction seems to be via increased eNOS expression and activity.