Insights into nucleoside hydrolase from Leishmania donovani inhibition: A new bioaffinity chromatography-based screening assay and docking studies

Leishmaniasis, a group of neglected infectious diseases, encompasses a serious health concern, particularly with visceral leishmaniasis exhibiting potentially fatal outcomes. Nucleoside hydrolase (NH) has a fundamental role in the purine salvage pathway, crucial for Leishmania donovani survival, and presents a promising target for developing new drugs for visceral leishmaniasis treatment. In this study, LdNH was immobilized into fused silica capillaries, resulting in immobilized enzyme reactors (IMERs). The LdNH-IMER activity was monitored on-flow in a multidimensional liquid chromatography system, with the IMER in the first dimension. A C18 analytical column in the second dimension furnished the rapid separation of the substrate (inosine) and product (hypoxanthine), enabling direct enzyme activity monitoring through product quantification. LdNH-IMER exhibited high stability and was characterized by determining the Michaelis-Menten constant. A known inhibitor (1-(β-d-Ribofuranosyl)-4-quinolone derivative) was used as a model to validate the established method in inhibitor recognition. Screening of three additional derivatives of 1-(β-d-Ribofuranosyl)-4-quinolone led to the discovery of novel inhibitors, with compound 2a exhibiting superior inhibitory activity (Ki = 23.37 ± 3.64 µmol/L) compared to the employed model inhibitor. Docking and Molecular Dynamics studies provided crucial insights into inhibitor interactions at the enzyme active site, offering valuable information for developing new LdNH inhibitors. Therefore, this study presents a novel screening assay and contributes to the development of potent LdNH inhibitors.

Synthesis and kinetic evaluation of phosphomimetic inhibitors targeting type B ribose-5-phosphate isomerase from Mycobacterium tuberculosis

Because tuberculosis is still a major health threat worldwide, identification of new drug targets is urgently needed. In this study, we considered type B ribose-5-phosphate isomerase from Mycobacterium tuberculosis as a potential target, and addressed known problems of previous inhibitors in terms of their sensitivity to hydrolysis catalyzed by phosphatase enzymes, which impaired their potential use as drugs. To this end, we synthesized six novel phosphomimetic compounds designed to be hydrolytically stable analogs of the substrate ribose 5-phosphate and the best known inhibitor 5-phospho-d-ribonate. The phosphate function was replaced by phosphonomethyl, sulfate, sulfonomethyl, or malonate groups. Inhibition was evaluated on type A and type B ribose-5-phosphate isomerases, and stability towards hydrolysis using alkaline phosphatase and veal serum was assessed. One of the phosphomimetic analogs, 5-deoxy-5-phosphonomethyl-d-ribonate, emerged as the first strong and specific inhibitor of the M. tuberculosis enzyme that is resistant to hydrolysis.

Engineering Selective TIMPs Using a Counter-Selective Screening Strategy

The yeast surface display platform provides a powerful approach for screening protein diversity libraries to identify binders with an enhanced affinity toward a binding partner. Here, we describe an adaptation of the approach to identify binders with enhanced specificity toward one among multiple closely related binding partners. Specifically, we describe methods for engineering selective matrix metalloproteinase (MMP) inhibitors via yeast surface display of a tissue inhibitor of metalloproteinase (TIMP) diversity library coupled with a counter-selective screening strategy. This protocol may also be employed for developing selective protein binders or inhibitors toward other targets.

Dual COX-2/15-LOX inhibitors: A new avenue in the prevention of cancer

Dual cyclooxygenase 2/15-lipoxygenase inhibitors constitute a valuable alternative to classical non-steroidal anti-inflammatory drugs (NSAIDs) and selective COX-2 (cyclooxygenase-2) inhibitors for the treatment of inflammatory diseases, as well as preventing the cancer. Indeed, these latter present diverse side effects, which are reduced or absent in dual-acting agents. In this review, COX-2 and 15-LOX (15-lipoxygenase) pathways are first described in order to highlight the therapeutic interest of designing such compounds. Various structural families of dual inhibitors are illustrated. This study discloses various structural families of dual 15-LOX/COX-2 inhibitors, thus pave the way to design potentially-active anticancer agents with balanced dual inhibition of these enzymes.

