Redox cycling of endogenous copper by thymoquinone leads to ROS-mediated DNA breakage and consequent cell death: putative anticancer mechanism of antioxidants

ATPase Copper Transporting Beta (ATP7B) Is a Novel Target for Improving the Therapeutic Efficacy of Docetaxel by Disulfiram/Copper in Human Prostate Cancer

Docetaxel has been the standard first-line chemotherapy for lethal metastatic prostate cancer (mPCa) since 2004, but resistance to docetaxel treatment is common. The molecular mechanisms of docetaxel resistance remain largely unknown and could be amenable to interventions that mitigate resistance. We have recently discovered that several docetaxel-resistant mPCa cell lines exhibit lower uptake of cellular copper and uniquely express higher levels of a copper exporter protein ATP7B. Knockdown of ATP7B by silencing RNAs (siRNA) sensitized docetaxel-resistant mPCa cells to the growth-inhibitory and apoptotic effects of docetaxel. Importantly, deletions of ATP7B in human mPCa tissues predict significantly better survival of patients after their first chemotherapy than those with wild-type ATP7B (P = 0.0006). In addition, disulfiram (DSF), an FDA-approved drug for the treatment of alcohol dependence, in combination with copper, significantly enhanced the in vivo antitumor effects of docetaxel in a docetaxel-resistant xenograft tumor model. Our analyses also revealed that DSF and copper engaged with ATP7B to decrease protein levels of COMM domain-containing protein 1 (COMMD1), S-phase kinase-associated protein 2 (Skp2), and clusterin and markedly increase protein expression of cyclin-dependent kinase inhibitor 1 (p21/WAF1). Taken together, our results indicate a copper-dependent nutrient vulnerability through ATP7B exporter in docetaxel-resistant prostate cancer for improving the therapeutic efficacy of docetaxel.

Mechanism of the antidiabetic action of Nigella sativa and Thymoquinone: a review

Introduction

Long used in traditional medicine, Nigella sativa (NS; Ranunculaceae) has shown significant efficacy as an adjuvant therapy for diabetes mellitus (DM) management by improving glucose tolerance, decreasing hepatic gluconeogenesis, normalizing blood sugar and lipid imbalance, and stimulating insulin secretion from pancreatic cells. In this review, the pharmacological and pharmacokinetic properties of NS as a herbal diabetes medication are examined in depth, demonstrating how it counteracts oxidative stress and the onset and progression of DM.

Methods

This literature review drew on databases such as Google Scholar and PubMed and various gray literature sources using search terms like the etiology of diabetes, conventional versus herbal therapy, subclinical pharmacology, pharmacokinetics, physiology, behavior, and clinical outcomes.

Results

The efficiency and safety of NS in diabetes, notably its thymoquinone (TQ) rich volatile oil, have drawn great attention from researchers in recent years; the specific therapeutic dose has eluded determination so far. TQ has anti-diabetic, anti-inflammatory, antioxidant, and immunomodulatory properties but has not proved druggable. DM's intimate link with oxidative stress, makes NS therapy relevant since it is a potent antioxidant that energizes the cell's endogenous arsenal of antioxidant enzymes. NS attenuates insulin resistance, enhances insulin signaling, suppresses cyclooxygenase-2, upregulates insulin-like growth factor-1, and prevents endothelial dysfunction in DM.

Conclusion

The interaction of NS with mainstream drugs, gut microbiota, and probiotics opens new possibilities for innovative therapies. Despite its strong potential to treat DM, NS and TQ must be examined in more inclusive clinical studies targeting underrepresented patient populations.

Disulfiram Enhances the Antineoplastic Activity and Sensitivity of Murine Hepatocellular Carcinoma to 5-FU via Redox Management

The efficacy of anticancer drug 5-FU is suppressed due to various factors, including severe side effects and decreased insensitivity during prolonged chemotherapy. Elevated endogenous copper (Cu) levels are one of the prominent hallmark features of cancer cells. In the present investigation, this feature was targeted in diethyl nitrosamine-phenobarbital-induced hepatocellular carcinoma (HCC) in a rat model system by an established anticancer drug, 5-FU, co-administered with copper and its chelating agent, disulfiram. After treatment with the test chemicals in HCC-induced rats, blood and liver samples were subjected to biochemical, molecular, and histopathological analyses. The analysis revealed that reactive oxygen species-mediated oxidative stress is the crucial etiological reason for the pathogenesis of HCC in rats, as evidenced by the significantly compromised activity of major antioxidant enzymes and elevated levels of oxidative damaged products with major histological alterations compared to the control. However, the combination of 5-FU with DSF demonstrated a significant improvement in most of the parameters, followed by 5-FU-Cu in the combination-treated groups. The combination treatment improved the histological details and triggered apoptosis in the cancer cells to a remarkable extent, as the levels of cleaved PARP and caspase-3 were significantly higher than those in the HCC rats treated with the drug alone. The present study envisages that manipulating the Cu-level greatly enhances the antineoplastic activity of 5-FU and sensitizes cancer cells to the increased efficacy of the drug.

Advances in research on the relationship between thymoquinone and pancreatic cancer

Pancreatic cancer has one of the worst prognoses among the most common cancers in the world. Its characteristics include a high rate of metastasis and chemotherapeutic resistance, which present major challenges to the medical community. The potential anticancer effects of thymoquinone (TQ), which is the main bioactive compound of the black seeds of the Nigella sativa plant, have recently received widespread attention for their potential use in treating pancreatic cancer. TQ can inhibit cell proliferation, promote cancer cell apoptosis, inhibit cell invasion and metastasis, enhance chemotherapeutic sensitivity, inhibit angiogenesis, and exert anti-inflammatory effects. These anticancer effects predominantly involve the nuclear factor (NF)-κB, phosphoinositide 3 kinase (PI3K)/Akt, Notch, transforming growth factor (TGF)-β, c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK) signaling pathways as well as the regulation of the cell cycle, matrix metallopeptidase (MMP)-9 expression, and pyruvate kinase isozyme type M2 (PKM2) activity. TQ regulates the occurrence and development of pancreatic cancer at multiple levels and through multiple targets that communicate with each other. In this review, we summarize and discuss the analogs and carriers of TQ that have been developed in recent years. Given its multilevel anticancer effects, TQ may become a new therapeutic drug for treating pancreatic cancer in the future. This review presents a brief introduction to the research that has been conducted on TQ in relation to pancreatic cancer to provide a theoretical basis for future studies on the topic.

Cell-penetrating peptide-conjugated copper complexes for redox-mediated anticancer therapy

Metal-based chemotherapeutics like cisplatin are widely employed in cancer treatment. In the last years, the design of redox-active (transition) metal complexes, such as of copper (Cu), has attracted high interest as alternatives to overcome platinum-induced side-effects. However, several challenges are still faced, including optimal aqueous solubility and efficient intracellular delivery, and strategies like the use of cell-penetrating peptides have been encouraging. In this context, we previously designed a Cu(II) scaffold that exhibited significant reactive oxygen species (ROS)-mediated cytotoxicity. Herein, we build upon the promising Cu(II) redox-active metallic core and aim to potentiate its anticancer activity by rationally tailoring it with solubility- and uptake-enhancing functionalizations that do not alter the ROS-generating Cu(II) center. To this end, sulfonate, arginine and arginine-rich cell-penetrating peptide (CPP) derivatives have been prepared and characterized, and all the resulting complexes preserved the parent Cu(II) coordination core, thereby maintaining its reported redox capabilities. Comparative in vitro assays in several cancer cell lines reveal that while specific solubility-targeting derivatizations (i.e., sulfonate or arginine) did not translate into an improved cytotoxicity, increased intracellular copper delivery via CPP-conjugation promoted an enhanced anticancer activity, already detectable at short treatment times. Additionally, immunofluorescence assays show that the Cu(II) peptide-conjugate distributed throughout the cytosol without lysosomal colocalization, suggesting potential avoidance of endosomal entrapment. Overall, the systematic exploration of the tailored modifications enables us to provide further understanding on structure-activity relationships of redox-active metal-based (Cu(II)) cytotoxic complexes, which contributes to rationalize and improve the design of more efficient redox-mediated metal-based anticancer therapy.

