Cellulose Functionalization Using N-Heterocyclic-Based Leaving Group Chemistry

There has been continuous interest in developing novel activators that facilitate the functionalization of cellulosic materials. In this paper, we developed a strategy in which trisubstituted triazinium salts act as cellulose preactivators. As leaving groups, these triazinium salts utilize N-heterocycles (pyridine, imidazole, and nicotinic acid). Initially, we optimized the synthetic route for developing these novel cellulose preactivators (triazinium salts), whose structures were confirmed using NMR spectroscopy. The surface zeta potential of cellulose changed from a negative value to a positive one after preactivation due to the cationic nature of these preactivators. To enhance the scope of the study, we functionalized the cellulose-preactivated materials with a series of amine- or hydroxy-containing aliphatic and aromatic hydrocarbons, nucleophilic amino acids (cysteine), colorants (2-aminoanthraquinone and 2-amino-3-methyl-anthraquinone), and biopolymer (zein protein). The treated samples were analyzed using FTIR, time-gated Raman spectroscopy, and reflection spectroscopy, and the success of the functionalization process was validated. To widen the scope of such chemistries, we synthesized four reactive agents containing N-heterocyclic-based leaving groups (pyridine and nicotinic acid) and successfully functionalized cellulose with them in one step. The proposed single- and two-step functionalization approaches will provide opportunities for chemically linking various chemical compounds to cellulose for different applications.

Analysis of Compressive Strength of Anhydrite Binder Using Full Factorial Design

Flue gas desulfurization gypsum (FGD gypsum) is obtained from the desulphurization of combustion gases in fossil fuel power plants. FGD gypsum can be used to produce anhydrite binder. This research is devoted to the investigation of the influence of the calcination temperature of FGD gypsum, the activators K2SO4 and Na2SO4, and their amount on the compressive strength of anhydrite binder during hydration. The obtained results showed that as the calcination temperature increased, the compressive strength of anhydrite binder decreased at its early age (up to 3 days) and increased after 28 days. The compressive strength of the anhydrite binder produced at 800 °C and 500 °C differed more than five times after 28 days. The activators K2SO4 and Na2SO4 had a large effect on the hydration of anhydrite binder at its early age (up to 3 days) in comparison with the anhydrite binder without activators. The presence of the activators of either K2SO4 or K2SO4 almost had no influence on the compressive strength after 28 days. To determine which factor, the calcination temperature of FGD gypsum (500-800 °C), the hydration time (3-28 days) or the amount (0-2%) of the activators K2SO4 and Na2SO4, has the greatest influence on the compressive strength, a 23 full factorial design was applied. Multiple linear regression was used to develop a mathematical model and predict the compressive strength of the anhydrite binder. The statistical analysis showed that the hydration time had the strongest impact on the compressive strength of the anhydrite binder using activators K2SO4 and Na2SO4. The activator K2SO4 had a greater influence on the compressive strength than the activator Na2SO4. The obtained mathematical model can be used to forecast the compressive strength of the anhydrite binder produced from FGD gypsum if the considered factors are within the same limiting values as in the suggested model since the coefficient of determination (R2) was close to 1, and the mean absolute percentage error (MAPE) was less than 10%.

Multicenter evaluation of light transmission platelet aggregation reagents: communication from the ISTH SSC Subcommittee on Platelet Physiology

BACKGROUND

Light transmission aggregation (LTA) is used widely by the clinical and research communities. Although it is a gold standard, there is a lack of interlaboratory harmonization.

OBJECTIVES

The primary objective was to assess whether sources of activators (mainly adenosine diphosphate [ADP], collagen, arachidonic acid, epinephrine, and thrombin receptor activating peptide6) and ristocetin contribute to poor LTA reproducibility. The secondary objective was to evaluate interindividual variability of results to appreciate the distribution of normal values and consequently better interpret pathologic results.

METHODS

An international multicenter study involving 28 laboratories in which we compared LTA results obtained with center-specific activators and a comparator that we supplied.

RESULTS

We report variability in the potency (P) of activators in comparison with the comparator. Thrombin receptor activating peptide 6 (P, 1.32-2.68), arachidonic acid (P, 0.87-1.43), and epinephrine (P, 0.97-1.34) showed the greatest variability. ADP (P, 1.04-1.20) and ristocetin (P, 0.98-1.07) were the most consistent. The data highlighted clear interindividual variability, notably for ADP and epinephrine. Four profiles of responses were observed with ADP from high-responders, intermediate-responders, and low-responders. A fifth profile corresponding to nonresponders (5% of the individuals) was observed with epinephrine.

CONCLUSION

Based on these data, the establishment and adoption of simple standardization principles should mitigate variability due to activator sources. The observation of huge interindividual variability for certain concentrations of activators should lead to a cautious interpretation before reporting a result as abnormal. Confidence can be taken from the fact that difference between sources is not exacerbated in patients treated with antiplatelet agents.

Recent Advances on PKM2 Inhibitors and Activators in Cancer Applications

Metabolic reprogramming of cells, from the normal mode of glucose metabolism named glycolysis, is a pivotal characteristic of impending cancerous cells. Pyruvate kinase M2 (PKM2), an important enzyme that catalyzes the final rate-limiting stage during glycolysis, is highly expressed in numerous types of tumors and aids in development of favorable conditions for the survival of tumor cells. Increasing evidence has suggested that PKM2 is one of promising targets for innovative drug discovery, especially for the developments of antitumor therapeutics. Herein, we systematically summarize the recent advancement on PKM2 modulators including inhibitors and activators in cancer applications. We also discussed the classifications of pyruvate kinases in mammals and the biological functions of PKM2 in this review. We do hope that this review would provide a comprehensive understanding of the current research on PKM2 modulators, which may benefit the development of more potent PKM2-related drug candidates to treat PKM2-associated diseases including cancers in future.

High-throughput discovery and characterization of viral transcriptional effectors in human cells

Viruses encode transcriptional regulatory proteins critical for controlling viral and host gene expression. Given their multifunctional nature and high sequence divergence, it is unclear which viral proteins can affect transcription and which specific sequences contribute to this function. Using a high-throughput assay, we measured the transcriptional regulatory potential of over 60,000 protein tiles across ∼1,500 proteins from 11 coronaviruses and all nine human herpesviruses. We discovered hundreds of transcriptional effector domains, including a conserved repression domain in all coronavirus Spike homologs, dual activation-repression domains in viral interferon regulatory factors (VIRFs), and an activation domain in six herpesvirus homologs of the single-stranded DNA-binding protein that we show is important for viral replication and late gene expression in Kaposi's sarcoma-associated herpesvirus (KSHV). For the effector domains we identified, we investigated their mechanisms via high-throughput sequence and chemical perturbations, pinpointing sequence motifs essential for function. This work massively expands viral protein annotations, serving as a springboard for studying their biological and health implications and providing new candidates for compact gene regulation tools.