Recent advances in the discovery of tropomyosin receptor kinases TRKs inhibitors: A mini review

The tropomyosin receptor tyrosine kinases (TRKs) control the cell proliferation mainly in the nervous system and are encoded by NTRK genes. Fusion and mutation of NTRK genes were detected in various types of cancers. Many small molecules TRK inhibitors have been discovered during the last two decades and some of them have entered clinical trials. Moreover, two of these inhibitors; larotrectinib and entrectinib; were approved by FDA for the treatment of TRK-fusion positive solid tumors. However, mutation of TRK enzymes resulted in resistance to both drugs. Therefore, next generation TRK inhibitors were discovered to overcome the acquired drug resistance. Additionally, the off-target and on-target adverse effects on the brain initiated the need for selective TRK subtype inhibitors. Indeed, some molecules were recently reported as selective TRKA or TRKC inhibitors with minimal CNS side effects. The current review highlighted the efforts done during the last three years in the design and discovery of novel TRK inhibitors.

Inhibitory activity of catecholic phosphonic and phosphinic acids against Helicobacter pylori ureolysis

Catechols have been reported to be potent covalent inhibitors of ureases, and they exhibit activity by modifying cysteine residues at the entrance to enzymatic active sites. Following these principles, we designed and synthesized novel catecholic derivatives that contained carboxylate and phosphonic/phosphinic functionalities and assumed expanded specific interactions. When studying the chemical stability of the molecules, we found that their intrinsic acidity catalyzes spontaneous esterification/hydrolysis reactions in methanol or water solutions, respectively. Regarding biological activity, the most promising compound, 2-(3,4-dihydroxyphenyl)-3-phosphonopropionic acid (15), exhibited significant anti-urease potential (K_i = 2.36 μM, Sporosarcinia pasteurii urease), which was reflected in the antiureolytic effect in live Helicobacter pylori cells at a submicromolar concentration (IC₅₀ = 0.75 μM). As illustrated by molecular modeling, this compound was bound in the active site of urease through a set of concerted electrostatic and hydrogen bond interactions. The antiureolytic activity of catecholic phosphonic acids could be specific because these compounds were chemically inert and not cytotoxic to eukaryotic cells.

The transmembrane domain of Frey1 harbors a transplantable inhibitory motif for intramembrane proteases

Although aspartic intramembrane-cleaving proteases (I-CLIPs) are crucial switches of multiple signaling pathways and involved in several devastating diseases, little is known about their physiological regulation. We have recently identified Frey regulator of sperm-oocyte fusion 1 (Frey1) as an inhibitory protein of Signal Peptide Peptidase-like 2c (SPPL2c), a member of this protease family. Employing structure modeling along with cell-based inhibition and interaction studies, we identify a short motif within the Frey1 transmembrane domain essential for inhibition of SPPL2c. Intriguingly, this motif can be transplanted to the SPPL2c substrate PLN, thereby transforming it into an inhibitor of this enzyme. It can be adopted for the generation of Notch1-based γ-Secretase inhibitors demonstrating its versatile use among aspartic I-CLIPs. In summary, we describe a mechanism of aspartic I-CLIP inhibition which allows the targeted generation of specific inhibitors of these enzymes and might enable the identification of endogenous negative regulators of these enzymes.

