Succinate Dehydrogenase Research Articles

Evaluation of toxicity of thymoquinone, as a bioactive compound of nigella sativa using isolated mitochondria from different organs

The purpose of this study is to examine thymoquinone (TQ), as a bioactive compound of Nigella sativa, from a safety point of view and to evaluate the possible toxic effects on isolated mitochondria as a screening tool for drug safety and predictive toxicology. Mitochondria were isolated form different organs (brain, heart, kidney and liver) and treated with various concentrations of TQ (0–2000 µM). Mitochondrial toxicity parameters such as succinate dehydrogenases (SDH) activity, mitochondrial swelling, lipid peroxidation, reactive oxygen species (ROS) formation and mitochondrial membrane potential (MMP) collapse were analyzed. Results showed that various concentrations of TQ did not induce any toxicity or abnormalities in isolated mitochondria obtained from brain, heart, kidney and liver. We demonstrated for the first time that TQ does not cause any detrimental effect on isolated mitochondria from different organs of rat. Our data highlight that TQ does not directly interact with mitochondria and disrupt the mitochondrial functions.

Comprehensive Investigation of Angiogenesis, PASS Score and Immunohistochemical Factors in Risk Assessment of Malignancy for Paraganglioma and Pheochromocytoma.

A challenging task in routine practice is finding the distinction between benign and malignant paragangliomas and pheochromocytomas. The aim of this study is to conduct a comparative analysis of angiogenesis by assessing intratumoral microvascular density (MVD) with immunohistochemical (IHC) markers (CD31, CD34, CD105, ERG), and S100 immunoreactivity, Ki67 proliferative index, succinate dehydrogenase B (SDHB) expressiveness, tumor size with one the most utilized score Pheochromocytoma of Adrenal Gland Scales Score (PASS), using tissue microarray (TMA) with 115 tumor samples, 61 benign (PASS < 4) and 54 potentially malignant (PASS ≥ 4). We found no notable difference between intratumoral MVD and potentially malignant behavior. The group of potentially malignant tumors is significantly larger in size, has lower intratumoral MVD, and a decreased number of S100 labeled sustentacular cells. Both groups have low proliferative activity (mean Ki67 is 1.02 and 1.22, respectively). Most tumors maintain SDHB expression, only 6 cases (5.2%) showed a loss of expression (4 of them in PASS < 4 group and 2 in PASS ≥ 4). PASS score is easily available for assessment and complemented with markers of biological behavior to complete the risk stratification algorithm. Size is directly related to PASS score and malignancy. Intratumoral MVD is extensively developed but it is not crucial in evaluating the malignant potential.

Unraveling the Impact of Pesticide Exposure on Apis Honey Bees: An Investigation on Succinate Dehydrogenase Subunit A (SDHA) Inhibition Mechanisms

AbstractConcerns about pollinator health and the influence on agricultural ecosystems have developed as a result of pesticide‐caused population declines in honey bees. The research looked at the properties of the SDHA subunit of the enzyme Succinate dehydrogenase, which is important for energy production and mitochondrial function. The goal was to investigate the structural and functional characteristics of SDHA in several Apis bee species, as well as how pesticides can limit its activity. In silico analyses were conducted to understand the structural characteristics of the SDHA subunit, assess evolutionary conservation, analyze deformation energy, and investigate potential pesticide binding. Thirteen pesticides were subjected to molecular docking studies with the Apis SDHA subunit. The study revealed the stability and conserved nature of the SDHA subunit across different Apis sp. Deformation energy analysis highlighted regions of local flexibility, particularly in the active site and interdomain interfaces. Molecular docking analysis indicated that pesticides such as Carboxin, Clothianidin, and Dithianon potentially interfere with FAD binding, while Fipronil and Sulfoxaflor may disrupt both FAD and dicarboxylate binding. This research sheds light on pesticides′ probable inhibitory effects on SDH, a vital enzyme in honey bee energy production and mitochondrial function. The findings highlight the importance of stringent pesticide controls and long‐term pest management measures to protect pollinator numbers and ecosystem health.

Potato glycoside alkaloids exhibit antifungal activity by regulating the tricarboxylic acid cycle pathway of Fusarium solani.

