Volume 42, Nº 3 (2016)

Antimicrobial peptides and proteins (AMPs) are among the most important components of the immune system of multicellular organisms. The role of AMPs is of particular importance for invertebrates which constitute the vast majority of species diversity of the living world, because these animals lack acquired immunity. The AMPs of animal origin are ribosomally-synthesized molecules that have, as a rule, a positive net charge and amphiphilic properties. They can act against bacteria, yeast and filamentous fungi, protozoa, and enveloped viruses. AMPs can also play a role of mediators of the immune system. Search and investigation for protective factors of the invertebrate host defense provide a better understanding of mechanisms of the innate immunity of humans and other mammals and give a key to a development of new medicines. The first part of this review focuses on special features of a structure, biosynthesis, regulation of gene expression, and molecular evolution of AMPs of invertebrates.

The effect of the peptide octarphin (TPLVTLFK), a selective agonist of the nonopioid β-endorphin receptor, on the activity of soluble (sGC) and membrane-bound guanylate cyclase (mGC) of peritoneal macrophages from mouse, rat, and guinea pig has been studied. It has been found that, in the concentration range of 10–1000 nM, octarphin increases the activity of sGC and has no effect on the activity of mGC in macrophages of these species. The activating effect of the peptide toward sGC was dose-dependent and was maximal at a concentration of 100 nM. These results indicate that the increase in the concentration of guanosine 3',5'-cyclophosphate in macrophages in the presence of octarphin occurs through the activation of sGC. It can be stated that the activating effect of octarphin on peritoneal macrophages is accomplished in the following way: an increase in the activity of inducible NO synthase → an increase in NO production → activation of sGC → an increase in the intracellular cGMP level.

MicroRNAs (miRNA) are non-coding small RNA molecules consisting of 20–24 nucleotides (nt), which regulate gene expression negatively at the post-transcriptional levels depending on the extent of complementation between miRNA and mRNA in a variety of eukaryotic organisms. They have attracted increasing attention recently. To date, a total of 1637 mature miRNAs from fishes have been deposited in the miRBase database (Release 21) and they are just a small portion of the miRNAs described in fish species. Especially in rainbow trout (Oncorhynchus mykiss) miRNAs, it is far from the numbers of miRNAs found in other fishes and many more miRNA remain to be discovered. In present study, we used known animal miRNAs to systematically search miRNA homologs in available expressed sequence tags (EST), genomic survey sequences (GSS), and transcript sequence assemblies (TSA) of O. mykiss based on the conservation of miRNA sequences. Following the filtering with a combination of stringent criteria, 39 miRNAs belonging to 25 independent families were identified, of which 14 are novel identified miRNAs firstly in O. mykiss. The randomly selected 13 miRNAs were verified by stem-loop RT-PCR indicating that the prediction method that we used to identify the miRNAs was effective. Furthermore, total of 94 target genes were predicted and their probable functions were illustrated. Their target genes are involved in transcription factors, development, metabolism, signaling, immunity, and cell division. The current study has provided an update on O. mykiss miRNAs and their targets, which will be helpful for future research on miRNA-mediated gene regulation in this important fish species.

The possibility of the effective delivery of lactoferrin to the cells of the innate immune system (neutrophils and monocytes) by means of biodegradable polyelectrolyte microcapsules has been shown. A study of the effect of the structural component of microcapsules, poly-L-arginine, has shown that the production of reactive oxygen species (ROS) was maximum at a concentration of the polyelectrolyte of 0.5 μg/mL. Increasing the polycation concentration significantly decreased the neutrophil viability and ROS production. The study of neutrophil apoptosis showed that hollow microcapsules containing no lactoferrin accelerated the apoptosis of phagocytes by 15–20%. Encapsulated lactoferrin inhibited the neutrophil apoptosis by 65–70%, whereas nonencapsulated lactoferrin decreased it by 35%. It was found that encapsulated lactoferrin reduced the production of TNF-α by THP-1 promonocytic cells to an approximately the same degree as nonencapsulated lactoferrin.

Lactuca indica L. (Compositae) has been used as a folk medicine for the treatment of intestinal disorders. Phytochemical constituents of L. indica were investigated, and their antioxidant and α-glucosidase inhibitory activities thoroughly studied. A phytochemical investigation of the aerial parts of L. indica resulted in the isolation and identification of eight phenolic compounds. The structures of the compounds were elucidated on the basis of spectroscopic evidence as apigenin, luteolin, isoquercitrin, chlorogenic acid, protocatechuic acid, p-hydroxymethyl benzoic acid, trans-cinnamic acid, and p-coumaric acid. Luteolin, isoquercitrin, chlorogenic acid, and p-hydroxymethyl benzoic acid showed antioxidant activities with IC₅₀ values in the range of 35.5–52.5 μM. In addition, apigenin and luteolin showed α-glucosidase inhibition activities with IC₅₀ values of 96.4 and 100.7 μM, respectively. These findings strongly suggest that L. indica is a potential source of natural antioxidants and/or anti-diabetic agents in pharmaceutical and health functional foods.

A novel series of 1,2,3-triazolo-carbazole chalcones were synthesized by the Claisen-Schmidt condensation reaction followed by the copper catalyzed Huisgen (2 + 3) cycloaddition reaction by conventional as well as microwave irradiation methods. The structures of the newly synthesized compounds were established on the basis of IR, ¹H NMR, ¹³C NMR, and mass spectral data. All the compounds were screened in vitro for antibacterial and antifungal activities.

We demonstrated that the secreted protein Noggin4 from Xenopus laevis was capable of the in vitro binding to the secreted factor Wnt8, one of the ligands of the Wnt/betaCatenin signaling pathway. It was also shown that posttranslational modifications occurring during secretion of these proteins from the embryonic cells were necessary for their effective interaction. Also, we proposed a method for the preparation of physiologically active secreted morphogenic proteins from the intercellular space of the Xenopus laevis embryos.