Protein targets in Mycobacterium tuberculosis and their inhibitors for therapeutic implications: A narrative review

Advancement in the area of anti-tubercular drug development has been full-fledged, yet, a very less number of drug molecules have reached phase II clinical trials, and therefore "End-TB" is still a global challenge. Inhibitors to specific metabolic pathways of Mycobacterium tuberculosis (Mtb) gain importance in strategizing anti-tuberculosis drug discovery. The lead compounds that target DNA replication, protein synthesis, cell wall biosynthesis, bacterial virulence and energy metabolism are emerging as potential chemotherapeutic options against Mtb growth and survival within the host. In recent times, the in silico approaches have become most promising tools in the identification of suitable inhibitors for specific protein targets of Mtb. An update in the fundamental understanding of these inhibitors and the mechanism of interaction may bring hope to future perspectives in novel drug development and delivery approaches. This review provides a collective impression of the small molecules with potential antimycobacterial activities and their target pathways in Mtb such as cell wall biosynthesis, DNA replication, transcription and translation, efflux pumps, antivirulence pathways and general metabolism. The mechanism of interaction of specific inhibitor with their respective protein targets has been discussed. The comprehensive knowledge of such an impactful area of research would essentially reflect in the discovery of novel drug molecules and effective delivery approaches. This narrative review encompasses the knowledge of emerging targets and promising n that could potentially translate in to the anti-TB-drug discovery.

Synthesis of sugar enones and their use as powerful synthetic precursors of thiodisaccharides

Monosaccharide derivatives having a double bond conjugated to a carbonyl (sugar enones or enuloses) are relevant synthetic tools. They are also suitable starting materials, or versatile intermediates, for the synthesis of a wide variety of natural or synthetic compounds with a broad spectrum of biological and pharmacological activities. The preparation of enones is mainly focused on the search for more efficient and diastereoselective synthetic methodologies. The usefulness of enuloses relies on the diverse reaction possibilities offered by alkene and carbonyl double bonds, which are prone to undergo varied reactions such as halogenation, nitration, epoxidation, reduction, addition, etc. The addition of thiol groups that led to sulfur glycomimetics, such as thiooligosaccharides, is particularly relevant. Therefore, the synthesis of enuloses and the Michael addition of sulfur nucleophiles to give thiosugars or thiodisaccharides are discussed here. Chemical modifications of the conjugate addition products to afford biologically active compounds are also reported.

Development of potent and selective FAAH inhibitors with improved drug-like properties as potential tools to treat neuroinflammatory conditions

The neuroprotective performance against neuroinflammation of the endocannabinoid system (ECS) can be remarkably improved by indirect stimulation mediated by the pharmacological inhibition of the key ECS catabolic enzyme fatty acid amide hydrolase (FAAH). Based on our previous works and aiming to discover new selective FAAH inhibitors , we herein reported a new series of carbamate-based FAAH inhibitors (4a-t) which showed improved drug disposition properties compared to the previously reported analogues 2a-b. The introduction of ionizable functions allowed us to obtain new FAAH inhibitors of nanomolar potency characterized by good water solubility and chemical stability at physiological pH. Interesting structure-activity relationships (SARs), deeply analyzed by molecular docking and molecular dynamic (MD) simulations, were obtained. All the newly developed inhibitors showed an excellent selectivity profile evaluated against monoacylglycerol lipase and cannabinoid receptors. The reversible mechanism of action was determined by a rapid dilution assay. Absence of toxicity was confirmed in mouse fibroblasts NIH3T3 (for compounds 4e, 4g, 4n-o, and 4s) and in human astrocytes cell line 1321N1 (for compounds 4e, 4n, and 4s). The absence of undesired cardiac effects was also confirmed for compound 4n. Selected analogues (compounds 4e, 4g, 4n, and 4s) were able to reduce oxidative stress in 1321N1 astrocytes and exhibited notable neuroprotective effects when tested in an ex vivo model of neuroinflammation.

