Practical synthesis of isoindolines yields potent colistin potentiators for multidrug-resistant Acinetobacter baumannii.

An efficient and practical one-pot synthesis of isoindolines from readily available starting materials was achieved under mild conditions by implementing an isoindole umpolung strategy. A variety of isoindolines were prepared with good to excellent yields. Biological screens of these identified compounds demonstrated that they are potent potentiators of colistin for multi-drug resistant Acinetobacter baumannii.

Inhibitory interactions of the 2,3-dihydro-6,7-dihydroxy-1H-isoindol-1-one scaffold with Bunyavirales cap-snatching endonucleases expose relevant drug design features.

The World Health Organization (WHO) identifies several bunyaviruses as significant threats to global public health security. Developing effective therapies against these viruses is crucial to combat future outbreaks and mitigate their impact on patient outcomes. Here, we report the synthesis of some isoindol-1-one derivatives and explore their inhibitory properties over an indispensable metal-dependent cap-snatching endonuclease (Cap-ENDO) shared among evolutionary divergent bunyaviruses. The compounds suppressed RNA hydrolysis by Cap-ENDOs, with IC50 values predominantly in the lower µM range. Molecular docking studies revealed the interactions with metal ions to be essential for the 2,3-dihydro-6,7-dihydroxy-1H-isoindol-1-one scaffold activity. Calorimetric analysis uncovered Mn2+ ions to have the highest affinity for sites within the targets, irrespective of aminoacidic variations influencing metal cofactor preferences. Interestingly, spectrophotometric findings unveiled sole dinuclear species formation between the scaffold and Mn2+. Moreover, the complexation of two Mn2+ ions within the viral enzymes appears to be favourable, as indicated by the binding of compound 11 to TOSV Cap-ENDO (Kd = 28 ± 3 µM). Additionally, the tendency of compound 11 to stabilize His+ more than His- Cap-ENDOs suggests exploitable differences in their catalytic pockets relevant to improving specificity. Collectively, our results underscore the isoindolinone scaffold's potential as a strategic starting point for the design of pan-antibunyavirus drugs.

Discovery of Potent Isoindolinone Inhibitors that Target an Active Conformation of PARP1 Using DNA-Encoded Libraries.

Inhibition of poly (ADP-ribose) polymerase-1 (PARP1), a DNA repair enzyme, has proven to be a successful strategy for the treatment of various cancers. With the appropriate selection conditions and protein design, DNA-encoded library (DEL) technology provides a powerful avenue to identify small molecules with the desired mechanism of action towards a target of interest. However, DNA-binding proteins, such as PARP1, can be challenging targets for DEL screening due to non-specific protein-DNA interactions. To overcome this, we designed and screened a PARP1 catalytic domain construct without the autoinhibitory helical domain. This allowed us to interrogate an active, functionally-relevant form of the protein resulting in the discovery of novel isoindolinone PARP1 inhibitors with single-digit nanomolar potency. These inhibitors also demonstrated little to no PARP1-DNA trapping, a property that could be advantageous in the clinic.

Improved Photodynamic Activity of Phthalocyanine by Adjusting the Chirality of Modified Amino Acids.

Herein, four zinc phthalocyanines (ZnPcs) with chiral lysine modification were synthesized. We found that the chirality of lysine and the chiral structure position strongly influence the properties of ZnPcs. Among the four ZnPcs, d-lysine-modified ZnPc through -NH2 on Cε [denoted N(ε)-d-lys-ZnPc] showed superior properties, including tumor enrichment, cancer cell uptake, and tumor retention capability, compared to the other three ZnPcs. Thus, chiral molecule modification is a simple and effective strategy to regulate the abovementioned properties to achieve a satisfactory antitumor outcome of drugs.

Exploration of the 2,3-dihydroisoindole pharmacophore for inhibition of the influenza virus PA endonuclease.