Chemopreventive Efficacy of Thymoquinone in Chemically Induced Urinary Bladder Carcinogenesis in Rat

The effects of thymoquinone (TQ) in a carcinogen-based models of urinary bladder cancer were evaluated, using 45 male rats in five groups. In negative control ( $n=10$ ), only tap water was given. In positive control ( $n=10$ ), the rats received 0.05% N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) in drinking water for 9 weeks. In preventive groups with 25 mg/kg ( $n=10$ ) and 50 mg/kg ( $n=10$ ), oral TQ was concurrently given with 0.05% BBN for 9 weeks and continued for one more week after cessation of BBN. Preventive-treatment group ( $n=5$ ) received 50 mg/kg TQ orally for 20 weeks. Five rats from each group were sequentially sacrificed in two phases: the induction phase at 12th week (except the last group) and the rest in postinduction phase at 20th week. The bladders were examined macroscopically for lesion formation, and the masses were submitted for histopathological evaluation. Markers for total oxidant status (TOS), inflammation (nuclear factor kappa B (NF-κB)), and angiogenesis (vascular endothelial growth factor (VEGF)) were also assessed. There was a reduced number of bladder lesions in the TQ groups versus the carcinogen group at both phases. Histopathological findings demonstrated a significant improvement in the abnormal morphological changes in the urothelium of the TQ-treated groups. Thymoquinone exerted a significant antioxidant and anti-inflammatory effect by a decrease in serum level of TOS and NF-κB at week 12 which was maintained low in phase two at week 20. The serum level of VEGF was also alleviated in the induction phase at week 12 and maintained low in postinduction period. In TQ preventive-treatment approach, a nonsignificant elevation of serum level of TOS and NF-κB and slight reduction in VEGF were observed at the end of the experiment. These data suggest that TQ may be effective in preventing bladder carcinogenesis, and the suggested mechanisms might be related to antioxidant, prooxidant, and anti-inflammatory properties of TQ.

The effects of thymoquinone on pancreatic cancer and immune cells

OBJECTIVES:

Black cumin is widely used as a spice and as a traditional treatment. The active ingredient in black cumin seeds is thymoquinone. Thymoquinone has shown anticancer effects in some cancers. We planned to investigate its anticancer effect on pancreatic cancer cell lines.

METHODS:

Thymoquinone chemical component in various doses was prepared and inoculated on pancreatic cancer cell culture, healthy mesenchymal stem cells, and peripheral blood mononuclear cell culture. IC50 values were calculated by absorbance data and measuring cell viability by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide staining of cells incubated with thymoquinone at 24, 48, and 72 h.

RESULTS:

There was dose-related cytotoxicity. Maximal cytotoxicity was observed at 24 h and 100 μM thymoquinone concentrations in pancreatic cancer cell culture and mesenchymal stem cells. Any concentration of thymoquinone was not cytotoxic to peripheral blood mononuclear cell. Thymoquinone even caused proliferation at a concentration of 6.25 μM.

CONCLUSIONS:

Since the cytotoxic concentration of thymoquinone on pancreatic cancer cell culture and mesenchymal stem cells is the same, it is not appropriate to use thymoquinone to achieve cytotoxicity in pancreatic cancer. However, since thymoquinone provides proliferation in peripheral blood mononuclear cell at a noncytotoxic dose, it may have an immune activator effect. Therefore, in vivo studies are needed to investigate the effect of thymoquinone on the immune system.

Water soluble transition metal [Ni(II), Cu(II) and Zn(II)] complexes of N-phthaloylglycinate bis(1,2-diaminocyclohexane). DNA binding, pBR322 cleavage and cytotoxicity

To validate the effect of metal ions in analogous ligand scaffolds on DNA binding and cytotoxic response, we have synthesized a series of water-soluble ionic N-phthaloylglycinate conjugated bis(diaminocyclohexane)M²⁺ complexes where M = Ni(II), Cu(II) and Zn(II) (1-3). The structural characterization of the complexes (1-3) was achieved by spectroscopic {FT-IR, EPR, UV-vis absorption data, ¹H NMR, ESI-MS and elemental analysis} and single crystal X-ray diffraction studies, which revealed different topologies for the late 3d-transition metals. The Ni(II) and Zn(II) complexes exhibited an octahedral geometry with coordinated labile water molecules in the P1̄ space group while the Cu(II) complex revealed a square planar geometry with the P2₁/c space lattice. In vitro DNA-complexation studies were performed employing various complementary biophysical methods to quantify the intrinsic binding constant K_b and K_sv values and to envisage the binding modes and binding affinity of (1-3) at the therapeutic targets. The corroborative results of these experiments revealed a substantial geometric and electronic effect of (1-3) on DNA binding and the following inferences were observed, (i) high K_b and K_sv values, (ii) remarkable cleavage efficiency via an oxidative pathway, (iii) condensation behavior and (iv) good cytotoxic response to HepG2 and PTEN-caP8 cancer cell lines, with copper(II) complex 2 outperforming the other two complexes as a most promising anticancer drug candidate. Copper(II) complexes have been proven in the literature to be good anticancer drug entities, displaying inhibition of uncontrolled-cell growth by multiple pathways viz., anti-angiogenesis, inducing apoptosis and reactive oxygen species mediated cell death phenomena. Nickel(II) and zinc(II) ionic complexes 1 and 3 have also demonstrated good chemotherapeutic potential in vitro and the bioactive 1,2-diaminocyclohexane fragment in these complexes plays an instrumental role in anticancer activity.

GSH Protects the Escherichia coli Cells from High Concentrations of Thymoquinone

The aim of the present study was to evaluate the potential protective effect of glutathione (GSH) on Escherichia coli cells grown in a high concentration of thymoquinone (TQ). This quinone, as the main active compound of Nigella sativa seed oil, exhibits a wide range of biological activities. At low concentrations, it acts as an antioxidant, and at high concentrations, an antimicrobial agent. Therefore, any interactions between thymoquinone and glutathione are crucial for cellular defense against oxidative stress. In this study, we found that GSH can conjugate with thymoquinone and its derivatives in vitro, and only fivefold excess of GSH was sufficient to completely deplete TQ and its derivatives. We also carried out studies on cultures of GSH-deficient Escherichia coli strains grown on a minimal medium in the presence of different concentrations of TQ. The strains harboring mutations in gene ΔgshA and ΔgshB were about two- and fourfold more sensitive (256 and 128 µg/mL, respectively) than the wild type. It was also revealed that TQ concentration has an influence on reactive oxygen species (ROS) production in E. coli strains—at the same thymoquinone concentration, the level of ROS was higher in GSH-deficient E. coli strains than in wild type.

Optical Detection of Copper Ions via Structural Dissociation of Plasmonic Sugar Nanoprobes

Heavy metal ions are known to cause environmental pollution and several human diseases because of their inherent toxicity. Among them, Cu²⁺ is an essential element for the human body, but its continuous exposure and accumulation may cause adverse effects. Thus, copper ion levels in aquatic environments are strictly regulated by international standards. Herein, we demonstrate a simple optical method for detecting Cu²⁺ using plasmonic sugar nanoprobes (PSNs) composed of gold nanoparticles and polysaccharides. Gold precursors were reduced to nanoparticles and spontaneously embedded in the sugar-based polymeric network with the sulfated residues of carrageenan during the polymerization procedure. Owing to the abundant functional residues of PSNs and their affinity toward Cu²⁺, we observed the Cu²⁺-mediated preferential dissociation of the PSNs, resulting in absorbance spectral shifts and scattering shifts of the PSNs. Based on these plasmon band shifts, Cu²⁺ below the EPA regulation level of 20 μM can be easily detected by the optimized experimental condition. Additionally, the reaction mechanism between the PSNs and Cu²⁺ was elucidated by indepth spectroscopic analyses, which revealed that the increased binding of Cu²⁺ to the sulfate groups in the PSNs induces the eventual decomposition of the PSNs.

