Diallyl disulfide increases rat h-ferritin, L-ferritin and transferrin receptor genes in vitro in hepatic cells and in vivo in liver

Biological Functions of Diallyl Disulfide, a Garlic-Derived Natural Organic Sulfur Compound

Garlic is widely accepted as a functional food and an excellent source of pharmacologically active ingredients. Diallyl disulfide (DADS), a major bioactive component of garlic, has several beneficial biological functions, including anti-inflammatory, antioxidant, antimicrobial, cardiovascular protective, neuroprotective, and anticancer activities. This review systematically evaluated the biological functions of DADS and discussed the underlying molecular mechanisms of these functions. We hope that this review provides guidance and insight into the current literature and enables future research and the development of DADS for intervention and treatment of multiple diseases.

Compounds of plants with activity against SARS-CoV-2 targets

INTRODUCTION

The COVID-19 global pandemic is a public health emergency due to its high virulence and mortality. Many vaccine development studies at clinical trials are currently conducted to combat SARS-CoV-2. Plants are a rich source of phytochemicals with different biological activities, including antiviral activities, which are the focus of many studies.

AREAS COVERED

This review shows compounds of traditional plants listed on RENISUS list have therapeutic properties against SARS-CoV-2 targets.

EXPERT OPINION

The rise of new variants, more pathogenic and virulent, impacts in the increase of mortality from SARS-CoV-2 infection, and thus, the control of the outbreaks of disease remains a global challenge. Other's drug and vaccines development is an essential element in controlling SARS-COV-2. Therefore, it is imperative that approach to tackle this pandemic has to be solidly evidence-informed. It should be noticed that the immune system does play critical roles in fighting viruses. Studies show that T cells levels decreased continuously as the disease progressed. T cell-mediated cellular immune response, probably by immunological memory, is essential for direct virus eradication after infection whilst B cells functions in producing antibodies that neutralize virus.But, have distinct patterns of T cell response exist in different patients, suggesting the possibility of distinct clinical approaches. Efforts are concentrated to elucidate the underlying immunological mechanisms in SARS-CoV-2 pathogenesis and progression for better design of diagnostic, therapeutic and preventive strategies. We seek to identify biomolecules with the potential to act in biomarkers that predict how severe the disease can get. But it is important to warn that the plants that produce the compounds mentioned here should not be used without a physician prescription. Finally, we speculate that these compounds may eventually attract the attention of physicians and researchers to perform tests in specific contexts of SARS-CoV-2 infection, and if they show positive results, be tested in Clinical trials.

A comprehensive understanding about the pharmacological effect of diallyl disulfide other than its anti-carcinogenic activities

Diallyl disulfide (DADS), an oil-soluble sulfur compound that is responsible for the biological effects of garlic, displays numerous biological activities, among which its anti-cancer activities are the most famous ones. In recent years, the pharmacological effects of DADS other than its anti-carcinogenic activities have attracted numerous attentions. For example, it has been reported that DADS can prevent the microglia-mediated neuroinflammatory response and depression-like behaviors in mice. In the cardiovascular system, DADS administration was found to ameliorate the isoproterenol- or streptozotocin-induced cardiac dysfunction via the activation of the nuclear factor E2-related factor 2 (Nrf2) and insulin-like growth factor (IGF)-phosphatidylinositol-3-kinase (PI3K)-protein kinase B (Akt) signaling. DADS administration can also produce neuroprotective effects in animal models of Alzheimer's disease and protect the heart, endothelium, liver, lung, and kidney against cellular or tissue damages induced by various toxic factors, such as the oxidized-low density lipoprotein (ox-LDL), carbon tetrachloride (CCl₄), ethanol, acetaminophen, Cis-Diammine Dichloroplatinum (CisPt), and gentamicin. The major mechanisms of action of DADS in disease prevention and/or treatment include inhibition of inflammation, oxidative stress, and cellular apoptosis. Mechanisms, including the activation of Akt, extracellular signal-regulated kinase 1/2 (ERK1/2), protein kinase A (PKA), and cyclic adenosine monophosphate-response element binding protein (CREB) and the inhibition of histone deacetylases (HDACs), can also mediate the cellular protective effects of DADS in different tissues and organs. In this review, we summarize and discuss the pharmacological effects of DADS other than its anti-carcinogenic activities, aiming to reveal more possibilities for DADS in disease prevention and/or treatment.

