Total Flavonoids from Clinopodium chinense (Benth.) O. Ktze Protect against Doxorubicin-Induced Cardiotoxicity In Vitro and In Vivo

TXB-001, A Newly-Developed Polymer-Conjugated Anthracycline, Alleviates Anthracycline-Induced Cardiotoxicity

Anthracycline anti-cancer drugs, which are used in cancer chemotherapy, frequently cause cardiotoxicity, the incidence of which depends on cumulative doses. TXB-001 is a new candidate polymer-conjugated pirarubicin (THP) with higher THP purity and content compared to previous P-THP (polymerized THP) and is expected to exhibit lower cardiotoxicity and higher efficacy against cancer cells. We examined the effects of TXB-001 on cardiac function and the pharmacokinetics after its intravenous administration compared with those of existing anthracyclines (doxorubicin (DOX), DOXIL (liposomal formulation of DOX), THP) in mice. Echocardiography and electrocardiography showed that DOX caused cardiac dysfunction in mice, with associated changes in organ weights, blood chemical parameters, and mRNA/protein expressions. DOXIL and THP induced similar, but weaker changes than DOX. TXB-001 did not significantly affect cardiac function or associated changes under the conditions of this study. The results of the pharmacokinetic evaluation revealed that the distributions of DOXIL and TXB-001 from plasma to heart tissue were lower than those of DOX and THP, while the distribution of TXB-001 was lower than that of DOXIL. Furthermore, TXB-001 did not show cardiac accumulation in contrast to DOXIL. In addition, the anthracycline exposure level of TXB-001 in the heart was lower than those of DOX, DOXIL, and THP, with less exposure being regarded as one reason for the low or no cardiotoxicity of TXB-001 in mice. Collectively, these results suggest the potential of TXB-001 as an anti-cancer drug with fewer side effects than anthracyclines, particularly cardiotoxicity. Novel TXB-001 may become an effective anti-cancer drug with fewer cardiotoxicity.

SESN2-Mediated AKT/GSK-3β/NRF2 Activation to Ameliorate Adriamycin Cardiotoxicity in High-Fat Diet-Induced Obese Mice

Aims: Obese patients are highly sensitive to adriamycin (ADR)-induced cardiotoxicity. However, the potential mechanism of superimposed toxicity remains to be elucidated. Sestrin 2 (SESN2), a potential antioxidant, could attenuate stress-induced cardiomyopathy; therefore, this study aims to explore whether SESN2 enhances cardiac resistance to ADR-induced oxidative damage in high-fat diet (HFD)-induced obese mice. Results: The results revealed that obesity decreased SESN2 expression in ADR-exposed heart. And, HFD mice may predispose to ADR-induced cardiotoxicity, which was probably associated with inhibiting protein kinase B (AKT), glycogen synthase kinase-3 beta (GSK-3β) phosphorylation and subsequently blocking nuclear localization of nuclear factor erythroid-2 related factor 2 (NRF2), ultimately resulting in cardiac oxidative damage. However, these destructive cascades and cardiac oxidative damage effects induced by HFD/sodium palmitate combined with ADR were blocked by overexpression of SESN2. Moreover, the antioxidant effect of SESN2 could be largely abolished by sh-Nrf2 or wortmannin. And sulforaphane, an NRF2 agonist, could remarkably reverse cardiac pathological and functional abnormalities caused by ADR in obese mice. Innovation and Conclusion: This study demonstrated that SESN2 might be a promising therapeutic target for improving anthracycline-related cardiotoxicity in obesity by upregulating activity of NRF2 via AKT/GSK-3β/Src family tyrosine kinase signaling pathway. Antioxid. Redox Signal. 40, 598-615.