Therapeutic Potential of Certain Terpenoids as Anticancer Agents: A Scoping Review

Cancer is a life-threatening disease and is considered to be among the leading causes of death worldwide. Chemoresistance, severe toxicity, relapse and metastasis are the major obstacles in cancer therapy. Therefore, introducing new therapeutic agents for cancer remains a priority to increase the range of effective treatments. Terpenoids, a large group of secondary metabolites, are derived from plant sources and are composed of several isoprene units. The high diversity of terpenoids has drawn attention to their potential anticancer and pharmacological activities. Some terpenoids exhibit an anticancer effect by triggering various stages of cancer progression, for example, suppressing the early stage of tumorigenesis via induction of cell cycle arrest, inhibiting cancer cell differentiation and activating apoptosis. At the late stage of cancer development, certain terpenoids are able to inhibit angiogenesis and metastasis via modulation of different intracellular signaling pathways. Significant progress in the identification of the mechanism of action and signaling pathways through which terpenoids exert their anticancer effects has been highlighted. Hence, in this review, the anticancer activities of twenty-five terpenoids are discussed in detail. In addition, this review provides insights on the current clinical trials and future directions towards the development of certain terpenoids as potential anticancer agents.

Identification of Ascorbic Acid and Gallic Acid as Novel Inhibitors of Secreted Frizzled-Related Protein for the Treatment of Obesity-Induced Type 2 Diabetes

Type 2 diabetes mellitus (T2D) has been reported as major public health issue rising at an alarming rate worldwide, and obesity is the leading risk factor for the development of T2D. Secreted frizzled-related protein 4 (SFRP4) released with inflammatory mediators from adipose tissues constrains the exocytosis of insulin containing granules from the pancreatic islets that leads towards the development to T2D. The significant overexpression of SFRP4 in diabetic patients and its involvement in islet dysfunction suggest its critical role in the development of diabetes. Thus, this study was designed to explore the potential of ascorbic acid (AA) and gallic acid (GA) against SFRP4 for the treatment of diabetes. Molecular docking approach was used for the prediction of binding interactions of AA and GA at the active pocket of SFRP4. Docking analysis indicated strong binding interactions of AA and GA to the amino acid residues at the active site of SFRP4. A significant reduction in the level of SFRP4 was observed in transfected cells treated with AA and GA. For the evaluation of the cytotoxicity of AA and GA against HepG2 cells, MTT assay was performed. The results of MTT assay demonstrated that AA and GA are non-cytotoxic towards HepG2 cells at concentration of 15 μM. The oral administration of AA and GA to diet-induced obese mice caused significant reduction in body weight, blood glucose level, and SFRP4 expression. The results of this study suggest that AA and GA have potential for the treatment of obesity-induced T2D.

Thymoquinone Ameliorate Hepatorenal Toxicity Associated With Propylthiouracil-Induced Hypothyroidism in Juvenile Rats

BACKGROUND

An increasing number of studies suggest that hypothyroidism may lead to hepatorenal toxicity. This study examined whether thymoquinone (TQ), the main active Nigella sativa constituent, could prevent the detrimental influences of hepatorenal toxicity of hypothyroidism during the juvenile period in rats.

METHODS

The male rats were randomly divided into four groups (n = 7), including control, propylthiouracil (PTU), PTU-TQ 5 mg/kg, and PTU-TQ 10 mg/kg. PTU was dissolved in drinking water at a concentration of 0.05% and administered for six weeks. In the PTU-TQ5 and PTU-TQ10 groups, animals received PTU plus 5 mg/kg and 10 mg/kg of the TQ (i.p.) for six weeks, respectively. The rats were evaluated after TQ treatment by measuring serum markers of liver and kidney function tests as well as oxidative stress biomarkers in liver and kidney tissues.

RESULTS

Administration of TQ (5 and 10 mg/kg) decreased oxidative stress damage in liver and kidney tissue in hypothyroidism rats with improvement in activities of antioxidant enzymes and a decrease in MDA in both liver and kidney homogenates. Furthermore, TQ treatment significantly inhibited the elevation of serum biochemical markers of liver and kidney function associated with this hepatorenal toxicity.

CONCLUSION

These results suggest that the protective effect of TQ in hypothyroidism-induced hepatorenal toxicity in rats is attributed to its ability to reduce oxidative stress in hepatic and renal tissues. However, more studies are recommended to investigate the exact mechanism (s) for the effect of TQ on hepatorenal outcomes of hypothyroidism in human subjects.

Concurrent Reactive Oxygen Species Generation and Aneuploidy Induction Contribute to Thymoquinone Anticancer Activity

Thymoquinone (TQ) is the main biologically active constituent of Nigella sativa. Many studies have confirmed its anticancer actions. Herein, we investigated the different anticancer activities of, and considered resistance mechanisms to, TQ. MTT and clonogenic data showed TQ’s ability to suppress breast MDA-MB-468 and T-47D proliferation at lower concentrations compared to other cancer and non-transformed cell lines tested (GI₅₀ values ≤ 1.5 µM). Flow-cytometric analyses revealed that TQ consistently induced MDA-MB-468 and T-47D cell-cycle perturbation, specifically inducing pre-G1 populations. In comparison, less sensitive breast MCF-7 and colon HCT-116 cells exhibited only transient increases in pre-G1 events. Annexin V/PI staining confirmed apoptosis induction in MDA-MB-468 and HCT-116 cells, which was continuous in the former and transient in the latter. Experiments revealed the role of reactive oxygen species (ROS) generation and aneuploidy induction in MDA-MB-468 cells within the first 24 h of treatment. The ROS-scavenger NAD(P)H dehydrogenase (quinone 1) (NQO1; DT-diaphorase) and glutathione (GSH) were implicated in resistance to TQ. Indeed, western blot analyses showed that NQO1 is expressed in all cell lines in this study, except those most sensitive to TQ-MDA-MB-468 and T-47D. Moreover, TQ treatment increased NQO1 expression in HCT-116 in a concentration-dependent fashion. Measurement of GSH activity in MDA-MB-468 and HCT-116 cells found that GSH is similarly active in both cell lines. Furthermore, GSH depletion rendered these cells more sensitive to TQ’s antiproliferative actions. Therefore, to bypass putative inactivation of the TQ semiquinone metabolite, the benzylamine analogue was designed and synthesised following modification of TQ’s carbon-3 atom. However, the structural modification negatively impacted potency against MDA-MB-468 cells. In conclusion, we disclose the following: (i) The anticancer activity of TQ may be a consequence of ROS generation and aneuploidy; (ii) Early GSH depletion could substantially enhance TQ’s anticancer activity; (iii) Benzylamine substitution at TQ’s carbon-3 failed to enhance anticancer activity.

Apoptotic and Non-Apoptotic Modalities of Thymoquinone-Induced Lymphoma Cell Death: Highlight of the Role of Cytosolic Calcium and Necroptosis

Simple Summary

Diffuse large B cell lymphoma (DLBCL) represents the most common type of non-Hodgkin lymphoma with a high curability rate. However, 40% of patients will relapse or exhibit refractory disease, and compromised apoptotic pathways is among the prognosis-worsening factors. Therefore, drugging non-apoptotic modalities might be therapeutically promising. Thymoquinone (TQ) has been reported to promote apoptosis in cancer cells. Herein, we show that TQ selectively kills DLBCL cells, either cell lines or primary lymphoma cells bearing resistance features to standard treatment. Investigations show that, although TQ induced apoptotic markers, non-apoptotic death was the major mechanism responsible for TQ-induced cellular demise. We demonstrate critical and selective roles of cytosolic calcium and necroptosis in TQ-induced non-apoptotic cell death. Finally, TQ exhibits an improved selectivity profile over conventional chemotherapy. Collectively, this work provides new insights into the mode of action of TQ and points to the therapeutic relevance of non-apoptotic modalities as a fail-safe mechanism for pro-apoptotic DLBCL therapies.

