Green Synthesis, Characterization, Encapsulation, and Measurement of the Release Potential of Novel Alkali Lignin Micro-/Submicron Particles.

The applicability of biopolymer micro-/nano- technology in human, veterinary medicine, pharmaceutical, and food technology is rapidly growing due to the great potential of biopolymer-based particles as effective carrier systems. The use of lignin as a basic heteropolymer biomatrix for the design of innovative micro-/submicron formulations allows the achievement of increased biocompatibility and offers various active functional groups presenting opportunities for customization of the physicochemical properties and bioactivities of the formulations for diverse applications. The aim of the present study was to develop a simple and ecofriendly methodology for the synthesis of lignin particles with micro- and submicron size; to evaluate their physicochemical, spectral, and structural characteristics; and to examine their capacity for encapsulation of biologically active molecules and potential for in vitro release of bioflavonoids in simulated gastrointestinal media. The presented methodologies apply cheap and green solvents; easy, straightforward, quick, and sensitive processes requiring little equipment, non-toxic substances, and simple methods for their characterization, the determination of encapsulation capacity towards the poorly water-soluble bioactive compounds morin and quercetin, and the in vitro release potential of the lignin matrices.

Green Solvents for Extraction of Natural Food Colorants from Plants: Selectivity and Stability Issues.

Consumers associate the color of food with its freshness and quality. More and more attention is being paid to natural colorants that bring additional health benefits to humans. Such natural substances are the carotenoids (yellow to orange), the anthocyanins (red to blue), and the betalains (red and yellow), which are very sensitive to exposure to light, air, high temperatures, and chemicals. Stability and diversity in terms of color can be optimized by using environmentally friendly and selective extraction processes that provide a balance between efficacy, safety, and stability of the resulting extracts. Green solvents like water, supercritical fluids, natural deep eutectic solvents, and ionic liquids are the most proper green solvents when combined with different extraction techniques like maceration, supercritical extraction, and ultrasound-assisted or microwave-assisted extraction. The choice of the right extracting agent is crucial for the selectivity of the extraction method and the stability of the prepared colorant. The present work reviews the green solvents used for the extraction of natural food colorants from plants and focuses on the issues related to the selectivity and stability of the products extracted.

Menadione Contribution to the In Vitro Radical Scavenging Potential of Phytochemicals Naringenin and Lignin.

Vitamin K3 (menadione), classified as a pro-vitamin, is a synthetic form of the fat-soluble family of vitamin K compounds. The combination of the vitamin with other molecules sharing structural and/or functional similarities, such as naturally occurring polyphenols, vitamins, or biopolymers, could potentiate mutual improvement of their antioxidant activity. The aim of the present study was to evaluate the role and contribution of vitamin K3 to the in vitro radical scavenging capacity of double and triple combinations with the phytochemicals naringenin and lignin, as well as assess possible intermolecular interactions between the bioactive compounds. Comparative analyses of the DPPH and ABTS radical scavenging activity of the pure substances vitamin K3, naringenin, and lignin; the two-component systems lignin/vitamin K3 and vitamin K3/naringenin; and the triple combination vitamin K3/flavonoid/lignin were carried out. The experimental results demonstrated increased DPPH and ABTS activities of the vitamin in combination with lignin compared to those of the two pure substances, i.e., a synergistic effect was observed. The registered significant increases in the radical scavenging activity of the triple combination determined via both methods are indicative of a remarkable potentiation effect, i.e., higher antioxidant potential exceeding the additive activity of the three pure substances.

Water-Soluble Alkali Lignin as a Natural Radical Scavenger and Anticancer Alternative.

