Indole Alkaloid Derivative B, a Novel Bifunctional Agent That Mitigates 5-Fluorouracil-Induced Cardiotoxicity

Cardioprotective potential of mitochondria-targeted antioxidant, mito-TEMPO, in 5-fluorouracil-induced cardiotoxicity

Purpose

The mitochondria-targeted antioxidants (MTAs) are known to offer protection against mitochondrial oxidative stress. The recent evidences support their role in mitigating oxidative stress-induced diseases, including cancer. Therefore, this study investigated cardioprotective potential of mito-TEMPO against 5-FU-induced cardiotoxicity.

Methods

Mito-TEMPO was administered to male BALB/C mice (intraperitoneally, 0.1 mg/kg b.w. for 7 days) followed by intraperitoneal administration of 5- FU (12 mg/kg b.w. for 4 days). During this period, mito-TEMPO treatment was also continued. The cardioprotective potential of mito-TEMPO was assessed by evaluating cardiac injury markers, extent of non-viable myocardium and histopathological alterations. Mitochondrial functional status and mitochondrial oxidative stress were assessed in cardiac tissue. 8-OHdG expression and apoptotic cell death were assessed using immunohistochemical techniques.

Results

The level of cardiac injury markers CK-MB and AST were significantly (P ≤ 0.05) decreased in mito-TEMPO pre-protected group which was further reflected in histopathology as decrease in the percentage of non-viable myocardial tissue, disorganization, and loss of myofibrils. Mito-TEMPO ameliorated mtROS, mtLPO and conserved mitochondrial membrane potential. Further, it had significantly (P ≤ 0.05) improved the activity of mitochondrial complexes and mitochondrial enzymes. A significant (P ≤ 0.05) increase in the level of mtGSH, activity of mitochondrial glutathione reductase, glutathione peroxidase, and mitochondrial superoxide dismutase was observed. A decreased expression of 8-OHdG and reduced apoptotic cell death were observed in mito-TEMPO pre-protected group.

Conclusion

Mito-TEMPO effectively mitigated 5-FU-induced cardiotoxicity by modulating mitochondrial oxidative stress, hence may serve as a protective agent/adjuvant in 5-FU-based combinatorial chemotherapy.

Naturally derived indole alkaloids targeting regulated cell death (RCD) for cancer therapy: from molecular mechanisms to potential therapeutic targets

Regulated cell death (RCD) is a critical and active process that is controlled by specific signal transduction pathways and can be regulated by genetic signals or drug interventions. Meanwhile, RCD is closely related to the occurrence and therapy of multiple human cancers. Generally, RCD subroutines are the key signals of tumorigenesis, which are contributed to our better understanding of cancer pathogenesis and therapeutics. Indole alkaloids derived from natural sources are well defined for their outstanding biological and pharmacological properties, like vincristine, vinblastine, staurosporine, indirubin, and 3,3′-diindolylmethane, which are currently used in the clinic or under clinical assessment. Moreover, such compounds play a significant role in discovering novel anticancer agents. Thus, here we systemically summarized recent advances in indole alkaloids as anticancer agents by targeting different RCD subroutines, including the classical apoptosis and autophagic cell death signaling pathways as well as the crucial signaling pathways of other RCD subroutines, such as ferroptosis, mitotic catastrophe, necroptosis, and anoikis, in cancer. Moreover, we further discussed the cross talk between different RCD subroutines mediated by indole alkaloids and the combined strategies of multiple agents (e.g., 3,10-dibromofascaplysin combined with olaparib) to exhibit therapeutic potential against various cancers by regulating RCD subroutines. In short, the information provided in this review on the regulation of cell death by indole alkaloids against different targets is expected to be beneficial for the design of novel molecules with greater targeting and biological properties, thereby facilitating the development of new strategies for cancer therapy.

