Inhibitor Of Isocitrate Lyase Research Articles

Inhibition of Candida albicans isocitrate lyase activity by cadiolides and synoilides from the ascidian Synoicum sp.

Tris-aromatic furanones (1−4) and related bis-aromatic diesters (5 and 6) isolated from the dark red ascidian Synoicum sp., were evaluated for their inhibitory activities toward Candida albicans isocitrate lyase (ICL). These studies led to the identification of compounds 1, 3, and 4 as potent ICL inhibitors, with IC50 values of 7.62, 17.16, and 10.36μM, respectively. Growth phenotype of ICL deletion mutants and Northern blot analysis data indicated that compound 1 inhibits the ICL expression in C. albicans under C2 carbon utilizing condition.

Biofilm-grown Burkholderia cepacia complex cells survive antibiotic treatment by avoiding production of reactive oxygen species.

The presence of persister cells has been proposed as a factor in biofilm resilience. In the present study we investigated whether persister cells are present in Burkholderia cepacia complex (Bcc) biofilms, what the molecular basis of antimicrobial tolerance in Bcc persisters is, and how persisters can be eradicated from Bcc biofilms. After treatment of Bcc biofilms with high concentrations of various antibiotics often a small subpopulation survived. To investigate the molecular mechanism of tolerance in this subpopulation, Burkholderia cenocepacia biofilms were treated with 1024 µg/ml of tobramycin. Using ROS-specific staining and flow cytometry, we showed that tobramycin increased ROS production in treated sessile cells. However, approximately 0.1% of all sessile cells survived the treatment. A transcriptome analysis showed that several genes from the tricarboxylic acid cycle and genes involved in the electron transport chain were downregulated. In contrast, genes from the glyoxylate shunt were upregulated. These data indicate that protection against ROS is important for the survival of persisters. To confirm this, we determined the number of persisters in biofilms formed by catalase mutants. The persister fraction in ΔkatA and ΔkatB biofilms was significantly reduced, confirming the role of ROS detoxification in persister survival. Pretreatment of B. cenocepacia biofilms with itaconate, an inhibitor of isocitrate lyase (ICL), the first enzyme in the glyoxylate shunt, reduced the persister fraction approx. 10-fold when the biofilms were subsequently treated with tobramycin. In conclusion, most Bcc biofilms contain a significant fraction of persisters that survive treatment with high doses of tobramycin. The surviving persister cells downregulate the TCA cycle to avoid production of ROS and at the same time activate an alternative pathway, the glyoxylate shunt. This pathway may present a novel target for combination therapy.

Advances in Mycobacterial Isocitrate Lyase Targeting and Inhibitors

Isocitrate lyase plays a key role for survival of Mycobacterium tuberculosis in the latent form during a chronic stage of infection. This enzyme is important for M. tuberculosis during steady stage growth when it converts isocitrate to succinate and glyoxylate. Then, the glyoxylate is condensed with acetyl-CoA to form malate by malate synthase. The carbon conserving glyoxylate pathway has not been observed in mammals; therefore, it has been determined as a potential drug target for discovery of a new antituberculosis agent. Novel active molecules should shorten the duration of therapy, prevent resistance development and eliminate latent disease. The review summarizes recent progresses in isocitrate lyase inhibitors, overviews structural analogues of several metabolic intermediates (3-nitropropionate, 3-bromopyruvate, itaconate, itaconic anhydride), peptide inhibitors, and recently developed inhibitors with various chemical structures. The largest inhibitory activity against isocitrate lyase (IC(50) of 0.10 ± 0.01 μM) and concomitantly a significant antimycobacterial activity has been presented by fluoroquinolone derivative 1-cyclopropyl-7-[3,5-dimethyl-4-(3-nitropropanoyl)piperazin-1-yl]-6-fluoro-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid, which has incorporated 3-nitropropionyl group as one of the structural analogue of succinate, a metabolic intermediate.

