14 research outputs found
Staphylococcus aureus Quorum Regulator SarA Targeted Compound, 2-[(Methylamino)methyl]phenol Inhibits Biofilm and Down-Regulates Virulence Genes
Staphylococcus aureus is a widely acknowledged Gram-positive pathogen for forming biofilm and virulence gene expressions by quorum sensing (QS), a cell to cell communication process. The quorum regulator SarA of S. aureus up-regulates the expression of many virulence factors including biofilm formation to mediate pathogenesis and evasion of the host immune system in the late phases of growth. Thus, inhibiting the production or blocking SarA protein might influence the down-regulation of biofilm and virulence factors. In this context, here we have synthesized 2-[(Methylamino)methyl]phenol, which was specifically targeted toward the quorum regulator SarA through in silico approach in our previous study. The molecule has been evaluated in vitro to validate its antibiofilm activity against clinical S. aureus strains. In addition, antivirulence properties of the inhibitor were confirmed with the observation of a significant reduction in the expression of representative virulence genes like fnbA, hla and hld that are governed under S. aureus QS. Interestingly, the SarA targeted inhibitor showed negligible antimicrobial activity and markedly reduced the minimum inhibitory concentration of conventional antibiotics when used in combination making it a more attractive lead for further clinical tests
Efficient resolution of (±)-trans-2,3-diphenylpiperazine using (1S)-(+)-10-camphorsulfonic acid and enrichment of enantiomeric purity of non-racemic 2,3-diphenylpiperazine using different achiral acids
Convenient Methods for the Synthesis of Chiral Amino Alcohols and Amines
Simple, convenient methods have been developed using readily available, easy-to-handle reagents to access a variety of chiral amino alcohols and amines, which have considerable potential for applications in asymmetric organic transformations. Scholars from this laboratory in India have
made significant contributions to this field, which is the subject of the current review
Self-Assembled Light-Harvesting System from Chromophores in Lipid Vesicles
Lipid vesicles are used as the organizational
structure of self-assembled
light-harvesting systems. Following analysis of 17 chromophores, six
were selected for inclusion in vesicle-based antennas. The complementary
absorption features of the chromophores span the near-ultraviolet,
visible, and near-infrared region. Although the overall concentration
of the pigments is low (âŒ1 ÎŒM for quantitative spectroscopic
studies) in a cuvette, the lipid-vesicle system affords high concentration
(â„10 mM) in the bilayer for efficient energy flow from donor
to acceptor. Energy transfer was characterized in 13 representative
binary mixtures using static techniques (fluorescenceâexcitation
versus absorptance spectra, quenching of donor fluorescence, modeling
emission spectra of a mixture versus components) and time-resolved
spectroscopy (fluorescence, ultrafast absorption). Binary donorâacceptor
systems that employ a boron-dipyrrin donor (S<sub>0</sub> â
S<sub>1</sub> absorption/emission in the blue-green) and a chlorin
or bacteriochlorin acceptor (S<sub>0</sub> â S<sub>1</sub> absorption/emission
in the red or near-infrared) have an average excitation-energy-transfer
efficiency (Ί<sub>EET</sub>) of âŒ50%. Binary systems
with a chlorin donor and a chlorin or bacteriochlorin acceptor have
Ί<sub>EET</sub> ⌠85%. The differences in Ί<sub>EET</sub> generally track the donor-fluorescence/acceptor-absorption
spectral overlap within a dipoleâdipole coupling (FoÌrster)
mechanism. Substantial deviation from single-exponential decay of
the excited donor (due to the dispersion of donorâacceptor
distances) is expected and observed. The time profiles and resulting
Ί<sub>EET</sub> are modeled on the basis of (FoÌrster)
energy transfer between chromophores relatively densely packed in
a two-dimensional compartment. Initial studies of two ternary and
one quaternary combination of chromophores show the enhanced spectral
coverage and energy-transfer efficacy expected on the basis of the
binary systems. Collectively, this approach may provide one of the
simplest designs for self-assembled light-harvesting systems that
afford broad solar collection and efficient energy transfer
Highly Enantioselective Synthesis of Chiral Allenes by Sequential Creation of Stereogenic Center and Chirality Transfer in a Single Pot Operation
Diblock Copolymer Micelles and Supported Films with Noncovalently Incorporated Chromophores: A Modular Platform for Efficient Energy Transfer
We report generation of modular, artificial light-harvesting assemblies where an amphiphilic diblock copolymer, poly(ethylene oxide)-block-poly(butadiene), serves as the framework for noncovalent organization of BODIPY-based energy donor and bacteriochlorin-based energy acceptor chromophores. The assemblies are adaptive and form well-defined micelles in aqueous solution and high-quality monolayer and bilayer films on solid supports, with the latter showing greater than 90% energy transfer efficiency. This study lays the groundwork for further development of modular, polymer-based materials for light harvesting and other photonic applications