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Plants (Basel, Switzerland) Jun 2024Lemon essential oil, derived from , possesses diverse health-promoting properties, including antioxidant, antimicrobial, and mood-enhancing effects. Despite its...
Lemon essential oil, derived from , possesses diverse health-promoting properties, including antioxidant, antimicrobial, and mood-enhancing effects. Despite its traditional use in aromatherapy and complementary medicine, there is a need for comprehensive investigations into its therapeutic potential, particularly in mitigating DNA damage and supporting health in palliative care settings. This study aimed to evaluate the antigenotoxic effects of lemon essential oil in human peripheral blood mononuclear cells and to explore its potential applications in palliative care. Treatment with lemon essential oil significantly reduced DNA damage, with 1% w/v with 3.13% DNA in tail demonstrating greater efficacy. Furthermore, lemon essential oil attenuated streptonigrin-induced DNA damage, suggesting a potential protective effect against oxidative stress, especially at 3% w/v, with 11.81% DNA in tail. Compared to olive oil treatment, the DNA damage was significantly lower with streptonigrin treatment alone, which had 47.06% DNA in tail, while the olive oil treatment resulted in 36.88% DNA in tail. These results can be attributed to the main constituents: limonene in lemon essential oil and oleic acid in olive oil. These results suggest a potential role in mitigating oxidative stress and supporting genomic stability. Further research is warranted to elucidate the mechanisms of action and clinical applications in palliative care.
PubMed: 38931055
DOI: 10.3390/plants13121623 -
Microorganisms May 2024is an emerging human pathogen that has a high rate of incidence in immunocompromised individuals. We have found a putative secondary metabolite pathway within , which...
is an emerging human pathogen that has a high rate of incidence in immunocompromised individuals. We have found a putative secondary metabolite pathway within , which may be a key factor in its pathogenesis. This novel pathway is encoded in a gene cluster spanning MAB_0284c to 0305 and is related to pathways, producing the secondary metabolites streptonigrin and nybomycin. We constructed an in-frame deletion of the MAB_0295 () gene and tested it in our animal model. We have previously shown that tadpoles, which have functional lungs and T cells, can serve as a reliable comparative model for persistent infection and pathogenesis. Here, we report that tadpoles intraperitoneally infected with the ∆ mutant exhibit early decreased bacterial loads and significantly increased survival compared with those infected with WT . ∆ mutant also induced lower transcript levels of several pro-inflammatory cytokines (, , , ) than those of WT in the liver and lungs. In addition, there was impaired macrophage recruitment and decreased macrophage infection in tadpoles infected with the ∆ mutant, by tail wound inoculation, compared to those infected with the WT bacteria, as assayed by intravital confocal microscopy. These data underline the relevance and usefulness of tadpoles as a novel comparative animal model to identify genetic determinants of immunopathogenesis, suggesting a role for this novel and uncharacterized pathway in pathogenesis and macrophage recruitment.
PubMed: 38930501
DOI: 10.3390/microorganisms12061120 -
The Journal of Antimicrobial... Jun 2024Riemerella anatipestifer encodes an iron acquisition system, but whether it encodes the iron efflux pump and its role in antibiotic resistance are largely unknown.
BACKGROUND
Riemerella anatipestifer encodes an iron acquisition system, but whether it encodes the iron efflux pump and its role in antibiotic resistance are largely unknown.
OBJECTIVES
To screen and identify an iron efflux gene in R. anatipestifer and determine whether and how the iron efflux gene is involved in antibiotic resistance.
METHODS
In this study, gene knockout, streptonigrin susceptibility assay and inductively coupled plasma mass spectrometry were used to screen for the iron efflux gene ietA. The MIC measurements, scanning electron microscopy and reactive oxygen species (ROS) detection were used to verify the role of IetA in aztreonam resistance and its mechanism. Mortality and colonization assay were used to investigate the role of IetA in virulence.