Synthesis and in vitro antimycobacterial and isocitrate lyase inhibition properties of novel 2-methoxy-2′-hydroxybenzanilides, their thioxo analogues and benzoxazoles

A new series of 2-methoxy-2′-hydroxybenzanilide derivatives and their thioxo analogues have been synthesised and characterised by IR, NMR and elemental analysis. These compounds were investigated for their in vitro antimycobacterial activities against Mycobacterium tuberculosis 331/88, Mycobacterium avium 330/88, Mycobacterium kansasii 235/80, clinically isolated M. kansasii 6509/96 and the ability to act as in vitro isocitrate lyase inhibitors. The best ICL inhibitors were two compounds from the thiobenzanilide group (8f, 8m), which exhibited an inhibition potential that was equal to the standard compound, 3-nitropropionic acid. In addition, the best antimycobacterial properties were exhibited by benzanilide derivatives 6h, 6k and 6l with 5-Cl and 4′ or 5′ Cl/Br substitution. For all the thiobenzanilide derivatives tested, two conformers were observed in the NMR spectra, which is most likely due to the hindered rotation of the C–N bond.

Salicylanilide derivatives block Mycobacterium tuberculosis through inhibition of isocitrate lyase and methionine aminopeptidase

The global burden of tuberculosis, its health and socio-economic impacts, the presence of drug-resistant forms and a potential threat of latent tuberculosis should serve as a strong impetus for the development of novel antituberculosis agents. We reported the in vitro activity of salicylanilide benzoates and pyrazine-2-carboxylates against Mycobacterium tuberculosis (minimum inhibitory concentrations as low as 0.5 μmol/L). Nineteen salicylanilide derivatives with mostly good antimycobacterial activity were evaluated for the inhibition of two essential mycobacterial enzymes, methionine aminopeptidase and isocitrate lyase, which are necessary for the maintenance of the latent tuberculosis infection. Salicylanilide derivatives act as moderate inhibitors of both mycobacterial and human methionine aminopeptidase and they also affect the function of mycobacterial isocitrate lyase. 4-Bromo-2-[4-(trifluoromethyl)phenylcarbamoyl]phenyl pyrazine-2-carboxylate was the most potent inhibitor of mycobacterial methionine aminopeptidase (41% inhibition at 10 μmol/L) and exhibited the highest selectivity. 5-Chloro-2-hydroxy-N-[4-(trifluoromethyl)phenyl]benzamide and 4-chloro-2-[4-(trifluoromethyl)phenylcarbamoyl]phenyl pyrazine-2-carboxylate caused 59% inhibition of isocitrate lyase at 100 μmol/L concentration and (S)-4-bromo-2-[4-(trifluoromethyl)phenylcarbamoyl]phenyl 2-acetamido-3-phenylpropanoate produced 22% inhibition at 10 μmol/L; this rate is approximately comparable to 3-nitropropionic acid. Inhibition of those enzymes contributes at least in part to the antimicrobial activity of the compounds.

Synthesis and characterization of pyruvate–isoniazid analogs and their copper complexes as potential ICL inhibitors

Currently used anti-tubercular drugs target actively growing Mycobacterium tuberculosis (Mtb) but there are no current therapies targeting persistent mycobacteria. Isocitrate lyase (ICL) is an important enzyme of the glyoxylate shunt pathway used by Mtb for sustaining intracellular infection in inflammatory macrophages under conditions of stress such as nutrient depletion and anaerobic metabolism. Since the humans do not possess this enzyme it constitutes an attractive target for selective drug design. Present work describes synthesis and structural characterization of pyruvate–isoniazid conjugates and their copper complexes with potent anti-tubercular activities against M. tuberculosis H37Rv.