Fusarium solani is a pathogenic fungus that causes significant harm, leading to crop yield reduction, fruit quality reduction, postharvest decay, and other diseases. This study used potato glycoside alkaloids (PGA) as inhibitors to investigate their effects on the mitochondrial structure and tricarboxylic acid (TCA) cycle pathway of F. solani. The results showed that PGA could inhibit the colony growth of F. solani (54.49%), resulting in the disappearance of the mitochondrial membrane and the loss of contents. PGA significantly decreased the activities of aconitase (ACO), isocitrate dehydrogenase (IDH), α-ketoglutarate dehydrogenase (α-KGDH), succinate dehydrogenase (SDH), fumarase (FH), malate dehydrogenase (MDH), succinyl-CoA synthetase (SCS), and increased the activity of citrate synthase (CS) in F. solani. After PGA treatment, the contents of acetyl coenzyme A (CoA), citric acid (CA), malic acid (L-MA), and α-ketoglutaric acid (α-KG) in F. solani were significantly decreased. The contents of isocitric acid (ICA), succinyl coenzyme A (S-CoA), succinic acid (SA), fumaric acid (FA), and oxaloacetic acid (OA) were significantly increased. Transcriptomic analysis showed that PGA could significantly affect the expression levels of 19 genes related to TCA cycle in F. solani. RT-qPCR results showed that the expression levels of ACO, IDH, α-KGDH, and MDH-related genes were significantly down-regulated, and the expression levels of SDH and FH-related genes were significantly up-regulated, which was consistent with the results of transcriptomics. In summary, PGA can achieve antifungal effects by reducing the tricarboxylic acid cycle's flow and regulating key genes' expression levels. This study reveals the antifungal mechanism of PGA from the perspective of TCA cycle, and provides a theoretical basis for the development and application of PGA as a biopesticide.

Design, Synthesis, Antifungal Activity, and Molecular Docking Studies of Novel Chiral Isoxazoline-Benzofuran-Sulfonamide Derivatives.

Succinate dehydrogenase (SDH) is one of the most important molecular targets for the development of novel fungicides. With the emerging problem of resistance in plant fungal pathogens, novel compounds with high fungicidal activity need to be developed, but the study of chiral pesticides for the inhibition of highly destructive plant pathogens has been rarely reported in recent years. Therefore, a series of novel chiral isoxazoline-benzofuran-sulfonamide derivatives were designed to investigate potential novel antifungal molecules. The chiral target compound 3a was cultured as a single crystal and confirmed using X-ray diffraction. All the target compounds were tested for antifungal activity, and compounds 3c, 3i, 3s, and 3r were found to have significant antifungal effects against S. sclerotiorum with EC50 values of 0.42 mg/L, 0.33 mg/L, 0.37 mg/L, and 0.40 mg/L, respectively, which were superior to the commercial fungicide fluopyram (EC50 = 0.47 mg/L). The IC50 value of compound 3i against the SDH of S. sclerotiorum was 0.63 mg/mL, which was further demonstrated by enzyme activity assays. Scanning electron microscopy showed that 3i had a significant inhibitory effect on S. sclerotiorum. In addition, the fluorescence quenching analysis assay indicated that compound 3i had a similar effect with the positive control fluopyram. Molecular docking exhibited that target compounds with chiral configuration had better affinity than racemic configuration, and 3i possessed stronger action than fluopyram, which was in keeping with the in vitro test results. These results would provide a basis and reference for the development of novel chiral fungicides.

Long-Term Protective Effects of Succinate Dehydrogenase Inhibition during Reperfusion with Malonate on Post-Infarction Left Ventricular Scar and Remodeling in Mice.