Impact of Antioxidant Natural Compounds on the Thyroid Gland and Implication of the Keap1/Nrf2 Signaling Pathway

BACKGROUND

Natural compounds with potential antioxidant properties have been used in the form of food supplements or extracts with the intent to prevent or treat various diseases. Many of these compounds can activate the cytoprotective Nrf2 pathway. Besides, some of them are known to impact the thyroid gland, often with potential side-effects, but in other instances, with potential utility in the treatment of thyroid disorders.

OBJECTIVE

In view of recent data regarding the multiple roles of Nrf2 in the thyroid, this review summarizes the current bibliography on natural compounds that can have an effect on thyroid gland physiology and pathophysiology, and it discusses the potential implication of the Nrf2 system in the respective mechanisms.

METHODS & RESULTS

Literature searches for articles from 1950 to 2018 were performed in PubMed and Google Scholar using relevant keywords about phytochemicals, Nrf2 and thyroid. Natural substances were categorized into phenolic compounds, sulfur-containing compounds, quinones, terpenoids, or under the general category of plant extracts. For individual compounds in each category, respective data were summarized, as derived from in vitro (cell lines), preclinical (animal models) and clinical studies. The main emerging themes were as follows: phenolic compounds often showed potential to affect the production of thyroid hormones; sulfur-containing compounds impacted the pathogenesis of goiter and the proliferation of thyroid cancer cells; while quinones and terpenoids modified Nrf2 signaling in thyroid cell lines.

CONCLUSION

Natural compounds that modify the activity of the Nrf2 pathway should be evaluated carefully, not only for their potential to be used as therapeutic agents for thyroid disorders, but also for their thyroidal safety when used for the prevention and treatment of non-thyroidal diseases.

Biochemical and histological liver changes occurred after iron supplementation and possible remediation by garlic consumption

Iron liver excess is associated to biochemical and histological liver perturbations. Our aim was to know even if fresh garlic consumption can remediate these problems. Three groups of rats were utilized: control group A, iron overload group B and garlic and iron overload group C. Important morphological and biochemical modifications were obtained in group B rats comparatively to control group A. Indeed, body and liver weights and liver iron contents increased, respectively, by 12.5 ± 0.06%; 17 ± 0.25% and 35 ± 0.11% comparatively to controls. Radical cation scavenging ability in liver cytosol of group B rats was significantly low (54 ± 0,1%) in comparison to group A. Garlic consumption allowed the group C to achieve an increase by 46 ± 0,11 and 75 ± 0,14% of total antioxidant capacity comparatively to group A and B rats. For the serum ALAT, ASAT, triglyceride and LDH levels, they increased in iron-treated rats, respectively, by 25 ± 0.21; 15 ± 0.12; 30 ± 0.14 and 22 ± 0.16% comparatively to controls. These perturbations were accompanied by deep histological changes. After food fresh garlic supplementation, we had found a deep regulation of all modified parameters showing a hepatoprotective effect of garlic against iron liver excess. Garlic chemical compounds have curative effects on iron liver excess.

Impact of JNK1, JNK2, and ligase Itch on reactive oxygen species formation and survival of prostate cancer cells treated with diallyl trisulfide

PURPOSE

In our previous study, we demonstrated that diallyl trisulfide (DATS) induced iron-dependent G2-M arrest of prostate cancer cell cycle. Moreover, ferritin degradation and an increase of labile iron pool has been linked to the activation of the JNK signaling axis. In the present work, we extended this study to determine which of the c-jun kinases is responsible for ferritin degradation and the role of iron in DATS-induced cell death. We hypothesized that JNK1 activates Itch ligase which will lead to ferritin ubiquitination, an increase in iron-dependent ROS formation and cell death.

METHODS

PC-3 prostate cancer cells were used in this study. Cell viability, concentration of ROS, labile iron pool, and changes in ferritin and P-Itch and DNA damage were determined.