Abstract

Targeting non-apoptotic modalities might be therapeutically promising in diffuse large B cell lymphoma (DLBCL) patients with compromised apoptotic pathways. Thymoquinone (TQ) has been reported to promote apoptosis in cancer cells, but little is known about its effect on non-apoptotic pathways. This work investigates TQ selectivity against DLBCL cell lines and the cell death mechanisms. TQ reduces cell viability and kills cell lines with minimal toxicity on normal hematological cells. Mechanistically, TQ promotes the mitochondrial caspase pathway and increases genotoxicity. However, insensitivity of most cell lines to caspase inhibition by z-VAD-fmk (benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone) pointed to a critical role of non-apoptotic signaling. In cells dying through non-apoptotic death, TQ increases endoplasmic reticulum (ER) stress markers and substantially increases cytosolic calcium ([Ca²⁺]_c) through ER calcium depletion and activation of store-operated calcium entry (SOCE). Chelation of [Ca²⁺]_c, but not SOCE inhibitors, reduces TQ-induced non-apoptotic cell death, highlighting the critical role of calcium in a non-apoptotic effect of TQ. Investigations showed that TQ-induced [Ca²⁺]_c signaling is primarily initiated by necroptosis upstream to SOCE, and inhibition necroptosis by necrostatin-1 alone or with z-VAD-fmk blocks the cell death. Finally, TQ exhibits an improved selectivity profile over standard chemotherapy agents, suggesting a therapeutic relevance of the pro-necroptotic effect of TQ as a fail-safe mechanism for DLBCL therapies targeting apoptosis.

Recent Findings on Thymoquinone and Its Applications as a Nanocarrier for the Treatment of Cancer and Rheumatoid Arthritis

Cancer causes a considerable amount of mortality in the world, while arthritis is an immunological dysregulation with multifactorial pathogenesis including genetic and environmental defects. Both conditions have inflammation as a part of their pathogenesis. Resistance to anticancer and disease-modifying antirheumatic drugs (DMARDs) happens frequently through the generation of energy-dependent transporters, which lead to the expulsion of cellular drug contents. Thymoquinone (TQ) is a bioactive molecule with anticancer as well as anti-inflammatory activities via the downregulation of several chemokines and cytokines. Nevertheless, the pharmacological importance and therapeutic feasibility of thymoquinone are underutilized due to intrinsic pharmacokinetics, including short half-life, inadequate biological stability, poor aqueous solubility, and low bioavailability. Owing to these pharmacokinetic limitations of TQ, nanoformulations have gained remarkable attention in recent years. Therefore, this compilation intends to critically analyze recent advancements in rheumatoid arthritis and cancer delivery of TQ. This literature search revealed that nanocarriers exhibit potential results in achieving targetability, maximizing drug internalization, as well as enhancing the anti-inflammatory and anticancer efficacy of TQ. Additionally, TQ-NPs (thymoquinone nanoparticles) as a therapeutic payload modulated autophagy as well as enhanced the potential of other drugs when given in combination. Moreover, nanoformulations improved pharmacokinetics, drug deposition, using EPR (enhanced permeability and retention) and receptor-mediated delivery, and enhanced anti-inflammatory and anticancer properties. TQ's potential to reduce metal toxicity, its clinical trials and patents have also been discussed.

Nutritional Value and Preventive Role of Nigella sativa L. and Its Main Component Thymoquinone in Cancer: An Evidenced-Based Review of Preclinical and Clinical Studies

In recent times, scientific attention has been paid to different foods and their bioactive components for the ability to inhibit the onset and progress of different types of cancer. Nigella sativa extract, powder and seed oil and its main components, thymoquinone and α-hederin, have showed potent anticancer and chemosensitizing effects against various types of cancer, such as liver, colon, breast, renal, cervical, lung, ovarian, pancreatic, prostate and skin tumors, through the modulation of various molecular signaling pathways. Herein, the purpose of this review was to highlight the anticancer activity of Nigella sativa and it constitutes, focusing on different in vitro, in vivo and clinical studies and projects, in order to underline their antiproliferative, proapoptotic, cytotoxic and antimetastatic effects. Particular attention has been also given to the synergistic effect of Nigella sativa and it constitutes with chemotherapeutic drugs, and to the synthesized analogs of thymoquinone that seem to enhance the chemo-sensitizing potential. This review could be a useful step towards new research on N. sativa and cancer, to include this plant in the dietary treatments in support to conventional therapies, for the best achievement of therapeutic goals.

Synthesis, Photoisomerization, Antioxidant Activity, and Lipid-Lowering Effect of Ferulic Acid and Feruloyl Amides

The Ugi four-component reaction employing naturally occurred ferulic acid (FA) is proposed as a convenient method to synthesize feruloyl tertiary amides. Applying this strategy, a peptoid-like derivative of ferulic acid (FEF77) containing 2 additional hydroxy-substituted aryl groups, has been synthesized. The influence of the configuration of the double bond of ferulic acid and feruloyl amide on the antioxidant activity has been investigated thanks to light-mediated isomerization studies. At the cellular level, both FA, trans and cis isomers of FEF77 were able to protect human endothelial cord vein (HECV) cells from the oxidative damage induced by exposure to hydrogen peroxide, as measured by cell viability and ROS production assays. Moreover, in steatotic FaO rat hepatoma cells, an in vitro model resembling non-alcoholic fatty liver disease (NAFLD), the molecules exhibited a lipid-lowering effect, which, along with the antioxidant properties, points to consider feruloyl amides for further investigations in a therapeutic perspective.

Causing DNA damage and stopping DNA repair - Vitamin D supplementation with Poly(ADP-ribose) polymerase 1 (PARP1) inhibitors may cause selective cell death of cancer cells: A novel therapeutic paradigm utilizing elevated copper levels within the tumour

Inhibitors of PARP1 are currently being used to treat malignancies and as maintenance drugs post chemotherapy. Vitamin D has been shown to have an anticancer effect (mediated by multiple mechanisms) and is usually deficient in cancer patients. We had previously proposed and experimentally validated the selective cell death of cancer cells caused due to interaction of vitamin D with elevated copper within malignant cells, leading to ROS mediated DNA damage. In this communication we propose a Vitamin D supplementation strategy with PARP1 inhibitor treatment which would have multifaceted benefits for therapy. Besides exerting its anticancer effects by other mechanisms and addressing the deficiency, Vitamin D in principle would cause selective ROS mediated DNA breakage in malignant cells, while sparing healthy non malignant cells. Since Vitamin D is also a known inhibitor of PARP1, this therapeutic strategy would push the malignant cells to apoptosis due to DNA breakage via the vitamin D-copper mechanism, in addition to inhibiting DNA repair. Since the available levels copper within normal cells are several fold less as compared to malignant cells, the normal cells would be spared of the Vitamin D induced, ROS mediated DNA damage and would be less likely to die due to PARP1 inhibition.

Effect of Nigella sativa L. supplementation on inflammatory and oxidative stress indicators: A systematic review and meta-analysis of controlled clinical trials

AIMS

The objective of the present study was to perform a systematic review and meta-analysis on randomized controlled trials (RCTs) assessing the effects of Nigella sativa L. supplementation on the circulating inflammatory and oxidative stress markers, including C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), total antioxidant capacity (TAC) and malondialdehyde (MDA).

METHODS

Systematic search was performed up to March 2020 using PubMed, Scopus, and ISI web of science databases. Two reviewers independently assessed study eligibility, extracted data, and evaluated methodological quality of included primary studies. Statistical heterogeneity was assessed using I-square (I²) statistic. Data were pooled by using the random-effect model and standardized mean difference (SMD) was considered as the summary effect size.