Aldehyde Dehydrogenases as Promising Targets for Treating Toxic Alde-hyde-related Diseases

<p>Background: Mammals are exposed to various endogenous and exogenous aldehydes, and aldehyde dehydrogenases (ALDHs) function to metabolize these aldehydes to acids to counteract aldehyde over-load. ALDHs therefore play important roles in a series of physiological and pathophysiological process-es. ALDHs activators and inhibitors are not only important probes for exploring ALDHs functions, but promising for the treatment of toxic aldehyde-related diseases. </p> <p> Methods: This review comprehensively summarized the categories and characteristics of 19 human ALDHs, elaborated their related biological pathways, such as alcohol metabolism, retinoic acid (RA) production, neurotransmitter metabolism, etc. Especially, reported ALDHs activators and inhibitors were summarized by listing their target, inhibition form and clinical application. </p> <p> Results: On the one hand, summarization of the types and relative functions is useful for further re-search on aldehyde metabolic pathways and related diseases. On the other hand, review of existing acti-vators and inhibitors of ALDHs contributes to discovering new leading compounds and provide new insights. </p> <p> Conclusion: In consideration of the important role ALDH plays in toxic aldehyde-related diseases, ALDHs are promising targets for the treatment of toxic aldehyde-related diseases, and advocate more research efforts to explore their pathophysiology and to develop new regulators. </p>.

Inhibitor and Activator: Dual Role of Subsurface Sulfide Enables Selective and Efficient Electro-Oxidation of Methanol to Formate on CuS@CuO Core-Shell Nanosheet Arrays

Selective electro-oxidation of aliphatic alcohols into value-added carboxylates at lower potentials than that of the oxygen evolution reaction (OER) is an environmentally and economically desirable anode reaction for clean energy storage and conversion technologies. However, it is challenging to achieve both high selectivity and high activity of the catalysts for the electro-oxidation of alcohols, such as the methanol oxidation reaction (MOR). Herein, a monolithic CuS@CuO/copper-foam electrode for the MOR with superior catalytic activity and almost 100% selectivity for formate is reported. In the core-shell CuS@CuO nanosheet arrays, the surface CuO directly catalyzes MOR, while the subsurface sulfide not only serves as an inhibitor to attenuate the oxidative power of the surface CuO to achieve selective oxidation of methanol to formate and prevent over-oxidation of formate to CO₂ but also serves as an activator to form more surface O defects as active sites and enhances the methanol adsorption and charge transfer to achieve superior catalytic activity. CuS@CuO/copper-foam electrodes can be prepared on a large scale by electro-oxidation of copper-foam at ambient conditions and can be readily utilized in clean energy technologies.

Imidazo[1,2-a]pyridine Derivatives as AMPK Activators: Synthesis, Structure-Activity Relationships, and Regulation of Reactive Oxygen Species in Renal Fibroblasts

Adenosine 5'-monophosphate activated protein kinase (AMPK) has emerged as a promising target for the discovery of drugs to treat diabetic nephropathy (DN). Herein, a series of imidazo[1,2-a]pyridines were designed and synthesized. Among them, the active compound (EC₅₀ =11.0 nM) showed good enzyme activation and molecular docking results showed hydrogen bonding interactions with the key amino acids Asn111 and Lys29 in the active site. Meanwhile, further cellular level experiments revealed that it could reduce reactive oxygen species (ROS) levels in NRK-49F cells induced by high glucose, and Western Blot experiments also demonstrate that it can increase the levels of p-AMPK and p-ACC and decrease the levels of TGF-β1. The results of this study extend the structural types of AMPK activators and provide novel lead compounds for the subsequent development.

Mitochondrial dynamics proteins as emerging drug targets

The importance of mitochondrial dynamics, the physiological process of mitochondrial fusion and fission, in regulating diverse cellular functions and cellular fitness has been well established. Several pathologies are associated with aberrant mitochondrial fusion or fission that is often a consequence of deregulated mitochondrial dynamics proteins; however, pharmacological targeting of these proteins has been lacking and is challenged by complex molecular mechanisms. Recent studies have advanced our understanding in this area and have enabled rational drug design and chemical screening strategies. We provide an updated overview of the regulatory mechanisms of fusion and fission proteins, their structure-function relationships, and the discovery of pharmacological modulators demonstrating their therapeutic potential. These advances provide exciting opportunities for the development of prototype therapeutics for various diseases.

Binding of RPR260243 at the intracellular side of the hERG1 channel pore domain slows closure of the helix bundle crossing gate

The opening and closing of voltage-dependent potassium channels is dependent on a tight coupling between movement of the voltage sensing S4 segments and the activation gate. A specific interaction between intracellular amino- and carboxyl-termini is required for the characteristically slow rate of channel closure (deactivation) of hERG1 channels. Compounds that increase hERG1 channel currents represent a novel approach for prevention of arrhythmia associated with prolonged ventricular repolarization. RPR260243 (RPR), a quinoline oxo-propyl piperidine derivative, inhibits inactivation and dramatically slows the rate of hERG1 channel deactivation. Here we report that similar to its effect on wild-type channels, RPR greatly slows the deactivation rate of hERG1 channels missing their amino-termini, or of split channels lacking a covalent link between the voltage sensor domain and the pore domain. By contrast, RPR did not slow deactivation of C-terminal truncated hERG1 channels or D540K hERG1 mutant channels activated by hyperpolarization. Together, these findings indicate that ability of RPR to slow deactivation requires an intact C-terminus, does not slow deactivation by stabilizing an interaction involving the amino-terminus or require a covalent link between the voltage sensor and pore domains. All-atom molecular dynamics simulations using the cryo-EM structure of the hERG1 channel revealed that RPR binds to a pocket located at the intracellular ends of helices S5 and S6 of a single subunit. The slowing of channel deactivation by RPR may be mediated by disruption of normal S5-S6 interactions.

Therapeutic Strategies to Activate p53

The p53 protein has appropriately been named the "guardian of the genome". In almost all human cancers, the powerful tumor suppressor function of p53 is compromised by a variety of mechanisms, including mutations with either loss of function or gain of function and inhibition by its negative regulators MDM2 and/or MDMX. We review herein the progress made on different therapeutic strategies for targeting p53.

Membrane targeting with palmitoylated lysine added to PP1-disrupting peptide induces PP1-independent signaling

Protein phosphatase-1 (PP1) is a ubiquitous enzyme involved in multiple processes inside cells. PP1-disrupting peptides (PDPs) are chemical tools that selectively bind to PP1 and release its activity. To restrict the activity of PDPs to a cellular compartment, we developed PDP-Mem, a cell membrane-targeting PDP. The membrane localization was achieved through the introduction of a palmitoylated lysine. PDP-Mem was shown to activate PP1α in vitro and to localize to the membrane of HeLa Kyoto and U2OS cells. However, in cells, the combination of the polybasic sequence for cell penetration and the membrane targeting palmitoylated lysine activates the MAPK signaling pathway and induces cytoplasmic calcium release independently of PP1 activation. Therefore, when targeting peptides to cellular membranes, undesired effects induced by the targeting sequence and lipid modification need to be considered.

