Potential of Pyridine Amphiphiles as Staphylococcal Nuclease Inhibitor

Abstract

The present study explores the potential of pyridine-based synthetic amphiphiles C1 and C2 having 4-carbon and 12-carbon hydrophobic tails, respectively, as staphylococcal nuclease inhibitors. UV-visible titration with calf-thymus DNA (CT-DNA) revealed a hypochromic shift in the absorbance bands of C1 and C2, whereas fluorescence titration indicated a reduction in the emission intensity of the monomer bands of the amphiphiles. Interaction of deoxyribonuclease I (DNase 1) and micrococcal nuclease (MNase) with C1 or C2 led to a decrease in the emission intensity of tryptophan at λ=345 nm along with an increase in the monomer emission intensity of C1 and C2 at λ=375 nm for DNase I and excimer emission intensity at λ=470 nm for both DNase I and MNase. Scatchard's analysis indicated superior interaction of C2 with DNase I. Circular dichroism spectroscopy revealed major changes in the secondary structures of both DNase I and MNase upon interaction with the amphiphiles. A solution-based nuclease assay in conjunction with gel electrophoresis indicated amphiphile-mediated protection against nuclease-directed DNA cleavage. Interestingly, C2 could render inhibition of nuclease present in the culture supernatant of Staphylococcus aureus MTCC 96, which highlights the therapeutic prospect of the amphiphile against S. aureus.

Anthraquinone‐Based Ligands as MNase Inhibitors: Insights from Inhibition Studies and Generation of a Payload Nanocarrier for Potential Anti‐MRSA Therapy

“…A fluorescence‐based nuclease assay [29] was conducted to ascertain the potential of the ligands as MNase inhibitor. In the absence of any ligand, a systematic reduction in the fluorescence emission intensity of CT‐DNA‐bound Hoechst dye at 450 nm was noted (Figure S1, Figure 2A), which suggested facile cleavage of CT‐DNA by MNase.…”

“…Screening of ligands as MNase inhibitor : A solution‐based nuclease assay was performed to determine the potential of the synthetic ligands as nuclease inhibitors. The nuclease assays were performed in multiple sets in Tris‐CaCl 2 buffer [29] . In these experiments, 1.0 μg of CT‐DNA was initially incubated in separate sets with Hoechst dye (1.0 μg mL −1 ) for 30 min in the dark.…”

“…The nuclease assays were performed in multiple sets in Tris-CaCl 2 buffer. [29] In these experiments, 1.0 μg of CT-DNA was initially incubated in separate sets with Hoechst dye (1.0 μg mL À 1 ) for 30 min in the dark. In another set, the enzyme solutions (2.0 units of MNase) were incubated with varying concentrations of the ligands C1-C6 for 30 min at 37 °C and 180 rpm.…”

“…To this end, a study has demonstrated that the antibiotic clindamycin in conjunction with immunoglobulin was able to hinder nuclease activity and promote bacterial clearance by neutrophils [28] . In another study, the prospect of pyridine‐based amphiphiles as MNase inhibitor has been reported [29] . In addition, there are other studies reporting the structural and energetic basis of substrate analog binding with MNase as well as elucidating the substrate specificity of rationally designed oligonucleotides against MNase [30,31] …”

“…[28] In another study, the prospect of pyridine-based amphiphiles as MNase inhibitor has been reported. [29] In addition, there are other studies reporting the structural and energetic basis of substrate analog binding with MNase as well as elucidating the substrate specificity of rationally designed oligonucleotides against MNase. [30,31] Given the high resistance of S. aureus strains to most of the therapeutic antibiotics and based on the germane role of MNase in establishing staphylococcal infection, deployment of a potent MNase inhibitor emerges as an alternate therapeutic strategy to combat the pathogen.…”