Several phytochemicals, which display antioxidant activity and inhibit cancer cell phenotypes, could be used for cancer treatment and prevention. Lignin, as a part of plant biomass, is the second most abundant natural biopolymer worldwide, and represents approximately 30% of the total organic carbon content of the biosphere. Historically, lignin-based products have been viewed as waste materials of limited industrial usefulness, but modern technologies highlight the applicability of lignin in a variety of industrial branches, including biomedicine. The aims of our preliminary study were to compare the antioxidant properties of water-soluble alkali lignin solutions, before and after UV-B irradiation, as well as to clarify their effect on colon cancer cell viability (Colon 26), applied at low (tolerable) concentrations. The results showed a high antioxidant capacity of lignin solutions, compared to a water-soluble control antioxidant standard (Trolox) and remarkable radical scavenging activity was observed after their UV-B irradiation. Diminishment of cell viability as well as inhibition of the proliferative activity of the colon cancer cell line with an increase in alkali lignin concentrations were observed. Our results confirmed that, due to its biodegradable and biocompatible nature, lignin could be a potential agent for cancer therapy, especially in nanomedicine as a drug delivery system.

Newly Synthesized Lignin Microparticles as Bioinspired Oral Drug-Delivery Vehicles: Flavonoid-Carrier Potential and In Vitro Radical-Scavenging Activity.

The aim of the present study was to synthesize lignin microparticles, to evaluate their physicochemical, spectral, morphological and structural characteristics, to examine their encapsulation and in vitro release potential and behaviour towards the flavonoid morin in simulated physiological medium and to assess the in vitro radical-scavenging potential of the morin-loaded lignin microcarrier systems. The physicochemical, structural and morphological characteristics of alkali lignin, lignin particles (LP) and morin-encapsulated lignin microparticles (LMP) were determined based on particle size distribution, SEM, UV/Vis spectrophotometric, FTIR and potentiometric titration analyses. The encapsulation efficiency of LMP was 98.1%. The FTIR analyses proved that morin was successfully encapsulated in the LP without unexpected chemical reactions between the flavonoid and the heteropolymer. The in vitro release performance of the microcarrier system was successfully mathematically described by Korsmeyer-Peppas and the sigmoidal models outlining the general role of diffusion during the initial stages of the in vitro release process in simulated gastric fluid (SGF), and the predominant contribution of biopolymer relaxation and erosion was determined in simulated intestinal medium (SIF). The higher radical-scavenging potential of LMP, as compared to that of LP, was proven via DPPH and ABTS assays. The synthesis of lignin microcarriers not only provides a facile approach for the utilization of the heteropolymer but also determines its potential for the design of drug-delivery matrices.

Docosahexaenoic Acid Potentiates the Anticancer Effect of the Menadione/Ascorbate Redox Couple by Increasing Mitochondrial Superoxide and Accelerating ATP Depletion.

BACKGROUND/AIM: Mitochondria-targeted anticancer drugs ("mitocans") of natural origin are attractive candidates as adjuvants in cancer therapy. The redox couple menadione/ascorbate (M/A), which belongs to the "mitocans" family, induces selective oxidative stress in cancerous mitochondria and cells, respectively. DHA has also been found to regulate the mevalonate pathway, which is closely related to the prenylation of the cytotoxic menadione to the non-cytotoxic menaquinone. The aim of this study was to elucidate the ability of docosahexaenoic acid (DHA) to potentiate the anticancer effect of M/A by increasing ROS production, as well as affecting steady-state ATP levels in cancer cells. MATERIALS AND METHODS: The experiments were performed on leukemic lymphocyte Jurkat. Cells were treated with DHA, M/A, and their combination (M/A/DHA) and four parameters were examined using the following assays: cell viability and proliferation, steady-state ATP, mitochondrial superoxide, intracellular hydroperoxides. Three independent experiments with two or six parallel measurements were performed for each parameter. RESULTS: The triple combination M/A/DHA was characterized by much higher antiproliferative activity and cytotoxicity than M/A and DHA administered alone. DHA significantly accelerated M/A-induced ATP depletion in cells, which was accompanied by an additional increase in mitochondrial superoxide compared to cells treated with M/A or DHA alone. CONCLUSION: DHA significantly enhanced M/A-induced cytotoxicity in leukemic lymphocytes by inducing severe mitochondrial oxidative stress and accelerated ATP depletion. Selective DHA-mediated suppression of cholesterol synthesis in cancer cells (involved in the prenylation of cytotoxic menadione to the less cytotoxic phylloquinone), as well as DHA-mediated inhibition of superoxide dismutase are suggested to underlie the potentiation of the anticancer effect of M/A.

