New Chloramphenicol Derivatives with a Modified Dichloroacetyl Tail as Potential Antimicrobial Agents

To combat the dangerously increasing pathogenic resistance to antibiotics, we developed new pharmacophores by chemically modifying a known antibiotic, which remains to this day the most familiar and productive way for novel antibiotic development. We used as a starting material the chloramphenicol base, which is the free amine group counterpart of the known chloramphenicol molecule antibiotic upon removal of its dichloroacetyl tail. To this free amine group, we tethered alpha- and beta-amino acids, mainly glycine, lysine, histidine, ornithine and/or beta-alanine. Furthermore, we introduced additional modifications to the newly incorporated amine groups either with protecting groups triphenylmethyl- (Trt) and tert-butoxycarbonyl- (Boc) or with the dichloroacetic group found also in the chloramphenicol molecule. The antimicrobial activity of all compounds was tested both in vivo and in vitro, and according to the results, the bis-dichloroacetyl derivative of ornithine displayed the highest antimicrobial activity both in vivo and in vitro and seems to be a dynamic new pharmacophore with room for further modification and development.

Recent Advances of Chitosan and its Derivatives in Biomedical Applications

Chitosan is the second-most abundant natural polysaccharide. It has unique characteristics, such as biodegradability, biocompatibility, and non-toxicity. Due to the existence of its free amine group and hydroxyl groups on its backbone chain, chitosan can undergo further chemical modifications to generate Chitosan Derivatives (CDs) that permit additional biomedical functionality. Chitosan and CDs can be fabricated into various forms, including Nanoparticles (NPs), micelles, hydrogels, nanocomposites and nano-chelates. For these reasons, chitosan and CDs have found a tremendous variety of biomedical applications in recent years. This paper mainly presents the prominent applications of chitosan and CDs for cancer therapy/diagnosis, molecule biosensing, viral infection, and tissue engineering over the past five years. Moreover, future research directions on chitosan are also considered.

CHITOSAN ISOLATION AND ITS APPLICATION TO REDUCE THE CONTENT OF METAL IONS IN WELLBORE WATER

<p class="abstrak">Potential water sources such as white shrimp shell waste <em>(Penaeus merguiensis)</em> can be used as a source of chitosan. Chitosan can be applied as an environmentally friendly adsorbent for water treatment because of its ability to adsorb metal ions. In this study, chitosan was isolated through several stages such as demineralization, deproteination, decolourization and deacetylation. The yield of chitosan obtained from this study was 17.73%. Characterization by infrared spectroscopy (FTIR) showed the absorption at 3355 cm^-1indicating the presence of amine (-NH₂) and hydroxyl (-OH) groups. The absorption of the carbonyl group (-C=O) at 1642 cm^-1 disappeared while the absorption of the free amine group (-NH₂) at 1590 cm^-1 increased indicating the successful deacetylation with a degree of deacetylation (DD) 78%. Application of chitosan in wellbore water did not affect on colour change and decreasing of iron (Fe) content due to low concentration of iron (Fe). However, chitosan can reduce the pH value of water and manganese (Mn) content. The results of ANOVA and DMRT test at 0.05 significance level showed that chitosan with various mass had different effects. The more the mass of chitosan added, the higher the content of manganese (Mn) will decrease.</p>

Anion Recognition Via polarized –N-H Fragments

Hydrogen bonding interaction and or proton transfer assets of synthetic molecules in presence of anionic species is pretty fascinating in the field of supramolecular analytical chemistry. Not only amide or urea based derivatives have appeared in the highlights, rather from last few decades, polarized free amine fragments (-NH2) have been brought under the study with prompt signaling. In this report, I will be focusing on the basic aspects which trigger free amine group to decode rapid anion recognition not only under organic media, but also under aqueous conditions in diverse environments.

Preparation and Electrical Properties of Activated Carbon Grafted with Polyaniline Nanofiber

Activated carbon (AC) grafted with polyaniline (PANi) was prepared. Firstly, surface modifications of AC were carried out using sulfuric acid/nitric acid and followed by sodium hydrosulfite/ammonia, resulting in nitro group functionalized AC and free amine group functionalized AC, respectively. Functionalized groups were confirmed by FTIR analysis. Then, PANi was deposited onto modified AC surface through oxidation polymerization of aniline using ammonium persulfate as an initiator. After that, AC-NO2/PANi composites (1:0.25 and 1:0.5) and AC-NH2-g-PANi (1:0.25 and 1:0.5) were prepared. SEM images revealed that PANi was successfully deposited onto modified AC surface due to polar-polar interaction (in case of AC-NO2) and grafting reaction (in case of AC-NH2). Interestingly, at low aniline concentration, PANi nanofiber was produced, resulting in PANi having the highest surface area. As a result, the PANi nanofiber on porous activated carbon electrode exhibited high EDL capacitance value of 242 F/g. In contrast, PANi granular form exhibited significantly decreased in EDL capacitance value.