The effects of chitosan and salicylic acid on elicitation of secondary metabolites and antioxidant activity of safflower under in vitro salinity stress

Plant Cell, Tissue and Organ Culture (PCTOC) - Biomass and in vitro ginsenoside accumulation in cell suspensions of Panax quinquefolius (L.) and P. sikkimensis (Ban.) are differentially affected,...     

Determining the interaction behavior of calf thymus DNA with berberine hydrochloride in the presence of linker histone: a biophysical study

Abstract

The binding of small molecules with histone-DNA complexes can cause an interference in vital cellular processes such as cell division and the growth of cancerous cells that results in apoptosis. It is significant to study the interaction of small molecules with histone-DNA complex for the purpose of better understanding their mechanism of action, as well as designing novel and more effective drug compounds. The fluorescence quenching of ct-DNA upon interaction with Berberine has determined the binding of Berberine to ct-DNA with K_sv?=?9.46?×?10⁷ M^?1. K_sv value of ct-DNA-Berberine in the presence of H1 has been observed to be 3.10?×?10⁷ M^?1, indicating that the H1 has caused a reduction in the binding affinity of Berberine to ct-DNA. In the competitive emission spectrum, ethidium bromide (EB) and acridine orange (AO) have been examined as intercalators through the addition of Berberine to ct-DNA complexes, which includes ctDNA-EB and ctDNA-AO. Although in the presence of histone H1 , we have observed signs of competition through the induced changes within the emission spectra, yet there has been apparently no competition between the ligands and probes. The viscosity results have confirmed the different behaviors of interaction between ctDNA and Berberine throughout the binary and ternary systems. We have figured out the IC50 and viability percent values at three different time durations of interaction between Berberine and MCF7 cell line. The molecular experiments have been completed by achieving the results of MTT assay, which have been confirmed to be in good agreement with molecular modeling studies.

Communicated by Ramaswamy H. Sarma     

Analyzing of expression of novel polypeptide complexes consisting of Shiga toxin B subunit and Adherence Fimbriae of Escherichia coli based on in silico modeling

Enterohemorrhagic (EHEC) and enteroaggregative (EAEC) are two pathotypes of diarrheagenic Escherichia coli. EAEC strains express adhesins called aggregate adherence fimbriae (AAFs) which the bacteria use to adhere to intestinal mucosa. EHEC virulence factor is Shiga toxin which belongs to the AB5 toxin family. B subunit, the nontoxic part of Shiga toxin (StxB), forms a homo pentamer and is responsible for binding to target cells. StxB has recently been proven to have adjuvant activity. In the current study we fused StxB encoding gene to 3' end of genes encoding two variants of AAFs, i.e., AAF/I and AAF/II. The in silico studies on tertiary structure and biochemical characteristics of Shiga toxin A subunit (StxA) revealed more resemblance to AAF/II than AAF/I. The constructs were prepared in a way that StxB could imitate its natural structure (pentamer formation) and its position (C-terminus) in the native toxin complex. The expression of these constructs showed the formation of AAF/II-B as a protein complex but with lower molecular mass than its expected size. In contrast, the AAF/I-B complex was not formed. Overall, the results of in silico studies and expression experiments together revealed that despite AAF/II-B expression, StxB failed to form pentamer. Therefore the observed protein complex has lower molecular mass. Since StxB is bound to AAF/II through disulfide bond, this bond prevents pentamer formation of StxB. However, due to the lack of disulfide bond between AAF/I and StxB, no protein complex is formed, thus StxB maintains its pentamer structure.     

Molecular phylogeny and ecogeography of Onobrychis viciifolia Scop. (Fabaceae) based on nrDNA ITS sequences and genomic ISSR fingerprinting

In this study 40 specimens from 8 representative Iranian populations of Onobrychis viciifolia SCOP. were collected from their natural habitats. The specimens were biometrically assessed using 43 quantitative and 15 qualitative morphological characters. At each sample site we recorded ecogeographical variables. In order to evaluate the difference between the variation due to phenotypic responses and genetic adaptation, we generated nucleotide sequence data from the internal transcribed spacer of the nuclear rDNA genes (ITS) and carried out genomic fingerprints using inter‐simple sequence repeat PCR (ISSR). Cluster analysis of morphological characters divided the eight populations into three major groups. Leaf length, leaflet length and width, calyx length, plant height, and stem length were introduced as diagnostic characters for three different morphological groups. Furthermore, canonical correspondence analysis (CCA) of ecogeographical data showed correlations between morphological variations and ecogeographical factors. Clay%, saturation percentage (SP), total neutralizing value (TNV%), texture, minimum temperature, and geographic separation were the main environmental variables associated with morphological groups of O. viciifolia. ISSR analysis revealed three main groups which are in correspondence with morphological groups, indicating that the three morphological groups have been shaped by genetic and phenotypic responses to environmental conditions. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Design of ultrasensitive bisphenol A–aptamer based on platinum nanoparticles loading to polyethyleneimine-functionalized carbon nanotubes