Molecular mechanisms in Alzheimer's disease and related potential treatments such as structural target convergence of antibodies and simple organic molecules

The amyloid cascade is the most frequently accepted hypothesis of Alzheimer's Disease (AD). According to this hypothesis, the formation of plaques precedes the appearance of fibrillary tangles. Therapeutic agents able to inhibit the formation of plaques are therefore considered as potential disease-modifying treatments (DMT) that could prevent or limit the progression of AD. Plaques are deposits formed by aggregates of amyloid-β (Aβ)-peptides. These peptides are metabolites of amyloid precursor protein (APP) first mediated by two enzymes: β-secretase 1 (BACE1) and γ-secretase. Molecular identification of these two enzymes has stimulated the development of their inhibitors. The clinical testing of these two classes of molecules has not been successful to date. The oligomerization of Aβ-peptides into plaques is now targeted by immunological approaches such as antibodies and vaccines. Structural consideration of the Aβ-peptide sequence led to the launch of the antibody Aducanumab. Several other antibodies are in late clinical phases. Progress in the understanding of the effects of N-truncated Aβ-peptides such as pE3-42, formed by the action of recently well characterized enzymes (aminopeptidase A, dipeptidylpeptidase-4 and glutaminyl cyclase) suggests that oligomerization can be limited either by enzyme inhibitors or antibody approaches. This strategy associating two structurally interconnected mechanisms is focused in this review.

Design, synthesis, biologically evaluation and molecular docking of C-glycosidic oximino carbamates as novel OfHex1 inhibitors

The inhibition of function-specific β-N-acetyl-D-hexosaminidases, such as OfHex1 from the Asian corn borer (Ostrinia furnacalis), is a promising strategy for the development of green pesticides. Among reported OfHex1 inhibitors, glycosyl inhibitors show especially high inhibitory activity. In this study, a series of novel C-glycosidic oximino carbamate derivatives were designed using the OfHex1 crystal structure and synthesized. Among the C-Glycoside derivatives studied, compound 7k exhibited the best inhibitory activity against OfHex1 (IC₅₀ = 47.47 μM). Compound 7k also exhibited excellent larvicidal activity against Plutella xylostella. The potential inhibitory mechanism of 7k was studied using molecular docking. Notably, compound 7k is the first reported C-glycoside inhibitor of OfHex1. These results provide direction for the rational design of novel OfHex1 inhibitors.

Protein profiling of hemolymph in Haemaphysalis flava ticks

Background

Tick hemolymph bathes internal organs, acts as an exchange medium for nutrients and cellular metabolites, and offers protection against pathogens. Hemolymph is abundant in proteins. However, there has been limited integrated protein analysis in tick hemolymph thus far. Moreover, there are difficulties in differentiating tick-derived proteins from the host source. The aim of this study was to profile the tick/host protein components in the hemolymph of Haemaphysalis flava.

Methods

Hemolymph from adult engorged H. flava females was collected by leg amputation from the Erinaceus europaeus host. Hemolymph proteins were extracted by a filter-aided sample preparation protocol, digested by trypsin, and assayed by liquid chromatography–tandem mass spectrometry (LC–MS/MS). MS raw data were searched against the UniProt Erinaceidae database and H. flava protein database for host- and tick-derived protein identification. Protein abundance was further quantified by intensity-based absolute quantification (iBAQ).

Results

Proteins extracted from hemolymph unevenly varied in size with intense bands between 100 and 130 kDa. In total, 312 proteins were identified in the present study. Therein 40 proteins were identified to be host-derived proteins, of which 18 were high-confidence proteins. Top 10 abundant host-derived proteins included hemoglobin subunit-α and subunit-β, albumin, serotransferrin-like, ubiquitin-like, haptoglobin, α-1-antitrypsin-like protein, histone H2B, apolipoprotein A-I, and C3-β. In contrast, 169 were high-confidence tick-derived proteins. These proteins were classified into six categories based on reported functions in ticks, i.e., enzymes, enzyme inhibitors, transporters, immune-related proteins, muscle proteins, and heat shock proteins. The abundance of Vg, microplusin and α-2-macroglobulin was the highest among tick-derived proteins as indicated by iBAQ.