Seasonal influenza A and B viruses represent a global concern. Antiviral drugs are crucial to treat severe influenza in high-risk patients and prevent virus spread in case of a pandemic. The emergence of viruses showing drug resistance, in particular for the recently licensed polymerase inhibitor baloxavir marboxil, drives the need for developing alternative antivirals. The endonuclease activity residing in the N-terminal domain of the polymerase acidic protein (PAN) is crucial for viral RNA synthesis and a validated target for drug design. Its function can be impaired by molecules bearing a metal-binding pharmacophore (MBP) able to coordinate the two divalent metal ions in the active site. In the present work, the 2,3-dihydro-6,7-dihydroxy-1H-isoindol-1-one scaffold is explored for the inhibition of influenza virus PA endonuclease. The structure-activity relationship was analysed by modifying the substituents on the lipophilic moiety linked to the MBP. The new compounds exhibited nanomolar inhibitory activity in a FRET-based enzymatic assay, and a few compounds (15-17, 21) offered inhibition in the micromolar range, in a cell-based influenza virus polymerase assay. When investigated against a panel of PA-mutant forms, compound 17 was shown to retain full activity against the baloxavir-resistant I38T mutant. This was corroborated by docking studies providing insight into the binding mode of this novel class of PA inhibitors.

Development of Novel Isoindolone-Based Compounds against Trypanosoma brucei rhodesiense.

This study identified the isoindolone ring as a scaffold for novel agents against Trypanosoma brucei rhodesiense and explored the structure-activity relationships of various aromatic ring substitutions. The compounds were evaluated in an integrated in vitro screen. Eight compounds exhibited selective activity against T. b. rhodesiense (IC50 <2.2 µm) with no detectable side activity against T. cruzi and Leishmania infantum. Compound 20 showed low nanomolar potency against T. b. rhodesiense (IC50 =40 nm) and no toxicity against MRC-5 and PMM cell lines and may be regarded as a new lead template for agents against T. b. rhodesiense. The isoindolone-based compounds have the potential to progress into lead optimization in view of their highly selective in vitro potency, absence of cytotoxicity and acceptable metabolic stability. However, the solubility of the compounds represents a limiting factor that should be addressed to improve the physicochemical properties that are required to proceed further in the development of in vivo-active derivatives.

AZD0284, a Potent, Selective, and Orally Bioavailable Inverse Agonist of Retinoic Acid Receptor-Related Orphan Receptor C2.

Inverse agonists of the nuclear receptor RORC2 have been widely pursued as a potential treatment for a variety of autoimmune diseases. We have discovered a novel series of isoindoline-based inverse agonists of the nuclear receptor RORC2, derived from our recently disclosed RORC2 inverse agonist 2. Extensive structure-activity relationship (SAR) studies resulted in AZD0284 (20), which combined potent inhibition of IL-17A secretion from primary human TH17 cells with excellent metabolic stability and good PK in preclinical species. In two preclinical in vivo studies, compound 20 reduced thymocyte numbers in mice and showed dose-dependent reduction of IL-17A containing γδ-T cells and of IL-17A and IL-22 RNA in the imiquimod induced inflammation model. Based on these data and a favorable safety profile, 20 was progressed to phase 1 clinical studies.

Light-induced activities of novel naphtho[1,8-ef]isoindole-7,8,10(9H)-trione and oxoisoaporphine derivatives towards mosquito larvae.

Infected mosquitoes are significant vectors of dengue, yellow fever, chikungunya, zika and other pathogens. In the view of increasing resistance in mosquito larvae control, photoactivated insecticides is a promising approach by utilizing highly toxic singlet oxygen produced by photosensitizer through irradiation. However, the choice of photosensitizer for mosquito control is limited. Here, we report a novel series of naphtho[1,8-ef]isoindole-7,8,10(9H)-trione and oxoisoaporphines derivatives as excellent type II photosensitizers. Meanwhile, the light-dependent activities against permethrin-susceptible and permethrin-resistant strain of Aedes aegypti mosquito larvae of these compounds were evaluated. Among them, compound 7b was proved to be potential photodynamic insecticide due to its excellent phototoxicity, the LC50 value was 0.19 µg mL-1 under visible light irradiation. The irradiation-generated enhancement in the activity was more than 520-fold. This compound could be the potential candidate in the search for new photoactivated insecticide leads. Importantly, 7b has good fluorescence quantum yield (ϕF = 0.70), it can be used as a fluorescence indicator in mosquito larvae to observe uptake and morphology change.