Effect of Alkali and Sulfate on the Hydration Characteristic of Cement-Based Materials Containing Coal Gasification Slag

Coal gasification slag is an inevitable by-product of the coal gasification process. This paper explored the feasibility of using activators (calcium hydroxide, sodium hydroxide, calcium sulfate, sodium sulfate) to promote the pozzolanic activity of milled coal gasification coarse slags (MCS), and analyzed the effect of alkali and sulfate activators on the hydration characteristic of cement-based materials containing MCS. Coal gasification slags with ignition lossses more than 15% were removed and the remaining slags were considered as cementitious material after milling. Scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and hydration heat tests were employed to analyze the hydration mechanism of the samples. Besides, the compressive strength values of cement mortars with MCS and activators were evaluated. The results showed that calcium hydroxide was conductive to the formation of hydration products and its crystallization could contribute to the strength improvement of the sample. Calcium sulfate mainly participated in the hydration process of cement to form ettringite (AFt) phases. Sodium hydroxide could accelerate the dissolution of active mineral phases of MCS, resulting in the pozzolanic activity being enhanced. Moreover, sodium sulfate could not only increase the formation of AFt phases, but also improved the alkalinity in sample to facilitate the production of gels. Among them, a better promotion effect could be obtained from the combined application of calcium hydroxide and sodium sulfate. In addition, the compressive strength values of cement mortars containing MCS tended to increase when activators were used. The sample activated by calcium hydroxide and sodium sulfate exhibited the highest strength, increasing by 18.55% at 28 days compared with the sample without an activator.

Targeting protein conformations with small molecules to control protein complexes

Dynamic protein complexes function in all cellular processes, from signaling to transcription, using distinct conformations that regulate their activity. Conformational switching of proteins can turn on or off their activity through protein-protein interactions, catalytic function, cellular localization, or membrane interaction. Recent advances in structural, computational, and chemical methodologies have enabled the discovery of small-molecule activators and inhibitors of conformationally dynamic proteins by using a more rational design than a serendipitous screening approach. Here, we discuss such recent examples, focusing on the mechanism of protein conformational switching and its regulation by small molecules. We emphasize the rational approaches to control protein oligomerization with small molecules that offer exciting opportunities for investigation of novel biological mechanisms and drug discovery.

Sirtuin 1-Activating Compounds: Discovery of a Class of Thiazole-Based Derivatives

Sirtuin 1 (SIRT1) is a NAD⁺-dependent deacetylase implicated in various biological and pathological processes, including cancer, diabetes, and cardiovascular diseases. In recent years, SIRT1-activating compounds have been demonstrated to exert cardioprotective effects. Therefore, this enzyme has become a feasible target to treat cardiovascular diseases, and many SIRT1 activators, of a natural or synthetic origin, have been identified. In the present work, we developed thiazole-based SIRT1 activators, which showed remarkably higher SIRT1 activation potencies compared with those of the reference compound resveratrol when tested in enzymatic assays. Thiazole 8, a representative compound of this series, was also subjected to further pharmacological investigations, where it was proven to reduce myocardial damage induced by an in vivo occlusion/reperfusion event, thus confirming its cardioprotective properties. In addition, the cardioprotective effect of compound 8 was significantly higher than that of resveratrol. Molecular modeling studies suggest the binding mode of these derivatives within SIRT1 in the presence of the p53-AMC peptide. These promising results could pave the way to further expand and optimize this chemical class of new and potent SIRT1 activators as potential cardioprotective agents.

Insights on the Modulation of SIRT5 Activity: A Challenging Balance

SIRT5 is a member of the Sirtuin family, a class of deacetylating enzymes consisting of seven isoforms, involved in the regulation of several processes, including gene expression, metabolism, stress response, and aging. Considering that the anomalous activity of SIRT5 is linked to many pathological conditions, we present herein an overview of the most interesting modulators, with the aim of contributing to further development in this field.

Τelomerase inhibitors and activators in aging and cancer: A systematic review

The main aim of the present systematic review was to summarize the most frequently used telomerase regulators with an impact on aging and cancer that are referred to in in vitro and in vivo studies. For this purpose, a systematic review of the available literature on telomerase regulators referred to in articles from PubMed and Scopus libraries published from 2002 to 2021 and in accordance with PRISMA 2020 criteria, was conducted. Articles were included if they met the following criteria: They referred to telomerase modulators in aging and in cancer and were in vitro and/or in vivo studies, while studies that did not provide sufficient data or studies not written in English were excluded. In the present systematic review, 54 publications were included, of which 29 were full-text published studies, 11 were full-text reviews, 10 structure-based design studies and 4 abstracts are reported in this review. Telomerase regulators were then categorized as synthetic direct telomerase inhibitors, synthetic indirect telomerase inhibitors, synthetic telomerase activators, natural direct telomerase activators, natural telomerase inhibitors and natural indirect telomerase activators, according to their origin and their activity. On the whole, as demonstrated herein, telomerase regulators appear to be promising treatment agents in various age-related diseases. However, further in vivo and in vitro studies need to be performed in order to clarify the potentiality of telomerase as a therapeutic target.

Amine- and Amino Acid-Based Compounds as Carbonic Anhydrase Activators

After being rather neglected as a research field in the past, carbonic anhydrase activators (CAAs) were undoubtedly demonstrated to be useful in diverse pharmaceutical and industrial applications. They also improved the knowledge of the requirements to selectively interact with a CA isoform over the others and confirmed the catalytic mechanism of this class of compounds. Amino acid and amine derivatives were the most explored in in vitro, in vivo and crystallographic studies as CAAs. Most of them were able to activate human or non-human CA isoforms in the nanomolar range, being proposed as therapeutic and industrial tools. Some isoforms are better activated by amino acids than amines derivatives and the stereochemistry may exert a role. Finally, non-human CAs have been very recently tested for activation studies, paving the way to innovative industrial and environmental applications.

Activation of carbonic anhydrase isoforms involved in modulation of emotional memory and cognitive disorders with histamine agonists, antagonists and derivatives

Carbonic anhydrases (CAs, EC 4.2.1.1) activators were shown to be involved in memory enhancement and learning in animal models of cognition. Here we investigated the CA activating effects of a large series of histamine based compounds, including histamine receptors (H1R - H4R) agonists, antagonists and other derivatives of this autacoid. CA activators may be thus useful for improving cognition as well as in diverse therapeutic areas (phobias, obsessive-compulsive disorder, generalised anxiety, post-traumatic stress disorders), for which activation of this enzyme was recently shown to be involved.

