AbstractTaxanes and platinum molecules, specifically paclitaxel and carboplatin, are widely used anticancer drugs that induce cell death and serve as first‐line chemotherapy for various cancer types. Show more
AbstractTaxanes and platinum molecules, specifically paclitaxel and carboplatin, are widely used anticancer drugs that induce cell death and serve as first‐line chemotherapy for various cancer types. Despite the efficient effect of both drugs on cancer cell proliferation, many tumours have innate resistance against paclitaxel and carboplatin, which leads to inefficient treatment and poor survival rates. Haploid human embryonic stem cells (hESCs) are a novel and robust platform for genetic screening. To gain a comprehensive view of genes that affect or regulate paclitaxel and carboplatin resistance, genome‐wide loss‐of‐function screens in haploid hESCs were performed. Both paclitaxel and carboplatin screens have yielded selected plausible gene lists and pathways relevant to resistance prediction. The effects of mutations in selected genes on the resistance to the drugs were demonstrated. Based on the results, an algorithm that can predict resistance to paclitaxel or carboplatin was developed. Applying the algorithm to the DNA mutation profile of patients' tumours enabled the separation of sensitive versus resistant patients, thus, providing a prediction tool. As the anticancer drugs arsenal can offer alternatives in case of resistance to either paclitaxel or carboplatin, an early prediction can provide a significant advantage and should improve treatment. The algorithm assists this unmet need and helps predict whether a patient will respond to the treatment and may have an immediate clinically actionable application. Show less
Title: Radiosensitization effect of iridium (III) complex on lung cancer cells via mitochondria apoptosis pathway.
Abstract: BACKGROUND: Lung cancer is the leading cause of cancer-related death in th Show more
Title: Radiosensitization effect of iridium (III) complex on lung cancer cells via mitochondria apoptosis pathway.
Abstract: BACKGROUND: Lung cancer is the leading cause of cancer-related death in the worldwide. Although cisplatin and other platinum-based drugs are widely used as radiosensitizers in radiotherapy and considered the first-line treatment for advanced lung cancer, their clinical utility is often limited by drug resistance and severe cytotoxic side effects. In recent years, iridium-based complexes and other transition metal cation complexes with similar structural properties have garnered increasing research interest due to their potential anticancer properties. METHODS: Recently, we synthesized a novel iridium (III) complex (Ir-1) and evaluated its safety and stability. The present study aimed to identify Ir-1 with potent anticancer activity by assessing its cytotoxic effects on lung cancer cells in vitro. Additionally, it investigated Ir-1's radiosensitizing efficacy and the underlying mechanisms. RESULTS: The results demonstrated that Ir-1 exhibited significant radiosensitizing effects on lung cancer cells. Ir-1 effectively reduced cell viability and colony formation, arrested the cell cycle at the G2/M phase, inhibited cell migration and invasion, decreased mitochondrial membrane potential, and increased reactive oxygen species (ROS) generation in lung cancer cells. Importantly, these cytotoxic effects were selective, with minimal impact on normal cells. Mechanistic studies showed that Ir-1 enhanced radiation-induced cancer cell death by disrupting mitochondrial function and activating the mitochondrial apoptotic pathway. This was evidenced by upregulated expression levels of Bax, Cytochrome c (Cyt-C), and Caspase9 proteins, along with reduced level of Bcl-2 protein. Notably, the addition of a Cyt-C inhibitor significantly reduced the expression of Cyt-C and Caspase9 proteins. Similarly, treatment with the Caspase9 inhibitor Z-LEHD-FMK also reduced Caspase9 protein level. CONCLUSION: This study provides robust evidence that Ir-1 is a promising and safe radiosensitizer for lung cancer therapy. Its ability to enhance radiation-induced cytotoxicity through mitochondrial dysfunction and activation of apoptotic pathways highlights its potential for clinical application. Show less
Platinum-based drugs are a mainstay in chemotherapy, with traditional forms exerting their work directly on DNA. In recent years, it has been observed that platinum complexes had the potential to indu Show more