Isoquercitrin alleviates pirarubicin-induced cardiotoxicity in vivo and in vitro by inhibiting apoptosis through Phlpp1/AKT/Bcl-2 signaling pathway

Introduction: Due to the cardiotoxicity of pirarubicin (THP), it is necessary to investigate new compounds for the treatment of THP-induced cardiotoxicity. Isoquercitrin (IQC) is a natural flavonoid with anti-oxidant and anti-apoptosis properties. Thus, the present study aimed to investigate the influence of IQC on preventing the THP-induced cardiotoxicity in vivo and in vitro. Methods: The optimal concentration and time required for IQC to prevent THP-induced cardiomyocyte damage were determined by an MTT assay. The protective effect was further verified in H9c2 and HCM cells using dichlorodihydrofluorescein diacetate fluorescent probes, MitoTracker Red probe, enzyme-linked immunosorbent assay, JC-1 probe, and real time-quantitative polymerase chain reaction (RT-qPCR). Rats were administered THP to establish cardiotoxicity. An electrocardiogram (ECG) was performed, and cardiac hemodynamics, myocardial enzymes, oxidative stress indicators, and hematoxylin-eosin staining were studied. Voltage-dependent anion channel 1 (VDAC1), adenine nucleotide translocase 1 (ANT1), and cyclophilin D (CYPD) were detected by qRT-PCR, and the Phlpp1/AKT/Bcl-2 axis proteins were detected by western blot, confirming that IQC markedly increased cell viability and superoxide dismutase (SOD) levels, diminished the levels of ROS and MDA, and elevated mitochondrial function and apoptosis in vivo and in vitro. Results: Results showed that IQC reduced THP-induced myocardial histopathological injury, electrocardiogram (ECG) abnormalities, and cardiac dysfunction in vivo. IQC also decreased serum levels of MDA, BNP, CK-MB, c-TnT, and LDH, while increasing levels of SOD and GSH. We also found that IQC significantly reduced VDAC1, ANT1, and CYPD mRNA expression. In addition, IQC controlled apoptosis by modulating Phlpp1/AKT/Bcl-2 signaling pathways. IQC markedly increased H9c2 and HCM cell viability and SOD levels, diminished the levels of ROS and MDA, and elevated mitochondrial function in H9c2 and HCM cells to defend against THP-induced cardiomyocyte apoptosis in vitro. The AKT inhibitor IMQ demonstrated that IQC lacked antioxidant and anti-apoptotic properties. Moreover, our data showed that IQC regulates Phlpp1 expression, thereby influencing the expression levels of p-AKT, cytochrome c, caspase-3, caspase-9, Bcl-2, and Bax. Discussion: In conclusion, our results indicate that IQC protects the changes in mitochondrial membrane permeability in cardiomyocytes by regulating the Phlpp1/AKT/Bcl-2 signaling pathway, inhibits the release of cytc from the mitochondrial inner membrane to the cytoplasm, forms apoptotic bodies, induces cell apoptosis, and reduces THP induced cardiotoxicity.

Fucoidan Protects against Doxorubicin-Induced Cardiotoxicity by Reducing Oxidative Stress and Preventing Mitochondrial Function Injury

Doxorubicin (DOXO) is a potent chemotherapeutic drug widely used to treat various cancers. However, its clinical application is limited due to serious adverse effects on dose-dependent cardiotoxicity. Although the underlying mechanism has not been fully clarified, DOXO-induced cardiotoxicity has been mainly attributed to the accumulation of reactive oxygen species (ROS) in cardiomyocytes. Fucoidan, as a kind of sulphated polysaccharide existing in numerous brown seaweed, has potent anti-oxidant, immune-regulatory, anti-tumor, anti-coagulate and anti-viral activities. Here, we explore the potential protective role and mechanism of fucoidan in DOXO-induced cardiotoxicity in mice. Our results show that oral fucoidan supplement exerts potent protective effects against DOXO-induced cardiotoxicity by reducing oxidative stress and preventing mitochondrial function injury. The improved effect of fucoidan on DOXO-induced cardiotoxicity was evaluated by echocardiography, cardiac myocytes size and cardiac fibrosis analysis, and the expression of genes related to cardiac dysfunction and remodeling. Fucoidan reduced the ROS content and the MDA levels but enhanced the activity of antioxidant enzymes GSH-PX and SOD in the mouse serum in a DOXO-induced cardiotoxicity model. In addition, fucoidan also increased the ATP production capacity and restored the levels of a mitochondrial respiratory chain complex in heart tissue. Collectively, this study highlights fucoidan as a potential polysaccharide for protecting against DOXO-induced cardiovascular diseases.

Inhibition of (Pro)renin Receptor-Mediated Oxidative Stress Alleviates Doxorubicin-Induced Heart Failure

AIM

Clinical utility of doxorubicin (DOX) is limited by its cardiotoxic side effect, and the underlying mechanism still needs to be fully elucidated. This research aimed to examine the role of (pro)renin receptor (PRR) in DOX-induced heart failure (HF) and its underlying mechanism.