Advances in indole-containing alkaloids as potential anticancer agents by regulating autophagy

Cancer is a leading cause of death worldwide, and cancer development is often associated with disturbances in the autophagy process. Autophagy is a catabolic process involved in many physiological processes, crucial for cell growth and survival. It is an intracellular lysosomal/vacuolar degradation system. In this system, inner cytoplasmic cell membrane is degraded by lysosomal hydrolases, and the products are released back into the cytoplasm. Indole alkaloids are natural products extensively found in nature and have been proven to possess various pharmacological activities. In recent years, pharmacological studies have demonstrated another potential of indole alkaloids, autophagy regulation. The regulation may contribute to the efficacy of indole alkaloids in preventing and treating cancer. This review summarizes the current understanding of indole alkaloids' effect on tumor cells and autophagy. Then, we focus on mechanisms by which indole alkaloids can target the autophagy process associated with cancer, including the PI3K/Akt/mTOR signaling pathway, MAPK signaling pathway, ROS signaling pathway, Beclin-1, and so on. Literature has been surveyed primarily from 2009 to Nov. 2021, and some semisynthetic or fully synthetic indole derivatives are also discussed.

Melatonin Attenuates Ropivacaine-Induced Apoptosis by Inhibiting Excessive Mitophagy Through the Parkin/PINK1 Pathway in PC12 and HT22 Cells

Melatonin, as an endogenous circadian indoleamine secreted by the pineal gland, executes extensive biological functions, including antioxidant, anti-inflammatory, anti-tumor, and neuroprotective effects. Although melatonin has been reported to serve as a potential therapeutic against many nerve injury diseases, its effect on ropivacaine-induced neurotoxicity remains obscure. Our research aimed to explore the impact and mechanism of melatonin on ropivacaine-induced neurotoxicity. Our results showed that melatonin pretreatment protected the cell viability, morphology, and apoptosis of PC12 and HT22 cells, and it also improved ropivacaine-induced mitochondrial dysfunction and the activation of mitophagy. In addition, we found that autophagy activation with rapamycin significantly weakened the protective effect of melatonin against ropivacaine-induced apoptosis, whereas autophagy inhibition with 3-MA enhanced the effect of melatonin. We also detected the activation of Parkin and PINK1, a canonical mechanism for mitophagy regulation, and results shown that melatonin downregulated the expression of Parkin and PINK1, and upregulated Tomm20 and COXIV proteins, so that those results indicated that melatonin protected ropivacaine-induced apoptosis through suppressing excessive mitophagy by inhibiting the Parkin/PINK1 pathway. Melatonin may be a useful potential therapeutic agent against ropivacaine-induced neurotoxicity.

Cardiotoxicity of Fluoropyrimidines: Epidemiology, Mechanisms, Diagnosis, and Management

Cancer is a growing public health problem; it is responsible annually for millions of deaths worldwide. Fluoropyrimidines are highly effective and commonly prescribed anti-neoplastic drugs used in a wide range of chemotherapy regimens against several types of malignancies. 5-fluorouracil and its prodrugs affect neoplastic cells in multiple ways by impairing their proliferation, principally through the inhibition of thymidylate synthase. Fluoropyrimidine-induced cardiotoxicity was described more than 50 years ago, but many details such as incidence, mechanisms, and treatment are unclear and remain disputed. Severe cardiotoxicity is not only life-threatening, but also leads to withdrawal from an optimal chemotherapy regimen and decreases survival rate. Differences in the frequency of cardiotoxicity are explained by different chemotherapy schedules, doses, criteria, and populations. Proposed pathophysiological mechanisms include coronary vasospasm, endothelial damage, oxidative stress, Krebs cycle disturbances, and toxic metabolites. Such varied pathophysiology of the cardiotoxicity phenomenon makes prevention and treatment more difficult. Cardiovascular disturbances, including chest pain, arrhythmias, and myocardial infarction, are among the most common side effects of this class of anti-neoplastic medication. This study aims to summarize the available data on fluoropyrimidine cardiotoxicity with respect to symptoms, incidence, metabolism, pathophysiological mechanism, diagnosis, management, and resistance.

