Background .The pharmacology, toxicology and pharmacokinetics of bioactive preparations derived from natural sources has become a flourishing field of research. However, researching complex extracts and natural products faces numerous challenges. More broadly in recent years the critique of pharmacological research, and specifically its design, the methods used and reporting has intensified.. Aims: This consensus document provides a perspective on what constitutes best practice in pharmacological research on bioactive preparations derived from natural sources, providing a perspective of what the leading specialist journals in the field consider as the core characteristics of good research. Approach ('Methods'). The editors in chief of seven journals developed this best practice statement in an iterative process. A first draft of the guidelines (prepared by MH) was then discussed and amended by the other authors. Outcomes. Core to this contribution is a table which provides detailed advice including simple points like a use of appropriate controls and the full taxonomic validity of the material under investigation (see also below), to the relevance of the model for the question being researched (e.g. can specific in silico or in vitro models really say s.th. about the species antiinflammatory activity?). Therefore, obviously, researchers must pay detailed attention to reporting and discussing such studies. This information must be discussed critically (as much as it is possible based on the published papers) in terms of their scientific quality and validity. While these points are obvious, as editors we are aware that they are often not properly implemented. Conclusion. We call for an approach which incorporates a careful design, meticulous execution and a detailed reporting of studies focusing on the pharmacology / bioactivity of bioactive preparations. Clearly testable research questions must be developed and investigated experimentally. As the founder of pharmacology Claude Bernard put it already in 1865: '…. either the experimenter's hypothesis will be disproved or it will be proved by experiment. When experiment disproves its preconceived ideas, the experimenter must discard or modify it.'

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The production of natural product compound libraries has been observed in nature for different organisms such as bacteria, fungi and plants; however, little is known about the mechanisms generating such chemically diverse libraries. Here we report mechanisms leading to the biosynthesis of the chemically diverse rhabdopeptide/xenortide peptides (RXPs). They are exclusively present in entomopathogenic bacteria of the genera Photorhabdus and Xenorhabdus that live in symbiosis with nematodes delivering them to insect prey, which is killed and utilized for nutrition by both nematodes and bacteria. Chemical diversity of the biologically active RXPs results from a combination of iterative and flexible use of monomodular nonribosomal peptide synthetases including substrate promiscuity, enzyme cross-talk and enzyme stoichiometry as shown by in vivo and in vitro experiments. Together, this highlights several of nature's methods for diversification, or evolution, of natural products and sheds light on the biosynthesis of the bioactive RXPs.

Many diseases have been described to be associated with inflammatory processes. The currently available anti-inflammatory drug therapy is often not successful or causes intolerable side effects. Thus, new anti-inflammatory substances are still urgently needed. Plants were the first source of remedies in the history of mankind. Since their chemical characterization in the 19th century, herbal bioactive compounds have fueled drug development. Also, nowadays, new plant-derived agents continuously enrich our drug arsenal (e.g., vincristine, galantamine, and artemisinin). The number of new, pharmacologically active herbal ingredients, in particular that of anti-inflammatory compounds, rises continuously. The major obstacle in this field is the translation of preclinical knowledge into evidence-based clinical progress. Human trials of good quality are often missing or, when available, are frequently not suitable to really prove a therapeutical value. This minireview will summarize the current situation of 6 very prominent plant-derived anti-inflammatory compounds: curcumin, colchicine, resveratrol, capsaicin, epigallocatechin-3-gallate (EGCG), and quercetin. We will highlight their clinical potential and/or pinpoint an overestimation. Moreover, we will sum up the planned trials in order to provide insights into the inflammatory disorders that are hypothesized to be beneficially influenced by the compound.