MAIN METHODS

Sprague Dawley (SD) rats were injected with an accumulative dosage of DOX (15 mg/kg) to induce HF. Cardiac functions were detected by transthoracic echocardiography examination. The levels of lactate dehydrogenase (LDH) and creatine kinase (CK) in serum were detected, and oxidative stress related injuries were evaluated. Furthermore, the mRNA expression of PRR gene and its related genes were detected by real-time PCR (RT-PCR), and protein levels of PRR, RAC1, NOX4 and NOX2 were determined by Western blot. Reactive oxygen species (ROS) were determined in DOX-treated rats or cells. Additionally, PRR and RAC1 were silenced with their respective siRNAs to validate the in vitro impacts of PRR/RAC1 on DOX-induced cardiotoxicity. Moreover, inhibitors of PRR and RAC1 were used to validate their effects in vivo.

KEY FINDINGS

PRR and RAC1 expressions increased in DOX-induced HF. The levels of CK and LDH as well as oxidative stress indicators increased significantly after DOX treatment. Oxidative injury and apoptosis of cardiomyocytes were attenuated both in vivo and in vitro upon suppression of PRR or RAC1. Furthermore, the inhibition of PRR could significantly down-regulate the expressions of RAC1 and NOX4 but not that of NOX2, while the inhibition of RAC1 did not affect PRR.

SIGNIFICANCE

Our findings showed that PRR inhibition could weaken RAC1-NOX4 pathway and alleviate DOX-induced HF via decreasing ROS production, thereby suggesting a promising target for the treatment of DOX-induced HF.

Cardiomyocyte Atrophy, an Underestimated Contributor in Doxorubicin-Induced Cardiotoxicity

Left ventricular (LV) mass loss is prevalent in doxorubicin (DOX)-induced cardiotoxicity and is responsible for the progressive decline of cardiac function. Comparing with the well-studied role of cell death, the part of cardiomyocyte atrophy (CMA) playing in the LV mass loss is underestimated and the knowledge of the underlying mechanism is still limited. In this review, we summarized the recent advances in the DOX-induced CMA. We found that the CMA caused by DOX is associated with the upregulation of FOXOs and “atrogenes,” the activation of transient receptor potential canonical 3-NADPH oxidase 2 (TRPC3-Nox2) axis, and the suppression of IGF-1-PI3K signaling pathway. The imbalance of anabolic and catabolic process may be the common final pathway of these mechanisms. At last, we provided some strategies that have been demonstrated to alleviate the DOX-induced CMA in animal models.

Inhibitory effects of Panax ginseng glycoproteins in models of doxorubicin-induced cardiac toxicity in vivo and in vitro

Doxorubicin (DOX) is an effective antineoplastic drug; however, its clinical application is limited owing to the side effect of fatal heart dysfunction on its use. Panax ginseng glycoproteins have antioxidant, antiapoptotic, and anti-inflammatory properties. Thus, the aim of this study was to investigate the effects and possible action mechanisms of P. ginseng glycoproteins against DOX-induced cardiotoxicity. To this end, we used an in vitro model of DOX-treated H9C2 cells and an in vivo model of DOX-treated rats. We found that P. ginseng glycoproteins markedly increased H9C2 cell viability, decreased creatine kinase and lactate dehydrogenase levels, and improved histopathological and electrocardiogram changes in rats, protecting them from DOX-induced cardiotoxicity. Furthermore, P. ginseng glycoproteins significantly inhibited myocardial oxidative insult through adjusting the intracellular ROS, MDA, SOD, and GSH levels in vitro and in vivo. In conclusion, our data suggest that P. ginseng glycoproteins alleviated DOX-induced myocardial oxidative stress-related cardiotoxicity. This natural product could be developed as a new candidate for alleviating DOX-induced cardiotoxicity.