Portland Versus Alkaline Cement: Continuity or Clean Break: "A Key Decision for Global Sustainability"

This review undertakes rigorous analysis of much of the copious literature available to the scientific community on the use of alkali-activated binders (AABs) in construction. The authors’ main intention is to categorically refute arguments of that part of the scientific community underestimating or even dismissing the actual potential of AABs as alternatives to Portland cement (PC). The main premise invoked in support of those arguments is a presumed lack of material resources for precursors that would make AAB industrial-scale production unfeasible anywhere on the planet (a substantial number of scientific papers show that the raw materials required for AAB manufacture are in abundance worldwide). The review also analyses the role of alkaline activators in the chemistry of AABs; it is important to clarify and highlight that alkaline activators are not, by any means, confined to the two synthetic products (caustic soda and waterglass) mostly employed by researchers; other sustainable and efficient products are widely available. Finally, the review deals with the versatility of AAB production processes. The technologies required for the large scale manufacturing of AABs are mostly already in place in PC factories; actually no huge investment is required to transform a PC plant in a AAB factory; and quality and compositional uniformity of Alkaline Cements (binders produced through an industrial process) would be guaranteed. The last conclusions extracted from this review-paper are related with: i) the low carbon footprint of one-part AABs and ii) the urgent need of exploring standardization formulas allowing the commercial development of (sustainable) binders different from PC.

Comparison of the Kinetic Parameters of Alternative Oxidases From Trypanosoma brucei and Arabidopsis thaliana-A Tale of Two Cavities

The alternative oxidase (AOX) is widespread in plants, fungi, and some protozoa. While the general structure of the AOX remains consistent, its overall activity, sources of kinetic activation and their sensitivity to inhibitors varies between species. In this study, the recombinant Trypanosoma brucei AOX (rTAO) and Arabidopsis thaliana AOX1A (rAtAOX1A) were expressed in the Escherichia coli ΔhemA mutant FN102, and the kinetic parameters of purified AOXs were compared. Results showed that rTAO possessed the highest V _max and K _m for quinol-1, while much lower V _max and K _m were observed in the rAtAOX1A. The catalytic efficiency (k _cat/K _m) of rTAO was higher than that of rAtAOX1A. The rTAO also displayed a higher oxygen affinity compared to rAtAOX1A. It should be noted that rAtAOX1a was sensitive to α-keto acids while rTAO was not. Nevertheless, only pyruvate and glyoxylate can fully activate Arabidopsis AOX. In addition, rTAO and rAtAOX1A showed different sensitivity to AOX inhibitors, with ascofuranone (AF) being the best inhibitor against rTAO, while colletochlorin B (CB) appeared to be the most effective inhibitor against rAtAOX1A. Octylgallate (OG) and salicylhydroxamic acid (SHAM) are less effective than the other inhibitors against protist and plant AOX. A Caver analysis indicated that the rTAO and rAtAOX1A differ with respect to the mixture of polar residues lining the hydrophobic cavity, which may account for the observed difference in kinetic and inhibitor sensitivities. The data obtained in this study are not only beneficial for our understanding of the variation in the kinetics of AOX within protozoa and plants but also contribute to the guidance for the future development of phytopathogenic fungicides.

The SAGA chromatin-modifying complex: the sum of its parts is greater than the whole

In this review, Soffers and Workman discuss the initial discovery of the canonical SAGA complex, the subsequent studies that have shaped our view on the internal organization of its subunits into modules, and the latest structural work that visualizes the modules and provides insights into their function.

There are many large protein complexes involved in transcription in a chromatin context. However, recent studies on the SAGA coactivator complex are generating new paradigms for how the components of these complexes function, both independently and in concert. This review highlights the initial discovery of the canonical SAGA complex 23 years ago, our evolving understanding of its modular structure and the relevance of its modular nature for its coactivator function in gene regulation.

Xanthones as P-glycoprotein modulators and their impact on drug bioavailability

Introduction: P-glycoprotein (P-gp) is an important efflux pump responsible for the extruding of many endogenous and exogenous substances out of the cells. P-gp can be modulated by different molecules - including xanthone derivatives - to surpass the multidrug resistance (MDR) phenomenon through P-gp inhibition, or to serve as an antidotal strategy in intoxication scenarios through P-gp induction/activation.Areas covered: This review provides a perspective on P-gp modulators, with particular focus on xanthonic derivatives, highlighting their ability to modulate P-gp expression and/or activity, and the potential impact of these effects on the pharmacokinetics, pharmacodynamics and toxicity of P-gp substrates.Expert opinion: Xanthones, of natural or synthetic origin, are able to modulate P-gp, interfering with its protein synthesis or with its mechanism of action, by decreasing or increasing its efflux capacity. These modulatory effects make the xanthonic scaffold a promising source of new derivatives with therapeutic potential. However, the mechanisms beyond the xanthones-mediated P-gp modulation and the chemical characteristics that make them more potent P-gp inhibitors or inducers/activators are still understudied. Furthermore, a new window of opportunity exists in the neuropathologies field, where xanthonic derivatives with potential to modulate P-gp should be further explored to optimize the prevention/treatment of brain pathologies.

Natural Sirtuin Modulators in Drug Discovery: A Review (2010 -2020)

There have been intense research interests in sirtuins since the establishment of their regulatory roles in a myriad of pathological processes. In the last two decades, much research efforts have been dedicated to the development of sirtuin modulators. Although synthetic sirtuin modulators are the focus, natural modulators remain an integral part to be further explored in this area as they are found to possess therapeutic potential in various diseases including cancers, neurodegenerative diseases, and metabolic disorders. Owing to the importance of this cluster of compounds, this review gives a current stand on the naturally occurring sirtuin modulators, , associated molecular mechanisms and their therapeutic benefits.. Furthermore, comprehensive data mining resulted in detailed statistical data analyses pertaining to the development trend of sirtuin modulators from 2010-2020. Lastly, the challenges and future prospect of natural sirtuin modulators in drug discovery will also be discussed.

Novel β-Glucocerebrosidase Activators That Bind to a New Pocket at a Dimer Interface and Induce Dimerization

Genetic, preclinical and clinical data link Parkinson's disease and Gaucher's disease and provide a rational entry point to disease modification therapy via enhancement of β-Glucocerebrosidase (GCase) activity. We discovered a new class of pyrrolo[2,3-b]pyrazine activators effecting both Vmax and Km. They bind to human GCase and increase substrate metabolism in the lysosome in a cellular assay. We obtained the first crystal structure for an activator and identified a novel non-inhibitory binding mode at the interface of a dimer, rationalizing the observed structure-activity relationship (SAR). The compound binds GCase inducing formation of a dimeric state at both endoplasmic reticulum (ER) and lysosomal pHs, as confirmed by analytical ultracentrifugation. Importantly, the pyrrolo[2,3-b]pyrazines have central nervous system (CNS) drug-like properties. Our findings are important for future drug discovery efforts in the field of GCase activation and provide a deeper mechanistic understanding of the requirements for enzymatic activation, pointing to the relevance of dimerization.

