Novel selective "on-off" fluorescence sensor based on julolidine hydrazone-Al3+ complex for Cu2+ ion: DFT study.

A hydrazone (T1) was synthesized by reacting 8-hydroxyjulolidine-9-carboxaldehyde with 2-furoic hydrazide and then modified with Al3+ ion to form a novel hydrazone Al3+ complex (T1-Al3+) in an aqueous solution (8% propylene glycol in 10 mM HEPES pH 5.5). The T1-Al3+ complex was studied as a Cu2+ selective sensor due to its highly efficient capacibility of paramagnetic quenching. The results showed that the T1-Al3+ complexed sensor possesses remarkable sensitivity and selectivity for Cu2+ ion in 8% propylene glycol in 10 mM HEPES pH 5.5 as compared with other tested analytes. Notably, this sensor has a broad linear detection range of 10-110 µM for Cu2+ ion and a detection limit level of 0.62 µM, which is lower than the Cu2+ concentration threshold in drinking water designated by the United States Environmental Protection Agency (EPA). Additionally, it was detectable for the presence of Cu2+ ion in mineral water and tap water samples. The selectivity of T1-Al3+ complexed sensor with Cu2+ ion could be explained by the basis of computation with Gaussian software complied with the basis sets of B3LYP/6-31 G(d,p)/LANL2DZ. Furthermore, only T1 exhibited anticancer efficacy against HeLa and U251 cells with MTT assay.

Electrospun Gelatin Fiber Mats Mixed With C.carandas Extract and its Enhanced Stability and Bioactivity.

Crude C. carandas fruits ethanol extract (CCE) constituents important bioactive compounds such as phenolics, flavonoids, and vitamin C. Its biological activities include anti-inflammatory, antioxidant, antibacterial, etc. The present work was carried out to study the optimal conditions for fabricating electrospun gelatin fiber mats (GFM) loaded with CCE (CCE-GFM) and to evaluate the release capacity and stability of these bioactive compounds loaded into GFM. The optimal conditions for electrospinning GFM were the electrospinning 30% (w/v) gelatin solution prepared in 25% (v/v) ethanol solution containing 30% (v/v) acetic acid, under the fixed electrostatic field strength of 20 kV and at a distance between noodle tip and ground of 15 cm. The feed rate of an electrospinning solution was 1.5 mL/h. The electrospun gelatin fibers were smooth and continuous under the optimized electrospinning conditions, with an average diameter of 235.69 ± 10.45 nm. Additionally, at the loading of 15% (w/w) CCE in GFM, CCE-GFM exhibited the highest DPPH radical scavenging activity with 88.22 ± 2.62% and the highest tyrosinase inhibitory activity with 38.17 ± 1.86%. Compared with free CCE, CCE-GFM was more thermally stable upon the heating and cooling cycle testing. CCE-GFM had the percent reductions in total contents of phenolics, flavonoids and vitamin C togethering with the percent reductions of DPPH scavenging and anti-tyrosinase activities slower than pure CCE had. Furthermore, the drug release efficiency from CCE-GFM of 15% (w/w) CCE loading that was tested using modified Franz diffusion cell in an acetate buffer solution of pH 5.5 was 30%. CCE-GFM has shown the potential to utilize a facial mask sheet containing CCE valuable in high antioxidant activity for cosmetic applications.

Flexible diaminodihydrotriazine inhibitors of Plasmodium falciparum dihydrofolate reductase: Binding strengths, modes of binding and their antimalarial activities.

