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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 -
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 -
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 -
Drug Design, Development and Therapy 2023Streptonigrin is an aminoquinone alkaloid isolated from and is gaining attention as a drug molecule owing to its potential antitumor and antibiotic effects. It was... (Review)
Review
Streptonigrin is an aminoquinone alkaloid isolated from and is gaining attention as a drug molecule owing to its potential antitumor and antibiotic effects. It was previously used as an anticancer drug but has been discontinued because of its toxic effects. However, according to the most recent studies, the toxicity of streptonigrin and its structurally modified derivatives has been reduced while maintaining their potential pharmacological action at lower concentrations. To date, many investigations have been conducted on this molecule and its derivatives to determine the most effective molecule with low toxicity to enable new drug discovery. Therefore, the main objective of this study is to provide a comprehensive review and to discuss the prospects for streptonigrin and its derived compounds, which may boost the molecule as a highly interesting target molecule for new drug design, development and therapy. To complete this review, relevant literature was collected from several scientific databases, including Google Scholar, PubMed, Scopus and ScienceDirect. Following a complete screening, the obtained information is summarized in the present review to provide a good reference and accelerate the development and utilization of streptonigrin and its derivatives as pharmaceuticals.
Topics: Streptonigrin; Antineoplastic Agents; Drug Design
PubMed: 37064433
DOI: 10.2147/DDDT.S388490 -
Angewandte Chemie (International Ed. in... Jan 2023We report that axially chiral biaryl boronic esters can be generated with control of atroposelectivity by a Binol-mediated dynamic thermodynamic resolution process....
We report that axially chiral biaryl boronic esters can be generated with control of atroposelectivity by a Binol-mediated dynamic thermodynamic resolution process. These intermediates can be progressed to enantioenriched products through stereoretentive functionalization of the carbon-boron bond. Finally, we have exploited this method in the first highly stereoselective total synthesis of P-streptonigrin.
PubMed: 36377668
DOI: 10.1002/anie.202213692 -
Molecules (Basel, Switzerland) Sep 2022Hybrids 1,4-quinone with quinoline were obtained by connecting two active structures through an oxygen atom. This strategy allows to obtain new compounds with a high...
Hybrids 1,4-quinone with quinoline were obtained by connecting two active structures through an oxygen atom. This strategy allows to obtain new compounds with a high biological activity and suitable bioavailability. Newly synthesized compounds were characterized by various spectroscopic methods. The enzymatic assay used showed that these compounds were a suitable DT-diaphorase (NQO1) substrates as evidenced by increasing enzymatic conversion rates relative to that of streptonigrin. Hybrids were tested in vitro against a panel of human cell lines including melanoma, breast, and lung cancers. They showed also a high cytotoxic activity depending on the type of 1,4-quinone moiety and the applied tumor cell lines. It was found that cytotoxic activity of the studied hybrids was increasing against the cell lines with higher NQO1 protein level, such as breast (MCF-7 and T47D) and lung (A549) cancers. Selected hybrids were tested for the transcriptional activity of the gene encoding a proliferation marker (H3 histone), cell cycle regulators (p53 and p21) and the apoptosis pathway (BCL-2 and BAX). The molecular docking was used to examine the probable interaction between the hybrids and NQO1 protein.
Topics: Antineoplastic Agents; Apoptosis; Benzoquinones; Cell Line, Tumor; Drug Screening Assays, Antitumor; Histones; Humans; Hydroxyquinolines; Molecular Docking Simulation; NAD(P)H Dehydrogenase (Quinone); Oxygen; Quinolines; Quinones; Streptonigrin; Tumor Suppressor Protein p53; bcl-2-Associated X Protein
PubMed: 36234741
DOI: 10.3390/molecules27196206 -
PLoS Pathogens Jun 2022The Neisseria gonorrhoeae Type IV pilus is a multifunctional, dynamic fiber involved in host cell attachment, DNA transformation, and twitching motility. We previously...