RESULTS

Twelve trials were identified to be suitable for our meta-analysis. The pooled results using random effects model indicated that Nigella sativa supplementation significantly reduced CRP (SMD: -0.35; 95% CI: -0.59, -0.12, P < 0.001, I² = 10.5%) and MDA concentrations (SMD: -0.56; 95% CI: -0.98, -0.15, P < 0.001, I² = 64.7%). Moreover, Nigella sativa supplementation increased TAC (SMD: 0.48; 95% CI: 0.09, 0.87, P = 0.01, I² = 65.6%) levels; however, it did not affect TNF-α (SMD: -0.35; 95% CI: -0.70, 0.01, P = 0.05, I² = 58.2%).

CONCLUSION

Nigella sativa supplementation is associated with improved inflammation and oxidative status. Additional prospective studies are recommended using higher supplementation doses and longer intervention period.

Chemopreventive and Anticancer Effects of Thymoquinone: Cellular and Molecular Targets

Thymoquinone (TQ) is a bioactive component derived from the seeds of Nigella sativa that are commonly as black cumin. Evidences indicate that the medicinal properties of TQ have been recognized for more than 2000 years. TQ has been shown to possess potent chemopreventive properties that include anti-inflammatory and anti-neoplastic activities. Recent studies have unraveled the multiple mechanisms through which TQ exerts its chemopreventive and anticancer activity in different cancer cells in a contextual manner. The present review aims to provide a brief compendium on the molecular mechanisms through which TQ inhibits signaling pathways underlying cancer genesis, progression, and metastasis.

Small molecules regulating reactive oxygen species homeostasis for cancer therapy

Elevated intracellular reactive oxygen species (ROS) and antioxidant defense systems have been recognized as one of the hallmarks of cancer cells. Compared with normal cells, cancer cells exhibit increased ROS to maintain their malignant phenotypes and are more dependent on the "redox adaptation" mechanism. Thus, there are two apparently contradictory but virtually complementary therapeutic strategies for the regulation of ROS to prevent or treat cancer. The first strategy, that is, chemoprevention, is to prevent or reduce intracellular ROS either by suppressing ROS production pathways or by employing antioxidants to enhance ROS clearance, which protects normal cells from malignant transformation and inhibits the early stage of tumorigenesis. The second strategy is the ROS-mediated anticancer therapy, which stimulates intracellular ROS to a toxicity threshold to activate ROS-induced cell death pathways. Therefore, targeting the regulation of intracellular ROS-related pathways by small-molecule candidates is considered to be a promising treatment for tumors. We herein first briefly introduce the source and regulation of ROS, and then focus on small molecules that regulate ROS-related pathways and show efficacy in cancer therapy from the perspective of pharmacophores. Finally, we discuss several challenges in developing cancer therapeutic agents based on ROS regulation and propose the direction of future development.

Redox cycling of copper by coumarin-di(2-picolyl)amine hybrid molecule leads to ROS-mediated modulation of redox scavengers, DNA damage and cell death in diethylnitrosamine induced hepatocellular carcinoma

Targeted therapy is a new strategy for cancer treatment that targets chemical entities specific to cancer cells than normal ones. One of the features associated with malignancy is the elevated copper which plays an integral role in angiogenesis. Work is in progress in our lab to identify new copper chelators to target elevated copper under targeted therapy for the killing of cancer cells. Recently, a coumarin-based copper chelator, di(2-picolyl)amine-3(bromoacetyl)coumarin hybrid molecule (ligand-L) has been synthesized by us, and also studied its copper-dependent macromolecular damage response in copper overloaded lymphocytes. The present study investigates the anticancer activity of ligand-L and its mode of action in rat model of diethylnitrosamine (DEN) induced hepatocellular carcinoma. It has been found that liver tissue has a marked increase in copper levels in DEN induced hepatocellular carcinoma. Ex vivo results showed that ligand-L inhibited cell viability, induced reactive oxygen species (ROS) generation, DNA damage, loss of mitochondrial membrane potential and caspase-3 activation in isolated hepatocellular carcinoma cells (HCC). All these effects induced by ligand-L were abrogated by neocuproine and N-acetylcysteine (ROS scavenger). Further, ligand-L treatment of animals bearing hepatocellular carcinoma results in an increment in the cellular redox scavengers, lipid peroxidation and DNA breakage in malignant hepatocytes. In vivo studies using ligand-L also showed that ligand-L possesses anticancer properties as evidenced by improvement in liver marker enzymes and liver surface morphology, and reduced alpha-fetoprotein in the treated group compared to untreated cancer-induced group. Overall, this study suggests that copper-ligand-L interaction leads to ROS generation which caused DNA damage and apoptosis in malignant cells. This study provides enough support to establish ligand-L as a clinically relevant lead molecule for the treatment of different malignancies.

Epigenetic role of thymoquinone: impact on cellular mechanism and cancer therapeutics

Thymoquinone is a natural product known for its anticancer activity. Preclinical studies indicated numerous mechanisms of action by which thymoquinone exerts its effects on cancer cells. Recent evidence has indicated that thymoquinone can modulate epigenetic machinery, like modifying histone acetylation and deacetylation, DNA methylation and demethylation, which are among the major epigenetic changes that can contribute to carcinogenesis. Moreover, thymoquinone can alter the genetic expression of various noncoding RNAs, such as miRNA and lncRNA, which are the key parts of cellular epigenetics. This review focuses on cellular epigenetic systems, epigenetic changes responsible for cancer and the counteraction of thymoquinone to target epigenetic challenges, which might be among the mechanisms of the thymoquinone effect in cancer cells.

Synthesis and Antitumor Activity Evaluation of Compounds Based on Toluquinol

Encouraged by the promising antitumoral, antiangiogenic, and antilymphangiogenic properties of toluquinol, a set of analogues of this natural product of marine origin was synthesized to explore and evaluate the effects of structural modifications on their cytotoxic activity. We decided to investigate the effects of the substitution of the methyl group by other groups, the introduction of a second substituent, the relative position of the substituents, and the oxidation state. A set of analogues of 2-substituted, 2,3-disubstituted, and 2,6-disubstituted derived from hydroquinone were synthesized. The results revealed that the cytotoxic activity of this family of compounds could rely on the hydroquinone/benzoquinone part of the molecule, whereas the substituents might modulate the interaction of the molecule with their targets, changing either its activity or its selectivity. The methyl group is relevant for the cytotoxicity of toluquinol, since its replacement by other groups resulted in a significant loss of activity, and in general the introduction of a second substituent, preferentially in the para position with respect to the methyl group, was well tolerated. These findings provide guidance for the design of new toluquinol analogues with potentially better pharmacological properties.

Cancer: Thymoquinone antioxidant/pro-oxidant effect as potential anticancer remedy

Recently, there is growing interest in the natural bioactive components having anticancer activity. Thymoquinone (TQ), the principle active constituent of black seed (Nigella sativa), has promising properties including anticancer and chemosensitizing peculiarities. The anticancer power of TQ is accomplished by several aspects; including promotion of apoptosis, arrest of cell cycle and ROS generation. In addition, it boosts the immune system and lessens the side effects associated with traditional anticancer therapy. TQ also controls angiogenesis and cancer metastasis. This review focuses on the potential aspects and mechanisms by which TQ acquires its actions.