Platinum-based drugs are a mainstay in chemotherapy, with traditional forms exerting their work directly on DNA. In recent years, it has been observed that platinum complexes had the potential to induce immunogenic cell death (ICD) and effectively trigger antitumor immune responses. Herein, to obtain novel platinum complexes with chemo-immunological properties, a series of Pt(ΙΙ)-N-heterocyclic carbene (Pt(ΙΙ)-NHC) complexes derived from 4,5-diarylimidazoles were synthesized. Among them, the dominant complex 3f was proved to exhibit better anti-liver cancer capacity compared to cisplatin and oxaliplatin. Complex 3f showed the ability to cause DNA damage by binding to DNA. In addition, it triggered intracellular reactive oxygen species (ROS) generation, affected the function of mitochondria, and blocked cells in G0/G1 phase, ultimately induced apoptosis in liver cancer cells. Furthermore, complex 3f activated endoplasmic reticulum stress (ERS) which promoted the release of damage-associated molecular patterns (DAMPs), induced ICD and dendritic cells (DCs) maturation. Interestingly, complex 3f also upregulated PD-L1, consequently converted "cold tumors" into "hot tumors". Overall, complex 3f had the potential to be regarded as a promising chemoimmunotherapy for the treatment of liver cancer. Show less
Cancer remains a major global health burden, with rising incidence and mortality linked to aging populations
and increased exposure to genotoxic agents. Oxidative stress plays a critical role in cance Show more
Cancer remains a major global health burden, with rising incidence and mortality linked to aging populations
and increased exposure to genotoxic agents. Oxidative stress plays a critical role in cancer development, progression, and
resistance to therapy. The nuclear factor erythroid 2-related factor 2 (NRF2)-Kelch-like ECH-associated protein 1
(KEAP1)-antioxidant response element (ARE) signaling pathway is central to maintaining redox balance by regulating
the expression of antioxidant and detoxification genes. Under physiological conditions, this pathway protects cells
from oxidative damage, however, sustained activation of NRF2 in cancer, often due to mutations in KEAP1, supports
tumor cell survival, drug resistance, and metabolic reprogramming. Recent studies demonstrate that NRF2 enhances
glutathione (GSH) synthesis, induces detoxifying enzymes, and upregulates drug efflux transporters, collectively
contributing to resistance against chemotherapy and targeted therapies. The inhibition of NRF2 using small molecules
or dietary phytochemicals has shown promise in restoring drug sensitivity in preclinical cancer models. This review
highlights the dual role of NRF2 in redox regulation and cancer therapy, emphasizing its potential as a therapeutic
target. While targeting NRF2 offers a novel approach to overcoming treatment resistance, further research is needed
to enhance specificity and facilitate clinical translation. Show less
Ferroptosis is a non-apoptotic type of cell death that is induced by uncontrolled iron-dependent phospholipid peroxidation and has important roles in disease. This Expert Recommendation article summar Show more
Ferroptosis is a non-apoptotic type of cell death that is induced by uncontrolled iron-dependent phospholipid peroxidation and has important roles in disease. This Expert Recommendation article summarizes ferroptosis regulation and mechanisms and provides recommendations to increase the reproducibility and robustness of ferroptosis research. Show less
Cisplatin and oxaliplatin are Pt(II) anticancer agents that are used to treat several cancers, usually in combination with other drugs. Their efficacy is diminished by dose-limiting peripheral neuropa Show more
Cisplatin and oxaliplatin are Pt(II) anticancer agents that are used to treat several cancers, usually in combination with other drugs. Their efficacy is diminished by dose-limiting peripheral neuropathy (PN) that affects ∼70% of patients. PN is caused by selective accumulation of the platinum drugs in the dorsal root ganglia (DRG), which overexpress transporters for cisplatin and oxaliplatin. To date, no drug is recommended for the prevention of PN. We report that Pt(IV) prodrugs of cisplatin or oxaliplatin do not induce neuropathic pain in mice, likely due to the lower accumulation of platinum in the DRG compared with Pt(II) drugs. Moreover, the multitargeting prodrug that combines cisplatin with paclitaxel, both strong inducers of PN, efficiently inhibited tumor growth in vivo without inducing neuropathic pain. The high antitumor efficacy of Pt(IV) prodrugs and their micellar counterparts and the low level of neuropathic pain associated with them make them ideal candidates for clinical use in cancer therapy. Show less
Submarine hydrothermal vents harbor diverse microbial communities and have long intrigued researchers studying the origin of life. Transition metals in these environments can be reduced by serpentiniz Show more