RESULTS
The deletion mutant ΔietA showed heightened susceptibility to streptonigrin, and prominent intracellular iron accumulation was observed in ΔfurΔietA under excess iron conditions. Additionally, ΔietA exhibited increased sensitivity to H2O2-produced oxidative stress. Under aerobic conditions with abundant iron, ΔietA displayed increased susceptibility to the β-lactam antibiotic aztreonam due to heightened ROS production. However, the killing efficacy of aztreonam was diminished in both WT and ΔietA under anaerobic or iron restriction conditions. Further experiments demonstrated that the efficiency of aztreonam against ΔietA was dependent on respiratory complexes Ⅰ and Ⅱ. Finally, in a duckling model, ΔietA had reduced virulence compared with the WT.
CONCLUSION
Iron efflux is critical to alleviate oxidative stress damage and β-lactam aztreonam killing in R. anatipestifer, which is linked by cellular respiration.
Topics: Oxidative Stress; Iron; Animals; Microbial Sensitivity Tests; Anti-Bacterial Agents; Riemerella; Aztreonam; Flavobacteriaceae Infections; Virulence; beta-Lactam Resistance; Ducks; Reactive Oxygen Species; Membrane Transport Proteins; Streptonigrin; Gene Knockout Techniques; Poultry Diseases; Bacterial Proteins
PubMed: 38629469
DOI: 10.1093/jac/dkae114 -
Proceedings of the National Academy of... Jan 2024
Topics: Streptonigrin; Bacteria
PubMed: 38227663
DOI: 10.1073/pnas.2320942121 -
Bioorganic Chemistry Feb 2024Overexpression of transglutaminase 2 (TGase 2; TG2) has been implicated in the progression of renal cell carcinoma (RCC) through the inactivation of p53 by forming a...
Overexpression of transglutaminase 2 (TGase 2; TG2) has been implicated in the progression of renal cell carcinoma (RCC) through the inactivation of p53 by forming a protein complex. Because most p53 in RCC has no mutations, apoptosis can be increased by inhibiting the binding between TG2 and p53 to increase the stability of p53. In the present study, a novel TG2 inhibitor was discovered by investigating the structure of 1H-benzo[d]imidazole-4,7-dione as a simpler chemotype based on the amino-1,4-benzoquinone moiety of streptonigrin, a previously reported inhibitor. Through structure-activity relationship (SAR) studies, compound 8j (MD102) was discovered as a potent TG2 inhibitor with an IC value of 0.35 µM, p53 stabilization effect and anticancer effects in the ACHN and Caki-1 RCC cell lines with sulforhodamine B (SRB) GI values of 2.15 µM and 1.98 µM, respectively. The binding property of compound 8j (MD102) with TG2 was confirmed to be reversible in a competitive enzyme assay, and the binding interaction was expected to be formed at the β-sandwich domain, a p53 binding site, in the SPR binding assay with mutant proteins. The mode of binding of compound 8j (MD102) to the β-sandwich domain of TG2 was analyzed by molecular docking using the crystal structure of the active conformation of human TG2. Compound 8j (MD102) induced a decrease in the downstream signaling of p-AKT and p-mTOR through the stabilization of p53 by TG2 inhibition, resulting in tumor cell apoptosis. In a xenograft animal model using ACHN cancer cells, oral administration and intraperitoneal injection of compound 8j (MD102) showed an inhibitory effect on tumor growth, confirming increased levels of p53 and decreased levels of Ki-67 in tumor tissues through immunohistochemical (IHC) tissue staining. These results indicated that the inhibition of TG2 by compound 8j (MD102) could enhance p53 stabilization, thereby ultimately showing anticancer effects in RCC. Compound 8j (MD102), a novel TG2 inhibitor, can be further applied for the development of an anticancer candidate drug targeting RCC.
Topics: Animals; Humans; Antineoplastic Agents; Carcinoma, Renal Cell; Cell Line, Tumor; Imidazoles; Kidney Neoplasms; Molecular Docking Simulation; Protein Glutamine gamma Glutamyltransferase 2; Transglutaminases; Tumor Suppressor Protein p53
PubMed: 38154386
DOI: 10.1016/j.bioorg.2023.107061 -
Proceedings of the National Academy of... Dec 2023Natural products that possess antibiotic and antitumor qualities are often suspected of working through oxidative mechanisms. In this study, two quinone-based small...
