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Shi Y, Derasp JS, Maschmeyer T, Hein JE. Phase transfer catalysts shift the pathway to transmetalation in biphasic Suzuki-Miyaura cross-couplings. Nat Commun 2024; 15:5436. [PMID: 38937470 PMCID: PMC11211432 DOI: 10.1038/s41467-024-49681-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 06/14/2024] [Indexed: 06/29/2024] Open
Abstract
The Suzuki-Miyaura coupling is a widely used C-C bond forming reaction. Numerous mechanistic studies have enabled the use of low catalyst loadings and broad functional group tolerance. However, the dominant mode of transmetalation remains controversial and likely depends on the conditions employed. Herein we detail a mechanistic study of the palladium-catalyzed Suzuki-Miyaura coupling under biphasic conditions. The use of phase transfer catalysts results in a remarkable 12-fold rate enhancement in the targeted system. A shift from an oxo-palladium based transmetalation to a boronate-based pathway lies at the root of this activity. Furthermore, a study of the impact of different water loadings reveals reducing the proportion of the aqueous phase increases the reaction rate, contrary to reaction conditions typically employed in the literature. The importance of these findings is highlighted by achieving an exceptionally broad substrate scope with benzylic electrophiles using a 10-fold reduction in catalyst loading relative to literature precedent.
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Affiliation(s)
- Yao Shi
- Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
| | - Joshua S Derasp
- Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada.
| | - Tristan Maschmeyer
- Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
| | - Jason E Hein
- Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada.
- Department of Chemistry, University of Bergen, Bergen, Norway.
- Acceleration Consortium, University of Toronto, Toronto, ON, Canada.
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2
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Dai J, Battini N, Zang Z, Luo Y, Zhou C. Novel Thiazolylketenyl Quinazolinones as Potential Anti-MRSA Agents and Allosteric Modulator for PBP2a. Molecules 2023; 28:molecules28104240. [PMID: 37241983 DOI: 10.3390/molecules28104240] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 05/16/2023] [Accepted: 05/17/2023] [Indexed: 05/28/2023] Open
Abstract
Bacterial infections caused by methicillin-resistant Staphylococcus aureus have seriously threatened public health. There is an urgent need to propose an existing regimen to overcome multidrug resistance of MRSA. A unique class of novel anti-MRSA thiazolylketenyl quinazolinones (TQs) and their analogs were developed. Some synthesized compounds showed good bacteriostatic potency. Especially TQ 4 was found to exhibit excellent inhibition against MRSA with a low MIC of 0.5 μg/mL, which was 8-fold more effective than norfloxacin. The combination of TQ 4 with cefdinir showed stronger antibacterial potency. Further investigation revealed that TQ 4, with low hemolytic toxicity and low drug resistance, was not only able to inhibit biofilm formation but also could reduce MRSA metabolic activity and showed good drug-likeness. Mechanistic explorations revealed that TQ 4 could cause leakage of proteins by disrupting membrane integrity and block DNA replication by intercalated DNA. Furthermore, the synergistic antibacterial effect with cefdinir might be attributed to TQ 4 with the ability to induce PBP2a allosteric regulation of MRSA and further trigger the opening of the active site to promote the binding of cefdinir to the active site, thus inhibiting the expression of PBP2a, thereby overcoming MRSA resistance and significantly enhancing the anti-MRSA activity of cefdinir. A new strategy provided by these findings was that TQ 4, possessing both excellent anti-MRSA activity and allosteric effect of PBP2a, merited further development as a novel class of antibacterial agents to overcome increasingly severe MRSA infections.
