ACS Bio & Med Chem Au最新文献

Undesired scalar and dipolar couplings are two major interactions that complicate structural and dynamic studies in solution nuclear magnetic resonance (NMR) spectroscopy. Recent developments in site-specific isotopic labeling technologies have gone a long way toward alleviating these problems. While some nuclei have intrinsic properties that make them suitable for specific NMR experiments, these same properties render them inefficient in other experiments. Site-specific isotopic labeling facilitates the controlled incorporation of isotopes to enable facile analysis of RNAs. Here, we describe the synthesis and incorporation of [1′-¹³C, 2-¹⁹F, 7-¹⁵N] adenosine 5′-triphosphate into the 9 kDa Escherichia coli rRNA, thus expanding the applications of previously synthesized [2-¹³C, 7-¹⁵N]-adenosine 5′-triphosphate, with the added benefit of ¹⁹F incorporation. We utilized these ¹³C and ¹⁵N probes to characterize the structural dynamic features within this RNA, and ¹⁹F was used to monitor binding interactions. Finally, we leveraged the chemical shielding anisotropy-dominated relaxation of ¹⁵N7-adenosine for straightforward analysis of R₁ and R_1ρ rates.

Human somatic angiotensin I-converting enzyme is a key zinc metallopeptidase in cardiovascular regulation that hydrolyzes angiotensin peptides (Ang I, Ang II), as well as other vasoactive peptides, including kinins (e.g., bradykinin), substance P, the acetylated tetrapeptide Ac-Ser-Asp-Lys-Pro, and the amyloid ß-peptide. Because of its enzymatic promiscuity, ACE and its substrates and products affect many physiological processes, including blood pressure control, hemopoiesis, reproduction, renal development/function, fibrosis, and immune response. ACE inhibitors are among the most important therapeutic agents available today for the treatment of hypertension, heart failure, coronary artery disease, renal insufficiency, and general atherosclerosis. However, they need much improvement because of the side effects seen in patients with long-term treatment due to nonselective inhibition of the N- and C-domains of ACE (referred to as nACE and cACE, respectively). Here, we report that ACE activity can be inhibited by ciprofloxacin, a potent fluoroquinolone antibiotic (IC₅₀ 202.7/K _i 33.8 μM for cACE). In addition, the high-resolution crystal structure of cACE in complex with ciprofloxacin reveals that it binds at an exosite away from the active site pocket, overlapping the position of a potential allosteric site with a different binding mode. The detailed structural information reported here will provide a useful scaffold for the design of future potent allosteric inhibitors.

The present study investigates the potential anti-infective and antibacterial properties of phenylalkyl acetophenones and anacardic acids isolated from the ethyl acetate extract of the leaves of Knema oblongifolia, along with synthetic derivatives that were generated. As antibiotic resistance grows, the discovery of new anti-infective agents becomes crucial. The study utilizes a phenotypic screening approach, employing a 3R infection model with Mycobacterium marinum (Mm) and Dictyostelium discoideum (Dd) as proxies for Mycobacterium tuberculosis and human macrophages. This model helps to distinguish between general antibiotics and specific anti-infectives that inhibit bacterial growth inside host cells. A previous screening carried out on a collection of 1600 plant natural extracts revealed K. oblongifolia as a significant source of anti-infective compounds. The ethyl acetate extract of this plant exhibited a strong inhibition of Mm intracellular growth in the infection model while minimally affecting bacterial growth in broth. HPLC bioactivity profiling of this extract based on a high-resolution microfractionation strategy uncovered that the activity was associated with different LC-peaks spread over the chromatogram. LC–MS-based metabolite profiling of the extract revealed that they shared common substructural elements. Based on such information, fractionation of the extract at a larger scale led to the isolation of 12 bioactive natural products (NPs): four newly described acetophenone NPs and eight salicylic acid derivatives (three of which were new). These NPs were further tested for their activities against Mm (antibacterial and anti-infective), Pseudomonas aeruginosa, and Staphylococcus aureus. Additionally, the study involved de novo synthesis of derivatives based on the backbones of the isolated acetophenones to enhance their bioactivity. Hemisynthesis on one of the isolated natural acetophenone was also carried out and resulted in an increase in potency but no increase in selectivity toward the inhibition of Mm intracellular growth. Overall, biological activity assessments revealed that some of the synthetic analogues generated were better candidates in terms of both selectivity and potency, with an improved activity profile compared to natural analogues. The best synthetic candidate reached an IC₅₀ of 0.59 μM for the inhibition of intracellular bacterial growth during infection (anti-infective activity).

Cyclic dinucleotides (CDNs) have become popular as immunotherapies triggering an immune response achieved via their activation of the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway. Many analogs of 2′3′-cGAMP, c-di-GMP, and c-di-AMP have been developed and shown as effective cancer vaccines and immuno-stimulators for the induction of both the adaptive and innate immune systems. Unfortunately, these CDNs have been dosed via intratumor route, which is not convenient, especially for tumors that are difficult to reach. We recently introduced endo-S-CDNs as potent STING agonists but in our prior report we did not evaluate the in vivo efficacies of these novel STING agonists. Herein, we conduct a more extensive structure activity relationship study as well as in vivo evaluation of our best endo-S-CDNs. We demonstrate that endo-S-CDNs can be dosed via subcutaneous route to provide robust protection against MC38 and B16–F10 tumor models.

The 3-hydroxy-β-lactam (3-HβL) group derived from the natural product tabtoxinine-β-lactam (TβL), an inhibitor of glutamine synthetase, was repurposed to develop an inhibitor of dihydrofolate synthetase (DHFS). We show that replacement of the carboxyl group of p-amino-benzoic acid (PABA) with a 3-HβL moiety on the chemical scaffold of a folate mimic results in a potent inhibitor of DHFS. Using a combination of in vitro steady-state kinetics, enzyme-coupled assays, and molecular modeling, we validate the essential role of the 3-HβL group in DHFS inhibition. We provide an optimized synthesis of the 3-(p-aminophenyl)-3-HβL component via a sequence of the C–C bond-forming Henry reaction and a β-lactam ring-closing Grignard reaction. We demonstrate full elaboration to an antifolate scaffold via chemical or chemoenzymatic conjugation of the PABA analogue 3-(p-aminophenyl)-3-HβL to a pterin mimic. In this proof-of-concept study, we provide the first evidence that the 3-HβL group can be used as a general pharmacophore for inhibitors of enzymes in the ATP-dependent carboxylate-amine ligase superfamily through carboxylate replacement on substrate scaffolds, which could have broad therapeutic applications.