Emerging roles of SIRT6 in human diseases and its modulators

The biological functions of sirtuin 6 (SIRT6; e.g., deacetylation, defatty-acylation, and mono-ADP-ribosylation) play a pivotal role in regulating lifespan and several fundamental processes controlling aging such as DNA repair, gene expression, and telomeric maintenance. Over the past decades, the aberration of SIRT6 has been extensively observed in diverse life-threatening human diseases. In this comprehensive review, we summarize the critical roles of SIRT6 in the onset and progression of human diseases including cancer, inflammation, diabetes, steatohepatitis, arthritis, cardiovascular diseases, neurodegenerative diseases, viral infections, renal and corneal injuries, as well as the elucidation of the related signaling pathways. Moreover, we discuss the advances in the development of small molecule SIRT6 modulators including activators and inhibitors as well as their pharmacological profiles toward potential therapeutics for SIRT6-mediated diseases.

Pharmacological Targeting of IRE1 in Cancer

IRE1α (inositol requiring enzyme 1 alpha) is one of the main transducers of the unfolded protein response (UPR). IRE1α plays instrumental protumoral roles in several cancers, and high IRE1α activity has been associated with poorer prognoses. In this context, IRE1α has been identified as a potentially relevant therapeutic target. Pharmacological inhibition of IRE1α activity can be achieved by targeting either the kinase domain or the RNase domain. Herein, the recent advances in IRE1α pharmacological targeting is summarized. We describe the identification and optimization of IRE1α inhibitors as well as their mode of action and limitations as anticancer drugs. The potential pitfalls and challenges that could be faced in the clinic, and the opportunities that IRE1α modulating strategies may present are discussed.

Experimental Investigation of NaOH and KOH Mixture in SCBA-Based Geopolymer Cement Composite

This research aimed at exploring the effects of a mixture of sodium hydroxide (NaOH) and potassium hydroxide (KOH) activators in a sugar cane bagasse ash (SCBA)-based geopolymer cement paste. Bagasse ash replacement was 20% of cement by weight. The mixture of NaOH and KOH comprised 4, 8, and 12 M solutions with mixing percentages of 0%, 20%, 40%, 60%, 80%, and 100% for all possible combinations. A pH test was performed on each possible combination of solutions. A Chapelle’s test, XRD, X-ray fluorescence (XRF), and SEM analysis were used to check whether the SCBA exhibited pozzolanic reactivity. Subsequently, the SCBA geopolymer cement paste was tested for compressive strength, water absorption, permeable porosity, and sorptivity. It was estimated that the geopolymer cement paste exhibited higher absorption and sorptivity values than control mixtures when molarity increased. However, the samples prepared with combinations of the 8 M activator solution exhibited consistent absorption, sorptivity, and compressive strength values when compared to the control and other geopolymer mixtures with 4 and 12 M activator solutions. Thus, the two activator solutions G8N₄₀8K₆₀ and G8N₂₀8K₈₀—where GxN_ayK_b represents the geopolymer concrete sample prepared by adding solutions of two bases, i.e., ‘xN_ayK_b’ showing an ‘a’ percentage of ‘x’ molar NaOH and a ‘b’ percentage of ‘y’ molar KOH—were obtained as the optimum molar ratio of the activator in geopolymer concrete. The geopolymer cement pastes, along with the optimum and control samples, were further tested for concrete durability, SEM, and TGA tests. The G8N₂₀8K₈₀ sample exhibited a better mechanical and durability performance than the G8N₄₀8K₆₀ sample. The durability performance of the geopolymer concrete was also superior to ordinary concrete. Moreover, the geopolymer concrete achieved a 21% reduction in global warming potential compared to the control mixture. Thus, it can be concluded that the use of SCBA in geopolymer concrete can address the ash disposal and CO₂ emission problems with enhanced durability.

The Effects of Aluminium Sulphate on Slag Paste Activated with Sodium Hydroxide and Sodium Silicate

This study investigates the characteristics of alkali-activated slag cement using aluminium sulphate (ALS) as an activator. The alkalis NaOH and Na₂SiO₃ were used as additional activators (denoted by alkali) at 5% and 10% of the weight of the ground granulated blast furnace slag (GGBFS). Three types of activators were considered. The first was when ALS was used alone. For the second, ALS and 5% alkali were used together. The third was when ALS and 10% alkali were used. ALS was used at concentrations of 2%, 4%, 6%, 8%, and 10% based on binder weight. Experimental results show that when ALS was used as a sole activator, the activity of GGBFS was low and its strength was below 1 MPa. However, compressive strength was improved when 5% or 10% alkali and ALS were used at the same time. This was effective at improving mechanical and microstructural performance when used with an additional activator capable of forming a more alkaline environment than using ALS as a sole activator.

Investigating the utility of adult zebrafish ex vivo whole hearts to pharmacologically screen hERG channel activator compounds

There is significant interest in the potential utility of small-molecule activator compounds to mitigate cardiac arrhythmia caused by loss of function of hERG1a voltage-gated potassium channels. Zebrafish (Danio rerio) have been proposed as a cost-effective, high-throughput drug-screening model to identify compounds that cause hERG1a dysfunction. However, there are no reports on the effects of hERG1a activator compounds in zebrafish and consequently on the utility of the model to screen for potential gain-of-function therapeutics. Here, we examined the effects of hERG1a blocker and types 1 and 2 activator compounds on isolated zkcnh6a (zERG3) channels in the Xenopus oocyte expression system as well as action potentials recorded from ex vivo adult zebrafish whole hearts using optical mapping. Our functional data from isolated zkcnh6a channels show that under the conditions tested, these channels are blocked by hERG1a channel blockers (dofetilide and terfenadine), and activated by type 1 (RPR260243) and type 2 (NS1643, PD-118057) hERG1a activators with higher affinity than hKCNH2a channels (except NS1643), with differences accounted for by different biophysical properties in the two channels. In ex vivo zebrafish whole hearts, two of the three hERG1a activators examined caused abbreviation of the action potential duration (APD), whereas hERG1a blockers caused APD prolongation. These data represent, to our knowledge, the first pharmacological characterization of isolated zkcnh6a channels and the first assessment of hERG enhancing therapeutics in zebrafish. Our findings lead us to suggest that the zebrafish ex vivo whole heart model serves as a valuable tool in the screening of hKCNH2a blocker and activator compounds.

Recent Advances of Natural Polyphenols Activators for Keap1-Nrf2 Signaling Pathway

The Keap1-Nrf2/ARE signaling pathway is an important defense system against exogenous and endogenous oxidative stress injury. The dysregulation of the signaling pathway is associated with many diseases, such as cancer, diabetes, and respiratory diseases. Over the years, a wide range of natural products has provided sufficient resources for the discovery of potential therapeutic drugs. Among them, polyphenols possess Nrf2 activation, not only inhibit the production of ROS, inhibit Keap1-Nrf2 protein-protein interaction, but also degrade Keap1 and regulate the Nrf2 related pathway. In fact, with the continuous improvement of natural polyphenols separation and purification technology and further studies on the Keap1-Nrf2 molecular mechanism, more and more natural polyphenols monomer components of Nrf2 activators have been gradually discovered. In this view, we summarize the research status of natural polyphenols that have been found with apparent Nrf2 activation and their action modes. On the whole, this review may guide the design of novel Keap1-Nrf2 activator.