Submarine hydrothermal vents harbor diverse microbial communities and have long intrigued researchers studying the origin of life. Transition metals in these environments can be reduced by serpentinization, potentially forming zeolite-supported transition metal nanoparticles capable of driving prebiotic chemistry. This inorganic structure could catalyze biochemical reactions, including converting metabolically crucial pyruvate before the emergence of biological processes. This study explores the catalytic interconversion of pyruvate and lactate, mediated by lactate dehydrogenase in biochemical systems, using inorganic zeolite Y-supported Ni nanoparticles (Ni/Y) under mild hydrothermal vent conditions. Our results demonstrate that Ni/Y effectively catalyzes the hydrogenation of pyruvate in an inert environment, facilitated by the in situ generation of H₂ through an autocatalytic reaction between Ni/Y and H₂O. Post-reaction analysis by X-ray absorption spectroscopy (XAS) revealed structural transformations in the catalyst, including the formation of unique nickel oxide and hydroxide species, along with extra-framework aluminum from zeolite dealumination, resulting in a thin amorphous nickel oxide/hydroxide layer. Notably, Ni/Y also enables the oxidative reconversion of lactate to pyruvate under atmospheric conditions-an essential reaction catalyzed by lactate dehydrogenase in biological systems. These findings underscore the potential prebiotic role of Ni/Y, suggesting they may have catalyzed the synthesis of key metabolic intermediates. Show less
AbstractPhotoactivatable metal complexes offer the prospect of novel drugs with low side effects and new mechanisms of action to combat resistance to current therapy. We highlight recent progress in t Show more
AbstractPhotoactivatable metal complexes offer the prospect of novel drugs with low side effects and new mechanisms of action to combat resistance to current therapy. We highlight recent progress in the design of platinum, ruthenium, iridium, gold and other transition metal complexes, especially for applications as anticancer and anti‐infective agents. In particular, understanding excited state chemistry related to identification of the bioactive species (excited state metallomics/pharmacophores) is important. Photoactivatable metallodrugs are classified here as photocatalysts, photorelease agents and ligand‐activated agents. Their activation wavelengths, cellular mechanisms of action, experimental and theoretical metallomics of excited states and photoproducts are discussed to explore new strategies for the design and investigation of photoactivatable metallodrugs. These photoactivatable metallodrugs have potential in clinical applications of Photodynamic Therapy (PDT), Photoactivated Chemotherapy (PACT) and Photothermal Therapy (PTT). Show less
Over the past decade, collective intelligence, i.e., the intelligence that emerges from collective efforts, has transformed complex problem-solving and decision-making. In drug discovery, decision-mak Show more
Over the past decade, collective intelligence, i.e., the intelligence that emerges from collective efforts, has transformed complex problem-solving and decision-making. In drug discovery, decision-making often relies on medicinal chemistry intuition. The present study explores the application of collective intelligence in drug discovery, focusing on lead optimization. Ninety-two Sanofi researchers with diverse expertise participated anonymously in an exercise centered on ADMET-related questions. Their feedback was used to build a collective intelligence agent, which was compared to an artificial intelligence model. The study led to three major conclusions: first, collective intelligence improves decision-making in optimizing ADMET endpoints, compared to individual decisions. Second, collective intelligence outperforms artificial intelligence for all other endpoints but hERG inhibition. Finally, we observe complementarity between collective human and artificial intelligence. Overall, this research highlights the potential of collective intelligence in drug discovery and the importance of a synergistic approach combining human and artificial intelligence in project decision making. Show less
2025 · Molecular Cancer · BioMed Central · added 2026-04-21
Ferroptosis, the non-apoptotic, iron-dependent form of cell death is an unavoidable outcome and byproduct of cellular metabolism. Reactive oxygen species generation during metabolic activities transce Show more