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Affiliation(s)
- Jie Dai
- Institute of Bioorganic & Medicinal Chemistry, Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China
| | - Narsaiah Battini
- Institute of Bioorganic & Medicinal Chemistry, Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China
| | - Zhonglin Zang
- Institute of Bioorganic & Medicinal Chemistry, Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China
| | - Yan Luo
- College of Pharmacy, National & Local Joint Engineering Research Center of Targeted and Innovative Therapeutics, Chongqing Key Laboratory of Kinase Modulators as Innovative Medicine, Chongqing University of Arts and Sciences, Chongqing 402160, China
| | - Chenghe Zhou
- Institute of Bioorganic & Medicinal Chemistry, Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China
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Park S, Lee JH, Kim YG, Hu L, Lee J. Fatty Acids as Aminoglycoside Antibiotic Adjuvants Against Staphylococcus aureus. Front Microbiol 2022; 13:876932. [PMID: 35633672 PMCID: PMC9133387 DOI: 10.3389/fmicb.2022.876932] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 04/27/2022] [Indexed: 11/14/2022] Open
Abstract
Fatty acids have diverse functions in the vast majority of cells. At high doses, they act as antimicrobials while, at low doses, they exhibit antibiofilm and antivirulence activities. In this study, the synergistic antibacterial and antibiofilm activities of 30 fatty acids and 11 antibiotics were investigated against methicillin-sensitive and methicillin-resistant Staphylococcus aureus strains. Of the 15 saturated and 15 unsaturated fatty acids examined, 16 enhanced the antibacterial activity of tobramycin. Combinatorial treatment with myristoleic acid (the most active) at 10 μg/ml and tobramycin at 10 μg/ml decreased cell survival by >4 log as compared with tobramycin treatment alone. Notably, aminoglycoside antibiotics, such as tobramycin, kanamycin, gentamicin, and streptomycin exhibited antimicrobial synergy with myristoleic acid. Co-treatment with myristoleic acid and antibiotics markedly decreased biofilm formation. Interestingly, co-treatment with tobramycin and myristoleic acid induced a reduction in S. aureus cell size. These results suggest that fatty acids, particularly myristoleic acid, can be used as aminoglycoside antibiotic adjuvants against recalcitrant S. aureus infections.
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Affiliation(s)
- Sunyoung Park
- School of Chemical Engineering, Yeungnam University, Gyeongsan, South Korea
| | - Jin-Hyung Lee
- School of Chemical Engineering, Yeungnam University, Gyeongsan, South Korea
| | - Yong-Guy Kim
- School of Chemical Engineering, Yeungnam University, Gyeongsan, South Korea
| | - Liangbin Hu
- School of Food & Biological Engineering, Shaanxi University of Science and Technology, Xi'an, China
| | - Jintae Lee
- School of Chemical Engineering, Yeungnam University, Gyeongsan, South Korea
- *Correspondence: Jintae Lee,
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Berndsen R, Cunningham T, Kaelin L, Callender M, Boldog WD, Viering B, King A, Labban N, Pollock JA, Miller HB, Blackledge MS. Identification and Evaluation of Brominated Carbazoles as a Novel Antibiotic Adjuvant Scaffold in MRSA. ACS Med Chem Lett 2022; 13:483-491. [PMID: 35295086 PMCID: PMC8919279 DOI: 10.1021/acsmedchemlett.1c00680] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 02/02/2022] [Indexed: 12/23/2022] Open
Abstract
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Antibiotic-resistant
infections are a pressing global concern,
causing millions of deaths each year. Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of nosocomial
infections in healthcare settings and is increasingly responsible
for community-acquired infections that are often more difficult to
treat. Antibiotic adjuvants are small molecules that potentiate antibiotics
through nontoxic mechanisms and show excellent promise as novel therapeutics.
Screening of low-molecular-weight compounds was employed to identify
novel antibiotic adjuvant scaffolds for further elaboration. Brominated
carbazoles emerged from this screening as lead compounds for further
evaluation. Lead carbazoles were able to potentiate several β-lactam
antibiotics in three medically relevant strains of MRSA. Gene expression
studies determined that these carbazoles were dampening the transcription
of key genes that modulate β-lactam resistance in MRSA. The
lead brominated carbazoles represent novel scaffolds for elaboration
as antibiotic adjuvants.