RESULTS

We observed that DATS induced ferritin degradation through JNK, Itch signaling axis. DATS did not induce neither ROS formation nor increase the LIP in JNK1-DN transfected cells. We also observed that DATS increased JNK-dependent activating phosphorylation of E3ligase Itch. The cells transfected with inactive form of Itch were more resistant against cytotoxicity of DATS and showed lower DATS-induced ferritin degradation. Desferrioxamine a specific iron chelator had no effect neither on cell viability nor DNA damage evaluated by comet assay.

CONCLUSIONS

These results suggest that JNK1-dependent increase in LIP is mediated by Itch ubiquitin ligase.

In vivo treatment by diallyl disulfide increases histone acetylation in rat colonocytes

Diallyl disulfide (DADS) is an organosulfur compound from garlic which exhibits various anticarcinogenic properties including inhibition of tumor cell proliferation. DADS antiproliferative effects were previously associated with an increase in histone acetylation in two human tumor colon cell lines, suggesting that DADS-induced histone hyperacetylation could be one of the mechanisms involved in its protective properties on colon carcinogenesis. The effects of DADS on histone H4 and H3 acetylation levels were investigated in vivo in colonocytes isolated from non-tumoral rat. Administrated by intracaecal perfusion or gavage, DADS increases histone H4 and H3 acetylation in colonocytes. Moreover, data generated using cDNA expression arrays suggest that DADS could modulate the expression of a subset of genes. These results suggest the involvement of histone acetylation in modulation of gene expression by DADS in normal rat colonocytes, which might play a role in its biological effects as well as in its anticarcinogenic properties in vivo.

Induction of H-ferritin synthesis by oxalomalate is regulated at both the transcriptional and post-transcriptional levels

Ferritin gene expression is complex and is controlled at transcriptional level in response to a variety of stimuli such as hormones, cytokines and cAMP. Iron, hemin and several compounds, chemically different, also activate the transcription of the ferritin gene. Ferritin biosynthesis is mainly regulated at post-transcriptional level by iron regulatory proteins (IRP1 and IRP2). We previously reported that oxalomalate, a competitive inhibitor of aconitase, remarkably decreases the IRP1 RNA-binding activity and induces a significant increase of ferritin expression. Here, we examined in cells cultured in presence of OMA the IRP1 intracellular content, ferritin biosynthesis and the transcriptional efficiency of H-ferritin gene promoter. Our results demonstrate a peculiar role of OMA that rapidly inactivates IRP1 without affecting IRP1 protein content and subsequently activates H-ferritin gene transcription leading to an overall increase of ferritin biosynthesis. We conclude that OMA regulates H-ferritin biosynthesis acting early at the post-transcriptional level and later on at transcriptional level.

Nrf2: a potential molecular target for cancer chemoprevention by natural compounds

One of the most prominent strategies of cancer chemoprevention might be protecting cells or tissues against various carcinogens and carcinogenic metabolites derived from exogenous or endogenous sources. This protection could be achieved through the induction of phase 2 detoxifying enzymes and antioxidant enzymes such as glutathione S-transferase, NAD(P)H quinone oxidoreductase 1, and heme oxygenase-1, a process that is mediated mainly by the antioxidant response elements (ARE) within the promoter regions of these genes. Nuclear factor-erythroid 2-related factor 2 (Nrf2), a member of the Cap 'n' collar (CNC) family of basic region-leucine zipper transcription factors, plays a key role in ARE-mediated gene expression. Under normal condition, Nrf2 is sequestered in the cytoplasm by an actin-binding protein, Kelch-like ECH associating protein 1 (Keap1), and upon exposure of cells to inducers such as oxidative stress and certain chemopreventive agents, Nrf2 dissociates from Keap1, translocates to the nucleus, binds to AREs, and transactivates phase 2 detoxifying and antioxidant genes. Several upstream signaling pathways including mitogen-activated protein kinases, protein kinase C, phosphatidylinositol 3-kinase, and transmembrane kinase are implicated in the regulation of Nrf2/ARE activity. Furthermore, many natural chemopreventive agents are known to induce Nrf2/ARE-dependent gene expression, also in part by regulating the turnover of the Nrf2 protein itself. This review discusses our current understanding of the Nrf2/ARE pathway as a potential molecular target for cancer chemoprevention, as well as the feasibility of screening natural compounds for activation of this pathway and as potential cancer preventive agents for human use.