Succinate dehydrogenase inhibition with malonate during initial reperfusion reduces myocardial infarct size in both isolated mouse hearts subjected to global ischemia and in in situ pig hearts subjected to transient coronary ligature. However, the long-term effects of acute malonate treatment are unknown. Here, we investigated whether the protective effects of succinate dehydrogenase inhibition extend to a reduction in scar size and adverse left ventricular remodeling 28 days after myocardial infarction. Initially, ten wild-type mice were subjected to 45 min of left anterior descending coronary artery (LAD) occlusion, followed by 24 h of reperfusion, and were infused during the first 15 min of reperfusion with saline with or without disodium malonate (10 mg/kg/min, 120 μL/kg/min). Malonate-treated mice depicted a significant reduction in infarct size (15.47 ± 3.40% of area at risk vs. 29.34 ± 4.44% in control animals, p < 0.05), assessed using triphenyltetrazolium chloride. Additional animals were then subjected to a 45 min LAD ligature, followed by 28 days of reperfusion. Treatment with a single dose of malonate during the first 15 min of reperfusion induced a significant reduction in scar area, measured using Picrosirius Red staining (11.94 ± 1.70% of left ventricular area (n = 5) vs. 23.25 ± 2.67% (n = 9), p < 0.05), an effect associated with improved ejection fraction 28 days after infarction, as determined using echocardiography, and an attenuated enhancement in expression of the pro-inflammatory and fibrotic markers NF-κB and Smad2/3 in remote myocardium. In conclusion, a reversible inhibition of succinate dehydrogenase with a single dose of malonate at the onset of reperfusion has long-term protective effects in mice subjected to transient coronary occlusion.

RANKL signaling drives skeletal muscle into the oxidative profile.

The bone-muscle unit refers to the reciprocal regulation between bone and muscle by mechanical interaction and tissue communication via soluble factors. The RANKL stimulation induces mitochondrial biogenesis and increases the oxidative capacity in osteoclasts and adipocytes. RANKL may bind to the membrane bound RANK or to osteoprotegerin (OPG), a decoy receptor that inhibits RANK-RANKL activation. RANK is highly expressed in skeletal muscle, but the contribution of RANKL to healthy skeletal muscle fiber remains elusive. Here we show that RANKL stimulation in C2C12-derived myotubes induced activation of mitochondrial biogenesis pathways as detected by RNA-seq and western blot. RANKL expanded the mitochondrial reticulum, as shown by mitochondrial DNA quantification and MitoTracker staining, and boosted the spare respiratory capacity. Using MEK and MAPK inhibitors, we found that RANKL signals via ERK and p38 to induce mitochondrial biogenesis. The soleus from OPG-/- and OPG+/- mice showed higher respiratory rates compared to C57BL6/J WT mice, which correlates with high serum RANKL levels. RANKL infusion using a mini-osmotic pump in WT mice increased the number of mitochondria, boosted the respiratory rate, increased succinate dehydrogenase activity in skeletal muscle, and improved the fatigue resistance of gastrocnemius. Therefore, our findings reveal a new role of RANKL as an osteokine-like protein that impacts muscle fiber metabolism.

Sensitivity of Lithuanian Zymoseptoria tritici to Quinone Outside Inhibitor and Succinate Dehydrogenase Inhibitor Fungicides

Septoria tritici blotch (STB) ais one of the most damaging winter wheat diseases worldwide, presenting a significant threat to its yields. The causal STB agent, Zymoseptoria tritici, also presents a challenge to control due to its rapid adaptation to fungicides. This requires researchers to continuously monitor the pathogen and investigate and explore strategies to manage the spread of the disease and the development of resistance in the pathogen. Therefore, this study presents the current situation and describes changes in the sensitivity of Z. tritici isolates from Lithuania to quinone outside inhibitors (QoIs) and succinate dehydrogenase inhibitors (SDHIs) for the years 2019–2022. The isolates were tested at five different concentrations of two QoI fungicides (azoxystrobin and pyraclostrobin) and three SDHI fungicides (fluxapyroxad, benzovindiflupyr, and bixafen). During the test period, the EC50 values of the tested QoIs increased, while no clear changes were observed in the SDHIs. The most pronounced shift was observed for the active QoI substance pyraclostrobin. The distribution of the EC50 values of the SDHI fungicides showcased one isolate with an outstandingly high EC50 value of 2.6 mg L−1. The results of this study did not reveal any strong patterns of cross-resistance between the fungicides tested. However, a significant positive, moderate correlation (r = 0.55) was found between fluxapyroxad and benzovindiflupyr. Overall, the results of this study contribute to the understanding of the fungicide-resistance situation of Z. tritici in Lithuania and may complement management strategies for the pathogen and its fungicide resistance.