Ferroptosis, the non-apoptotic, iron-dependent form of cell death is an unavoidable outcome and byproduct of cellular metabolism. Reactive oxygen species generation during metabolic activities transcends to Fe2+-induced lipid peroxidation, leading to ferroptosis. Cancer cells being highly metabolic are more prone to ferroptosis. However, their neoplastic nature enables them to bypass ferroptosis and become ferroptosis-resistant. The capability of cancer cells to reprogram its metabolic activities is one of its finest abilities to abort oxidative damage, and hence ferroptosis. Moreover, the reprogrammed metabolism of cancer cells, also associates with the radical trapping antioxidant Show less
2025 · Chemistry – A European Journal · Wiley · added 2026-05-21
AbstractNew, asymmetric quinizarin‐Au(I)‐NHC complexes were designed, isolated, and fully characterised including by single crystal X‐ray crystallography. Cytotoxicity studies showed effective growth Show more
AbstractNew, asymmetric quinizarin‐Au(I)‐NHC complexes were designed, isolated, and fully characterised including by single crystal X‐ray crystallography. Cytotoxicity studies showed effective growth inhibition in HeLa cervical cancer cells with IC50 values ranging from 2.4 μM to 5.3 μM. The successful cellular uptake was evidenced by X‐ray fluorescence imaging on cryo‐preserved whole HeLa cells and the sub‐cellular localisation was monitored by live‐cell fluorescence microscopy. Notably, complex 2 b showed circumvention of acquired anthracycline resistance in K562 leukaemia cells as well as synergistic activity with doxorubicin against both wild‐type and anthracycline‐resistant Nalm‐6 leukaemia cells. Interestingly, sub‐cellular localisation towards mitochondria proved to be more important than the compounds’ overall cytotoxicity for potent antiproliferative activity and to achieve effective resistance circumvention. Show less
Jeseok Jeon, Tae-Hong Kang · 2025 · International journal of molecular sciences · MDPI · added 2026-04-20
Transcription-coupled repair (TCR) and R-loops are two interrelated processes critical to the maintenance of genome stability during transcription. TCR, a specialized sub-pathway of nucleotide excisio Show more
Transcription-coupled repair (TCR) and R-loops are two interrelated processes critical to the maintenance of genome stability during transcription. TCR, a specialized sub-pathway of nucleotide excision repair, rapidly removes transcription-blocking lesions from the transcribed strand of active genes, thereby safeguarding transcription fidelity and cellular homeostasis. In contrast, R-loops, RNA-DNA hybrid structures formed co-transcriptionally, play not only regulatory roles in gene expression and replication but can also contribute to genome instability when persistently accumulated. Recent experimental evidence has revealed dynamic crosstalk between TCR and R-loop resolution pathways. This review highlights current molecular and cellular insights into TCR and R-loop biology, discusses the impact of their crosstalk, and explores emerging therapeutic strategies aimed at optimizing DNA repair and reducing disease risk in conditions such as cancer and neurodegenerative disorders. Show less
BACKGROUND: Globally, the onset and progression of multiple human diseases are associated with mitochondrial dysfunction and dysregulation of Ca2+ uptake dynamics mediated by the mitochondrial calcium Show more
BACKGROUND: Globally, the onset and progression of multiple human diseases are associated with mitochondrial dysfunction and dysregulation of Ca2+ uptake dynamics mediated by the mitochondrial calcium uniporter (MCU) complex, which plays a key role in mitochondrial dysfunction. Despite relevant studies, the underlying pathophysiological mechanisms have not yet been fully elucidated.
AIM OF REVIEW: This article provides an in-depth analysis of the current research status of the MCU complex, focusing on its molecular composition, regulatory mechanisms, and association with diseases. In addition, we conducted an in-depth analysis of the regulatory effects of agonists, inhibitors, and traditional Chinese medicine (TCM) monomers on the MCU complex and their application prospects in disease treatment. From the perspective of medicinal chemistry, we conducted an in-depth analysis of the structure-activity relationship between these small molecules and MCU and deduced potential pharmacophores and binding pockets. Simultaneously, key structural domains of the MCU complex in Homo sapiens were identified. We also studied the functional expression of the MCU complex in Drosophila, Zebrafish, and Caenorhabditis elegans. These analyses provide a basis for exploring potential treatment strategies targeting the MCU complex and provide strong support for the development of future precision medicine and treatments.