Photobiomodulation therapy preconditioning modifies nitric oxide pathway and oxidative stress in human-induced pluripotent stem cell-derived ventricular cardiomyocytes treated with doxorubicin

Doxorubicin (DOX) is an anthracycline antibiotic that exhibits high heart toxicity. Human-induced pluripotent stem cell-derived ventricular cardiomyocytes (hiPSC-vCMs) are important in vitro models for testing drug cardiotoxicity. Photobiomodulation therapy (PBMT) is a non-invasive therapy that stimulates cells growth and self-repair using light irradiation. This study aimed to investigate the in vitro effects of PBMT preconditioning on cardiotoxicity induced by DOX. HiPSC-vCMs were treated with PBMT for 500 s, followed by the addition of 2 μM DOX. LED irradiation preconditioning parameters were at 660 nm with an irradiance of 10 mW/cm², performing 5 J/cm², followed by 24-h DOX exposure (2 μM). Human iPSC-vCMs treated with 2 μM DOX or irradiated with PBMT composed the second and third groups, respectively. The control group did neither receive PBMT preconditioning nor DOX and was irradiated with a white standard lamp. Cells from all groups were collected to perform mRNA and miRNA expressions quantification. PBMT, when applied before the DOX challenge, restored the viability of hiPSC-vCMs and reduced ROS levels. Although downregulated by DOX, myocardial UCP2 mRNA expression presented marked upregulation after PBMT preconditioning. Expression of eNOS and UCP2 mRNA and NO production were decreased after DOX exposure, and PBMT preconditioning before the DOX challenge reversed these changes. Moreover, our data indicated that PBMT preconditioning lowered the miR-24 expression. Our data suggested that PBMT preconditioning ameliorated in vitro DOX-induced cardiotoxicity on transcription level, restoring NO levels and reducing oxidative stress.

Didymin attenuates doxorubicin-induced cardiotoxicity by inhibiting oxidative stress

Objective

This study was designed to investigate the protective effects of didymin (Did) on doxorubicin (DOX)-induced cardiotoxicity.

Methods

After pretreatment with Did (2, 4, 8 mg/kg intraperitoneal i.p.) for 7 d, the male C57 mice were injected with single dose of DOX (20 mg/kg i.p.). The cardioprotective effect of Did was observed on the 7th day after DOX treatment.

Results

DOX delayed body growth and caused cardiac tissue injury, oxidative stress, and mitochondrial dysfunction. Similar experiments in H9C2 cardiomyocytes showed that DOX reduced cell viability, increased generation of reactive oxygen species (ROS) and fragmentation of DNA, decreased mitochondrial membrane potential, and induced cardiomyocyte apoptosis. However, all of these adverse effects were suppressed by Did pretreatment. Did increased protein expression of glutamate-L-cysteine ligase catalytic subunit (GCL), heme oxygenase 1 (HO-1), and nuclear factor erythroid 2-related factor 2 (Nrf2). Besides, Did also induced activation of PI3K/AKT.

Conclusion

These findings indicated Did prevented DOX-induced cardiac injury and apoptosis via activating PI3K/AKT/Nrf2 signaling pathway.

In Vivo and In Vitro Protective Effects of Rosmarinic Acid against Doxorubicin-Induced Cardiotoxicity

Doxorubicin (DOX) is an anticancer medicine that may trigger cardiomyopathy. Rosmarinic acid (RA) has shown antioxidant, anti-inflammatory, and anticancer effects. This investigation assessed the cardioprotective effect of RA on DOX-induced-toxicity in both in vivo and in vitro experiments. Male rats were randomized on 7 groups: (1) control, (2) DOX (2 mg/kg, per 48 h, 12d, i.p), (3) RA (40 mg/kg, 12d, i.p.), (4-6) RA (10, 20, 40 mg/kg, 16d, i.p.)+ DOX, (7) Vitamin E (200 mg/kg, per 48 h, 16d, i.p.) + DOX and then indices of cardiac function were estimated. Also, DOX and rosmarinic acid effects were examined on MCF7 cells (breast cancer cells line) to clarify that both cardiotoxicity and anticancer effects were analyzed. DOX increased heart to body weight ratio, RRI, QA, STI, QRS duration and voltage, attenuated HR, blood pressure, Max dP/dt, Min dP/dt, LVDP, enhanced MDA, declined GSH amount, and caused fibrosis and necrosis in cardiac tissue. Administration of RA ameliorated the toxic effects of DOX. In vitro studies showed that RA did not affect the cytotoxic effect of DOX. RA as an antioxidant, anti-inflammatory, and cardioprotective compound could be a promising compound to help minimize DOX-induced cardiotoxicity.