Conclusions

Numerous tick- and host-derived proteins were identified in hemolymph. The protein profile of H. flava hemolymph revealed a sophisticated protein system in the physiological processes of anticoagulation, digestion of blood meal, and innate immunity. More investigations are needed to characterize tick-derived proteins in hemolymph.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05287-7.

Recent advances on discovery of enzyme inhibitors from natural products using bioactivity screening

The essence of enzymes is to keep the homeostasis and balance of human by catalyzing metabolic responses and modulating cell. Suppression of enzyme slows the progress of some diseases, making it a therapeutic target. Therefore, it is important to develop enzyme inhibitors by proper bioactivity screening strategies for the future treatment of some major diseases. In this review, we summarized the recent (2015-2020) applications of several screening strategies (electrophoretically mediated microanalysis, enzyme immobilization, affinity chromatography, and affinity ultrafiltration) in finding enzyme inhibitors from certain species of bioactive natural compounds of plant origin (flavonoids, alkaloids, phenolic acids, saponins, anthraquinones, coumarins). At the same time, the advantages and disadvantages of each strategy were also discussed, and the future possible development direction in enzyme inhibitor screening has prospected. To sum up, it is expected to help readers select suitable screening strategies for enzyme inhibitors and provide useful information for the study of the biological of specific kinds of natural products. This article is protected by copyright. All rights reserved.

A ligand selection strategy to customize small molecule probes for activity-based protein profiling (LS-ABPP)

Activity-based probes (ABPs) are the key components of activity-based protein profiling (ABPP). However, designing a probe that shows target-specific as well as site-selective binding can be a challenging and time-consuming task, often requiring complex synthetic procedures to provide a selection of probes from which to choose the ideal one. In this chapter, we present a ligand selection (LS) approach that allows us to rapidly diversify probe molecules in order to meet the steric and electronic demands of the binding site of any target enzyme. The central element of this method is a trifunctional LS probe synthesized from tyrosine in five steps, consisting of a highly reactive pentafluorophenyl (PFP) ester in addition to an electrophilic chloroacetamide warhead, and a bioorthogonal alkyne reporter group. By reacting a variety of primary amine ligands with the PFP ester, a probe library is created and screened for optimal binding characteristics to the target enzyme. With the optimized probe in hand, a compound library is subsequently screened by competitive profiling to identify potential enzyme inhibitors. Conveniently, this protocol is highly adaptable to a large variety of target proteins, representing a valuable tool for enzyme characterization and the discovery of enzyme inhibitors. Here, we apply this method exemplarily to the cysteine protease 3CL^pro of the coronavirus SARS-CoV-2.

Inhibitory activities of grape bioactive compounds against enzymes linked with human diseases

A quest for identification of novel, safe and efficient natural compounds, as additives in the modern food and cosmetic industries, has been prompted by concerns about toxicity and side effects of synthetic products. Plant phenolic compounds are one of the most documented natural products due to their multifarious biological applications. Grape (Vitis vinifera) is an important source of phenolic compounds such as phenolic acids, tannins, quinones, coumarins and, most importantly, flavonoids/flavones. This review crisply encapsulates enzyme inhibitory activities of various grape polyphenols towards different key human-ailment-associated enzymes: xanthine oxidase (gout), tyrosinase (hyperpigmentation), α-amylase and α-glucosidase (diabetes mellitus), pancreatic lipase (obesity), cholinesterase (Alzheimer's disease), angiotensin i-converting enzymes (hypertension), α-synuclein (Parkinson's disease) and histone deacetylase (various diseases). The review also depicts the enzyme inhibitory mechanism of various grape polyphenols and briefly discusses their stature as potential therapeutic and drug development candidates. KEY POINTS: • Nineteen major bioactive polyphenols from the grape/grape products and their disease targets are presented • Sixty-two important polyphenols as enzyme inhibitors from grape/grape products are presented • A thorough description and graphical presentation of biological significance of polyphenols against various diseases.