BSA/DNA binding behavior and the photophysicochemical properties of novel water soluble zinc(II)phthalocyanines directly substituted with piperazine groups.

In the current research, two novel zinc(II) phthalocyanines (ZnPcs) (1 and 2) directly connecting with 4-(4-methylpiperazin-1-yl)phenyl groups have been synthesized through the Suzuki-Miyaura coupling reaction. These ZnPcs 1 and 2 were converted to their water-soluble derivatives (1Q and 2Q) by quaternization. The photochemical and photophysical properties were determined in DMSO for the non-ionic zinc(II) phthalocyanines (1 and 2) and in both DMSO and aqueous solutions for the quaternized cationic derivatives (1Q and 2Q) to establish their photosensitizer capabilities in photodynamic therapy (PDT). The spectrofluorometric and spectrophotometric techniques were employed for the determination of interaction between water-soluble ZnPcs (1Q and 2Q) and BSA or ct-DNA. The binding constants of these compounds to BSA were found in the order of 108 M-1. The binding constant of the ct-DNA interaction with 2Q (1.09 × 105 M-1) was found higher than 1Q (6.87 × 104 M-1). The thermodynamic constants were determined for both 1Q and 2Q. The endothermic and spontaneous nature of interaction was observed with ct-DNA. Besides, the thermal denaturation and viscosity studies proved the non-intercalative mode of binding for both compounds to ct-DNA.

Synthesis and Bioactivities of Marine Pyran-Isoindolone Derivatives as Potential Antithrombotic Agents.

2,5-Bis-[8-(4,8-dimethyl-nona-3,7-dienyl)-5,7-dihydroxy-8-methyl-3-keto-1,2,7,8-teraahydro-6H-pyran[a]isoindol-2-yl]-pentanoic acid (FGFC1) is a marine pyran-isoindolone derivative isolated from a rare marine microorganism Stachybotrys longispora FG216, which showed moderate antithrombotic(fibrinolytic) activity. To further enhance its antithrombotic effect, a series of new FGFC1 derivatives (F1-F7) were synthesized via chemical modification at C-2 and C-2' phenol groups moieties and C-1″ carboxyl group. Their fibrinolytic activities in vitro were evaluated. Among the derivatives, F1-F4 and F6 showed significant fibrinolytic activities with EC50 of 59.7, 87.1, 66.6, 82.8, and 42.3 µM, respectively, via enhancement of urokinase activity. Notably, derivative F6 presented the most remarkable fibrinolytic activity (2.72-fold than that of FGFC1). Furthermore, the cytotoxicity of derivative F6 was tested as well as expression of Fas/Apo-1 and IL-1 on HeLa cells. The results showed that, compared to FGFC1, derivative F6 possessed moderate cytotoxicity and apoptotic effect on HeLa cells (statistical significance p > 0.1), making F6 a potential antithrombotic agent towards clinical application.

New class of hantaan virus inhibitors based on conjugation of the isoindole fragment to (+)-camphor or (-)-fenchone hydrazonesv.

This work presents the design and synthesis of camphor, fenchone, and norcamphor N-acylhydrazone derivatives as a new class of inhibitors of the Hantaan virus, which causes haemorrhagic fever with renal syndrome (HFRS). A cytopathic model was developed for testing chemotherapeutics against the Hantaan virus, strain 76-118. In addition, a study of the antiviral activity was carried out using a pseudoviral system. It was found that the hit compound possesses significant activity (IC50 = 7.6 ± 2 µM) along with low toxicity (CC50 > 1000 µM). Using molecular docking procedures, the binding with Hantavirus nucleoprotein was evaluated and the correlation between the structure of the synthesised compounds and the antiviral activity was established.

Structure-Based Design of Potent and Orally Active Isoindolinone Inhibitors of MDM2-p53 Protein-Protein Interaction.