The Great Healing Potential Hidden in Plant Preparations of Antioxidant Properties: A Return to Nature?

The application of chemicals in industry and agriculture has contributed to environmental pollution and exposure of living organisms to harmful factors. The development of new pharmaceutical agents enabled successful therapy of various diseases, but their administration may be connected with side effects. Oxidative stress has been found to be involved into etiology of numerous diseases as well as harmful action of drugs and chemicals. For some time, plant origin substances have been studied as potential protective agents alleviating toxicity of various substances and symptoms of diseases. The aim of the current review was to present the diversity of the research performed during the last five years on animal models. The outcomes showed a huge protective potential inherent in plant preparations, including alleviating prooxidative processes, strengthening antioxidant defence, ameliorating immune parameters, and reversing histopathological changes. In many cases, plant origin substances were proved to be comparable or even better than standard drugs. Such findings let us suggest that in the future the plant preparations could make adjuvants or a replacement for pharmaceutical agents. However, the detailed research regarding dose and way of administration as well as the per se effects needs to be performed. In many studies, the last issue was not studied, and in some cases, the deleterious effects have been observed.

Clinopodium tomentosum (Kunth) Govaerts Leaf Extract Influences in vitro Cell Proliferation and Angiogenesis on Primary Cultures of Porcine Aortic Endothelial Cells

Clinopodium tomentosum (Kunth) Govaerts is an endemic species in Ecuador, where it is used as an anti-inflammatory plant to treat respiratory and digestive affections. In this work, effects of a Clinopodium tomentosum ethanolic extract (CTEE), prepared from aerial parts of the plant, were investigated on vascular endothelium functions. In particularly, angiogenesis activity was evaluated, using primary cultures of porcine aortic endothelial cells (pAECs). Cells were cultured for 24 h in the presence of CTEE different concentrations (10, 25, 50, and 100 μg/ml); no viability alterations were found in the 10-50 μg/ml range, while a slight, but significant, proliferative effect was observed at the highest dose. In addition, treatment with CTEE was able to rescue LPS-induced injury in terms of cell viability. The CTEE ability to affect angiogenesis was evaluated by scratch test analysis and by an in vitro capillary-like network assay. Treatment with 25-50 μg/ml of extract caused a significant increase in pAEC's migration and tube formation capabilities compared to untreated cells, as results from the increased master junctions' number. On the other hand, CTEE at 100 μg/ml did not induce the same effects. Quantitative PCR data demonstrated that FLK-1 mRNA expression significantly increased at a CTEE dose of 25 μg/ml. The CTEE phytochemical composition was assessed through HPLC-DAD; rosmarinic acid among phenolic acids and hesperidin among flavonoids were found as major phenolic components. Total phenolic content and total flavonoid content assays showed that flavonoids are the most abundant class of polyphenols. The CTEE antioxidant activity was also showed by means of the DPPH and ORAC assays. Results indicate that CTEE possesses an angiogenic capacity in a dose-dependent manner; this represents an initial step in elucidating the mechanism of the therapeutic use of the plant.

Nrf2-dependent antioxidant response mediated the protective effect of tanshinone IIA on doxorubicin-induced cardiotoxicity

Doxorubicin (DOX), a potent and widely used anticancer agent, can give rise to severe cardiotoxicity that limits its clinical use by inducing oxidative stress. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is the central regulator of cellular responses to electrophilic/oxidative stress, which serves a critical role in maintenance of normal cardiac function. Tanshinone IIA (Tan IIA) has previously been reported to protect against DOX-induced cardiotoxicity. The aim of the present study was to elucidate whether Nrf2 signaling serves a role in the underlying mechanism. In the animal model, DOX induced acute cardiotoxicity, whereas Tan IIA pretreatment reduced the activity of myocardial enzymes, and increased activity of the antioxidant enzymes superoxide dismutase, catalase and glutathione (GSH). Furthermore, Tan IIA pretreatment (3-10 µM) significantly increased the cell viability and markedly restored morphological changes in DOX-injured H9c2 cells, decreased the generation of reactive oxygen species, and increased the level of intracellular GSH. Additionally, Tan IIA pretreatment also induced the nuclear accumulation of Nrf2 and its downstream genes heme oxygenase-1, NAD(P)H dehydrogenase (quinone) 1, and glutamate-cysteine ligase catalytic subunit in both the mice cardiac tissues and H9c2 cells. Nrf2 knockdown by small interfering RNA downregulated Tan IIA-induced Nrf2 activation and reversed the effect of Tan IIA on the DOX-induced inhibition of cell viability. These results suggest that the Nrf2-dependent antioxidant response mediates the protective effect of Tan IIA on DOX-induced cardiotoxicity.