Sanguinarine induces apoptosis of human lens epithelial cells by increasing reactive oxygen species via the MAPK signaling pathway

Posterior capsular opacification (PCO) remains a major complication of cataract surgery and is the most common reason for loss of vision. PCO is primarily associated with uncontrolled proliferation of residual human lens epithelial cells (HLEs). Sanguinarine is a type of benzophenanthridine alkaloid extracted from the herbaceous plant Sanguinaria canadensis, which is widely used for its anti‑microbial, anti‑inflammatory, anti‑oxidative and anti‑proliferative properties. However, studies examining the effect of sanguinarine on HLEs and the underlying mechanism are scarce. The present study aimed to investigate the effects of sanguinarine on HLEs. An MTT assay was used to determine the effect of sanguinarine on cell viability. Flow cytometry was used to evaluate cell apoptosis, and the mitochondrial membrane potential and reactive oxygen species (ROS) levels. A caspase 3/7 activity assay was also used to evaluate cell apoptosis, while western blotting was performed to determine protein levels. The results demonstrated that sanguinarine exerted an anti‑proliferative effect by inducing ROS, and caused cell apoptosis via mitochondrial and caspase‑dependent pathways. Treatment with sanguinarine led to the loss of mitochondrial membrane potential. Sanguinarine also significantly increased the phosphorylation levels of c‑Jun N‑terminal kinase and p38, which indicated the involvement of the mitogen‑activated protein kinase signaling pathway. These results suggested that sanguinarine may have a noteworthy pro‑apoptotic effect on HLEs, and may be used as a potential drug for PCO or even cataract prevention.

Solvent based optimization for extraction and stability of thymoquinone from Nigella sativa Linn. and its quantification using RP-HPLC

The Nigella sativa pharmacological properties are mainly ascribed to its volatile oil, of which thymoquinone is an important bioactive component. Surprisingly, till date, no standard formulation or thymoquinone rich N. sativa extract is under clinical use probably due to its poor extraction and lesser stability in the already used solvents. In the present investigation solubility, extraction, percent composition and total antioxidant activity from the seeds of N. sativa was explored using five solvents. An HPLC method was standardized in an isocratic system (C-18 column, flow rate of 1.0 ml/min, mobile phase-water:methanol: 30:70, detection wavelength-254 nm, retention time-8.77 min) for quantification of thymoquinone. To further confirm the presence of thymoquinone in the respective extracts absorbance spectra analysis has been carried out and compared with pure thymoquinone. Additionally total antioxidant activity of Nigella sativa extracts has been evaluated using ascorbic acid as standard. Our results showed maximum percentage yield in aqueous extract while methanol having the least yield and the ethanol, benzene and hexane extracts exhibited moderate yields. A linear standard calibration curve of thymoquinone showed R² as 0.999 and % RSD as 7.166. The HPLC analysis revealed maximum percentage composition of thymoquinone in the benzene extract, whereas in the hexane and methanol extracts the content was less. Aqueous and ethanol extracts displayed insignificant thymoquinone content. Absorbance spectra analysis confirms the presence of thymoquinone peak in the benzene, hexane and methanol extracts while aqueous and ethanol extracts showed minimal absorbance. Maximum total antioxidant activity was observed in the aqueous extract while minimum was observed in the methanolic extract. Weak positive (+ 0.3676) correlation was established between percent composition of thymoquinone and antioxidant activity among different extracts indicating that thymoquinone may not be the only factor for antioxidant activity, but other phytochemicals might also contribute. However, we for the first time demonstrated that the benzene extract of N. sativa has better solubility and percent composition of thymoquinone as compared to other solvents. It can be concluded that the solubility, differential composition of bioactive components among these extracts may have diverse effects on the total antiradical activity. Thus, our study provides insights on optimization and standardization of bioactive rich formulation of N. sativa.

Hormetic dose response to L-ascorbic acid as an anti-cancer drug in colorectal cancer cell lines according to SVCT-2 expression

_L-Ascorbic acid (vitamin C, AA) exhibits anti-cancer effects with high-dose treatment through the generation of reactive oxygen species (ROS) and selective damage to cancer cells. The anti-cancer effects of _L-ascorbic acid are determined by sodium-dependent vitamin C transporter 2 (SVCT-2), a transporter of _L-ascorbic acid. In this study, we demonstrate that _L-ascorbic acid treatment showed efficient anti-cancer activity in cell lines with high expression levels of SVCT-2 for a gradient concentration of _L-ascorbic acid from 10 μM −2 mM. However, in low SVCT-2 expressing cell lines, high-dose _L-ascorbic acid (>1 mM) showed anti-cancer effects but low-dose (<10 μM) treatment induced cell proliferation. Such conflicting results that depend on the concentration are called a hormetic dose response. A hormetic dose response to low-dose _L-ascorbic acid was also observed in high SVCT-2 expressing cell lines in the presence of a SVCT family inhibitor. Insufficient uptake of _L-ascorbic acid in low SVCT-2 expressing cancer cell lines cannot generate sufficient ROS to kill cancer cells, resulting in the hormetic response. Molecular analysis confirmed the increased expression of cancer proliferation markers in the hormetic dose response. These results suggest that _L-ascorbic exhibits a biphasic effect in cancer cells depending on SVCT-2 expression.

Thymoquinone: A novel strategy to combat cancer: A review

The higher consumption of fruit, herbs, spices, and vegetables is well known and practical strategy to cure human cancers owing to their presence of bioactive compounds. Among these, Nigella sativa is a promising source of bioactive compounds including thymoquinone, monoterpenes, p-cymene and α-piene etc. Thymoquinone has been found effective to inhibit the different cancer stages such as proliferation, migration and invasion. It also acts as anticancer agent against different human cancers such as breast, pancreatic, prostate, blood, oral, bone, head and neck, cervical, liver and lung. It significantly mediated miR-34a up-regulation, enhanced the levels of miR-34a through p53, and down controlled Rac1 expression. Thymoquinone induces apoptosis, regulates the levels of pro- and anti- apoptotic genes. It also has been known to lower the phosphorylation of NF-κB and IKKα/β and reduces the metastasis as well as also lowered the ERK1/2 and PI3K activities. Thymoquinone inhibits the metastasis through activation of JNK and p38. The present review article highlights the anticancer perspectives of thymoquinone in human by various pathways and use of this compound as diet based therapy has proven new pharmacological agent against several types of cancers.

Comprehensive Investigation of the Antioxidant and Pro-oxidant Effects of Phenolic Compounds: A Double-Edged Sword in the Context of Oxidative Stress?

Oxidative stress (OS) is a health-threatening process that is involved, at least partially, in the development of several diseases. Although antioxidants can be used as a chemical defense against OS, they might also exhibit pro-oxidant effects, depending on environmental conditions. In this work, such a dual behavior was investigated for phenolic compounds (PhCs) within the framework of the density functional theory and based on kinetic data. Multiple reaction mechanisms were considered in both cases. The presence of redox metals, the pH, and the possibility that PhCs might be transformed into benzoquinones were identified as key aspects in the antioxidant versus pro-oxidant effects of these compounds. The main virtues of PhCs as antioxidants are their radical trapping activity, their regeneration under physiological conditions, and their behavior as OH-inactivating ligands. The main risks of PhCs as pro-oxidants are predicted to be the role of phenolate ions in the reduction of metal ions, which can promote Fenton-like reactions, and the formation of benzoquinones that might cause protein arylation at cysteine sites. Although the benefits seem to overcome the hazards, to properly design chemical strategies against OS using PhCs, it is highly recommended to carefully explore their duality in this context.

Therapeutic Potential of Thymoquinone in Glioblastoma Treatment: Targeting Major Gliomagenesis Signaling Pathways

Glioblastoma multiforme (GBM) is one of the most devastating brain tumors with median survival of one year and presents unique challenges to therapy because of its aggressive behavior. Current treatment strategy involves surgery, radiotherapy, immunotherapy, and adjuvant chemotherapy even though optimal management requires a multidisciplinary approach and knowledge of potential complications from both the disease and its treatment. Thymoquinone (TQ), the main bioactive component of Nigella sativa L., has exhibited anticancer effects in numerous preclinical studies. Due to its multitargeting nature, TQ interferes in a wide range of tumorigenic processes and counteract carcinogenesis, malignant growth, invasion, migration, and angiogenesis. TQ can specifically sensitize tumor cells towards conventional cancer treatments and minimize therapy-associated toxic effects in normal cells. Its potential to enter brain via nasal pathway due to volatile nature of TQ adds another advantage in overcoming blood-brain barrier. In this review, we summarized the potential role of TQ in different signaling pathways in GBM that have undergone treatment with standard therapeutic modalities or with TQ. Altogether, we suggest further comprehensive evaluation of TQ in preclinical and clinical level to delineate its implied utility as novel therapeutics to combat the challenges for the treatment of GBM.