Synthesis, bioactivity evaluation and theoretical study of nicotinamide derivatives containing diphenyl ether fragments as potential succinate dehydrogenase inhibitors

To obtain nicotinamide fungicides with higher inhibitory activity against Rhizoctonia solani, 24 nicotinamide derivatives were designed and synthesized by introducing the diphenyl ether fragments into the structure of boscalid. Biological assays revealed that the obtained compounds exhibited varying degrees of antifungal activity. Among them, compound 2-chloro-N-(2-(2,4-dichlorophenoxy)phenyl)nicotinamide (7g) exhibited prominent biological activity against R. solani (EC50 = 0.034 mg/L), surpassing the inhibitory effect of boscalid. Experimentally, compound 7g was a promising fungicide with low toxicity that targeted succinate dehydrogenase, as confirmed by the tests of cytotoxicity, inhibition of enzyme activity, mitochondrial membrane potential, and mycelial respiration. This study highlighted the potential of nicotinamide derivatives containing diphenyl ether fragments designed based on theoretical calculations as succinate dehydrogenase inhibitor (SDHI) fungicides.

Outcomes of SDHB Pathogenic Variant Carriers.

Carriers of germline pathogenic variants (PVs) in succinate dehydrogenase type B (SDHB) are at increased risk of developing pheochromocytomas and paragangliomas (PPGLs). Understanding their outcomes can guide recommendations for risk assessment and early detection. We performed a systematic review and meta-analysis of the following outcomes in SDHB PV carriers: age-specific risk of developing tumors, metastatic progression, second primary tumor development, and mortality. PubMed, MEDLINE, and EMBASE were searched. Sixteen studies met the inclusion criteria and were sorted into 4 outcome categories: age-specific penetrance, metastatic disease, risk of second tumor, and mortality. We assessed heterogeneity and performed a meta-analysis across studies using a random-effects model with the DerSimonian and Laird method. Penetrance of PPGLs for nonproband/nonindex SDHB PV carriers by age 20 was 4% (95% CI, 3%-6%), 11% (95% CI, 8%-15%) by age 40, 24% (95% CI, 19%-31%) by age 60%, and 35% (95% CI, 25%-47%) by age 80. The overall risk of metastatic disease for nonproband/nonindex carriers with PPGLs was 9% (95%, CI 5%-16%) per lifetime. In all affected cases (combining both proband/index and nonproband/nonindex carriers with tumors), the risk of a second tumor was 24% (95% CI, 18%-31%) and all-cause 5-year mortality was 18% (95% CI, 6%-40%). Penetrance for PPGLs in SDHB PV carriers increases linearly with age. Affected carriers are at risk of developing and dying of metastatic disease, or of developing second tumors. Lifelong surveillance is appropriate.

A hemoprotein with a zinc-mirror heme site ties heme availability to carbon metabolism in cyanobacteria

Heme has a critical role in the chemical framework of the cell as an essential protein cofactor and signaling molecule that controls diverse processes and molecular interactions. Using a phylogenomics-based approach and complementary structural techniques, we identify a family of dimeric hemoproteins comprising a domain of unknown function DUF2470. The heme iron is axially coordinated by two zinc-bound histidine residues, forming a distinct two-fold symmetric zinc-histidine-iron-histidine-zinc site. Together with structure-guided in vitro and in vivo experiments, we further demonstrate the existence of a functional link between heme binding by Dri1 (Domain related to iron 1, formerly ssr1698) and post-translational regulation of succinate dehydrogenase in the cyanobacterium Synechocystis, suggesting an iron-dependent regulatory link between photosynthesis and respiration. Given the ubiquity of proteins containing homologous domains and connections to heme metabolism across eukaryotes and prokaryotes, we propose that DRI (Domain Related to Iron; formerly DUF2470) functions at the molecular level as a heme-dependent regulatory domain.

Novel Aminocoumarin Derivatives against Phytopathogenic Fungi: Design, Synthesis and Structure-Activity Relationships.