Protective effect of dioscin against doxorubicin-induced cardiotoxicity via adjusting microRNA-140-5p-mediated myocardial oxidative stress

Clinical application of doxorubicin (DOX) is limited because of its cardiotoxicity. Thus, exploration of effective lead compounds against DOX-induced cardiotoxicity is necessary. The aim of the present study was to investigate the effects and possible mechanisms of dioscin against DOX-induced cardiotoxicity. The in vitro model of DOX- treated H9C2 cells and the in vivo models of DOX-treated rats and mice were used in this study. The results showed that discoin markedly increased H9C2 cell viability, decreased the levels of CK, LDH, and improved histopathological and electrocardio- gram changes in rats and mice to protect DOX-induced cardiotoxicity. Furthermore, dioscin significantly inhibited myocardial oxidative insult through adjusting the levels of intracellular ROS, MDA, SOD, GSH and GSH-Px in vitro and in vivo. Our data also indicated that dioscin activated Nrf2 and Sirt2 signaling pathways, and thereby affected the expression levels of HO-1, NQO1, Gst, GCLM, Keap1 and FOXO3a through decreasing miR-140-5p expression level. In addition, the level of intracellular ROS was significantly increased in H9C2 cells treated by DOX after miR-140-5p mimic transfection, as well as the down-regulated expression levels of Nrf2 and Sirt2, which were markedly reversed by dioscin. In conclusion, our data suggested that dioscin alleviated DOX-induced cardiotoxicity through modulating miR-140-5p-mediated myocardial oxidative stress. This natural product should be developed as a new candidate to alleviate cardiotoxicity caused by DOX in the future.

Protective effect of dioscin against doxorubicin-induced cardiotoxicity via adjusting microRNA-140-5p-mediated myocardial oxidative stress

Clinical application of doxorubicin (DOX) is limited because of its cardiotoxicity. Thus, exploration of effective lead compounds against DOX-induced cardiotoxicity is necessary. The aim of the present study was to investigate the effects and possible mechanisms of dioscin against DOX-induced cardiotoxicity. The in vitro model of DOX- treated H9C2 cells and the in vivo models of DOX-treated rats and mice were used in this study. The results showed that discoin markedly increased H9C2 cell viability, decreased the levels of CK, LDH, and improved histopathological and electrocardio- gram changes in rats and mice to protect DOX-induced cardiotoxicity. Furthermore, dioscin significantly inhibited myocardial oxidative insult through adjusting the levels of intracellular ROS, MDA, SOD, GSH and GSH-Px in vitro and in vivo. Our data also indicated that dioscin activated Nrf2 and Sirt2 signaling pathways, and thereby affected the expression levels of HO-1, NQO1, Gst, GCLM, Keap1 and FOXO3a through decreasing miR-140-5p expression level. In addition, the level of intracellular ROS was significantly increased in H9C2 cells treated by DOX after miR-140-5p mimic transfection, as well as the down-regulated expression levels of Nrf2 and Sirt2, which were markedly reversed by dioscin. In conclusion, our data suggested that dioscin alleviated DOX-induced cardiotoxicity through modulating miR-140-5p-mediated myocardial oxidative stress. This natural product should be developed as a new candidate to alleviate cardiotoxicity caused by DOX in the future.

Antioxidant and Protective Effects of Schinus terebinthifolius Raddi Against Doxorubicin-Induced Toxicity