Redox-mediated Anticancer Activity of Anti-parasitic Drug Fenbendazole in Triple-negative Breast Cancer Cells.

BACKGROUND/AIM: An increasing number of studies are reporting anticancer activity of widely used antiparasitic drugs and particularly benzimidazoles. Fenbendazole is considered safe and tolerable in most animal species at the effective doses as an anthelmintic. Little is known about the redox-modulating properties of fenbendazole and the molecular mechanisms of its antiproliferative effects. Our study aimed to investigate the possibility of selective redox-mediated treatment of triple-negative breast cancer cells by fenbendazole without affecting the viability and redox status of normal breast epithelial cells. MATERIALS AND METHODS: The experiments were performed on three cell lines: normal breast epithelial cells (MCF-10A) and cancer breast epithelial cells (MCF7 - luminal adenocarcinoma, low metastatic; MDA-MB-231 - triple-negative adenocarcinoma, highly metastatic). Cells were treated with fenbendazole for 48-h and three parameters were analyzed using conventional assays: cell viability and proliferation, level of intracellular superoxide, and level of hydroperoxides. RESULTS: The data demonstrated that MDA-MB-231 cells were more vulnerable to fenbendazole-induced oxidative stress than MCF-7 cells. In normal breast epithelial cells MCF-10A, fenbendazole significantly suppressed oxidative stress compared to untreated controls. These data correlate with the effect of fenbendazole on cell viability and the IC50 values, which is indirect evidence of the potential targeting anticancer effect of the drug, especially in MDA-MB-231 cells. CONCLUSION: The difference in the levels of oxidative stress induced by fenbendazole in MDA-MB-231 and MCF-7 indicates that the two types of breast cancer respond to the drug through different redox-related mechanisms.

Antimicrobial Potential of Conjugated Lignin/Morin/Chitosan Combinations as a Function of System Complexity.

As natural biopolymers, chitosan and lignin are characterized by their good biocompatibility, high biodegradability and satisfactory biosafety. The active polymers' functional groups are responsible for the potential of these biomaterials for use as carrier matrices in the construction of polymer−drug conjugates with prospective applicability in the fields of medicine, food and agriculture­subjects that have attracted attention in recent years. Hence, the aim of this research was to place substantial emphasis on the antimicrobial potential of flavonoid−biopolymer complex systems by assessment of the probable synergetic, additive or antagonistic effects arising as a function of systemic complexity. The joint implementation of morin, chitosan and lignin in conjugated two- and three-component systems provoked species-dependent antimicrobial synergistic and/or potentiation effects against the activity of the tested bacterial strains Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and the clinical isolate Bacillus cereus. The double combinations of morin−chitosan and morin−lignin resulted in a 100% increase in their inhibitory activity against S. aureus as compared to the pure biocompounds. The inhibitory effects of the three-component system, in decreasing order, were: S. aureus (IZ = 15.7 mm) > P. aeruginosa (IZ = 15 mm) > B. cereus and E. coli (IZ = 14 mm). All tested morin-containing two- and three-component systems exhibited clear and significant potentiation effects, especially against S. aureus and B. cereus. The results obtained are a prerequisite for the potential use of the studied conjugated lignin−morin−chitosan combinations in the construction of novel drug-carrier formulations with improved bioactivities.

In Vivo Radioprotective Potential of Newly Synthesized Azomethine and Styrylquinoline Derivatives and a Natural Polyphenol: A Preliminary Study.