The Neisseria gonorrhoeae Type IV pilus is a multifunctional, dynamic fiber involved in host cell attachment, DNA transformation, and twitching motility. We previously reported that the N. gonorrhoeae pilus is also required for resistance against hydrogen peroxide-, antimicrobial peptide LL-37-, and non-oxidative, neutrophil-mediated killing. We tested whether the hydrogen peroxide, LL-37, and neutrophil hypersensitivity phenotypes in non-piliated N. gonorrhoeae could be due to elevated iron levels. Iron chelation in the growth medium rescued a nonpiliated pilE mutant from both hydrogen peroxide- and antimicrobial peptide LL-37-mediated killing, suggesting these phenotypes are related to iron availability. We used the antibiotic streptonigrin, which depends on free cytoplasmic iron and oxidation to kill bacteria, to determine whether piliation affected intracellular iron levels. Several non-piliated, loss-of-function mutants were more sensitive to streptonigrin killing than the piliated parental strain. Consistent with the idea that higher available iron levels in the under- and non-piliated strains were responsible for the higher streptonigrin sensitivity, iron limitation by desferal chelation restored resistance to streptonigrin in these strains and the addition of iron restored the sensitivity to streptonigrin killing. The antioxidants tiron and dimethylthiourea rescued the pilE mutant from streptonigrin-mediated killing, suggesting that the elevated labile iron pool in non-piliated bacteria leads to streptonigrin-dependent reactive oxygen species production. These antioxidants did not affect LL-37-mediated killing. We confirmed that the pilE mutant is not more sensitive to other antibiotics showing that the streptonigrin phenotypes are not due to general bacterial envelope disruption. The total iron content of the cell was unaltered by piliation when measured using ICP-MS suggesting that only the labile iron pool is affected by piliation. These results support the hypothesis that piliation state affects N. gonorrhoeae iron homeostasis and influences sensitivity to various host-derived antimicrobial agents.
Topics: Bacterial Proteins; Fimbriae, Bacterial; Hydrogen Peroxide; Iron; Neisseria gonorrhoeae; Streptonigrin
PubMed: 35714158
DOI: 10.1371/journal.ppat.1010561 -
Journal of Microbiology, Immunology,... Dec 2022Klebsiella pneumoniae is a gram-negative opportunistic pathogen that causes diseases mostly in immunocompromised individuals. Recently, hypervirulent K. pneumoniae...
BACKGROUND
Klebsiella pneumoniae is a gram-negative opportunistic pathogen that causes diseases mostly in immunocompromised individuals. Recently, hypervirulent K. pneumoniae strains also cause severe disease in healthy individuals. Capsular polysaccharide (CPS) is the major virulence determinant in hypervirulent K. pneumoniae and protects the cell against the bactericidal activity of the immune system. Gallic acid (GA), a natural phenolic compound, is known to exhibit wide spectrum antibacterial activity; however, its effect on hypervirulent K. pneumoniae remains largely unresolved. We aimed to identify the effects of GA on CPS biosynthesis in hypervirulent K. pneumoniae.
METHODS
Antibacterial activity of GA was evaluated by counting colonies. CPS amount was determined by glucuronic acid content. The transcriptions of cps gene cluster were measured by quantitative real time PCR (qRT-PCR) and the β-galactosidase activity. The effect of GA on the resistance of K. pneumoniae to streptonigrin (SNG), an iron-activated antibiotic, was evaluated. The effect of GA on the resistance of K. pneumoniae to serum killing and phagocytosis by macrophages was observed.
RESULTS
GA inhibited the growth and CPS biosynthesis in K. pneumoniae. GA may affect the iron availability in K. pneumoniae, thus possibly repressing the cps transcription. In addition, GA reduced the resistance of K. pneumoniae to serum killing and enhanced its susceptibility to phagocytosis.
CONCLUSION
GA possesses bactericidal activity and inhibits the CPS biosynthesis in hypervirulent K. pneumoniae, thereby facilitating pathogen clearance by the host immune system. Therefore, GA may represent a promising strategy for the prevention or treatment of patients with hypervirulent K. pneumoniae infections.
Topics: Humans; Klebsiella pneumoniae; Gallic Acid; Virulence Factors; Anti-Bacterial Agents; Iron; Klebsiella Infections
PubMed: 34326026
DOI: 10.1016/j.jmii.2021.07.002