Doxorubicin is an anticancer drug whose toxic effects on non-cancer cells are associated with increased oxidative stress. This study investigated the chemical composition, antioxidant activity of the methanolic extract of Schinus terebinthifolius Raddi leaves (MESL) as well as effects against doxorubicin-induced toxicity in human erythrocytes, K562 human erythroleukemia cells, and mouse hearts. The chemical composition indicated the presence of phenolic compounds, flavonoids, tannins, and ascorbic acid. MESL showed antioxidant activity by scavenging free radicals and inhibiting hemolysis and lipid peroxidation in human erythrocytes incubated with an oxidizing agent, and was able to increase the enzymatic activity of superoxide dismutase and glutathione peroxidase in human erythrocytes, without influencing the activity of enzyme catalase. The increase of oxidative hemolysis and malondialdehyde levels in erythrocytes incubated with doxorubicin was reduced by treatment with MESL. The cytotoxic activity of doxorubicin in erythroleukemia cells treated with MESL was unmodified. Additionally, the extract protected mice against the doxorubicin-induced cardiotoxicity. In conclusion, the MESL exhibits antioxidant activity, reducing doxorubicin-induced oxidative stress without changing the anticancer action of the drug, and protects against doxorubicin-induced cardiotoxicity. Hence, these findings suggest that these effects are via anti-oxidative by inhibiting free radicals, decreased oxidative stress, and increased antioxidant enzyme activity.

Effects of Polyphenols on Oxidative Stress-Mediated Injury in Cardiomyocytes

Cardiovascular diseases are the main cause of mortality and morbidity in the world. Hypertension, ischemia/reperfusion, diabetes and anti-cancer drugs contribute to heart failure through oxidative and nitrosative stresses which cause cardiomyocytes nuclear and mitochondrial DNA damage, denaturation of intracellular proteins, lipid peroxidation and inflammation. Oxidative or nitrosative stress-mediated injury lead to cardiomyocytes apoptosis or necrosis. The reactive oxygen (ROS) and nitrogen species (RNS) concentration is dependent on their production and on the expression and activity of anti-oxidant enzymes. Polyphenols are a large group of natural compounds ubiquitously expressed in plants, and epidemiological studies have shown associations between a diet rich in polyphenols and the prevention of various ROS-mediated human diseases. Polyphenols reduce cardiomyocytes damage, necrosis, apoptosis, infarct size and improve cardiac function by decreasing oxidative stress-induced production of ROS or RNS. These effects are achieved by the ability of polyphenols to modulate the expression and activity of anti-oxidant enzymes and several signaling pathways involved in cells survival. This report reviews current knowledge on the potential anti-oxidative effects of polyphenols to control the cardiotoxicity induced by ROS and RNS stress.

The effect of a number of H9C2 rat cardiomyocytes passage on repeatability of cytotoxicity study results

The embryonic cardiomyocyte cell line H9C2 is commonly used in numerous in vitro studies, including cardiotoxicity analyses of new drugs. So far no results were published for studies on cell parameters variability during the cell line ageing process. For this reason the aim of the study was to evaluate the effect of a number of H9C2 rat embryonic cardiomyocytes passages on repeatability of study results for selected cytotoxicity parameters, with doxorubicin as a model toxic agent. The cultures were passaged twenty-five times. Cells from passage 1, 5, 10, 15, 20 and 25 were treated with doxorubicin for 24 h. Then drug cytotoxicity was evaluated with the MTT test and additionally the nuclear factor erythroid 2–related factor (Nrf2) gene expression was examined. The analysis of oxidative stress intensity and cell morphology was also assessed. The microscopic appearance of cells indicates that untreated cardiomyocytes morphology changes as well as sensitivity to toxic effects increases with the number of passages. Also an increase in oxidative stress in cells occurs with further passaging of cardiomyocytes. Statistical significance of differences in conducted tests results depended on doxorubicin concentration but in many cases the H9C2 line was found to be a reliable in vitro model only for the first five passages. For this reason it is important to take into consideration that further culturing of cardiomyocytes may not ensure repeatability of study results due to the culture ageing.

The differential effects of green tea on dose-dependent doxorubicin toxicity

Background

Doxorubicin (DOX) is an anticancer drug displaying cardiac and hepatic adverse effects mostly dependent on oxidative stress. Green tea (GT) has been reported to play a protective role in diseases resulting from oxidative stress.

Objective

The objective of this study was to evaluate if GT protects against DOX-induced oxidative stress, heart and liver morphological changes, and metabolic disorders.

Methods

Male Wistar rats received intraperitoneal injection of DOX (1.0 or 2.0 mg/kg b.w.) for 7 weeks or concomitantly GT extract soluble in drinking water.

Results

There were multidirectional effects of GT on blood metabolic parameters changed by DOX. Among all tested biochemical parameters, statistically significant protection of GT against DOX-induced changes was revealed in case of blood fatty acid–binding protein, brain natriuretic peptide, and superoxide dismutase.

