Three new classes of ionic organoselenium
compounds containing
cationic benzimidazolium and imidazolium ring systems with selenocyanates
as counterions are described. The cyclization of N,N′-disubstituted
benzimidazolium and imidazolium bromides having N-(CH2)2-Br and N-(CH2)3-Br groups in the presence of potassium selenocyanate
(KSeCN) led to formation of the corresponding selenazolium selenocyanates
(21a, 21b, 22a, and 22b) and selenazinium selenocyanates (21c, 21d, 22c, and 22d). However, the open-chain
selenocyanates with additional selenocyanate counterions (21e, 21f, 22e, and 22f) were
formed from the N,N′-disubstituted benzimidazolium and imidazolium
bromides having N-(CH2)6-Br
groups. Mechanistic studies were carried out to understand the feasibility
of such cyclization processes in the presence of KSeCN. The compounds
were studied further for their potencies to catalytically reduce H2O2 in the presence of thiols. Interestingly, the
cyclic selenazolium (21a, 21b, 22a, and 22b) and selenazinium compounds (21c, 21d, 22c, and 22d) exhibited
significantly higher antioxidant activities than the corresponding
acyclic selenocyanates (21f, 22e, and 22f). Selected compounds (22d and 22e) were further evaluated for their potencies in modulating the intracellular
level of reactive oxygen species (ROS) in a representative macrophage
cell line (RAW 264.7). Owing to the cationic nature of compounds,
they may target and scavenge mitochondrial ROS in the cellular medium.
Controlled and sustained release of drug-like small molecules in an aqueous medium still remains a challenging problem due to rapid infiltration of liquid water in most reported drug release systems. However, internal-superhydrophobicity with an antifouling property extending beyond the surface of a material recently has been recognized as a potential avenue for sustained and extended release of drug-like small molecules. Sluggish removal of metastable trapped air in a superhyrophobic material provides a basis to achieve extended release of encapsulated small molecules. In this article, naturally abundant medical-cotton-extensively used in wound management including control of bleeding, absorbance of secretions and protecting wounds from contamination-is strategically exploited in tailoring (from rapid to extended) the release of small molecules by appropriate modulation of liquid water wettability. Modulation included bio-mimicked adhesive and non-adhesive superhydrophobicity of the medical cotton without erosion of any polymeric material. In this process, amine 'reactive' nano-complexes (RNC) were prepared by just mixing branched poly(ethylenimine) (BPEI) with dipentaerythritol pentaacrylate (5Acl) in ethanol with appropriate compositions. Then they were covalently immobilized on fibrous medical-cotton through a facile and robust 1,4-conjugated addition reaction. Residual acrylate moieties in the immobilized RNC provide an opportunity to tailor water wettability through strategic and appropriate post-chemical modification of RNC-coated medical cotton with a primary amine containing various small molecules. This medical-cotton with tunable wettability was exploited further to control the release rate of small molecules from rapid (<24 h) to sustained (>100 days) times. A volatile solvent induced transient and reversible switching of anti-fouling properties which allowed further varying the amount of post-loading small molecules into the medical cotton up to 2.36 wt% without compromising the embedded anti-wetting property. Thus, our current approach has immense potential to develop appropriate materials for a sustained and controlled release of small molecules from a clinically relevant substrate (i.e., medical-cotton) and may be useful in various bio-medical applications including improving wound management, preventing bacterial infections, better pain management, etc.
The biothiol-reactive organotrisulfide-based fluorogenic donors of H2S are designed for the monitoring of intracellular and lysosomal delivery of H2S with a concomitant turn-on fluorescence.
Highly selective synthesis of trisulfides over disulfides is demonstrated along with their potential as anti-proliferative agents and sustained donors of H2S.
We describe herein the rational development of organopolysulfide-based fluorogenic donor of hydrogen sulfide (H2S) DCI-PS, which can be activated by the antioxidant selenoenzyme thioredoxin reductase (TrxR) with concomitant release of...
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