The aim of the present study was to investigate the radioprotective activity of silymarin, a plant substance with hepatoprotective activity, of four newly synthesized structural derivatives of anthranilic acid azomethines, and alkyl-2-styrylquinolinic acid, as well as to establish and assess the influence of the solvent type and bioactive compound dose on the in vivo radioprotective potential of the natural and novel synthetic compounds. Male Wistar strain rats weighing 110-120 g were used for the in vivo experiments. Fifteen minutes after i.p. injection of the compounds, the experimental animals were irradiated by 8 Gy. Results indicate that the compound 2-{[(3,5-dihydro-2-hydroxyphenyl)methylen] amino}-benzoic acid in a dose of 60 mg/kg body weight exhibited the highest radioprotective effect, whereas the natural extract silymarin did not manifest radioprotective potential, even in high doses.

Effect of Alpha-tocopheryl Succinate on the Cytotoxicity of Anticancer Drugs Towards Leukemia Lymphocytes.

BACKGROUND/AIM: This study analysed the effect of α-tocopheryl succinate (α-TS) on the redox-state of leukemia and normal lymphocytes, as well as their sensitization to fifteen anticancer drugs. MATERIALS AND METHODS: Cell viability was analyzed by trypan blue staining and automated counting of live and dead cells. Apoptosis was analyzed by FITC-Annexin V test. Oxidative stress was evaluated by the intracellular levels of reactive oxygen species (ROS) and protein-carbonyl products. RESULTS: Most combinations (α-TS plus anticancer drug) exerted additive or antagonistic effects on the proliferation and viability of leukemia lymphocytes. α-TS combined with barasertib, bortezomib or lonafarnib showed a strong synergistic cytotoxic effect, which was best expressed in the case of barasestib. It was accompanied by impressive induction of apoptosis and increased production of ROS, but insignificant changes in protein-carbonyl levels. α-TS plus barasertib did not alter the viability and did not induce oxidative stress and apoptosis in normal lymphocytes. CONCLUSION: α-TS could be a promising adjuvant in second-line anticancer therapy, particularly in acute lymphoblastic leukemia, to reduce the therapeutic doses of barasertib, bortezomib, and lonafarnib, increasing their effectiveness and minimizing their side effects.

Application of microfluidic chips in anticancer drug screening.

With the continuous development of drug screening technology, new screening methodologies and technologies are constantly emerging, driving drug screening into rapid, efficient and high-throughput development. Microfluidics is a rising star in the development of innovative approaches in drug discovery. In this article, we summarize the recent years' progress of microfluidic chip technology in drug screening, including the developmental history, structural design, and applications in different aspects of microfluidic chips on drug screening. Herein, the existing microfluidic chip screening platforms are summarized from four aspects: chip structure design, sample injection and drive system, cell culture technology on a chip, and efficient remote detection technology. Furthermore, this review discusses the application and developmental prospects of using microfluidic chips in drug screening, particularly in screening natural product anticancer drugs based on chemical properties, pharmacological effects, and drug cytotoxicity.

Clinoptilolite Microparticles as Carriers of Catechin-Rich Acacia catechu Extracts: Microencapsulation and In Vitro Release Study.

The main goal of the present study was to investigate the microencapsulation, in vitro release capacity and efficiency of catechin-rich Acacia catechu extract by Clinosorbent-5 (CLS-5) microparticles by in-depth detailed analyses and mathematical modelling of the encapsulation and in vitro release kinetics behaviour of the polyphenol-mineral composite system. The bioflavanol encapsulation and release efficiency on/from the mineral matrix were assessed by sorption experiments and interpretative modelling of the experimental data. The surface and spectral characteristics of the natural bioactive substance and the inorganic microcarrier were determined by Fourier Transform Infrared Spectroscopy (FTIR) and Ultraviolet/Visible (UV/Vis) spectrophotometric analyses. The maximum extent of catechin microencapsulation in acidic medium was 32%. The in vitro release kinetics study in simulated enzyme-free gastric medium (pH = 1.2) approved 88% maximum release efficiency achieved after 24 h. The in vitro release profile displayed that the developed bioflavanol/clinoptilolite microcarrier system provided sustained catechin in vitro release behaviour without an initial burst effect. Thus, the results from the present study are essential for the design and development of innovative catechin-CLS-5 microcarrier systems for application in human and veterinary medicine.

Catechins within the Biopolymer Matrix-Design Concepts and Bioactivity Prospects.