KEY SCIENTIFIC CONCEPTS OF REVIEW: The MCU complex exhibits varying behavior across different tissues and plays various roles in metabolic functions. It consists of six MCU subunits, an essential MCU regulator (EMRE), and solute carrier 25A23 (SLC25A23). They regulate processes, such as mitochondrial Ca2+ (mCa2+) uptake, mitochondrial adenosine triphosphate (ATP) production, calcium dynamics, oxidative stress (OS), and cell death. Regulation makes it a potential target for treating diseases, especially cardiovascular diseases, neurodegenerative diseases, inflammatory diseases, metabolic diseases, and tumors. Show less
TLDR: Investigation of anticancer and antitrypanosomatid activities of eight monoanionic metal bis(dithiolene) complexes showed that [Ph4P][Pt(tBu-thiazdt)2] and [Ph4P][Pd(tBu-thiazdt)2] complexes mig Show more
TLDR: Investigation of anticancer and antitrypanosomatid activities of eight monoanionic metal bis(dithiolene) complexes showed that [Ph4P][Pt(tBu-thiazdt)2] and [Ph4P][Pd(tBu-thiazdt)2] complexes might have potential as novel anticancer and antitrypanosomatid agents as alternatives to current therapeutics. Show less
Abstract
Ferroptosis, a novel form of regulated cell death induced by the excessive accumulation of lipid peroxidation products, plays a pivotal role in the suppression of tumorigenesis. Two Show more
Abstract
Ferroptosis, a novel form of regulated cell death induced by the excessive accumulation of lipid peroxidation products, plays a pivotal role in the suppression of tumorigenesis. Two prominent mitochondrial ferroptosis defense systems are glutathione peroxidase 4 (GPX4) and dihydroorotate dehydrogenase (DHODH), both of which are localized within the mitochondria. However, the existence of supplementary cellular defense mechanisms against mitochondrial ferroptosis remains unclear. Our findings unequivocally demonstrate that inactivation of mitochondrial respiratory chain complex I (MCI) induces lipid peroxidation and consequently invokes ferroptosis across GPX4 low-expression cancer cells. However, in GPX4 high expression cancer cells, the MCI inhibitor did not induce ferroptosis, but increased cell sensitivity to ferroptosis induced by the GPX4 inhibitor. Overexpression of the MCI alternative protein yeast NADH-ubiquinone reductase (NDI1) not only quells ferroptosis induced by MCI inhibitors but also confers cellular protection against ferroptosis inducers. Mechanically, MCI inhibitors actuate an elevation in the NADH level while concomitantly diminishing the CoQH2 level. The manifestation of MCI inhibitor-induced ferroptosis can be reversed by supplementation with mitochondrial-specific analogues of CoQH2. Notably, MCI operates in parallel with mitochondrial-localized GPX4 and DHODH to inhibit mitochondrial ferroptosis, but independently of cytosolically localized GPX4 or ferroptosis suppressor protein 1(FSP1). The MCI inhibitor IACS-010759, is endowed with the ability to induce ferroptosis while concurrently impeding tumor proliferation in vivo. Our results identified a ferroptosis defense mechanism mediated by MCI within the mitochondria and suggested a therapeutic strategy for targeting ferroptosis in cancer treatment. Show less
2025 · RSC Medicinal Chemistry · Royal Society of Chemistry · added 2026-05-21
AuL4 triggers necroptosis and paraptosis in A549 cells.
TLDR: AuL4 emerged as the most active compound, exhibited potent anticancer activity, triggering mitochondrial membrane depolarization and indu Show more
AuL4 triggers necroptosis and paraptosis in A549 cells.
TLDR: AuL4 emerged as the most active compound, exhibited potent anticancer activity, triggering mitochondrial membrane depolarization and inducing necroptosis and paraptosis in human lung adenocarcinoma cells-a mechanism distinct from conventional apoptosis-inducing gold complexes. Show less
Dean G. Brown · 2025 · Journal of Medicinal Chemistry · ACS Publications · added 2026-04-20
An analysis of dose, dose frequency, human pharmacokinetics, and potential drug-drug interactions (DDI) was performed on small-molecule oral drugs approved by the FDA from 2020 to 2024 (n = 104 Show more
An analysis of dose, dose frequency, human pharmacokinetics, and potential drug-drug interactions (DDI) was performed on small-molecule oral drugs approved by the FDA from 2020 to 2024 (n = 104). Although most oral drugs are administered QD (67%), BID and TID regimens are also regularly approved (32%). First-in-class (FIC) drugs and drugs with Orphan Drug Designation (ODD) have a higher frequency of BID or TID administration compared to drugs without those designations (BID and TID = 50% for FIC drugs vs 19% for non-FIC; BID and TID = 41% for ODD vs 20% non-ODD). Most drugs are >95% plasma protein bound (58%), with a large fraction >99% bound (29%). Of these drugs, 22% have black box warnings and 42% list contraindications. An examination of DDI revealed the most frequent warning around CYP3A4 induction (60%). These findings will help medicinal chemists better understand and predict typical and nontypical profiles of oral drugs. Show less
We hypothesize that predictable variations in environmental conditions caused by night/day cycles created opportunities and hazards that initiated information dynamics central to life's origin. Increa Show more