Effect of Carbonation on Abrasion Resistance of Alkali-Activated Slag with Various Activators

The effect of carbonation on the abrasion resistance of alkali-activated slag (AAS) was investigated. Various activator sets were selected for synthesizing AAS specimens, and the compressive strength was measured before and after carbonation. The abrasion resistance of the specimens was measured in accordance with the ASTM C944 test method. The relationship between the mass loss caused by abrasion and compressive strength was analyzed to understand the effect of matrix strength on abrasion resistance. Test results showed that the decrease in compressive strength of AAS specimens by carbonation reduced their abrasion resistance. In addition, the abrasion resistance of AAS before and after carbonation was sensitively influenced by activator type. It can be concluded that additional caution is required when using AAS where abrasion may have occurred.

The first activation study of the β-carbonic anhydrases from the pathogenic bacteria Brucella suis and Francisella tularensis with amines and amino acids

The activation of the β-class carbonic anhydrases (CAs, EC 4.2.1.1) from the bacteria Brucella suis and Francisella tularensis with amine and amino acids was investigated. BsuCA 1 was sensitive to activation with amino acids and amines, whereas FtuCA was not. The most effective BsuCA 1 activators were L-adrenaline and D-Tyr (K_As of 0.70–0.95 µM). L-His, L-/D-Phe, L-/D-DOPA, L-Trp, L-Tyr, 4-amino-L-Phe, dopamine, 2-pyridyl-methylamine, D-Glu and L-Gln showed activation constants in the range of 0.70–3.21 µM. FtuCA was sensitive to activation with L-Glu (K_A of 9.13 µM). Most of the investigated compounds showed a weak activating effect against FtuCA (K_As of 30.5–78.3 µM). Many of the investigated amino acid and amines are present in high concentrations in many tissues in vertebrates, and their role in the pathogenicity of the two bacteria is poorly understood. Our study may bring insights in processes connected with invasion and pathogenic effects of intracellular bacteria.

Quinoline Derivatives Kill Mycobacterium tuberculosis by Activating Glutamate Kinase

There is a great need for identification and development of new anti-tuberculosis drugs with novel targets. Recent drug-discovery efforts typically focus on identifying inhibitors but not activators that perturb metabolic enzymes' functions as a means to kill Mycobacterium tuberculosis (Mtb). Here, we describe a class of quinoline compounds, Z0933/Z0930, which kill Mtb by acting as activators of glutamate kinase (GK), a previously untargeted enzyme catalyzing the first step of proline biosynthesis. We further show that Z0933/Z0930 augment proline production and induce Mtb killing via proline-derived redox imbalance and production of reactive oxygen species. This work highlights the effectiveness of gain-of-function probes against Mtb and provides a framework for the discovery of next-generation allosteric activators of GK.

Activators of Sirtuin-1 and their Involvement in Cardioprotection

SIRT1 is a nicotinamide adenosine dinucleotide (NAD+)-dependent deacetylase, which removes acetyl groups from many target proteins, such as histone proteins, transcription factors and cofactors. SIRT1-catalyzed deacetylation of these factors modulates the activity of downstream proteins, thus influencing many biological processes. SIRT1 is involved in the regulation of metabolism, inflammation, and tumor growth. The activity of this enzyme is related to the beneficial health effects of calorie restriction, such as lifespan extension and, in particular, the activation of SIRT1 has a positive impact on the cardiovascular system. Therefore, SIRT1 is considered as an attractive drug target and modulation of SIRT1 may represent a new therapeutic strategy against cardiovascular diseases, as small molecules able to activate SIRT1 can be considered as cardioprotective agents. In this review, we summarize both natural and synthetic compounds developed as SIRT1 activators, with a focus on their promising therapeutic applications in cardiovascular pathologies.

Comparison of the amine/amino acid activation profiles of the β- and γ-carbonic anhydrases from the pathogenic bacterium Burkholderia pseudomallei

The β-class carbonic anhydrase (CA, EC 4.2.1.1) from the pathogenic bacterium Burkholderia pseudomallei, BpsCAβ, that is responsible for the tropical disease melioidosis was investigated for its activation with natural and non-natural amino acids and amines. Previously, the γ-CA from this bacterium has been investigated with the same library of 19 amines/amino acids, which show very potent activating effects on both enzymes. The most effective BpsCAβ activators were L- and D-DOPA, L- and D-Trp, L-Tyr, 4-amino-L-Phe, histamine, dopamine, serotonin, 2-pyridyl-methylamine, 1-(2-aminoethyl)-piperazine and L-adrenaline with KAs of 0.9-27 nM. Less effective activators were D-His, L- and D-Phe, D-Tyr, 2-(2-aminoethyl)pyridine and 4-(2-aminoethyl)-morpholine with KAs of 73 nM-3.42 µM. The activation of CAs from bacteria, such as BpsCAγ/β, has not been considered previously for possible biomedical applications. It would be of interest to perform studies in which bacteria are cultivated in the presence of CA activators, which may contribute to understanding processes connected with the virulence and colonization of the host by pathogenic bacteria.

Activation studies with amines and amino acids of the β-carbonic anhydrase encoded by the Rv3273 gene from the pathogenic bacterium Mycobacterium tuberculosis

The activation of a β-class carbonic anhydrase (CAs, EC 4.2.1.1) from Mycobacterium tuberculosis, encoded by the gene Rv3273 (mtCA 3), was investigated using a panel of natural and non-natural amino acids and amines. mtCA 3 was effectively activated by D-DOPA, L-Trp, dopamine and serotonin, with KAs ranging between 8.98 and 12.1 µM. L-His and D-Tyr showed medium potency activating effects, with KAs in the range of 17.6-18.2 µM, whereas other amines and amino acids were relatively ineffective activators, with KAs in the range of 28.9-52.2 µM. As the physiological roles of the three mtCAs present in this pathogen are currently poorly understood and considering that inhibition of these enzymes has strong antibacterial effects, discovering molecules that modulate their enzymatic activity may lead to a better understanding of the factors related to the invasion and colonisation of the host during Mycobacterium tuberculosis infection.

Inhibition of α-, β-, γ-, and δ-carbonic anhydrases from bacteria and diatoms with N'-aryl-N-hydroxy-ureas

The inhibition of α-, β-, γ-, and δ-class carbonic anhydrases (CAs, EC 4.2.1.1) from bacteria (Vibrio cholerae and Porphyromonas gingivalis) and diatoms (Thalassiosira weissflogii) with a panel of N'-aryl-N-hydroxy-ureas is reported. The α-/β-CAs from V. cholerae (VchCAα and VchCAβ) were effectively inhibited by some of these derivatives, with KIs in the range of 97.5 nM - 7.26 µM and 52.5 nM - 1.81 µM, respectively, whereas the γ-class enzyme VchCAγ was less sensitive to inhibition (KIs of 4.75 - 8.87 µM). The β-CA from the pathogenic bacterium Porphyromonas gingivalis (PgiCAβ) was not inhibited by these compounds (KIs > 10 µM) whereas the corresponding γ-class enzyme (PgiCAγ) was effectively inhibited (KIs of 59.8 nM - 6.42 µM). The δ-CA from the diatom Thalassiosira weissflogii (TweCAδ) showed effective inhibition with these derivatives (KIs of 33.3 nM - 8.74 µM). As most of these N-hydroxyureas are also ineffective as inhibitors of the human (h) widespread isoforms hCA I and II (KIs > 10 µM), this class of derivatives may lead to the development of CA inhibitors selective for bacterial/diatom enzymes over their human counterparts and thus to anti-infectives or agents with environmental applications.