Inhibition of murine double minute 2 (MDM2)-p53 protein-protein interaction with small molecules has been shown to reactivate p53 and inhibit tumor growth. Here, we describe rational, structure-guided, design of novel isoindolinone-based MDM2 inhibitors. MDM2 X-ray crystallography, quantum mechanics ligand-based design, and metabolite identification all contributed toward the discovery of potent in vitro and in vivo inhibitors of the MDM2-p53 interaction with representative compounds inducing cytostasis in an SJSA-1 osteosarcoma xenograft model following once-daily oral administration.

Investigation of the biological and photophysicochemical properties of new non-peripheral fluorinated phthalocyanines.

This study presents the synthesis of a series of new tetra-substituted phthalocyanines bearing 3,5-bis(trifluoromethyl)phenoxy groups at non-peripheral positions. The resulting macromolecules were characterized by performing different spectroscopic methods including 1H NMR, UV-Vis, FT-IR, and mass spectroscopy. In this study, the synergistic effect of phthalocyanines used as colorants in ink formulas with other chemicals available was probed for the first time. The synergistic effect of methyl laurate on the biological and antioxidant activities of the compounds (2-5) was investigated. Moreover, the therapeutic properties of the complexes (3, 6, and 7) were investigated using photochemical methods. Upon comparison, complex 7 (ΦΔ = 0.42) was found to be more effective than complex 6 (ΦΔ = 0.40) and complex 3 (ΦΔ = 0.27) in terms of producing singlet oxygen. The results confirmed that the heavy atom effect improves the therapeutic effects.

(+)-Camphor and (-)-borneol derivatives as potential anti-orthopoxvirus agents.

Although the World Health Organisation had announced that smallpox was eradicated over 40 years ago, the disease and other related pathogenic poxviruses such as monkeypox remain potential bioterrorist weapons and could also re-emerge as natural infections. We have previously reported (+)-camphor and (-)-borneol derivatives with an antiviral activity against the vaccinia virus. This virus is similar to the variola virus (VARV), the causative agent of smallpox, but can be studied at BSL-2 facilities. In the present study, we evaluated the antiviral activity of the most potent compounds against VARV, cowpox virus, and ectromelia virus (ECTV). Among the compounds tested, 4-bromo-N'-((1R,4R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ylidene)benzohydrazide 18 is the most effective compound against various orthopoxviruses, including VARV, with an EC50 value of 13.9 µM and a selectivity index of 206. Also, (+)-camphor thiosemicarbazone 9 was found to be active against VARV and ECTV.

Insight on [1,3]thiazolo[4,5-e]isoindoles as tubulin polymerization inhibitors.

A series of [1,3]thiazolo[4,5-e]isoindoles has been synthesized through a versatile and high yielding multistep sequence. Evaluation of the antiproliferative activity of the new compounds on the full NCI human tumor cell line panel highlighted several compounds that are able to inhibit tumor cell proliferation at micromolar-submicromolar concentrations. The most active derivative 11g was found to cause cell cycle arrest at the G2/M phase and induce apoptosis in HeLa cells, following the mitochondrial pathway, making it a lead compound for the discovery of new antimitotic drugs.

Synthesis of novel nicotinamide susbstituted phthalocyanine and photodynamic antomicrobial chemotherapy evaluation potentiated by potassium iodide against the gram positive S. aureus and gram negative E. coli.

In the present work, we propose the synthesis of novel nicotinamide subsituted phthlocyanine photosensitizer (PS) and characterized by FTIR, UV-visible, H-NMR and MALDI Toff spectroscopy. Nicotinamide plays a vital rule in the central nervous system and its potential as a therapeutic for neurodegenerative disease. Nicotinamide substituted PS (3) efficiently produced ROS via type-1 process as measured by DCF assay. We observed that our PS after red light illumination (22 J/cm2) killed gram positive S. aureus upto 3 log reduction. Furher the addition of Potassium Iodide (100 mM) significantly potentiated PS at lower concentrations and enhanced the bacterial killing upto 6 log reduction against the S. aureus. We further found that the synergistic effect of PS and KI also eradicated the gram negative E. coli strain at lower concentraion of PS and found to killed E. coli upto 5 log reduction under the red light illumination at 22 J/cm2 of light dose. The conjugation of such biologically important form of vitamin B3 with PS would be a great addition and could pav the way for the novel photodynamic agent in the treatement of cancer and infectious diseases. A new symmetrical Nicotinamide tetrasubstituted zinc phthalocyanine (3) was synthesized. Upon addition of potassium Iodide with PS, the PS exhibited significant photodynamic activity with 5-6 logs reduction in bacterial load was achieved.