Epidemiological studies and clinical investigations proposed that catechins extracts alone may not provide a sufficient level of bioactivities and promising therapeutic effects to achieve health benefits due to a number of constraints related to poor oral absorption, limited bioavailability, sensitivity to oxidation, etc. Modern scientific studies have reported numerous techniques for the design of micro- and nano-bio-delivery systems as novel and promising strategies to overcome these obstacles and to enhance catechins' therapeutic activity. The objective assessment of their benefits, however, requires a critical comparative estimation of the advantages and disadvantages of the designed catechins-biocarrier systems, their biological activities and safety administration aspects. In this respect, the present review objectively outlines, compares and assesses the recent advances related to newly developed design concepts of catechins' encapsulation into various biopolymer carriers and their release behaviour, with a special emphasis on the specific physiological biofunctionalities of the innovative bioflavonoid/biopolymer delivery systems.

Selective Targeting of Cancerous Mitochondria and Suppression of Tumor Growth Using Redox-Active Treatment Adjuvant.

Redox-active substances and their combinations, such as of quinone/ascorbate and in particular menadione/ascorbate (M/A; also named Apatone®), attract attention with their unusual ability to kill cancer cells without affecting the viability of normal cells as well as with the synergistic anticancer effect of both molecules. So far, the primary mechanism of M/A-mediated anticancer effects has not been linked to the mitochondria. The aim of our study was to clarify whether this "combination drug" affects mitochondrial functionality specifically in cancer cells. Studies were conducted on cancer cells (Jurkat, Colon26, and MCF7) and normal cells (normal lymphocytes, FHC, and MCF10A), treated with different concentrations of menadione, ascorbate, and/or their combination (2/200, 3/300, 5/500, 10/1000, and 20/2000 µM/µM of M/A). M/A exhibited highly specific and synergistic suppression on cancer cell growth but without adversely affecting the viability of normal cells at pharmacologically attainable concentrations. In M/A-treated cancer cells, the cytostatic/cytotoxic effect is accompanied by (i) extremely high production of mitochondrial superoxide (up to 15-fold over the control level), (ii) a significant decrease of mitochondrial membrane potential, (iii) a decrease of the steady-state levels of ATP, succinate, NADH, and NAD+, and (iv) a decreased expression of programed cell death ligand 1 (PD-L1)-one of the major immune checkpoints. These effects were dose dependent. The inhibition of NQO1 by dicoumarol increased mitochondrial superoxide and sensitized cancer cells to M/A. In normal cells, M/A induced relatively low and dose-independent increase of mitochondrial superoxide and mild oxidative stress, which seems to be well tolerated. These data suggest that all anticancer effects of M/A result from a specific mechanism, tightly connected to the mitochondria of cancer cells. At low/tolerable doses of M/A (1/100-3/300 µM/µM) attainable in cancer by oral and parenteral administration, M/A sensitized cancer cells to conventional anticancer drugs, exhibiting synergistic or additive cytotoxicity accompanied by impressive induction of apoptosis. Combinations of M/A with 13 anticancer drugs were investigated (ABT-737, barasertib, bleomycin, BEZ-235, bortezomib, cisplatin, everolimus, lomustine, lonafarnib, MG-132, MLN-2238, palbociclib, and PI-103). Low/tolerable doses of M/A did not induce irreversible cytotoxicity in cancer cells but did cause irreversible metabolic changes, including: (i) a decrease of succinate and NADH, (ii) depolarization of the mitochondrial membrane, and (iii) overproduction of superoxide in the mitochondria of cancer cells only. In addition, M/A suppressed tumor growth in vivo after oral administration in mice with melanoma and the drug downregulated PD-L1 in melanoma cells. Experimental data suggest a great potential for beneficial anticancer effects of M/A through increasing the sensitivity of cancer cells to conventional anticancer therapy, as well as to the immune system, while sparing normal cells. We hypothesize that M/A-mediated anticancer effects are triggered by redox cycling of both substances, specifically within dysfunctional mitochondria. M/A may also have a beneficial effect on the immune system, making cancer cells "visible" and more vulnerable to the native immune response.