Synthesis of various 3-nitropropionamides as Mycobacterium tuberculosis isocitrate lyase inhibitor

Various 3-nitropropionamides were synthesized and evaluated for in vitro activities against log and starved phase culture of two mycobacterial species and Mycobacterium tuberculosis (MTB) isocitrate lyase (ICL) enzyme inhibition studies. Among 22 compounds, 1-cyclopropyl-7-(3,5-dimethyl-4-(3-nitropropanoyl)piperazin-1-yl)-6-fluoro-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (22) was found to be the most active compound in vitro with MICs of 0.16 and 0.04 μM against log- and starved-phase culture of MTB. Compound 22 also showed good enzyme inhibition of MTB ICL with IC(50) of 0.10 ± 0.01 μM. The docking studies also confirmed the binding potential of the compounds at the ICL active site.

Synthetic analogs of indole-containing natural products as inhibitors of sortase A and isocitrate lyase

Guided by the inhibitory activities of indole-containing natural products against isocitrate lyase (ICL) from Candida albicans and sortase A (SrtA) from Staphylococcus aureus, a series of compounds structurally analogous to natural products were synthesized. Eight SrtA inhibitors and an ICL inhibitor having higher activities than the natural products were discovered by screening the enzyme inhibitory activities of synthesized compounds. Among the SrtA inhibitors discovered, six exhibited higher activities than p-hydroxymercuribenzoic acid, which suggests that these compounds have great potential as alternative antibacterial agents.

Flexible metabolism in Metarhizium anisopliae and Beauveria bassiana: role of the glyoxylate cycle during insect pathogenesis

Insect pathogenic fungi such as Metarhizium anisopliae and Beauveria bassiana have an increasing role in the control of agricultural insect pests and vectors of human diseases. Many of the virulence factors are well studied but less is known of the metabolism of these fungi during the course of insect infection or saprobic growth. Here, we assessed enzyme activity and gene expression in the central carbon metabolic pathway, including isocitrate dehydrogenase, aconitase, citrate synthase, malate synthase (MLS) and isocitrate lyase (ICL), with particular attention to the glyoxylate cycle when M. anisopliae and B. bassiana were grown under various conditions. We observed that ICL and MLS, glyoxylate cycle intermediates, were upregulated during growth on 2-carbon compounds (acetate and ethanol) as well as in insect haemolymph. We fused the promoter of the M. anisopliae ICL gene (Ma-icl) to a marker gene (mCherry) and showed that Ma-icl was upregulated when M. anisopliae was grown in the presence of acetate. Furthermore, Ma-icl was upregulated when fungi were engulfed by insect haemocytes as well as during appressorium formation. Addition of the ICL inhibitor 3-nitroproprionate delayed conidial germination and inhibited appressorium formation. These results show that these insect pathogenic fungi have a flexible metabolism that includes the glyoxylate cycle as an integral part of germination, pathogenesis and saprobic growth.

Bromophenols as Candida albicans isocitrate lyase inhibitors

A new series of bromophenols was synthesized by reactions of corresponding phenol analogs with bromine. The synthesized compounds were tested for inhibitory activity against isocitrate lyase (ICL) of Candida albicans and antimicrobial activity against Gram-positive and, Gram-negative bacteria and fungi. Among the synthesized bromophenols, bis(3-bromo-4,5-dihydroxyphenyl)methanone (11) and (3-bromo-4,5-dihydroxyphenyl)(2,3-dibromo-4,5-dihydroxyphenyl)methanone (12) displayed potent inhibitory activities against ICL, showing a stronger inhibitory effects than were found with natural bromophenol 1. The preliminary structure–activity relationships were investigated in order to determine the essential structural requirements for the inhibitory activities of these compounds against ICL of C. albicans.