Novel BuChE-IDO1 inhibitors from sertaconazole: Virtual screening, chemical optimization and molecular modeling studies.

In our effort towards the identification of novel BuChE-IDO1 dual-targeted inhibitor for the treatment of Alzheimer's disease (AD), sertaconazole was identified through a combination of structure-based virtual screening followed by MM-GBSA rescoring. Preliminary chemical optimization was performed to develop more potent and selective sertaconazole analogues. In consideration of the selectivity and the inhibitory activity against target proteins, compounds 5c and 5d were selected for the next study. Further modification of compound 5c led to the generation of compound 10g with notably improved selectivity towards BuChE versus AChE. The present study provided us with a good starting point to further design potent and selective BuChE-IDO1 inhibitors, which may benefit the treatment of late stage AD.

Structure-Activity Relationships of Benzamides and Isoindolines Designed as SARS-CoV Protease Inhibitors Effective against SARS-CoV-2.

Inhibition of coronavirus (CoV)-encoded papain-like cysteine proteases (PLpro ) represents an attractive strategy to treat infections by these important human pathogens. Herein we report on structure-activity relationships (SAR) of the noncovalent active-site directed inhibitor (R)-5-amino-2-methyl-N-(1-(naphthalen-1-yl)ethyl) benzamide (2 b), which is known to bind into the S3 and S4 pockets of the SARS-CoV PLpro . Moreover, we report the discovery of isoindolines as a new class of potent PLpro inhibitors. The studies also provide a deeper understanding of the binding modes of this inhibitor class. Importantly, the inhibitors were also confirmed to inhibit SARS-CoV-2 replication in cell culture suggesting that, due to the high structural similarities of the target proteases, inhibitors identified against SARS-CoV PLpro are valuable starting points for the development of new pan-coronaviral inhibitors.

Solvent-free synthesis of isoindolo[2,1-c]pyrazolo[1,5-a]quinazoline and pyrazolo[5',1':2,3]pyrimido[6,1-a]isoindol derivatives through a one-pot three-component reaction.

Some 5-substituted 3-aminopyrazoles were used for the synthesis of isoindolo[2,1-c]pyrazolo[1,5-a]quinazoline and pyrazolo[5',1':2,3]pyrimido[6,1-a]isoindol derivatives via a mild and efficient one-pot three-component reaction with 2-formylbenzoic acid and different CH-acids under solvent-free condition.

Investigation of tyrosinase enzyme (from mushroom) inhibitory activities and antioxidant properties of new fluorine-containing phthalocyanines.

A series of new peripherally or nonperipherally substituted phthalocyanines bearing 4-(trifluoromethoxy)thiophenyl groups was synthesized. In addition, a new metal-free phthalocyanine bearing 4-(trifluoromethoxy)phenoxy on the nonperipheral position was prepared. The resulting phthalocyanines were characterized using some spectroscopic techniques such as 1 H nuclear magnetic resonance, Fourier-transform infrared spectroscopy, and UV-Vis spectroscopy, together with elemental analysis. When the tyrosinase enzyme inhibition activities of the synthesized phthalocyanines were examined, molecules 2b and 3b showed an inhibitory activity against the enzyme with IC50 values of 176.2 ± 0.65 and 284.4 ± 1.03, respectively. The inhibition types of the molecules and standard inhibitor kojic acid were found as competitive for 2b, mixed for 1b and kojic acid, and uncompetitive for 3b. Antioxidant activities were also assessed by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and reducing power assays, and the molecules showed moderate antioxidant activities.