Conclusion

DOX caused oxidative stress in both organs. It was inhibited by GT in the heart but remained unchanged in the liver. DOX-induced general toxicity and histopathological changes in the heart and in the liver were mitigated by GT at a higher dose of DOX and augmented in rats treated with a lower dose of the drug.

Cytotoxicity of three naturally occurring flavonoid derived compounds (artocarpesin, cycloartocarpesin and isobavachalcone) towards multi-factorial drug-resistant cancer cells

INTRODUCTION

Cancer remains an aggressive deadly disease, if drug resistance develops. This problem is aggravated by the fact that multiple rather than single mechanisms are involved in resistance and that multidrug resistance (MDR) phenomena cause inefficacy of many clinical established anticancer drugs. We are seeking for novel cytotoxic phytochemicals to combat drug-resistant tumour cells.

METHODS

In the present study, we investigated the cytotoxicity of three naturally occurring flavonoids including two flavones artocarpesin (1) and cycloartocarpesin (2) and one chalcone, isobavachalcone (3) against 9 drug-sensitive and MDR cancer cell lines. The resazurin reduction assay was used to evaluate the cytotoxicity of these compounds, whilst caspase-Glo assay was used to detect caspase activation. Cell cycle, mitochondrial membrane potential (MMP) and levels of reactive oxygen species (ROS) were all analysed via flow cytometry.

RESULTS

Flavones 1 and 2 as well as chalcone 3 displayed cytotoxic effects at various extent on all the 9 tested cancer cell lines with IC50 values respectively below 106 µM, 50 µM and 25 µM. The IC50 values for the three investigational flavonoids ranged from 23.95 µM (towards hepatocarcinoma HepG2 cells) to 105 µM [towards colon carcinoma HCT116 (p53(-/-)) cells] for 1, from 15.51 µM (towards leukemia CCRF-CEM cells) to 49.83 µM [towards glioblastoma U87MG.ΔEGFR cells] for 2 and from 2.30 µM (towards CCRF-CEM cells) to 23.80 µM [towards colon carcinoma HCT116 (p53(+/+)) cells] for 3 and from 0.20 µM (towards CCRF-CEM cells) to 195.12 µM (towards leukemia CEM/ADR5000 cells) for doxorubicin. Compounds 2 and 3 induced apoptosis in CCRF-CEM leukemia cells, mediated by caspase activation and the disruption of MMP.

CONCLUSIONS

The three tested flavonoids and mostly chalcone 3 are potential cytotoxic natural products that deserve more investigations to develop novel antineoplastic drugs against multifactorial drug-resistant cancers.

Cytotoxicity of two naturally occurring flavonoids (dorsmanin F and poinsettifolin B) towards multi-factorial drug-resistant cancer cells

INTRODUCTION

The expression of diverse resistance mechanisms in cancer cells is one of the major barriers to successful cancer chemotherapy.

METHODS

In the present study, we assessed the cytotoxicity of two naturally occurring flavonoids dorsmanin F (1, a flavanone) and poinsettifolin B (2, a chalcone) against 9 drug-sensitive and multidrug-resistant (MDR) cancer cell lines. The resazurin reduction assay was used to evaluate the cytotoxicity of these compounds, whilst caspase-Glo assay was used to detect caspase activation. Cell cycle, mitochondrial membrane potential (MMP) and levels of reactive oxygen species (ROS) were all analysed via flow cytometry.

RESULTS

Compounds 1 and 2 displayed cytotoxic effects with IC50 values below 34 µM in all the 9 tested cancer cell lines. The IC50 values for flavanone 1 and chalcone 2 ranged from 5.34 µM and 1.94 µM (towards leukaemia CCRF-CEM cells) to 33.30 µM and 28.92 µM (towards MDA-MB-231-BCRP cells), respectively, and from 0.20 µM (against CCRF-CEM cells) to 195.12 µM (against CEM/ADR5000 cells) for doxorubicin. The compounds induced apoptosis in CCRF-CEM leukaemia cells, mediated by MMP disruption and increased ROS production.

CONCLUSIONS

Dorsmain F and poinsettifolin B are potential cytotoxic natural products that deserve more investigations to develop novel antineoplastic drugs against multifactorial drug-resistant cancers.