Antioxidant Properties and Redox-Modulating Activity of Chitosan and Its Derivatives: Biomaterials with Application in Cancer Therapy.

Many studies have shown that mitochondrial metabolism has a fundamental role in induction of carcinogenesis due to the influence of increased levels of reactive oxygen species (ROS) generation in all steps of oncogene transformation and cancer progression. It is widely accepted that the anticancer effect of conventional anticancer drugs is due to induction of oxidative stress and elevated intracellular levels of ROS, which alter the redox homeostasis of cancer cells. On the other hand, the harmful side effects of conventional anticancer chemotherapeutics are also due to increased production of ROS and disruption of redox homeostasis of normal cells and tissues. Therefore, there is a growing interest toward the development of natural antioxidant compounds from various sources, which could impact the redox state of cancer and normal cells by different pathways and could prevent damage from oxidant-mediated reactions. It is known that chitosan exhibits versatile biological properties, including biodegradability, biocompatibility, and a less toxic nature. Because of its antioxidant, antibacterial, anticancer, anti-inflammatory, and immunostimulatory activities, the biopolymer has been used in a wide variety of pharmaceutical, biomedical, food industry, health, and agricultural applications and has been classified as a new physiologically bioactive material.

Resveratrol Modulates the Redox-status and Cytotoxicity of Anticancer Drugs by Sensitizing Leukemic Lymphocytes and Protecting Normal Lymphocytes.

BACKGROUND/AIM: The study is directed to the effect of resveratrol on the redox-status and viability of leukemic and normal lymphocytes, as well as its ability to sensitize leukemic lymphocytes to anticancer drugs. MATERIALS AND METHODS: Cytotoxicity was analyzed by trypan blue staining, apoptosis - by Annexin V test, and oxidative stress - by the intracellular levels of reactive oxygen species (ROS) and protein-carbonyl products. RESULTS: Incubation of resveratrol in combination with the majority of anticancer drugs resulted in higher toxicity than resveratrol or drug alone. In the case of leukemic lymphocytes treated with barasertib and everolimus in the presence of resveratrol, synergistic cytotoxicity was accompanied by strong induction of apoptosis, increased levels of hydroperoxides and insignificant changes in protein-carbonyl products. None of these parameters changed in normal lymphocytes. CONCLUSION: Resveratrol is a promising supplementary compound for anticancer therapy, that may allow reduction of the therapeutic doses of barasertib and everolimus, minimizing their side-effects.

Vitamins C and K3: A Powerful Redox System for Sensitizing Leukemia Lymphocytes to Everolimus and Barasertib.

BACKGROUND/AIM: Recent studies provided convincing evidence for the anticancer activity of combined application of vitamin C and pro-vitamin K3 (menadione). The molecular pathways underlying this process are still not well established. The present study aimed to investigate the effect of the combination of vitamin C plus pro-vitamin K3 on the redox status of leukemia and normal lymphocytes, as well as their sensitizing effect for a variety of anticancer drugs. MATERIALS AND METHODS: Cytotoxicity of the substances was analyzed by trypan blue staining and automated counting of live and dead cells. Apoptosis was analyzed by fluorescein isothiocyanate-annexin V test. Oxidative stress was evaluated by the intracellular levels of reactive oxygen and nitrogen species and protein-carbonyl products. RESULTS: Combined administration of 300 µM vitamin C plus 3 µM pro-vitamin K3 reduced the viability of leukemia lymphocytes by ~20%, but did not influence the viability of normal lymphocytes. All combinations of anticancer drug plus vitamins C and K3 were characterized by synergistic cytotoxicity towards Jurkat cells, compared to cells treated with drug alone for 24 h. In the case of barasertib and everolimus, this synergistic cytotoxicity increased within 72 hours. It was accompanied by strong induction of apoptosis, but a reduction of level of hydroperoxides and moderately increased protein-carbonyl products in leukemia cells. CONCLUSION: Leukemia lymphocytes were more sensitive to combined administration of anticancer drug (everolimus or barasertib) plus vitamins C and K3, compared to normal lymphocytes. The combination of vitamin C plus K3 seems to be a powerful redox system that could specifically influence redox homeostasis of leukemia cells and sensitize them to conventional chemotherapy.