Phytopathogenic fungi is the most devastating reason for the decrease of the agricultural production and food safety. To develop new fungicidal agents for resistance concerning, a novel series of aminocoumarin derivatives were synthesized and their fungicidal activity were investigated both in vitro and in vivo. Transmission electron microscope (TEM), scanning electron microscope (SEM), RNA-Seq, 3D-QSAR and molecular docking were applied to reveal the underlying anti-fungal mechanisms. Most of the compounds exhibited significant fungicidal activity. Notably, compound 10c had a more extensive fungicidal effect than positive control. TEM indicated that compound 10c could cause abnormal morphology of cell walls, vacuoles and release of cellular contents. Transcriptional analysis data indicated that 895 and 653 out of 1548 differential expressed genes (DEGs) were up-regulated and down-regulated respectively. The Go and KEGG enrichment indicated that the coumarin derivatives could induce significant changes of succinate dehydrogenase (SDH), Acetyl-coenzyme A synthetase (ACCA) and pyruvate dehydrogenase (PDH) genes, which contributed to the disorders of glucolipid metabolism and the dysfunction of mitochondrial. The results demonstrated that aminocoumarins with schiff-base as core moieties could be the promising lead compounds for the discovery of novel fungicides.

SUCCINATE-RECEPTOR SYSTEM OF BONE AND CARTILAGE TISSUE IN PATIENTS WITH METABOLIC PHENOTYPE OF OSTEOARTHRITIS

Introduction. Currently, osteoarthritis (OA) has been identified as a polyetiological disease, where several phenotypes have been identified based on the leading frequency. Obviously, each clinical phenotype corresponds only to its fundamental changes on the part of various organs and systems. Un-til recently, special attention was paid to the study of metabolic processes in osteoarthritis (OA) and was paid to the state of the cartilage, but more and more interest was focused on the biochemistry of the subchondral bone, its microarchitectonics and signal function. Aid. To study the features of the manifestation of the succinate-receptor system of bone and cartilage tissue in patients with the metabolic phenotype of osteoarthritis. Material and methods. 42 patients took part in the study and were divided into 2 groups: 1 group – patients without articular disease, normal body mass index; 2 group – patients with metabolic phenotype of OA. The subjects were collected complaints, anamnesis, as well as general clinical and orthopedic examination. The levels of succinate, succinate receptor (SUCNR1) and succinate dehydrogenase (SDH) are measured in bone and cartilage tissue homogenates. Results. In the 2 group, an increase in SUCNR1 expression was detected in all studied areas of the joint in comparison with the 1 group. In the 2 group, the differences were tissue-specific in the distribution of SUCNR1 with a predominant increase in the amount of the receptor in the subchondral bone compared to the loaded (p=0.031) and non-loaded zone of cartilage (p=0.001). In the 1 group, the studied areas of cartilage and bone did not dif-fer in the amount of SUCNR1 from each other. In the group of patients with the metabolic phenotype of OA, an increase in mitochondrial succinate was found both in the subchondral bone tissue and in different zones of cartilage compared to the 1 group. The final indicators of SDH activity in the mito-chondria of the studied joint zones that we obtained turned out to be low in both groups, however, relatively high enzyme activity was observed in the subchondral zone of the bone of the group of metabolic phenotype of OA. Conclusion. In patients with the metabolic phenotype of OA, high expression of SUCNR1 in joint tissues is observed, which is tissue-specific with a predominant increase in the amount of SUCNR1 in the subchondral bone. We found higher levels of succinate in the subchondral bone and cartilaginous areas of joints in patients with the metabolic phenotype of OA and suggest that the succinate-SUCNR1 interaction in affected joints in OA is adaptive in nature.