Here, a highly sensitive electrochemical aptasensor based on a novel signal amplification strategy for the determination of bisphenol A (BPA) was developed. Construction of the aptasensor began with the deposition of highly dispersed platinum nanoparticles (PtNPs)/acid-oxidized carbon nanotubes (CNTs–COOH) functionalized with polyethyleneimine (PEI) at the surface of glassy carbon (PtNPs/PEI/CNTs–COOH/GC) electrode. After immobilizing the amine-capped capture probe (ssDNA1) through the covalent amide bonds formed by the carboxyl groups on the nanotubes and the amino groups on the oligonucleotides, we employed a designed complementary BPA–aptamer (ssDNA2) as a detection probe to hybridize with the ssDNA1. By adding BPA as a target, the aptamer specifically bound to BPA and its end folded into a BPA-binding junction. Because of steric/conformational restrictions caused by aptamer–BPA complex formation at the surface of modified electrode, the interfacial electron transfer of [Fe(CN)₆]^3−/4− as a probe was blocked. Sensitive quantitative detection of BPA was carried out by monitoring the decrease of differential pulse voltammetric responses of [Fe(CN)₆]^3−/4− peak current with increasing BPA concentrations. The newly developed aptasensor embraced a number of attractive features such as ease of fabrication, low detection limit, excellent selectivity, good stability and a wide linear range with respect to BPA.     

Self-assembly of trimethyl chitosan and poly(anionic amino acid)-peptide antigen conjugate to produce a potent self-adjuvanting nanovaccine delivery system

Short peptides derived from virulent pathogen proteins are promising antigens for the development of vaccines against infectious diseases. However, in order to mimic the danger signals associated with natural infection and stimulate an adaptive immune response, peptide antigens must be co-delivered with immune adjuvants. In this study, a group A streptococcus (GAS) M-protein derived B-cell epitope: J8, and universal T-helper epitope P25 containing peptides, were chemically coupled with different anionic amino acid-based polymers. The poly(anionic amino acid)-peptide antigen conjugates were mixed with trimethyl chitosan (TMC) to produce self-adjuvanting nanoparticulate vaccine candidates. TMC from two different sources were used to analyse their effect on immunogenicity. The nanoparticles produced from a peptide modified with 10 residues of polyglutamic acid and fungal TMC (NP5) stimulated production of the highest levels of serum antibodies in outbred mice. These antibodies were opsonic against all clinical GAS isolates tested.     

Design and synthesis of 4-methoxyphenylacetic acid esters as 15-lipoxygenase inhibitors and SAR comparative studies of them

A group of 4-methoxyphenylacetic acid esters were designed, synthesized and evaluated as potential inhibitors of soybean 15-lipoxygenase (SLO) on the basis of eugenol and esteragol structures. Compounds 7d–e showed the best IC₅₀ in SLO inhibition (IC₅₀ = 3.8 and 1.9 μM, respectively). All compounds were docked in SLO active site and showed that carbonyl group of compounds is oriented toward the Fe^III–OH moiety in the active site of enzyme and fixed by hydrogen bonding with hydroxyl group. It is assumed that lipophilic interaction of ligand–enzyme would be in charge of inhibiting the enzyme activity. The selectivity of the synthetic esters in inhibiting of 15-HLOb was also compared with 15-HLOa by molecular modeling and multiple alignment techniques.     

Modulation of peripheral inflammation by the substance P N-terminal metabolite substance P1-7

The N-terminal metabolite of the undecapeptide substance P (SP), substance P1-7 (SP1-7), is known to modulate nociception in the central nervous system (CNS) and often has opposite effects from SP. This study investigated the ability of SP(1-7) to modulate the vasodilatation response to SP in anaesthetized rats under different injury conditions using a blister model of inflammation on the hind footpad. The results indicated that SP1-7 inhibited the vascular response to SP in a dose-dependent manner. The putative antagonists naloxone and D-Pro2-D-Phe7-SP1-7 (D-SP1-7) reversed the effect of SP1-7. D-SP1-7 improved the responsiveness to SP under chronic nerve injury, which suggests a role for endogenous SP1-7 in this model. SP1-7 did not inhibit the response to electrical stimulation of the sciatic nerve, which indicates that the heptapeptide interacts at a post-terminal binding site. The current results suggest that SP1-7 may have inhibitory properties in inflammation, analogous to its antinociceptive role in the central nervous system.     

Two eudesmanolides from Sonchus macrocarpus

The aerial parts of Sonchus macrocarpus afforded, in addition to known triterpenes, two new eudesmanolides.