Restrained management of copper level enhances the antineoplastic activity of imatinib in vitro and in vivo

The present study was designed to investigate if elevated copper level can be targeted to enhance the efficacy of a significant anticancer drug, imatinib (ITB). The antineoplastic activity of this drug was assessed in the HepG2, HEK-293, MCF-7 and MDA-MD-231 cells targeting elevated copper level as their common drug target. The cell lines were treated with the different doses of copper chloride (Cu II) and disulfiram (DSF) alone as well as in their combinations with the drug for 24 h in standard culture medium and conditions. The treated cells were subjected to various assays including MTT, PARP, p-53, caspase-7, caspase-3, LDH and single cell electrophoresis. The study shows that DSF and Cu (II) synergizes the anticancer activity of ITB to a significant extent in a dose-specific way as evidenced by the combinations treated groups. Furthermore, the same treatment strategy was employed in cancer-induced rats in which the combinations of ITB-DSF and ITB-Cu II showed enhanced antineoplastic activity as compared to ITB alone. However, DSF was more effective than Cu (II) as an adjuvant to the drug. Hence, restrained manipulation of copper level in tumor cells can orchestrate the redox and molecular dispositions inside the cells favoring the induction of apoptosis.

Modulation of diverse oncogenic transcription factors by thymoquinone, an essential oil compound isolated from the seeds of Nigella sativa Linn

Thymoquinone (TQ), isolated almost fifty years ago, is the main bioactive constituent of black seed essential oil extracted from the seed of Nigella sativa. TQ has been shown to have promising effects against a variety of inflammatory diseases and cancer. Cancer development is a multistep process where normal cells acquire qualities that enable the cells to proliferate continuously and migrate to distant sites in the human body. Drugs that interfere with this process are considered potential anti-cancer therapeutics, which may ultimately result in their clinical usage. TQ is once such compound which has been reported to modulate several major signaling pathways and key oncogenic molecules that play a prominent role in cancer initiation, progression, invasion, metastasis, and angiogenesis. Various studies have reported that TQ can enhance the anti-cancer potential when co-administered with several chemotherapeutic agents while reducing their toxic side effects. In addition, TQ has been shown to inhibit the growth of breast, prostate, pancreatic, colon, lung, and hematological malignancies in different mouse models of cancer. This review focuses on TQ's chemical and pharmacological properties, its diverse molecular targets and also provides clear evidence on its promising potential under preclinical and clinical settings.

Enhancing conventional chemotherapy drug cisplatin-induced anti-tumor effects on human gastric cancer cells both in vitro and in vivo by Thymoquinone targeting PTEN gene

Combination chemotherapy regimen with several anti-tumor drugs is a strategy to improve outcome. Thymoquinone (TQ) has been reported to exert biological activity on various types of human cancers without obvious toxicity. However, only few studies showed the anti-tumor effects of TQ combination with cisplatin on gastric cancer (GC). Here, we showed pretreatment with 5μM TQ significantly increased the apoptotic effects induced by cisplatin on GC cell lines. Combined treatment of cisplatin with TQ represented a significantly superior tumor suppression effect than either agent alone in a xenograft tumor mouse model. Interestingly, TQ pretreatment following cisplatin caused a significant increase in the levels of PTEN, an obvious decrease in p-AKT, CyclinD1, P-glycoprotein (P-gp), meanwhile, TQ and cisplatin also led to an increase in Bax, Cyt C, AIF, cleaved caspase 9, and cleaved caspase 3, and a decrease in Bcl-2, procaspase-9, procaspase-3. Moreover, results in vitro, showed that a combination of TQ and cisplatin represents a more effective anti-tumor agent than either agent alone in a xenograft tumor mouse model. In conclusion, TQ significantly augments cisplatin-induced anti-tumor effects on gastric cancer both in vitro and in vivo, through inhibiting PI3K/AKT signaling pathway, activating the mitochondrial pathway, and down-regulating P-glycoprotein by up-regulating PTEN gene. TQ might be as a promising candidate as a cancer chemopreventive or chemotherapeutic agent for antineoplastic combination therapy and merits further clinical investigation.

North African Medicinal Plants Traditionally Used in Cancer Therapy

Background: Cancer is a major cause of mortality worldwide with increasing numbers by the years. In North Africa, the number of cancer patients is alarming. Also shocking is that a huge number of cancer patients only have access to traditional medicines due to several factors, e.g., economic difficulties. In fact, medicinal plants are widely used for the treatment of several pathologies, including cancer. Truthfully, herbalists and botanists in North African countries prescribe several plants for cancer treatment. Despite the popularity and the potential of medicinal plants for the treatment of cancer, scientific evidence on their anticancer effects are still scarce for most of the described plants.

Objective: Bearing in mind the lack of comprehensive and systematic studies, the aim of this review is to give an overview of studies, namely ethnobotanical surveys and experimental evidence of anticancer effects regarding medicinal plants used in North Africa for cancer therapy.

Method: The research was conducted on several popular search engines including PubMed, Science Direct, Scopus and Web of Science. The research focused primarily on English written papers published between the years 2000 and 2016.

Results: This review on plants traditionally used by herbalists in North Africa highlights that Morocco and Algeria are the countries with most surveys on the use of medicinal plants in folk medicine. Among the plethora of plants used, Nigella sativa and Trigonella foenum-graecum are the most referred ones by herbalists for the treatment of cancer. Moreover, a plethora of scientific evidence qualifies them as candidates for further drug development. Furthermore, we report on the underlying cellular and molecular mechanisms.

Conclusion: Overall, this review highlights the therapeutic potential of some medicinal plants as anticancer agents. The North African flora offers a rich source of medicinal plants for a wide array of diseases, including cancer. The elucidation of their modes of action represents an indispensable condition for the rational development of new drugs for cancer treatment. Furthermore, testing the anticancer activity in vivo and in clinical trials are warranted to explore the full therapeutic potential of North African plants for cancer therapy.

Thymoquinone, as an anticancer molecule: from basic research to clinical investigation

Thymoquinone is an anticancer phytochemical commonly found in black cumin. In this review, we discuss the potential of thymoquinone as anticancer molecule, its mechanism of action and future usage in clinical applications. Thymoquinone exhibits anticancer activity via numerous mechanisms of action, specifically by showing selective antioxidant and oxidant activity, interfering with DNA structure, affecting carcinogenic signaling molecules/pathways and immunomodulation. In vitro activity of thymoquinone has been further implicated in animal models of cancer; however, no clinical application has been proven yet. This is the optimum time to focus on clinical trials for developing thymoquinone as a future drug in cancer therapeutics.

Metal chelator TPEN selectively induces apoptosis in K562 cells through reactive oxygen species signaling mechanism: implications for chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a hematologic disorder characterized by the constitutive expression of BCR-ABL tyrosine kinase. Although successful implementation of tyrosine kinase inhibitors for the treatment of CML remain a traditional choice for molecularly targeted therapy, some patients present primary or secondary resistance to such therapy. Therefore, alternative therapeutic strategies are required to treat resistant CML cells. Accordingly, new anti-proliferative and/or pro-apoptotic compounds would be needed for clinical treatment. In the present investigation, we demonstrate that TPEN (e.g. 3 μM), a lipid-soluble metal chelator, induces apoptosis in K562 cells via a molecular cascade involving H₂O₂ ≫ JNK, NF-κB > c-JUN, P73 > PUMA, BAX > loss of ΔΨ_m > CASPASE-3 > nuclei/DNA fragmentation. Fragmentation of the nuclei and DNA are indicative of cell death by apoptosis. Remarkably, the antioxidant N-acetyl-cysteine, and inhibitors of the transcription factors CASPASE 3 and (JNK) kinase, decreased oxidative stress (OS) and cell death in these cells. This is evidenced by fluorescence microscopy, flow cytometry and immunocytochemistry for OS markers (e.g. generation of H₂O₂ and DJ 1 oxidation) and nuclear expression of apoptotic markers (e.g. activated caspase 3 and JNK kinase). In addition, TPEN causes no detectable damage in human peripheral blood lymphocyte cells (hPBLCs). We conclude that TPEN selectively induces apoptosis in K562 cells via an OS-mechanism. Our findings may provide insight into more effective CML anticancer therapies.