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Affiliation(s)
- Rachel Berndsen
- Department of Chemistry, High Point University, High Point, North Carolina 27268, United States
| | - Taylor Cunningham
- Department of Chemistry, High Point University, High Point, North Carolina 27268, United States
| | - Lauren Kaelin
- Department of Chemistry, High Point University, High Point, North Carolina 27268, United States
| | - Makayla Callender
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - W. Dexter Boldog
- Department of Chemistry, High Point University, High Point, North Carolina 27268, United States
| | - Brianna Viering
- Department of Chemistry, High Point University, High Point, North Carolina 27268, United States
| | - Ashley King
- Department of Chemistry, High Point University, High Point, North Carolina 27268, United States
| | - Najwa Labban
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Julie A. Pollock
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Heather B. Miller
- Department of Chemistry, High Point University, High Point, North Carolina 27268, United States
| | - Meghan S. Blackledge
- Department of Chemistry, High Point University, High Point, North Carolina 27268, United States
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Zhang PL, Gopala L, Zhang SL, Cai GX, Zhou CH. An unanticipated discovery towards novel naphthalimide corbelled aminothiazoximes as potential anti-MRSA agents and allosteric modulators for PBP2a. Eur J Med Chem 2021; 229:114050. [PMID: 34922190 DOI: 10.1016/j.ejmech.2021.114050] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 11/26/2021] [Accepted: 12/09/2021] [Indexed: 12/14/2022]
Abstract
Available therapeutic strategies are urgently needed to conquer multidrug resistance of MRSA. A visible effort was guided towards the advancement of novel antibacterial framework of naphthalimide corbelled aminothiazoximes, and desired to assert some insight on the conjunction of individual pharmacophore with distinct biological activities and unique action mechanism. Preliminary assessment displayed that dimethylenediamine derivative 13d presented a wonderful inhibition on MRSA (MIC = 0.5 μg/mL), and showed excellent membrane selectivity (HC50 > 200 μg/mL) from an electrostatic distinction of the electronegative bacterial membranes and the electroneutral mammalian membranes. Moreover, 13d could effectually relieve the development of MRSA resistance. Investigations into explaining the mechanism of anti-MRSA disclosed that 13d displayed strong lipase affinity, which facilitated its permeation into cell membrane, causing membrane depolarization, leakage of cytoplasmic contents and lactate dehydrogenase (LDH) inhibition. Meanwhile, 13d could exert interaction with DNA to hinder biological function of DNA, and disrupt the antioxidant defense system of MRSA through up-regulation of ROS subjected the strain to oxidative stress. In particular, the unanticipated mechanism for naphthalimide corbelled aminothiazoximes that 13d could suppress the expression of PBP2a by inducing allosteric modulation of PBP2a and triggering the open of the active site, was discovered for the first time. These findings of naphthalimide corbelled aminothiazoximes as a small-molecule class of anti-MRSA agents held promise in strategies for treatment of MRSA infections.
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Affiliation(s)
- Peng-Li Zhang
- Institute of Bioorganic & Medicinal Chemistry, Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China
| | - Lavanya Gopala
- Institute of Bioorganic & Medicinal Chemistry, Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China
| | - Shao-Lin Zhang
- School of Pharmaceutical Sciences, Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, Chongqing University, Chongqing, 401331, China.
| | - Gui-Xin Cai
- Institute of Bioorganic & Medicinal Chemistry, Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China.
| | - Cheng-He Zhou
- Institute of Bioorganic & Medicinal Chemistry, Key Laboratory of Applied Chemistry of Chongqing Municipality, School of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China.
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Speri E, Qian Y, Janardhanan J, Masitas C, Lastochkin E, De Benedetti S, Wang M, Schroeder VA, Wolter WR, Oliver AG, Fisher JF, Mobashery S, Chang M. Structure-Activity Relationship for the Picolinamide Antibacterials that Selectively Target Clostridioides difficile. ACS Med Chem Lett 2021; 12:991-995. [PMID: 34141083 DOI: 10.1021/acsmedchemlett.1c00135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 05/03/2021] [Indexed: 11/28/2022] Open
Abstract
Clostridioides difficile is a leading health threat. This pathogen initiates intestinal infections during gut microbiota dysbiosis caused by oral administration of antibiotics. C. difficile is difficult to eradicate due to its ability to form spores, which are not susceptible to antibiotics. To address the urgent need for treating recurrent C. difficile infection, antibiotics that selectively target C. difficile over common gut microbiota are needed. We herein describe the class of picolinamide antibacterials which show potent and selective activity against C. difficile. The structure-activity relationship of 108 analogues of isonicotinamide 4, a compound that is equally active against methicillin-resistant Staphylococcus aureus and C. difficile, was investigated. Introduction of the picolinamide core as exemplified by analogue 87 resulted in exquisite potency and selectivity against C. difficile. The ability of the picolinamide class to selectively target C. difficile and to prevent gut dysbiosis holds promise for the treatment of recurrent C. difficile infection.