SOME FEATURES OF CELLULAR ENERGY SUPPLY OF THE BODY IN PREMATURE INFANTS WITH SEVERE FORMS OF PERINATAL PATHOLOGY

The nature of postnatal adaptation of newborns, their further growth, development, health status and quality of life largelydepend on the well-being of intrauterine development and maturity at birth. Premature birth under hypoxia causes signifi cant metabolic disorders in the body, is accompanied by a high risk of severe organ dysfunction, which requires in-depth research to clarify the features of intracellular metabolism in order to further improve methods of diagnosis and treatment of newborns with various forms of perinatal pathology.Aim of the research. To study the trends of changes in energy metabolism in premature infants with severe forms of perinatal pathology to investigate the possibility of using them as additional criteria of hypoxic damage to the body in conditions of morphological and functional immaturity.Materials and methods. Clinical and laboratory examinations were performed on 68 newborns with severe forms of perinatal pathology at the gestational age of 32 to 34 weeks; the comparison group consisted of 27 conditionally healthy newborns at the gestational age of 34 to 37 weeks. Inclusion criteria for the main study group: gestational age at birth from 32 to 34 weeks, clinical signs of severe perinatal pathology. Exclusion criteria: gestational age at birth &lt; 32 and ≥ 37 weeks, diagnosed congenital malformations and septic conditions. The list of diseases was determined according to the International Classifi cation of Diseases, X Revision. The following blood serum laboratory parameters were studied: lactate level, glycerol-3-phosphate dehydrogenase (GPDH) (EC 1.1.99.5), succinate dehydrogenase (SDH), NADH dehydrogenase (NADH) (EC 1.6.5.3); the electron transport chain coeffi cient (ETC) was calculated. Laboratory studies were performed using micromethods. The study was conducted in accordance with the provisions of GCP (1996), the Convention of the Council of Europe on Human Rights and Biomedicine (April 4, 1997), the Declaration of Helsinki of the World Medical Association (1964-2008), Order of the Ministry of Health of Ukraine No. 690 dated September 23, 2009 (as amended by Order of the Ministry of Health of Ukraine No. 523 dated July 12, 2012). Protocol of scientifi c research of the Biomedical Ethics Committee of BSMU dated September 12, 2015. Informed written consent was obtained from the parents of the patients before the study with an explanationof the purpose, objectives and methods of laboratory testing. Statistical processing of the results was performed using STATISTICA software (StatSoft Inc., USA, version 10). Comparison of quantitative indicators with normal distribution was performed using Student’s t-test, and the probability of diff erences was considered statistically signifi cant at p&lt;0.05. The complex of studies was conducted within the framework of the planned research topics of the Department of Pediatrics, Neonatology and Perinatal Medicine of the Bukovinian State Medical University: «Improvement of the areas of prognosis, diagnostics and treatment of perinatal pathology in newborns and infants, optimization of the schemes of catamenial observation and rehabilitation» (State registration No. 0115U002768, term of execution 01.2015-12.2019) and «Chronobiological and adaptive aspects and features of vegetative regulation in pathological conditions in children of diff erent age groups» (State registration No. 0122U002245, term of execution 01.2020-12.2024).Results. In newborns of the main group, in comparison with the control group, a signifi cant decrease in GFDH and SDHwas found, which indicates a signifi cant impairment of the activity of enzymes of the respiratory chain and explains the lack of oxygen absorption in the body at the cellular and tissue level, causing the severity of the condition of newborns. Determination of the level of GPDH and SDH in the dynamics of observation in children showed some improvement in these indicators. In the severe condition of newborns, a signifi cant increase in the NADPH index was found, with a further probable increase in its level in the dynamics of observation. Calculations of ETC coeffi cient in cord blood showed a signifi cant decrease of this indicator in comparison with the control group. The identifi ed disorders of intracellular energy metabolism under hypoxia indicate the expediency of conducting comprehensive scientifi c research to study the possibilities of appropriate pharmacological correction to improve the eff ectiveness of treatment of severe forms of perinatal pathology in premature infants.Conclusions: 1. The results of the study revealed a signifi cant decrease in GPDH and SDH at elevated levels of NADPH andETC coeffi cient, which confi rms the presence of signifi cant disturbances in intracellular energy metabolism and mitochondrial oxidation processes. 2. Timely detection of metabolic disorders with the determination of mitochondrial oxidation, in particular energy metabolism, is an important area for improving diagnostic measures in severe forms of perinatal pathology in preterm infants with hypoxic damage to the body in the pathogenesis.

Gene replacement therapies for inherited disorders of neurotransmission: Current progress in succinic semialdehyde dehydrogenase deficiency.