The IL-6/STAT Signaling Pathway and PPARα Are Involved in Mediating the Dose-Dependent Cardioprotective Effects of Fenofibrate in 5-Fluorouracil-Induced Cardiotoxicity

PURPOSE

The cardiotoxicity of anticancer drugs such as 5-fluorouracil (5FU) is a major complication that challenges their clinical usefulness. Thus there is a critical need to find new protective drugs to defend against these harmful side effects. Up to now, there have been no studies evaluating the possible cardioprotective effects of fenofibrate (FEN) in 5FU-induced cardiotoxicity. Therefore, we aimed in the current model to evaluate such an effect of FEN and to explore different mechanisms mediating it.

METHODS

We used FEN (25, 50, 100 mg/kg/day) administered orally for 7 days with induction of cardiotoxicity by intraperitoneal (i.p.) injection of 5FU (150 mg/kg) on the fifth day.

RESULTS

The current study showed that 5FU succeeded in inducing cardiotoxicity, manifested by significantly elevated levels of cardiac enzymes, tissue malondialdehyde (MDA), interleukin 6 (IL-6), signal transducer and activator of transcription 4 (STAT4), and caspase-3. Furthermore, the 5FU group showed toxic histopathological changes including marked cardiac damage and a significant decrease in reduced glutathione (GSH), total antioxidant capacity (TAC), and peroxisome proliferator-activated receptor alpha (PPARα) expression. FEN reversed 5FU-induced cardiotoxicity by various mechanisms including upregulation of PPARα, inhibition of the IL-6/STAT signaling pathway, and anti-inflammatory, antiapoptotic, and antioxidant properties.

CONCLUSION

FEN demonstrated a significant cardioprotective effect against 5FU-induced cardiac damage.

Synthesis, structural characterization and electrochemical and magnetic studies of M(hfac)2 (M = CuII, CoII) and Nd(hfac)3 complexes of 4-amino-TEMPO

Three mononuclear complexes [M(hfac)x(ATEMPO)y], where M = Cu (11) and Co (12), x = y = 2; M = Nd (13), x = 4, y = 1, and two polynuclear complexes [{Cu(hfac)2(ATEMPO)}n], where n = 2 (14) and 4 (15), were obtained by the reaction of M(hfac)x (M = CuII, CoII, NdIII; x = 2, 3) with 4-amino-TEMPO (4-amino-2,2,6,6-tetramethylpiperidin-N-oxyl) in good yields and their structural, electrochemical and magnetic properties were examined. In all cases, the radical is coordinated to the metal through the amino group, except 15, and the metal ions have an octahedral geometry, except 13. Different coordination architectures of the copper complexes were obtained as a function of the stoichiometry and solvents used. In complexes 11 and 12 the radicals show an equatorial-equatorial and axial-equatorial arrangement, respectively, giving rise to two distinct 2D supramolecular systems through intermolecular interactions. Compound 13 is the first example of a lanthanide complex of the ATEMPO radical. The NdIII ion adopts a rare nine-coordination via binding to four hfac ligands and the radical. The dinuclear complex 14 shows a (Cu-O)2 core in which the CuII ions are bridged by the oxygen atoms from the hfac ligands. In compound 15 the ATEMPO radical acts as a bidentate ligand through the amino and nitroxyl groups leading to an unprecedented tetranuclear square-shaped framework. Cyclic voltammetry showed redox processes associated with the copper and TEMPO moieties. Electrochemical impedance spectroscopy revealed the temperature dependence of the conductivity for compound 15 with a maximum of 2.09 × 10-5 S cm-1 at 408 K. The magnetic behavior of complexes 11-15 is determined by metal-radical interactions. Ferromagnetic interaction has been observed for complex 11 due to the existence of two different exchange pathways arising from the conformational arrangement of the radicals around the metal center, whereas the single conformation of the radical in complex 14 resulted in a weak antiferromagnetic coupling. In complex 15 both O-Cu and N-Cu contacts are present giving rise to ferromagnetic and antiferromagnetic interactions, respectively.