2-(2-Hydroxyethyl)piperazine derivatives as potent human carbonic anhydrase inhibitors: Synthesis, enzyme inhibition, computational studies and antiglaucoma activity

Targeting Carbonic Anhydrases (CAs) represents a strategy to treat several diseases, from glaucoma to cancer. To widen the structure-activity relationships (SARs) of our series of piperazines endowed with potent human carbonic anhydrase (hCA) inhibition, a new series of chiral piperazines carrying a (2-hydroxyethyl) group was prepared. The Zn-binding function, the 4-sulfamoylbenzoyl moiety, was connected to one piperazine N-atom, while the other nitrogen was decorated with alkyl substituents. In analogy to the approach used for the synthesis of the previously reported series, the preparation of the new compounds started with (R)- and (S)-aspartic acid. A partial racemization occurred during the synthesis. In order to overcome this problem, other chemical strategies were investigated. The inhibitory activity of the new polar derivatives against four hCAs isoforms I, II, IV and IX using a stopped flow CO₂ hydrase assay was determined. Some compounds showed potency in the nanomolar range and a preference for inhibiting hCA IX.

Engineering Tissue Inhibitors of Metalloproteinases Using Yeast Surface Display

Yeast surface display (YSD) has been extensively used for protein design, engineering, and directed evolution in the past two decades. Here, we describe methods for directed evolution of tissue inhibitors of metalloproteinase (TIMP), the natural inhibitors of matrix metalloproteinases (MMPs), through design and generation of a combinatorial library of TIMP mutants and screening the targeted TIMP library of variants toward MMP binding using YSD. This protocol can be adopted to other natural enzyme inhibitors and similar protein binders such as antibodies.

Irreversible inhibitors of the proline racemase (PRAC) unveil innovative mechanism of action as antibacterial against Clostridioides difficile

Proline racemases (PRAC), catalyzing the L-proline and D-proline interconversion, are essential factors in eucaryotic pathogenes such as Trypanosoma cruzi, Trypanosoma vivax and Clostridioides difficile. If the discovery of irreversible inhibitors of Trypanosoma cruzi PRAC (TcPRAC) led to innovative therapy of the Chagas disease, no inhibitors of CdPRAC have been discovered to date. However, Clostridioides difficile, due to an increased incidence in recent years, is considered as a major cause of health threat. In this work, we have taken into account the similarity between TcPRAC and CdPRAC enzymes to design new inhibitors of CdPRAC. Starting from (E) 4-oxopent-2-enoic acid TcPRAC irreversible inhibitors, we synthesized 4-aryl substituted analogues and evaluated their CdPRAC enzymatic inhibition against eleven strains of Clostridioides difficile. This study resulted in promising candidates and allowed for identification of (E)-4-(3-bromothiophen-2-yl)-4-oxobut-2-enoic acid 20 that was chosen for complementary in vivo studies and did not reveal in vivo toxicity.

Synthesis and structure-activity relationship studies of 2,4-thiazolidinediones and analogous heterocycles as inhibitors of dihydrodipicolinate synthase

Dihydrodipicolinate synthase (DHDPS), responsible for the first committed step of the diaminopimelate pathway for lysine biosynthesis, has become an attractive target for the development of new antibacterial and herbicidal agents. Herein, we report the discovery and exploration of the first inhibitors of E. coli DHDPS which have been identified from screening lead and are not based on substrates from the lysine biosynthesis pathway. Over 50 thiazolidinediones and related analogues have been prepared in order to thoroughly evaluate the structure-activity relationships against this enzyme of significant interest.