Anticancer Chemodiversity of Ranunculaceae Medicinal Plants: Molecular Mechanisms and Functions

The buttercup family, Ranunculaceae, comprising more than 2,200 species in at least 62 genera, mostly herbs, has long been used in folk medicine and worldwide ethnomedicine since the beginning of human civilization. Various medicinal phytometabolites have been found in Ranunculaceae plants, many of which, such as alkaloids, terpenoids, saponins, and polysaccharides, have shown anti-cancer activities in vitro and in vivo. Most concerns have been raised for two epiphany molecules, the monoterpene thymoquinone and the isoquinoline alkaloid berberine. At least 17 genera have been enriched with anti-cancer phytometabolites. Some Ranunculaceae phytometabolites induce the cell cycle arrest and apoptosis of cancer cells or enhance immune activities, while others inhibit the proliferation, invasion, angiogenesis, and metastasis, or reverse the multi-drug resistance of cancer cells thereby regulating all known hallmarks of cancer. These phytometabolites could exert their anti-cancer activities via multiple signaling pathways. In addition, absorption, distribution, metabolism, and excretion/toxicity properties and structure/activity relationships of some phytometabolites have been revealed assisting in the early drug discovery and development pipelines. However, a comprehensive review of the molecular mechanisms and functions of Ranunculaceae anti-cancer phytometabolites is lacking. Here, we summarize the recent progress of the anti-cancer chemo- and pharmacological diversity of Ranunculaceae medicinal plants, focusing on the emerging molecular machineries and functions of anti-cancer phytometabolites. Gene expression profiling and relevant omics platforms (e.g. genomics, transcriptomics, proteomics, and metabolomics) could reveal differential effects of phytometabolites on the phenotypically heterogeneous cancer cells.

Glutathione maintenance mitigates age-related susceptibility to redox cycling agents

Isolated hepatocytes from young (4-6mo) and old (24-26mo) F344 rats were exposed to increasing concentrations of menadione, a vitamin K derivative and redox cycling agent, to determine whether the age-related decline in Nrf2-mediated detoxification defenses resulted in heightened susceptibility to xenobiotic insult. An LC50 for each age group was established, which showed that aging resulted in a nearly 2-fold increase in susceptibility to menadione (LC50 for young: 405μM; LC50 for old: 275μM). Examination of the known Nrf2-regulated pathways associated with menadione detoxification revealed, surprisingly, that NAD(P)H: quinone oxido-reductase 1 (NQO1) protein levels and activity were induced 9-fold and 4-fold with age, respectively (p=0.0019 and p=0.018; N=3), but glutathione peroxidase 4 (GPX4) declined by 70% (p=0.0043; N=3). These results indicate toxicity may stem from vulnerability to lipid peroxidation instead of inadequate reduction of menadione semi-quinone. Lipid peroxidation was 2-fold higher, and GSH declined by a 3-fold greater margin in old versus young rat cells given 300µM menadione (p<0.05 and p≤0.01 respectively; N=3). We therefore provided 400µMN-acetyl-cysteine (NAC) to hepatocytes from old rats before menadione exposure to alleviate limits in cysteine substrate availability for GSH synthesis during challenge. NAC pretreatment resulted in a >2-fold reduction in cell death, suggesting that the age-related increase in menadione susceptibility likely stems from attenuated GSH-dependent defenses. This data identifies cellular targets for intervention in order to limit age-related toxicological insults to menadione and potentially other redox cycling compounds.

Chk1 and DNA-PK mediate TPEN-induced DNA damage in a ROS dependent manner in human colon cancer cells

Recently, we showed that the metal chelator TPEN targets colon cancer cells through redox cycling of copper. Here, we studied the DNA damage potential of TPEN and deciphered the role of Chk1, ATM and DNA-PK in TPEN-induced toxicity in 3 human colon cancer cell lines, HCT116, SW480 and HT29. We also investigated the role of reactive oxygen species (ROS) in TPEN-induced DNA damage. TPEN reduced cell viability in a dose- and time-dependent manner. Cytotoxicity was associated with significant DNA damage and higher expression of γ-H2AX protein and activation of ATM/ATR signaling pathway. Cell death by TPEN was dependent on ROS generation as evidenced by the reversal of cell viability, and DNA damage and the abrogation of γ-H2AX levels in the presence of antioxidants. Treatment with antioxidants, however, failed to reverse cytotoxicity at high TPEN concentrations (10µM). TPEN-induced cell death was also dependent on the redox cycling of copper since the copper chelator neocuproine inhibited DNA damage and reduced pChk1, γ-H2AX, and ATM protein expression. Cell death by low TPEN concentrations, involved ATM/ATR signaling in all 3 cell lines, since pre-incubation with specific inhibitors of ATM and DNA-PK led to the recovery of cells from TPEN-induced DNA damage. In addition, siRNA silencing of Chk1, DNA-PK and ATM abrogated the expression of γ-H2AX and reversed cell death, suggesting that Chk1 and DNA-PK mediate TPEN-induced cytotoxicity in colon cancer cells. This study shows for the first time the involvement of Chk1, DNA-PK and ATM in TPEN-induced DNA damage and confirms our previous findings that ROS generation and the redox cycling of copper in response to TPEN are the main mechanisms by which this compound induces cell death in human colon cancer cells. Inhibition of ATM or DNA-PK did not reverse cytotoxicity at high TPEN concentrations that cause excessive levels of ROS and irreversible cellular damage.

Effects of benzo[a]pyrene as an environmental pollutant and two natural antioxidants on biomarkers of reproductive dysfunction in male rats

Benzo[a]pyrene (B[a]P) is an environmental toxicant and endocrine disruptor. Therefore, the aim of the present study was to investigate the toxicity of B[a]P in testis of rats and also to study the role of silymarin and thymoquinone (TQ) as natural antioxidants in the alleviation of such toxicity. Data of the present study showed that levels of testosterone, estrogen and progesterone were significantly decreased after treatment of rats with B[a]P. In addition, B[a]P caused downregulation of the expressions of steroidogenic enzymes including CYP17A1 and CP19A1, and decreased the activity of 17-β hydroxysteroid dehydrogenase (17β-HSD). Moreover, B[a]P decreased the activities of antioxidant enzymes including catalase (CAT), glutathione peroxidase (GPX) and superoxide dismutase (SOD), and significantly increased free radicals levels in testis of male rats. However, pretreatment of rats with silymarin prior to administration of B[a]P was found to restore the level of free radicals, antioxidant status, and activities of steroidogenic enzymes to their normal levels in testicular tissues. Moreover, histopathological finding showed that silymarin recovered the abnormalities occurred in tubules caused by B[a] P in testis of rats. On the other hand, TQ showed pro-oxidant effects and did not ameliorate the toxic effects of B[a] P on the testicular tissue since it decreased antioxidant enzymes activities and inhibited the protein expression of CYP11A1 and CYP21A2 compared to control rats. Moreover, TQ decreased the levels of testosterone, estrogen, and progesterone either in the presence or absence of B[a]P. It is concluded that B[a]P decreased testosterone levels, inhibited antioxidant enzymes activities, caused downregulation of CYP isozymes involved in steroidogenesis, and increased free radical levels in testis. Moreover, silymarin was more effective than TQ in restoring organism health and alleviating the deleterious effects caused by B[a]P in the testis of rats. Due to its negative impact, it is highly recommended to limit the use of TQ as a dietary supplement since millions of people in the Middle East are using it to improve their health.