Angiogenesis contributes to various pathological conditions. Due to the resistance against existing antiangiogenic therapy, an urgent need exists to understand the molecular basis of vessel growth and to identify new targets for antiangiogenic therapy. Here we show that cyclin-dependent kinase 5 (Cdk5), an important modulator of neuronal processes, regulates endothelial cell migration and angiogenesis, suggesting Cdk5 as a novel target for antiangiogenic therapy. Inhibition or knockdown of Cdk5 reduces endothelial cell motility and blocks angiogenesis in vitro and in vivo. We elucidate a specific signaling of Cdk5 in the endothelium; in contrast to neuronal cells, the motile defects upon inhibition of Cdk5 are not caused by an impaired function of focal adhesions or microtubules but by the reduced formation of lamellipodia. Inhibition or down-regulation of Cdk5 decreases the activity of the small GTPase Rac1 and results in a disorganized actin cytoskeleton. Constitutive active Rac1 compensates for the inhibiting effects of Cdk5 knockdown on migration, suggesting that Cdk5 exerts its effects in endothelial cell migration via Rac1. Our work elucidates Cdk5 as a pivotal new regulator of endothelial cell migration and angiogenesis. It suggests Cdk5 as a novel, pharmacologically accessible target for antiangiogenic therapy and provides the basis for a new therapeutic application of Cdk5 inhibitors as antiangiogenic agents.Angiogenesis is involved in various pathological conditions, including arthritis, psoriasis, diabetic retinopathy, macula degeneration, and cancer (1). During recent years, the search for antiangiogenic compounds and their molecular targets has been intensified. Due to its key role in angiogenesis, research initially focused on vascular endothelial growth factor (VEGF). VEGF receptor inhibitors such as the monoclonal antibody bevacizumab (Avastin) as well as VEGF tyrosine kinase inhibitors such as sunitinib (Sutent) or sorafenib (Nexavar) have been approved for cancer therapy. Unfortunately, the benefits of these therapeutics are at best transitory and mostly followed by a restoration of tumor growth and progression (2). This resistance to antiangiogenic therapy causes a great need for new targets to inhibit vessel growth, interfering with steps in the angiogenic cascade different from the response to a single growth factor.Cyclin-dependent kinase 5 (Cdk5) is a small serine/threonine kinase belonging to the family of Cdks. In contrast to the cell cycle-related Cdks (e.g. Cdks 1, 2, 4, or 6), Cdk5 is not implicated in cell cycle control (3). Instead, it is an important regulator of neuronal development, and it controls various processes in postmitotic neurons (4). Although it is expressed ubiquitously, so far, just a few reports indicate a function of Cdk5 beyond the nervous system. Scarcely anything is known about a potential function of Cdk5 in the vasculature, and its exact functions and signaling mechanisms in the endothelium remain unknown (5-8).Our aim was to close this gap of knowledge. This i...

The most frequently used parameters to describe the barrier properties of endothelial cells (ECs) in vitro are (i) the macromolecular permeability, indicating the flux of a macromolecular tracer across the endothelium, and (ii) electrical impedance of ECs grown on gold-film electrodes reporting on the cell layer’s tightness for ion flow. Due to the experimental differences between these approaches, inconsistent observations have been described. Here, we present the first direct comparison of these assays applied to one single cell type (human microvascular ECs) under the same experimental conditions. The impact of different pharmacological tools (histamine, forskolin, Y-27632, blebbistatin, TRAP) on endothelial barrier function was analyzed by Transwell® tracer assays and two commercial impedance devices (xCELLigence®, ECIS®). The two impedance techniques provided very similar results for all compounds, whereas macromolecular permeability readings were found to be partly inconsistent with impedance. Possible reasons for these discrepancies are discussed. We conclude that the complementary combination of both approaches is highly recommended to overcome the restrictions of each assay. Since the nature of the growth support may contribute to the observed differences, structure-function relationships should be based on cells that are consistently grown on either permeable or impermeable growth supports in all experiments.

Deregulation of cyclin-dependent kinases (CDKs) has been associated with many cancer types and has evoked an interest in chemical inhibitors with possible therapeutic benefit. While most known inhibitors display broad selectivity towards multiple CDKs, recent work highlights CDK9 as the critical target responsible for the anticancer activity of clinically evaluated drugs. In this review, we discuss recent findings provided by structural biologists that may allow further development of highly specific inhibitors of CDK9 towards applications in cancer therapy. We also highlight the role of CDK9 in inflammatory processes and diseases.

Objective: The presence of linkage disequilibrium (LD) forms the basis for a range of uses, including the fine-mapping of diseases and studies on human genealogy. Recent findings indicate that single nucleotide polymorphisms (SNP) can occur in blocks of limited haplotypic diversity with high degrees of LD. Commonly used measures for LD, such as r² and D′, consider only two loci and might miss information to appropriately describe LD in larger haplotypic structures. Methods: We introduce the Normalized Entropy Difference, Ε, as a new multilocus measure for LD. A related quantity, ΔS, provides an approximate χ² test for the significance of LD. The ability of the measure to detect haplotype blocks is investigated using simulated data sets as well as a real data set previously analyzed by Daly et al. (2001). Results: Ε allows for arbitrary numbers of loci, describes LD with regard to the loci sequence, and can be interpreted as a multilocus extension of r². The application of Ε to the data sets demonstrated the measure’s ability to appropriately describe simultaneous multilocus LD and to detect haplotype blocks. Conclusions: Ε is a reasonable multilocus LD measure and might be of potential use in the construction of the human haplotype map.