Natural products that possess antibiotic and antitumor qualities are often suspected of working through oxidative mechanisms. In this study, two quinone-based small molecules were compared. Menadione, a classic redox-cycling compound, was confirmed to generate high levels of reactive oxygen species inside . It inactivated iron-cofactored enzymes and blocked growth. However, despite the substantial levels of oxidants that it produced, it was unable to generate significant DNA damage and was not lethal. Streptonigrin, in contrast, was poorer at redox cycling and did not inactivate enzymes or block growth; however, even in low doses, it damaged DNA and killed cells. Its activity required iron and oxygen, and in vitro experiments indicated that its quinone moiety transferred electrons through the adjacent iron atom to oxygen. Additionally, in vitro experiments revealed that streptonigrin was able to damage DNA without inhibition by catalase, indicating that hydrogen peroxide was not involved. We infer that streptonigrin can reduce bound oxygen directly to a ferryl species, which then oxidizes the adjacent DNA, without release of superoxide or hydrogen peroxide intermediates. This scheme allows streptonigrin to kill a bacterial cell without interference by scavenging enzymes. Moreover, its minimal redox-cycling behavior avoids alerting either the OxyR or the SoxRS systems, which otherwise would block killing. This example highlights qualities that may be important in the design of oxidative drugs. These results also cast doubt on proposals that bacteria can be killed by stressors that merely stimulate intracellular O and HO formation.
Topics: Oxidants; Hydrogen Peroxide; Anti-Bacterial Agents; Streptonigrin; Oxidative Stress; Escherichia coli; Oxygen; Iron; DNA; Quinones
PubMed: 38109539
DOI: 10.1073/pnas.2312110120 -
Food Microbiology Oct 2023Salmonella is known to survive in raw/pasteurized milk and cause foodborne outbreaks. Lactoferrin, present in milk from all animal sources, is an iron-binding...
Salmonella is known to survive in raw/pasteurized milk and cause foodborne outbreaks. Lactoferrin, present in milk from all animal sources, is an iron-binding glycoprotein that limits the availability of iron to pathogenic bacteria. Despite the presence of lactoferrins, Salmonella can grow in milk obtained from different animal sources. However, the mechanism by which Salmonella overcomes iron scarcity induced by lactoferrin in milk is not evaluated yet. Salmonella employs the DNA binding transcriptional regulator Fur (ferric update regulator) to mediate iron uptake during survival in iron deplete conditions. To understand the importance of Fur in Salmonella milk growth, we profiled the growth of Salmonella Typhimurium Δfur (ST4/74Δfur) in both bovine and camel milk. ST4/74Δfur was highly inhibited in milk compared to wild-type ST4/74, confirming the importance of Fur mediated regulation of iron metabolism in Salmonella milk growth. We further studied the biology of ST4/74Δfur to understand the importance of iron metabolism in Salmonella milk survival. Using increasing concentrations of FeCl, and the antibiotic streptonigrin we show that iron accumulates in the cytoplasm of ST4/74Δfur. We hypothesized that the accumulated iron could activate oxidative stress via Fenton's reaction leading to growth inhibition. However, the inhibition of ST4/74Δfur in milk was not due to Fenton's reaction, but due to the 'iron scarce' conditions of milk and microaerophilic incubation conditions which made the presence of the fur gene indispensable for Salmonella milk growth. Subsequently, survival studies of 14 other transcriptional mutants of ST4/74 in milk confirmed that RpoE-mediated response to extracytoplasmic stress is also important for the survival of Salmonella in milk. Though we have data only for fur and rpoE, many other Salmonella transcriptional factors could play important roles in the growth of Salmonella in milk, a theme for future research on Salmonella milk biology. Nevertheless, our data provide early insights into the biology of milk-associated Salmonella.