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Affiliation(s)
- Enrico Speri
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Yuanyuan Qian
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Jeshina Janardhanan
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Cesar Masitas
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Elena Lastochkin
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Stefania De Benedetti
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Man Wang
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Valerie A. Schroeder
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - William R. Wolter
- Freimann Life Sciences Center, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Allen G. Oliver
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Jed F. Fisher
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Mayland Chang
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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Chang M, Mahasenan KV, Hermoso JA, Mobashery S. Unconventional Antibacterials and Adjuvants. Acc Chem Res 2021; 54:917-929. [PMID: 33512995 DOI: 10.1021/acs.accounts.0c00776] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The need for new classes of antibacterials is genuine in light of the dearth of clinical options for the treatment of bacterial infections. The prodigious discoveries of antibiotics during the 1940s to 1970s, a period wistfully referred to as the Golden Age of Antibiotics, have not kept up in the face of emergence of resistant bacteria in the past few decades. There has been a renewed interest in old drugs, the repurposing of the existing antibiotics and pairing of synergistic antibiotics or of an antibiotic with an adjuvant. Notwithstanding, discoveries of novel classes of these life-saving drugs have become increasingly difficult, calling for new paradigms. We describe, herein, three strategies from our laboratories toward discoveries of new antibacterials and adjuvants using computational and multidisciplinary experimental methods. One approach targets penicillin-binding proteins (PBPs), biosynthetic enzymes of cell-wall peptidoglycan, for discoveries of non-β-lactam inhibitors. Oxadiazoles and quinazolinones emerged as two structural classes out of these efforts. Several hundred analogs of these two classes of antibiotics have been synthesized and fully characterized in our laboratories. A second approach ventures into inhibition of allosteric regulation of cell-wall biosynthesis. The mechanistic details of allosteric regulation of PBP2a of Staphylococcus aureus, discovered in our laboratories, is outlined. The allosteric site in this protein is at 60 Å distance to the active site, whereby ligand binding at the former makes access to the latter by the substrate possible. We have documented that both quinazolinones and ceftaroline, a fifth-generation cephalosporin, bind to the allosteric site in manifestation of the antibacterial activity. Attempts at inhibition of the regulatory phosphorylation events identified three classes of antibacterial adjuvants and one class of antibacterials, the picolinamides. The chemical structures for these hits went through diversification by synthesis of hundreds of analogs. These analogs were characterized in various assays for identification of leads with adjuvant and antibacterial activities. Furthermore, we revisited the mechanism of bulgecins, a class of adjuvants discovered and abandoned in the 1980s. These compounds potentiate the activities of β-lactam antibiotics by the formation of bulges at the sites of septum formation during bacterial replication, which are points of structural weakness in the envelope. These bulges experience rupture, which leads to bacterial death. Bulgecin A inhibits the lytic transglycosylase Slt of Pseudomonas aeruginosa as a likely transition-state mimetic for its turnover of the cell-wall peptidoglycan. Once damage to cell wall is inflicted by a β-lactam antibiotic, the function of Slt is to repair the damage. When Slt is inhibited by bulgecin A, the organism cannot cope with it and would undergo rapid lysis. Bulgecin A is an effective adjuvant of β-lactam antibiotics. These discoveries of small-molecule classes of antibacterials or of adjuvants to antibacterials hold promise in strategies for treatment of bacterial infections.
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Affiliation(s)
- Mayland Chang
- Department of Chemistry and Biochemistry, University of Notre Dame, McCourtney Hall, Notre Dame Indiana 46556, United States
| | - Kiran V. Mahasenan
- Department of Chemistry and Biochemistry, University of Notre Dame, McCourtney Hall, Notre Dame Indiana 46556, United States
| | - Juan A. Hermoso
- Departamento de Cristalografía y Biología Estructural, Instituto de Química-Física “Rocasolano”, CSIC, Serrano 119, 28006-Madrid Spain
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, University of Notre Dame, McCourtney Hall, Notre Dame Indiana 46556, United States
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Speri E, Janardhanan J, Masitas C, Schroeder VA, Lastochkin E, Wolter WR, Fisher JF, Mobashery S, Chang M. Discovery of a Potent Picolinamide Antibacterial Active against Clostridioides difficile. ACS Infect Dis 2020; 6:2362-2368. [PMID: 32786277 PMCID: PMC7716698 DOI: 10.1021/acsinfecdis.0c00479] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A major challenge for chemotherapy of bacterial infections is perturbation of the intestinal microbiota. Clostridioides difficile is a Gram-positive bacterium of the gut that can thrive under this circumstance. Its production of dormant and antibiotic-impervious spores results in chronic disruption of normal gut flora and debilitating diarrhea and intestinal infection. C. difficile is responsible for 12,800 deaths per year in the United States. Here, we report the discovery of 2-(4-(3-(trifluoromethoxy)phenoxy)picolinamido)benzo[d]oxazole-5-carboxylate as an antibacterial with potent and selective activity against C. difficile. Its MIC50 and MIC90 (the concentration required to inhibit the growth of 50% and 90% of all the tested strains, respectively) values, documented across 101 strains of C. difficile, are 0.12 and 0.25 μg/mL, respectively. The compound targets cell wall biosynthesis, as assessed by macromolecular biosynthesis assays and by scanning electron microscopy. Animals infected with a lethal dose of C. difficile and treated with compound 1 had a similar survival compared to treatment with vancomycin, which is the frontline antibiotic used for C. difficile infection.
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