Neurodevelopment is a highly organized and complex process involving lasting and often irreversible changes in the central nervous system. Inherited disorders of neurotransmission (IDNT) are a group of genetic disorders where neurotransmission is primarily affected, resulting in abnormal brain development from early life, manifest as neurodevelopmental disorders and other chronic conditions. In principle, IDNT (particularly those of monogenic causes) are amenable to gene replacement therapy via precise genetic correction. However, practical challenges for gene replacement therapy remain major hurdles for its translation from bench to bedside. We discuss key considerations for the development of gene replacement therapies for IDNT. As an example, we describe our ongoing work on gene replacement therapy for succinic semialdehyde dehydrogenase deficiency, a GABA catabolic disorder.

Interaction of 6-Bromo- and 6-Chloro-Ubiquinone derivatives with mitochondrial electron transfer system

To understand the reaction mechanism of quinone-mediated electron transfer, a series of ubiquinone (Q)-derivatives with a bromine or chlorine atom at the 6-position and a different alkyl side chains at the 5-position of the benzoquinone ring were synthesized and characterized. The chemical properties and electron transfer activities were compared with the native ubiquinone, Q0C10. The redox midpoint potential of 6-Bromo- and 6-chloro-Q derivatives is 142 mV and 148 mV, respectively. These 6-halo-Q derivatives are reducible by ascorbate alone or by succinate in the presence of succinate-ubiquinone reductase. The reduced 6-halo-Q (6-halo-QH2) can be oxidized by cytochrome c alone or via ubiquinol-cytochrome c reductase. In the presence of cytochrome c oxidase and cytochrome c, 6-halo-QH2 is oxidizable by oxygen. 6-Halo-Q derivatives are reducible by succinate via succinate-ubiquinone reductase. They function as an electron-mediator connecting succinate-Q reductase and cytochrome c oxidase and bypass ubiquinol-cytochrome c reductase in the mitochondrial electron-transfer chain. This bypassing results in a decrease in energy coupling efficiency and a lower P/O ratio. These compounds might have therapeutic value in treating diseases that are caused by the oversupply of energy.

A retrospective study of paraganglioma of the urinary bladder and literature review.

To review and summarize the characteristics and therapy of paraganglioma of the urinary bladder (PUB). Patients who underwent the operation in Peking Union Medical College Hospital between January 2012 and December 2021 were reviewed for this retrospective study. A total of 29 patients, comprising 9 (31%) men and 20 (69%) women, were included. The main manifestations were hypertension, palpitation, and micturition syncope. Eight patients had an increased 24-h urinary catecholamine, and seven of them had increased norepinephrine. Normetanephrine in seven patients was increased. Six of 18 metaiodobenzylguanidine and 8 of 22 octreotide scans were positive. In total, 15 cases underwent laparoscopic partial cystectomy and 14 underwent transurethral resection of bladder tumor. In all patients, the immunohistochemical index of Melan-A, AE1/AE3, and α-inhibin were negative, and chromogranin A, S-100, and succinate dehydrogenase were positive. The Ki-67 of 28/29 cases was under 5%, and 1 case with a Ki-67 of 20% was diagnosed with malignant PUB. A total of 27 patients had a regular follow-up, 2 patients were lost during the follow-up, 3 patients had a recurrence, and 1 of these patients died within 1 year of surgery. The symptoms all disappeared or were relieved after the surgery. The transurethral surgery approach fits PUB tumors with a size <3 cm or that protrudes into the bladder and can significantly reduce the postoperative hospital stay. Early detection and treatment are effective, and regular review is necessary after the surgery.

Resistance risk assessment for benzovindiflupyr in Sclerotium rolfsii and transmission of resistance genes among population.