A series of flexible diaminodihydrotriazines or cycloguanil (Cyc) analogues are developed and shown to inhibit P. falciparum dihydrofolate reductase (PfDHFR) of the wild type or those carrying either single (S108N), double (C59R + S108N and A16V + S108T), triple (N51I + C59R + S108N and C59R + S108N + I164L) or quadruple (N51I + C59R + S108N + I164L) mutations, responsible for antifolate resistance. The flexibility of the side chain at position N1 has been included in the design so as to avoid unfavourable steric interaction with the side chain of residue 108 of the resistant mutants. The inhibition constants of many inhibitors for the mutant enzymes are in the low nanomolar region. Regaining of drug binding efficacies was achieved with both A16V and S108N series of mutants. X-ray studies of some enzyme-inhibitor complexes designed for optimal interaction with the mutant enzymes reveal the modes of binding in line with the Ki values. A number of these compounds show excellent antimalarial activities against resistant P. falciparum bearing the mutant enzymes, and exhibit low cytotoxicity to mammalian cells, making them good candidates for further development as antimalarial drugs.

Electrospun cellulose acetate doped with astaxanthin derivatives from Haematococcus pluvialis for in vivo anti-aging activity.

This research aims to study the release, in vivo anti-aging activity against Caenorhabditis elegans and stability of astaxanthins in a crude acetone extract of Haematococcus pluvialis from electrospun cellulose acetate (CA) nanofibers. The content and 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging activity of astaxanthins in the crude extract were also determined. The content of astaxanthins was reported in terms of total carotenoid content (TCC) and found to be 10.75 ± 0.16 mg gcE-1. IC50 of DPPH radical scavenging activity for astaxanthins was 233.33 ± 4.18 µg mL-1. It has been well known that astaxanthins are very unstable under environmental conditions, so the electrospinning technique was used to enhance their stability. In order to fabricate CA nanofibers containing a crude acetone extract of H. pluvialis, various solvent systems and percent loading of the crude acetone extract were studied. The optimal solvent system for fabrication of CA nanofibers was the acetone/dimethylformamide (DMF) system (2 : 1 v/v) with incorporation of 0.25% v/v Tween80, resulting in good morphology of CA nanofibers with av. 420 nm diameter. The loading efficiency (%) of the crude astaxanthins extract was 5% w/w of CA. With regard to the results of the in vivo oxidative stress assay, C. elegans pre-treated with 200 µg mL-1 of the crude extract had a survival percent of 56 after administration of 250 mM of paraquat for 8 h. Under phosphate-buffered saline (pH 7.4) containing 10% v/v acetone, the release of astaxanthins from the CA nanofibers loaded with the crude extract exhibited a prolonged profile. The stability of astaxanthins in electrospun CA nanofibers was examined using the freeze-thaw cycle testing through a DPPH radical scavenging assay. It was found that their stability was significantly different (P < 0.05) after the 12th freeze-thaw cycle compared with the crude extract.

Hybridization of pyrrolidinyl peptide nucleic acids and DNA: selectivity, base-pairing specificity, and direction of binding.

[structure: see text] A mixed-base, beta-amino acid containing, pyrrolidinyl peptide nucleic acid (PNA) binds strongly and selectively to complementary DNA in an exclusively antiparallel fashion. The PNA-DNA binding specificity strictly follows the Watson-Crick base-pairing rules.

Pyrrolidinyl peptide nucleic acid with α/ß-peptide backbone: A conformationally constrained PNA with unusual hybridization properties.

We describe herein a new conformationally constrained analog of PNA carrying an alternating α/ß amino acid backbone consisting of (2'R,4'R)-nucleobase-subtituted proline and (1S,2S)-2-aminocyclopentanecarboxylic acid (acpcPNA). The acpcPNA has been synthesized and evaluated for DNA, RNA and self-pairing properties by thermal denaturation experiments. It can form antiparallel hybrids with complementary DNA with high affinity and sequence specificity. Unlike other PNA systems, the thermal stability of acpcPNA·DNA hybrid is largely independent of G+C contents, and is generally higher than that of acpcPNA·RNA hybrid with the same sequence. Thermodynamic parameters analysis suggest that the A·T base pairs in the acpcPNA·DNA hybrids are enthalpically stabilized over G·C pairs. The acpcPNA also shows a hitherto unreported behavior, namely the inability to form self-pairing hybrids. These unusual properties should make the new acpcPNA a potentially useful candidate for various applications including microarray probes and antigene agents.