Burkholderia pseudomalleiIsocitrate Lyase Is a Persistence Factor in Pulmonary Melioidosis: Implications for the Development of Isocitrate Lyase Inhibitors as Novel Antimicrobials

Burkholderia pseudomallei, the causative agent of melioidosis, has often been called the great "mimicker," and clinical disease due to this organism may include acute, chronic, and latent pulmonary infections. Interestingly, chronic pulmonary melioidosis is often mistaken for tuberculosis, and this can have significant consequences, as the treatments for these two infections are radically different. The recurrent misdiagnosis of melioidosis for tuberculosis has caused many to speculate that these two bacterial pathogens use similar pathways to produce latent infections. Here we show that isocitrate lyase is a persistence factor for B. pseudomallei, and inhibiting the activity of this enzyme during experimental chronic B. pseudomallei lung infection forces the infection into an acute state, which can then be treated with antibiotics. We found that if antibiotics are not provided in combination with isocitrate lyase inhibitors, the resulting B. pseudomallei infection overwhelms the host, resulting in death. These results suggest that the inhibition of isocitrate lyase activity does not necessarily attenuate virulence as previously observed for Mycobacterium tuberculosis infections but does force the bacteria into a replicating state where antibiotics are effective. Therefore, isocitrate lyase inhibitors could be developed for chronic B. pseudomallei infections but only for use in combination with effective antibiotics.

ChemInform Abstract: 5‐Hydroxyindole‐Type Alkaloids, as Candida albicans Isocitrate Lyase Inhibitors, from the Tropical Sponge Hyrtios sp.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

5-Hydroxyindole-type alkaloids, as Candida albicans isocitrate lyase inhibitors, from the tropical sponge Hyrtios sp.

Chemical investigations of the tropical marine sponge Hyrtios sp. have resulted in the isolation of a new alkaloid, 1-carboxy-6-hydroxy-3,4-dihydro-β-carboline ( 1) together with the known metabolites, 6-hydroxy-3,4-dihydro-1-oxo-β-carboline ( 2), 5-hydroxy-1 H-indole-3-carboxylic acid methyl ester ( 3), serotonin ( 4), hyrtiosin A ( 5), 5-hydroxyindole-3-carbaldehyde ( 6), and hyrtiosin B ( 7). Their structures were elucidated on the basis of mass spectrometry and detailed 2D NMR spectroscopic data. Hyrtiosin B ( 7) displayed a potent inhibitory activity against isocitrate lyase (ICL) of Candida albicans with an IC 50 value of 89.0 μM.

Inhibition of Candida albicans isocitrate lyase activity by sesterterpene sulfates from the tropical sponge Dysidea sp.

Seven sesterterpene sulfates ( 1– 7) were isolated from the tropical sponge Dysidea sp. and their inhibitory activities against isocitrate lyase (ICL) from Candida albicans were evaluated. Among the isolated natural products compound 6 and 7 were found to be strong ICL inhibitors. The isolated compounds ( 1– 7) also showed potent antibacterial effect against Bacillus subtilis and Proteus vulgaris, but did not display antifungal activity.

Synthesis and evaluation of hydroquinone derivatives as inhibitors of Isocitrate Lyase

Isocitrate lyase (ICL) is envisaged as an attractive drug target for the development of antimicrobial agents. We have prepared a series of hydroquinone derivatives on the basis of the structure of halisulfates, a naturally occurring inhibitor of ICL. The obtained derivatives were evaluated against ICL of C. albicans. The preliminary structure-activity relationships and the minimal structural requirements for potency were established through structural modifications.

Inhibition of the Pathogenicity of Magnaporthe grisea by Bromophenols, Isocitrate Lyase Inhibitors, from the Red Alga Odonthalia corymbifera

Magnaporthe grisea is a fungal pathogen of rice that forms appressoria that penetrate the outer cuticle of the rice plant. Data from recent studies indicate that M. grisea isocitrate lyase (ICL), a key enzyme in the glyoxylate cycle, is highly expressed during appressorium-mediated plant infection. Bromophenols isolated from the red alga Odonthalia corymbifera exhibited potent ICL inhibitory activity and blocked appressoria formation by M. grisea in a concentration-dependent manner. In addition, these compounds protected the rice plants from infection by M. grisea. Rice plants infected with wild-type M. grisea Guy 11 exhibited significantly lower disease severity with bromophenol treatment than without, and the treatment effect was comparable to the behavior of the Deltaicl knockout mutant I-10. The protective effect of bromophenols and their strong inhibition of appressorium formation on rice plants suggest that ICL inhibitors may be promising candidates for crop protection, particularly to protect rice plants against M. grisea.

