Discovery of potent polyphosphate kinase 1 (PPK1) inhibitors using structure‐based exploration of PPK1Pharmacophoric space coupled with docking analyses

Inorganic polyphosphate (polyP) is present in all living forms of life. Studied mainly in prokaryotes, polyP and its associated enzymes are vital in diverse metabolic activities, in some structural functions, and most importantly in stress responses. Bacterial species, including many pathogens, encode a homolog of a major polyP synthesis enzyme, Poly Phosphate Kinase (PPK) with 2 different genes coding for PPK1 and PPK2. Genetic deletion of the ppk1 gene leads to reduced polyP levels and the consequent loss of virulence and stress adaptation responses. This far, no PPK1 homolog has been identified in higher‐order eukaryotes, and, therefore, PPK1 represents a novel target for chemotherapy. The aim of the current study is to investigate PPK1 from Escherichia coli with comprehensive understanding of the enzyme's structure and binding sites, which were used to design pharmacophores and screen a library of compounds for potential discovery of selective PPK1 inhibitors. Verification of the resultant inhibitors activities was conducted using a combination of mutagenic and chemical biological approaches. The metabolic phenotypic maps of the wild type E. coli (WT) and ppk1 knockout mutant were generated and compared with the metabolic map of the chemically inhibited WT. In addition, biofilm formation ability was measured in WT, ppk1 knockout mutant, and the chemically inhibited WT. The results demonstrated that chemical inhibition of PPK1, with the designed inhibitors, was equivalent to gene deletion in altering specific metabolic pathways, changing the metabolic fingerprint, and suppressing the ability of E. coli to form a biofilm.     

Leishmania donovani infection differentially regulates small G‐proteins

Leishmania is a protozoan parasite that resides and replicates in macrophages and causes leishmaniasis. The parasite alters the signaling cascade in host macrophages and evades the host machinery. Small G‐proteins are GTPases, grouped in 5 different families that play a crucial role in the regulation of cell proliferation, cell survival, apoptosis, intracellular trafficking, and transport. In particular, the Ras family of small G‐proteins has been identified to play a significant role in the cellular functions mentioned before. Here, we studied the differential expression of the most important small G‐proteins during Leishmania infection. We found major changes in the expression of different isoforms of Ras, mainly in N‐Ras. We observed that Leishmania donovani infection led to enhanced N‐Ras expression, whereas it inhibited K‐Ras and H‐Ras expression. Furthermore, an active N‐Ras pull‐down assay showed enhanced N‐Ras activity. L donovani infection also increased extracellular signal–regulated kinase 1/2 phosphorylation and simultaneously decreased p38 phosphorylation. In contrast, pharmacological inhibition of Ras led to reduction in the phosphorylation of extracellular signal–regulated kinase 1/2 and enhanced the phosphorylation of p38 in Leishmania‐infected cells, which could lead to increased interleukin‐12 expression and decreased interleukin‐10 expression. Indeed, farnesylthiosalicyclic acid (a Ras inhibitor), when used at the effective level in L donovani–infected macrophages, reduced amastigotes in the host macrophages. Thus, upregulated N‐Ras expression during L donovani infection could be a novel immune evasion strategy of Leishmania and would be a potential target for antileishmanial immunotherapy.     

Karyological studies of Iranian <Emphasis Type="Italic">Allium</Emphasis> L. (Amaryllidaceae) species with focus on sect. <Emphasis Type="Italic">Acanthoprason</Emphasis>. 1. Mitotic chromosomes

Eighteen species and subspecies (34 accessions) of Allium sect. Acanthoprason and 11 species (17 accessions) belonging to other subgenera and sections of Allium were karyologically investigated and include first reports for 12 species. The examined plants of 47 accessions were diploid, three accessions of two species were tetraploid, and in the A. bisotunense accession, we found a mix of di- and triploid individuals. B chromosomes were found in 10 accessions. A basic chromosome number of x = 8 was confirmed for all investigated members of subg. Melanocrommyum and subg. Allium, and x = 9 for Allium tripedale of subg. Nectaroscordum. Idiograms were drawn for each accession, and metaphase images are presented illustrating observed chromosomal variations. Also, karyotype features and asymmetry parameters were calculated for all accessions. Chromosomal aberrations, e.g. aneuploid cells or loss of whole or parts of chromosome arms, were rarely observed. In general, the karyotypes showed low variation in inter- and intrachromosomal asymmetry especially inside of the taxonomic groups, though satellited chromosomes were good markers for subgenera and even specific for two studied sections of subg. Allium. Six different types of satellites were recognized, two of them were newly described: Type P was prevalent in subg. Melanocrommyum, and type O in sect. Codonoprasum. Statistical analyses were performed on five karyological parameters to test correct relationships and also to test previous grouping hypotheses. Although our data confirm distinct karyological characters for the subgenera investigated, the remarkable morphological diversity inside of subg. Melanocrommyum is not mirrored by striking karyological differences.     

Regulation of autophagy by polyphenols: Paving the road for treatment of neurodegeneration

In the present paper, we will discuss on the importance of autophagy in the central nervous system, and outline the relation between autophagic pathways and the pathogenesis of neurodegenerative disorders. The potential therapeutic benefits of naturally occurring phytochemicals as pharmacological modulators of autophagy will also be addressed. Our findings provide renewed insight on the molecular modes of protection by polyphenols, which is likely to be at least in part mediated not only by their potent antioxidant and anti-inflammatory effects, but also through modulation of autophagic processes to remove the aberrant protein aggregates.     

Targeting ncRNAs by plant secondary metabolites: The ncRNAs game in the balance towards malignancy inhibition

The current trend of combining state of the art technologies with quondam treatments in order to overcome existing gaps in the clinical area determined an increased interest into polyphenols, common dietary phytochemicals, for the prevention and treatment of chronic diseases, especially cancer. The reemergence of polyphenols in the cancer field is sustained by advanced-omics technologies able to identify coding and non-coding genes and their related signaling pathways modulated by natural compounds. Identification of the structural correspondence between interacting molecules will allow the development of more targeted and informed therapeutic strategies for cancer management.