Activation studies of the α- and β-carbonic anhydrases from the pathogenic bacterium Vibrio cholerae with amines and amino acids

The α- and β-class carbonic anhydrases (CAs, EC 4.2.1.1) from the pathogenic bacterium Vibrio cholerae, VchCAα, and VchCAβ, were investigated for their activation with natural and non-natural amino acids and amines. The most effective VchCAα activators were L-tyrosine, histamine, serotonin, and 4-aminoethyl-morpholine, which had KAs in the range of 8.21-12.0 µM. The most effective VchCAβ activators were D-tyrosine, dopamine, serotonin, 2-pyridyl-methylamine, 2-aminoethylpyridine, and 2-aminoethylpiperazine, which had KAs in the submicromolar - low micromolar range (0.18-1.37 µM). The two bacterial enzymes had very different activation profiles with these compounds, between each other, and in comparison to the human isoforms hCA I and II. Some amines were selective activators of VchCAβ, including 2-pyridylmethylamine (KA of 180 nm for VchCAβ, and more than 20 µM for VchCAα and hCA I/II). The activation of CAs from bacteria, such as VchCAα/β has not been considered previously for possible biomedical applications. It would be of interest to study in more detail the extent that CA activators are implicated in the virulence and colonisation of the host by such pathogenic bacteria, which for Vibrio cholerae, is highly dependent on the bicarbonate concentration and pH in the surrounding tissue.

Interrogating PP1 Activity in the MAPK Pathway with Optimized PP1-Disrupting Peptides

Protein phosphatase‐1 (PP1)‐disrupting peptides (PDPs) are selective chemical modulators of PP1 that liberate the active PP1 catalytic subunit from regulatory proteins; thus allowing the dephosphorylation of nearby substrates. We have optimized the original cell‐active PDP3 for enhanced stability, and obtained insights into the chemical requirements for stabilizing this 23‐mer peptide for cellular applications. The optimized PDP‐Nal was used to dissect the involvement of PP1 in the MAPK signaling cascade. Specifically, we have demonstrated that, in human osteosarcoma (U2OS) cells, phosphoMEK1/2 is a direct substrate of PP1, whereas dephosphorylation of phosphoERK1/2 is indirect and likely mediated through enhanced tyrosine phosphatase activity after PDP‐mediated PP1 activation. Thus, as liberators of PP1 activity, PDPs represent a valuable tool for identifying the substrates of PP1 and understanding its role in diverse signaling cascades.

[Non-neurogenic activators of myocyte contraction and their role in the realization of the accumulative-evacuating functions of the urinary bladder]

The search for and use of alternative biomarkers of the hyperactive bladder has garnered increasing attention in recent years because they may be considered pathogenetically significant and used as surrogate biomarkers. Promising agents that have met these criteria include proteins cytokines, neurotrophins, tumor necrosis factor (TNF), nerve growth factor (NGF), fibrinopeptides A and B, C-reactive protein, membrane-bound ATPase. Analysis of current scientific literature has demonstrated that specialists in many fields of medicine show interest in endogenous proteins that do not belong to neurotransmitters but affect the contractile ability of myocytes. The presented data indicate the feasibility and prospects of their use, but further studies and evaluation are needed. Based on the present literature review, the authors conclude that endogenous proteins activating myocyte contractility are of great clinical value as promising markers for detecting detrusor overactivity, its severity, and evaluation of the treatment effectiveness. The authors suggest that proteins of this group can play an important role not only in the pathogenesis of bladder function disorders but also in the physiological process of urination as an additional non-neurogenic humeral component.

The first activation study of a δ-carbonic anhydrase: TweCAδ from the diatom Thalassiosira weissflogii is effectively activated by amines and amino acids

The activation of the δ-class carbonic anhydrase (CAs, EC 4.2.1.1) from the diatom Thalassiosira weissflogii (TweCAδ) was investigated using a panel of natural and non-natural amino acids and amines. The most effective activator of TweCAδ was d-Tyr (K_A of 51 nM), whereas several other amino acids and amines, such as L-His, L-Trp, d-Trp, dopamine and serotonin were submicromolar activators (K_As from 0.51 to 0.93 µM). The most ineffective activator of TweCAδ was 4-amino-l-Phe (18.9 µM), whereas d-His, l-/d-Phe, l-/d-DOPA, l-Tyr, histamine, some pyridyl-alkylamines, l-adrenaline and aminoethyl-piperazine/morpholine were moderately potent activators (K_As from 1.34 to 8.16 µM). For any δ-CA, there are no data on the crystal structure, homology modelling and the amino acid residues that are responsible for proton transfer to the active site are currently unknown making it challenging to provide a detailed rational for these findings. However, these data provide further evidence that this class of underexplored CA deserves more attention.

A Statistical Thermodynamic Model for Ligands Interacting With Ion Channels: Theoretical Model and Experimental Validation of the KCNQ2 Channel

Ion channels are important therapeutic targets, and their pharmacology is becoming increasingly important. However, knowledge of the mechanism of interaction of the activators and ion channels is still limited due to the complexity of the mechanisms. A statistical thermodynamic model has been developed in this study to characterize the cooperative binding of activators to ion channels. By fitting experimental concentration-response data, the model gives eight parameters for revealing the mechanism of an activator potentiating an ion channel, i.e., the binding affinity (K_A), the binding cooperative coefficients for two to four activator molecules interacting with one channel (γ, μ, and ν), and the channel conductance coefficients for four activator binding configurations of the channel (a, b, c, and d). Values for the model parameters and the mechanism underlying the interaction of ztz240, a proven KCNQ2 activator, with the wild-type channel have been obtained and revealed by fitting the concentration-response data of this activator potentiating the outward current amplitudes of KCNQ2. With these parameters, our model predicted an unexpected bi-sigmoid concentration-response curve of ztz240 activation of the WT-F137A mutant heteromeric channel that was in good agreement with the experimental data determined in parallel in this study, lending credence to the assumptions on which the model is based and to the model itself. Our model can provide a better fit to the measured data than the Hill equation and estimates the binding affinity, as well as the cooperative coefficients for the binding of activators and conductance coefficients for binding states, which validates its use in studying ligand-channel interaction mechanisms.