Vitamin K: Redox-modulation, prevention of mitochondrial dysfunction and anticancer effect.

This review is directed to the redox-modulating properties and anticancer effect of vitamin K. The concept is focused on two aspects: (i) redox-cycle of vitamin K and its effect on the calcium homeostasis, "oncogenic" and "onco-suppressive" reactive oxygen species and the specific induction of oxidative stress in cancer; (ii) vitamin K plus C as a powerful redox-system, which forms a bypass between mitochondrial complexes II and III and thus prevents mitochondrial dysfunction, restores oxidative phosphorylation and aerobic glycolysis, modulates the redox-state of endogenous redox-pairs, eliminates the hypoxic environment of cancer cells and induces cell death. The analyzed data suggest that vitamin C&K can sensitize cancer cells to conventional chemotherapy, which allows achievement of a lower effective dose of the drug and minimizing the harmful side-effects. The review is intended for a wide audience of readers - from students to specialists in the field.

Mitochondrial Dysfunction and Redox Imbalance as a Diagnostic Marker of "Free Radical Diseases".

The intracellular redox balance (redox status) is a dynamic system that may change via many factors. Mitochondria are one of the most important among them. These organelles are the main intracellular source of energy. They are essential for maintaining cellular homeostasis due to regulation of many biochemical processes. The mitochondrial dynamics change during cellular activities and in some cases, can cause an overproduction of reactive oxygen species (ROS), which encourages the induction of oxidative DNA damage and up- or down-regulation of phosphatases, proliferative/anti-proliferative factors, apoptotic/anti-apoptotic factors, etc. Moreover, mitochondrial dysfunction and redox imbalance can continuously support and contribute to a wide range of pathologies, termed as "free radical diseases" (e.g., cancer, neurodegeneration, atherosclerosis, inflammation, etc.). This review article is focused on the mitochondrial dysfunction and cellular redox status as a hallmark of cell homeostasis and diagnostic marker of cancer. It is intended to broad readership - from students to specialists in the field.

Synergistic Cytotoxicity of Melatonin and New-generation Anticancer Drugs Against Leukemia Lymphocytes But Not Normal Lymphocytes.

The present study demonstrates specific sensitization of leukemia lymphocytes towards anticancer drugs using melatonin and clarifies the role of reactive oxygen species (ROS) for induction of apoptosis. The study covers four conventional and 11 new-generation anticancer drugs. Four parameters were analyzed simultaneously in leukemia and normal lymphocytes treated with drug, melatonin, or their combination: cell viability, induction of apoptosis, level of reactive oxygen species (ROS), and level of protein-carbonyl products. Almost all investigated combinations of melatonin with new-generation anticancer drugs were characterized by synergistic cytotoxicity towards leukemia lymphocytes, while the combinations with conventional drugs exhibited additive or antagonistic effects on cell viability. In leukemia lymphocytes, the additive cytotoxicity of doxorubicin plus melatonin was accompanied by low levels of ROS and protein-carbonyl products, as well as by suppression of apoptosis. In normal lymphocytes, none of the studied parameters changed significantly compared to cells treated with doxorubicin only. The combinations of everolimus plus melatonin and barasertib plus melatonin exhibited impressive synergistic cytotoxic effects on leukemia lymphocytes but did not affect the viability of normal lymphocytes. In leukemia cells, the synergistic cytotoxicity was accompanied by strong induction of apoptosis but a decrease of ROS to a level below that of the control. In normal lymphocytes, these combinations did not affect the level of ROS nor of protein-carbonyl products, and did not induce apoptosis. The data suggest that melatonin is a promising supplementary component in chemotherapy which allows the therapeutic doses of anticancer drugs to be reduced, minimizing their side-effects.