Topics: Animals; Cattle; Salmonella typhimurium; Lactoferrin; Repressor Proteins; Iron; Milk; Bacterial Proteins; Gene Expression Regulation, Bacterial
PubMed: 37567619
DOI: 10.1016/j.fm.2023.104326 -
Molecules (Basel, Switzerland) Jul 2023This review uses the National Cancer Institute (NCI) COMPARE program to establish an extensive list of heterocyclic iminoquinones and quinones with similarities in... (Review)
Review
This review uses the National Cancer Institute (NCI) COMPARE program to establish an extensive list of heterocyclic iminoquinones and quinones with similarities in differential growth inhibition patterns across the 60-cell line panel of the NCI Developmental Therapeutics Program (DTP). Many natural products and synthetic analogues are revealed as potential NAD(P)H:quinone oxidoreductase 1 (NQO1) substrates, through correlations to dipyridoimidazo[5,4-]benzimidazoleiminoquinone (DPIQ), and as potential thioredoxin reductase (TrxR) inhibitors, through correlations to benzo[1,2,4]triazin-7-ones and pleurotin. The strong correlation to NQO1 infers the enzyme has a major influence on the amount of the active compound with benzo[]perimidines, phenoxazinones, benz[]pyrido[1,2-]indole-6,11-quinones, seriniquinones, kalasinamide, indolequinones, and furano[2,3-]naphthoquinones, hypothesised as prodrugs. Compounds with very strong correlations to known TrxR inhibitors had inverse correlations to the expression of both reductase enzymes, NQO1 and TrxR, including naphtho[2,3-][1,4]oxazepane-6,11-diones, benzo[]carbazole-1,4-diones, pyranonaphthoquinones (including kalafungin, nanaomycin A, and analogues of griseusin A), and discorhabdin C. Quinoline-5,8-dione scaffolds based on streptonigrin and lavendamycin can correlate to either reductase. Inhibitors of TrxR are not necessarily (imino)quinones, e.g., parthenolides, while oxidising moieties are essential for correlations to NQO1, as with the mitosenes. Herein, an overview of synthetic methods and biological activity of each family of heterocyclic imino(quinone) is provided.
Topics: United States; National Cancer Institute (U.S.); Quinones; Indolequinones; Oxidoreductases; NAD(P)H Dehydrogenase (Quinone); Antineoplastic Agents; Neoplasms
PubMed: 37446864
DOI: 10.3390/molecules28135202 -
Microbiology Spectrum Aug 2023The bacterium Riemerella anatipestifer requires iron for growth, but the mechanism of iron uptake is not fully understood. In this study, we disrupted the Feo system and...
The bacterium Riemerella anatipestifer requires iron for growth, but the mechanism of iron uptake is not fully understood. In this study, we disrupted the Feo system and characterized its function in iron import in R. anatipestifer ATCC 11845. Compared to the parent strain, the growth of the Δ Δ and Δ strains was affected under Fe-limited conditions, since the absence of the system led to less intracellular iron than in the parent strain. In parallel, the Δ strain was shown to be less sensitive to streptonigrin, an antibiotic that requires free iron to function. The sensitivity of the Δ strain to hydrogen peroxide was also observed to be diminished compared with that of the parent strain, which could be related to the reduced intracellular iron content in the Δ strain. Further research revealed that and were directly regulated by iron through the Fur regulator and that the transcript levels of and were significantly increased in medium supplemented with 1 mM MnCl, 400 μM ZnSO, and 200 μM CuCl. Finally, it was shown that the Δ strain of R. anatipestifer ATCC 11845 was significantly impaired in its ability to colonize the blood, liver, and brain of ducklings. Taken together, these results demonstrated that FeoAB supports ferrous iron acquisition in R. anatipestifer and plays an important role in R. anatipestifer colonization. In Gram-negative bacteria, the Feo system is an important ferrous iron transport system. R. anatipestifer encodes an Feo system, but its function unknown. As iron uptake may be required for oxidative stress protection and virulence, understanding the contribution of iron transporters to these processes is crucial. This study showed that the Δ strain is debilitated in its ability to import iron and that its intracellular iron content was constitutively low, which enhanced the resistance of the deficient strain to HO. We were surprised to find that, in addition to responding to iron, the Feo system may play an important role in sensing manganese, zinc, and copper stress. The reduced colonization ability of the Δ strain also sheds light on the role of iron transporters in host-pathogen interactions. This study is important for understanding the cross talk between iron and other metal transport pathways, as well as the pathogenic mechanism in R. anatipestifer.
Topics: Virulence; Bacterial Proteins; Hydrogen Peroxide; Iron; Membrane Transport Proteins
PubMed: 37272830
DOI: 10.1128/spectrum.01373-23