Oxidation of Methylalumoxane Oligomers

The anions formed from methylalumoxane (MAO) and suitable donors (e.g. octamethyltrisiloxane) are amenable to mass spectrometric (MS) analysis. Their composition as deduced from this data allows direct insight into the chemical transformations of their neutral precursors. One such process is oxidation, which is well-known to be facile for MAO without any clear idea of what actually occurs at a molecular level. Addition of O₂ to MAO results in immediate gelation, but MS analysis reveals no corresponding change to the composition of the principal oligomeric anions. A slow (hours) reaction does occur that involves net incorporation of Me₂ AlOMe into the oligomeric anions, and the identities of the OMe-containing anions were confirmed by ¹ H NMR spectroscopy, MS/MS analysis, and addition of an authentic sample of Me₂ AlOMe to MAO. The result tallies with the fact that addition of O₂ to MAO produces Me₂ AlOMe from free Me₃ Al which eventually leads to formation of oxidized MAO oligomers and changes in ion abundance. Aging of the oxygenated MAO results in further growth of the oligomers similar to that of the non-oxidized species. Mass spectrometric analysis therefore reveals useful insights into the environmental history of a given MAO batch.

Activation Profile Analysis of CruCA4, an α-Carbonic Anhydrase Involved in Skeleton Formation of the Mediterranean Red Coral, Corallium rubrum

CruCA4, a coral α-carbonic anhydrase (CA, EC 4.2.1.1) involved in the biomineralization process of the Mediterranean red coral, Corallium rubrum, was investigated for its activation with a panel of amino acids and amines. Most compounds showed considerable activating properties, with a rather well defined structure-activity relationship. The most effective CruCA4 activators were d-His, 4-H₂N-l-Phe, Histamine, Dopamine, Serotonin, 1-(2-Aminoethyl)-piperazine, and l-Adrenaline, with activation constants in the range of 8-98 nM. Other amines and amino acids, such as d-DOPA, l-Tyr, 2-Pyridyl-methylamine, 2-(2-Aminoethyl) pyridine and 4-(2-Aminoethyl)-morpholine, were submicromolar CruCA4 activators, with K_A ranging between 0.15 and 0.93 µM. Since it has been shown that CA activators may facilitate the initial phases of in-bone mineralization, our study may be relevant for finding modulators of enzyme activity, which can enhance the formation of the red coral skeleton.

Autophagy: A Druggable Process

Macroautophagy (hereafter called autophagy) is a vacuolar, lysosomal pathway for catabolism of intracellular material that is conserved among eukaryotic cells. Autophagy plays a crucial role in tissue homeostasis, adaptation to stress situations, immune responses, and the regulation of the inflammatory response. Blockade or uncontrolled activation of autophagy is associated with cancer, diabetes, obesity, cardiovascular disease, neurodegenerative disease, autoimmune disease, infection, and chronic inflammatory disease. During the past decade, researchers have made major progress in understanding the three levels of regulation of autophagy in mammalian cells: signaling, autophagosome formation, and autophagosome maturation and lysosomal degradation. As we discuss in this review, each of these levels is potentially druggable, and, depending on the indication, may be able to stimulate or inhibit autophagy. We also summarize the different modulators of autophagy and their potential and limitations in the treatment of life-threatening diseases.

Therapeutic Implications of Autophagy Inducers in Immunological Disorders, Infection, and Cancer

Autophagy is an essential catabolic program that forms part of the stress response and enables cells to break down their own intracellular components within lysosomes for recycling. Accumulating evidence suggests that autophagy plays vital roles in determining pathological outcomes of immune responses and tumorigenesis. Autophagy regulates innate and adaptive immunity affecting the pathologies of infectious, inflammatory, and autoimmune diseases. In cancer, autophagy appears to play distinct roles depending on the context of the malignancy by either promoting or suppressing key determinants of cancer cell survival. This review covers recent developments in the understanding of autophagy and discusses potential therapeutic interventions that may alter the outcomes of certain diseases.

Small molecules as activators in medicinal chemistry (2000-2016)

INTRODUCTION

From therapeutic point of view, it is often beneficial to enhance the expression of certain enzymes whose low expression is responsible for the observed ailment. Small molecules as activators of several enzymes have great biological potential as anti-microbial and anti-cancer agents, for the treatment of diabetes, obesity, metabolic disorders, and for the treatment of neurological disorders including Alzheimer's disease. This review covers patents describing small molecules as activators, and provides structural leads for the design of even more potent activators. Area covered: This review is focused on small molecules that have been explored as activators of enzymes in the last and current decade (2000-2016). Expert opinion: The ability to modulate activity of enzymes has long been a quest of medicinal chemistry. This has been the impetus behind the development of a plethora of drugs as enzyme inhibitors. However only a few enzyme activators as drugs have made it to the market. Disorders characterized by supressed enzyme activity can be treated by enhancing the activity of a specific enzyme.

Luminally Acting Agents for Constipation Treatment: A Review Based on Literatures and Patents

Constipation is one of the most frequently reported gastrointestinal (GI) disorders that negatively impacts quality of life and is associated with a significant economic burden to the patients and society. Traditional treatments including lifestyle modification and laxatives are often ineffective in the more severe forms of constipation and over the long term. New medications targeting at intestinal chloride channels and colonic serotonin receptors have been demonstrated effective in recent years. Emerging agents focusing on improving intestinal secretion and/or colonic motility have been shown effective in animal models and even in clinical trials. Recognization of the role of cystic fibrosis transmembrane regulator (CFTR) and calcium-activated chloride channels (CaCCs) in intestine fluid secretion and motility modulation makes CFTR and CaCCs promising molecule targets for anti-constipation therapy. Although there are multiple choices for constipation treatment, there is still a recognized need for new medications in anti-constipation therapy. The present review covers the discovery of luminally acting agents for constipation treatment described in both patents (2011–present) and scientific literatures.

Cellular Models and In Vitro Assays for the Screening of modulators of P-gp, MRP1 and BCRP

Adenosine triphosphate (ATP)-binding cassette (ABC) transporters are highly expressed in tumor cells, as well as in organs involved in absorption and secretion processes, mediating the ATP-dependent efflux of compounds, both endogenous substances and xenobiotics, including drugs. Their expression and activity levels are modulated by the presence of inhibitors, inducers and/or activators. In vitro, ex vivo and in vivo studies with both known and newly synthesized P-glycoprotein (P-gp) inducers and/or activators have shown the usefulness of these transport mechanisms in reducing the systemic exposure and specific tissue access of potentially harmful compounds. This article focuses on the main ABC transporters involved in multidrug resistance [P-gp, multidrug resistance-associated protein 1 (MRP1) and breast cancer resistance protein (BCRP)] expressed in tissues of toxicological relevance, such as the blood-brain barrier, cardiovascular system, liver, kidney and intestine. Moreover, it provides a review of the available cellular models, in vitro and ex vivo assays for the screening and selection of safe and specific inducers and activators of these membrane transporters. The available cellular models and in vitro assays have been proposed as high throughput and low-cost alternatives to excessive animal testing, allowing the evaluation of a large number of compounds.