We hypothesize that predictable variations in environmental conditions caused by night/day cycles created opportunities and hazards that initiated information dynamics central to life's origin. Increased daytime temperatures accelerated key chemical reactions but also caused the separation of double-stranded polynucleotides, leading to hydrolysis, particularly of single-stranded RNA. Daytime solar UV radiation promoted the synthesis of organic molecules but caused broad damage to protocell macromolecules. We hypothesize that inter-related simultaneous adaptations to these hazards produced molecular dynamics necessary to store and use information. Self-replicating RNA heritably reduced the hydrolysis of single strands after separation during warmer daytime periods by promoting sequences that formed hairpin loops, generating precursors to transfer RNA (tRNA), and initiating tRNA-directed evolutionary dynamics. Protocell survival during daytime promoted sequences in self-replicating RNA within protocells that formed RNA-peptide hybrids capable of scavenging UV-induced free radicals or catalyzing melanin synthesis from tyrosine. The RNA-peptide hybrids are precursors to ribosomes and the triplet codes for RNA-directed protein synthesis. The protective effects of melanin production persist as melanosomes are found throughout the tree of life. Similarly, adaptations mitigating UV damage led to the replacement of Na+ by K+ as the dominant mobile cytoplasmic cation to promote diel vertical migration and selected for homochirality. We conclude that information dynamics emerged in early life through adaptations to predictably fluctuating opportunities and hazards during night/day cycles, and its legacy remains observable in extant life. Show less
2025 · Frontiers in pharmacology · Frontiers · added 2026-04-21
Background/ObjectivesNew computational methods, based on statistical, machine learning, and deep learning techniques using drug-related entities (e.g., genes, protein bindings, etc.), help reduce the Show more
Background/ObjectivesNew computational methods, based on statistical, machine learning, and deep learning techniques using drug-related entities (e.g., genes, protein bindings, etc.), help reduce the costs of in-vitro experiments through drug-drug interaction prediction (DDIp). This review examines recent advances in DDIp. It presents an in-depth review of the state-of-the-art studies relating to semi-supervised, supervised, self-supervised learning, and other techniques such as graph-based learning and matrix factorization methods for predicting DDIs. All possible interactions between drugs are not known, and accurately predicting interactions is even more difficult due to the complex nature of drug-drug interactions (DDI).MethodsOf the 49 papers published in Web of Science in the last 6 years, 24 papers were considered relevant based on information presented in their titles and abstracts. The included articles focus specifically on predicting DDIs using a type of machine learning algorithm. Excluded articles focused on drug discovery, drug repurposing, molecular representation, or the extraction of biomedical interactions. The methodology, results limitations, and future research directions were studied for each paper. Common challenges, limitations, and future research directions were analyzed.Results and conclusionThe main limitations are class imbalance, poor performance on new drugs, limited explainability, and the need for additional data sources. Show less
2025 · Journal of the American Chemical Society · ACS Publications · added 2026-05-21
TLDR: The synthesis and evaluation of a series of asymmetric redox-active water-soluble Au(I) bis-N-heterocyclic carbenes (Au(I) bis-NHCs) is presented, exploring the structure-activity relationships Show more
TLDR: The synthesis and evaluation of a series of asymmetric redox-active water-soluble Au(I) bis-N-heterocyclic carbenes (Au(I) bis-NHCs) is presented, exploring the structure-activity relationships between redox activity, water solubility and ICD induction. Show less
2025 · International journal of molecular sciences · MDPI · added 2026-04-20
In this study, the changes in the DNA native conformation induced by pH changes in the alkaline and acidic regions were examined. It was shown by the methods of low gradient viscometry and flow birefr Show more
In this study, the changes in the DNA native conformation induced by pH changes in the alkaline and acidic regions were examined. It was shown by the methods of low gradient viscometry and flow birefringence that protonation and deprotonation of nitrogen bases inside the double helix cause a change in the persistent length of DNA. The pK values shift with the change in the ionic strength of the solution (NaCl concentration). The additional charges appearing on the DNA bases are not shielded by counterions from the solution. The increase and decrease in the volume of the DNA coil in solution resulting from protonation and deprotonation of base pairs, respectively, are mainly determined by changes in the persistent length of the macromolecule. The stability of the double-helical conformation of DNA ensures the steadiness of the equilibrium rigidity of this macromolecule. The emergence of charges on the bases, resulting from DNA protonation or deprotonation, weakens and even disrupts the hydrogen bonds between complementary bases. However, at the first stage, this occurs without altering the stacking interactions of base pairs, as reflected in the absorption spectra of DNA and in the stability of the DNA persistent length at different pH levels. Show less