Induction of detoxifying enzymes by garlic organosulfur compounds through transcription factor Nrf2: effect of chemical structure and stress signals

Garlic organosulfur compounds (OSCs) are recognized as a group of potential chemopreventive compounds. It is known that garlic OSCs can modulate drug metabolism systems, especially various phase II detoxifying enzymes, though the mechanism underlying their inductive effect on these enzymes remains largely unknown. In the present study, we investigated the transcriptional levels of NAD(P)H:quinone oxidoreductase 1 (NQO1) and heme oxygenase 1 (HO1) genes, the reporter activity mediated by antioxidant response element (ARE), and the protein level of transcription factor nuclear factor E2-related factor 2 (Nrf2), after administration of three major garlic OSCs--diallyl sulfide (DAS), diallyl disulfide (DADS), and diallyl trisulfide (DATS)--in human hepatoma HepG2 cells. Our results showed that ARE activation and Nrf2 protein accumulation were well correlated with phase II gene expression induction. The structure-activity relationship study indicated that the third sulfur in the structure of OSCs contributed substantially to their bioactivities, and that allyl-containing OSCs were more potent than propyl-containing OSCs. To better understand the signaling events involved in the upregulation of detoxifying enzymes by DATS, ARE activity and Nrf2 protein levels were examined after transient transfection of HepG2 cells with mutant Nrf2, cotreatment with antioxidants, and pretreatment with protein kinase inhibitors. DATS-induced ARE activity was inhibited by dominant-negative Nrf2 Kelch-like ECH-associating protein 1 and constructs. Cotreatment with thiol antioxidants decreased the ARE activity and Nrf2 protein level induced by DATS. Three major mitogen-activated protein kinases (MAPKs)--extracellular signal-regulated protein kinase, c-Jun N-terminal kinase, and p38--were activated by DATS treatment. However, the inhibition of these MAPKs did not affect DATS-induced ARE activity. Pretreatment with various upstream protein kinase inhibitors showed that the protein kinase C pathway was not directly involved in DATS-induced ARE activity, but instead the calcium-dependent signaling pathway appeared to play a role in the DATS-induced cytoprotective effect.

Dietary chemopreventive compounds and ARE/EpRE signaling

Chemoprevention comprises multiple intervention methods using either pharmacological or dietary agents to impede, arrest, or reverse carcinogenesis at various stages. Development of dietary compounds as potential cancer chemopreventive agents is highly desirable, due to their safety, low toxicity, and general acceptance as dietary supplements. In this review, potential application of the dietary detoxifying enzyme inducers for chemoprevention and their relevant signaling events are discussed. Overall, the detoxifying enzyme system plays an important role in determining the final fate of carcinogens/procarcinogens and their subsequent impact on carcinogenesis. Among those positive regulators, phenolic and sulfur-containing compounds are two major classes of dietary detoxifying enzyme inducers. Regulation of many detoxifying enzymes by dietary chemopreventive compounds is mediated by the antioxidant response element (ARE)/electrophile response element (EpRE), which is located in the promoter region of related genes. Transcription factor nuclear factor E2-related factor 2 (Nrf2) binds to the ARE sequence to initiate gene expression. In response to treatments of various detoxifying enzyme inducers, several signal transduction pathways, including the oxidative stress, mitogen-active protein kinase, protein kinase C, and phosphatidylinositol 3-kinase pathways, are activated. The consequences of the activation of these signaling cascades, whether directly or indirectly, lead to the dissociation of Nrf2 from its cytosolic sequester Kelch-like ECH associating protein 1, nuclear translocation, and accumulation of Nrf2 protein in the nucleus, and ultimately increase the expression level of detoxifying enzymes through transcriptional activation of ARE/EpRE in those responsible genes.