Sclerotium rolfsii is a destructive soil-borne fungal pathogen which is distributed worldwide. In previous study, the succinate dehydrogenase inhibitor (SDHI) fungicide benzovindiflupyr has been identified for its great antifungal activity against Sclerotium rolfsii. This study is aimed to investigate the resistance risk and mechanism of benzovindiflupyr in Sclerotium rolfsii. Eight stable benzovindiflupyr-resistant isolates were generated by fungicide adaptation. Although the obtained eight resistant isolates have a stronger pathogenicity than the parental sensitive isolate, they have a fitness penalty in the mycelial growth and sclerotia formation compared to the parental isolate. A positive cross-resistance existed in the resistant isolates between benzovindiflupyr and thifluzamide, carboxin, boscalid and isopyrazam. Three-point mutations, including SdhBN180D, SdhCQ68E and SdhDH103Y, were identified in the benzovindiflupyr-resistant isolates. However, molecular docking analysis indicated that only SdhDH103Y could influence the sensitivity of Sclerotium rolfsii to benzovindiflupyr. After mycelial co-incubation of resistant isolates and the sensitive isolate, resistance genes may be transmitted to the sensitive isolate. The in vivo efficacy of benzovindiflupyr and thifluzamide against benzovindiflupyr-resistant isolates was a little lower than that against the sensitive isolate but with no significant difference. The results suggested a low to medium resistance risk of Sclerotium rolfsii to benzovindiflupyr. However, once resistance occurs, it is possible to spread in the population of Sclerotium rolfsii. This study is helpful to understanding the risk and mechanism of resistance to benzovindiflupyr in multinucleate pathogens such as Sclerotium rolfsii. © 2024 Society of Chemical Industry.

Drp1 controls complex II assembly and skeletal muscle metabolism by Sdhaf2 action on mitochondria.

The dynamin-related guanosine triphosphatase, Drp1 (encoded by Dnm1l), plays a central role in mitochondrial fission and is requisite for numerous cellular processes; however, its role in muscle metabolism remains unclear. Here, we show that, among human tissues, the highest number of gene correlations with DNM1L is in skeletal muscle. Knockdown of Drp1 (Drp1-KD) promoted mitochondrial hyperfusion in the muscle of male mice. Reduced fatty acid oxidation and impaired insulin action along with increased muscle succinate was observed in Drp1-KD muscle. Muscle Drp1-KD reduced complex II assembly and activity as a consequence of diminished mitochondrial translocation of succinate dehydrogenase assembly factor 2 (Sdhaf2). Restoration of Sdhaf2 normalized complex II activity, lipid oxidation, and insulin action in Drp1-KD myocytes. Drp1 is critical in maintaining mitochondrial complex II assembly, lipid oxidation, and insulin sensitivity, suggesting a mechanistic link between mitochondrial morphology and skeletal muscle metabolism, which is clinically relevant in combatting metabolic-related diseases.

Induction of human hepatic cytochrome P-450 3A4 expression by antifungal succinate dehydrogenase inhibitors

Succinate dehydrogenase inhibitors (SDHIs) are widely-used fungicides, to which humans are exposed and for which putative health risks are of concern. In order to identify human molecular targets for these agrochemicals, the interactions of 15 SDHIs with expression and activity of human cytochrome P-450 3A4 (CYP3A4), a major hepatic drug metabolizing enzyme, were investigated in vitro. 12/15 SDHIs, i.e., bixafen, boscalid, fluopyram, flutolanil, fluxapyroxad, furametpyr, isofetamid, isopyrazam, penflufen, penthiopyrad, pydiflumetofen and sedaxane, were found to enhance CYP3A4 mRNA expression in human hepatic HepaRG cells and primary human hepatocytes exposed for 48 h to 10 µM SDHIs, whereas 3/15 SDHIs, i.e., benzovindiflupyr, carboxin and thifluzamide, were without effect. The inducing effects were concentrations-dependent for boscalid (EC50=22.5 µM), fluopyram (EC50=4.8 µM) and flutolanil (EC50=53.6 µM). They were fully prevented by SPA70, an antagonist of the Pregnane X Receptor, thus underlining the implication of this xenobiotic-sensing receptor. Increase in CYP3A4 mRNA in response to SDHIs paralleled enhanced CYP3A4 protein expression for most of SDHIs. With respect to CYP3A4 activity, it was directly inhibited by some SDHIs, including bixafen, fluopyram, fluxapyroxad, isofetamid, isopyrazam, penthiopyrad and sedaxane, which therefore appears as dual regulators of CYP3A4, being both inducer of its expression and inhibitor of its activity. The inducing effect nevertheless predominates for these SDHIs, except for isopyrazam and sedaxane, whereas boscalid and flutolanil were pure inducers of CYP3A4 expression and activity. Most of SDHIs appear therefore as in vitro inducers of CYP3A4 expression in cultured hepatic cells, when, however, used at concentrations rather higher than those expected in humans in response to environmental or dietary exposure to these agrochemicals.