Inhibition of infection of the rice blast fungus by halisulfate 1, an isocitrate lyase inhibitor

Halisulfate 1, a sesterterpene sulfate and an isocitrate lyase (ICL) inhibitor that is isolated from tropical sponge Hippospongia spp., reduces both appressorium formation and infection of rice plants by the fungus Magnaporthe grisea. Rice plants infected with wild-type M. grisea Guy 11 exhibited significantly lower disease severity after halisulfate 1 treatment than without, and the treatment effect was comparable to the behavior of the Delta icl knockout mutant I-10. The protection observed upon applying halisulfate 1 to rice plants suggests that the ICL inhibitor may be a promising candidate for crop protection, particularly to protect rice plants against M. grisea.

Sesterterpene sulfates as isocitrate lyase inhibitors from tropical sponge Hippospongia sp.

Two sesterterpene sulfates ( 1– 2) were isolated from tropical sponge Hippospongia sp. and their inhibitory activities against isocitrate lyase (ICL) from the rice blast fungus Mgnaporthe grisea were evaluated. Compound 3 was obtained by hydrolysis of compound 1. Compounds 1 and 3 were found to be potent ICL inhibitors, which inhibited appressorium formation and C 2 carbon utilization in M. grisea. Our results suggest that ICL plays crucial role in appressorium formation of M. grisea and is a new target for the protection of rice blast disease.

A high throughput screening approach to identify isocitrate lyase inhibitors from traditional Chinese medicine sources

AbstractIsocitrate lyase (ICL) catalyses the first step of the glyoxylate bypass pathway, which reversibly cleaves isocitrate into succinate and glyoxylate. This pathway occurs in a wide range of pathogens and plays a key role in the pathogenesis of Mycobacterium tuberculosis (MTB) suggesting that it may represent a drug target for the treatment of tuberculosis. ICL was cloned, expressed, and purified, and a high‐throughput screen (HTS) developed to screen active extracts derived from traditional Chinese medicines (TCMs) for inhibition of ICL. A colorimetric assay based on the formation of glyoxylate‐phenylhydrazone was used to measure ICL activity. The assay had signal to noise (S/N) of 12.74 and Z′ factor of 0.72, indicating that the assay was suitable for HTS. Screening of a collection of 465 extracts derived from TCMs resulted in the identification of two extracts from Illicium verum Hook.f (Illiciaceae, XHD‐1) and Zingiber officinale Rosc (Zingiberaceae, XHD‐2), which inhibited ICL with IC50 values of 47.7 ± 16.9 and 18.2 ± 0.9 µg/ml, respectively. Drug Dev. Res. 67:818–823, 2006. © 2007 Wiley‐Liss, Inc.

Mycobacterium tuberculosis isocitrate lyases 1 and 2 are jointly required for in vivo growth and virulence

Genes involved in fatty acid catabolism have undergone extensive duplication in the genus Mycobacterium, which includes the etiologic agents of leprosy and tuberculosis. Here, we show that prokaryotic- and eukaryotic-like isoforms of the glyoxylate cycle enzyme isocitrate lyase (ICL) are jointly required for fatty acid catabolism and virulence in Mycobacterium tuberculosis. Although deletion of icl1 or icl2, the genes that encode ICL1 and ICL2, respectively, had little effect on bacterial growth in macrophages and mice, deletion of both genes resulted in complete impairment of intracellular replication and rapid elimination from the lungs. The feasibility of targeting ICL1 and ICL2 for chemical inhibition was shown using a dual-specific ICL inhibitor, which blocked growth of M. tuberculosis on fatty acids and in macrophages. The absence of ICL orthologs in mammals should facilitate the development of glyoxylate cycle inhibitors as new drugs for the treatment of tuberculosis.