C1'-Branched acyclic nucleoside phosphonates mimicking adenosine monophosphate: Potent inhibitors of Trypanosoma brucei adenine phosphoribosyltransferase

Some pathogens, including parasites of the genus Trypanosoma causing Human and Animal African Trypanosomiases, cannot synthesize purines de novo and they entirely rely on the purine salvage pathway (PSP) for their nucleotide generation. Thus, their PSP enzymes are considered as promising drug targets, sparsely explored so far. Recently, a significant role of acyclic nucleoside phosphonates (ANPs) as inhibitors of key enzymes of PSP, namely of 6-oxopurine phosphoribosyltransferases (PRTs), has been discovered. Herein, we designed and synthesized two series of new ANPs branched at the C1' position as mimics of adenosine monophosphate. The novel ANPs efficaciously inhibited Trypanosoma brucei adenine PRT (TbrAPRT1) activity in vitro and it was shown that the configuration on the C1' chiral centre strongly influenced their activity: the (R)-enantiomers proved to be more potent compared to the (S)-enantiomers. Two ANPs, with K_i values of 0.39 μM and 0.57 μM, represent the most potent TbrAPRT1 inhibitors reported to date and they are an important tool to further study purine metabolism in various parasites.

Recent advances in the synthesis of 5'-deoxynucleoside phosphonate analogs

The present review focuses on the synthesis of cyclic 5-deoxynucleoside phosphonate analogs. The formation of various phosphonate alkyl moieties is accomplished through (i) Wittig (or HWE) type condensation to the nucleoside aldehyde moiety; (ii) nucleophilic displacement reaction using phosphonate anion or Lewis acid; (iii) Arbuzov reaction; (iv) olefin cross-metathesis between vinyl phosphonates and vinylated nucleosides; and (v) radical reaction and Pd catalyzed alkyne. For the coupling of nucleobases with cyclic moieties, the Mitsunobu reaction, and Sonogashira-type cross-coupling are usually applied. For the coupling of furanose moieties with nucleobases, Vorbrüggen-type condensation is generally applied. Addition reactions mediated by selenium ions are mainly applied for the coupling of carbocyclic moieties. Their biological activity results are summarized.

DNA-binding activities of compounds acting as enzyme inhibitors, ion channel blockers and receptor binders

The DNA-binding activities of compounds used as remedies can display DNA-protection, but also damaging effects in biological systems. The current review compiles literature data on DNA-binding activities of drugs widely used as remedies with different therapeutic indications. The compounds are classified according their mechanism of action: enzyme inhibitors, ion channel inhibitors, inhibitors of viral RNA replication and HIV protease and receptor agonists. DNA binding was reported for such widely used drugs as paracetamol, aspirin, metformin, statins and many others. The capability of the drug to bind DNA is sometimes coupled to genotoxic effects, but in some cases - to genome protection. Data on atoms and chemical groups involved in the drug-DNA interactions are also presented. In many cases the same atoms are involved in both interactions of the compounds with proteins and DNA.

Galantamine-Memantine Combination and Kynurenine Pathway Enzyme Inhibitors in the Treatment of Neuropsychiatric Disorders

The kynurenine pathway (KP) is a major route for L-tryptophan (L-TRP) metabolism, yielding a variety of bioactive compounds including kynurenic acid (KYNA), 3-hydroxykynurenine (3-HK), quinolinic acid (QUIN), and picolinic acid (PIC). These tryptophan catabolites are involved in the pathogenesis of many neuropsychiatric disorders, particularly when the KP becomes dysregulated. Accordingly, the enzymes that regulate the KP such as indoleamine 2,3-dioxygenase (IDO)/tryptophan 2,3-dioxygenase, kynurenine aminotransferases (KATs), and kynurenine 3-monooxygenase (KMO) represent potential drug targets as enzymatic inhibition can favorably rebalance KP metabolite concentrations. In addition, the galantamine-memantine combination, through its modulatory effects at the alpha7 nicotinic acetylcholine receptors and N-methyl-D-aspartate receptors, may counteract the effects of KYNA. The aim of this review is to highlight the effectiveness of IDO-1, KAT II, and KMO inhibitors, as well as the galantamine-memantine combination in the modulation of different KP metabolites. KAT II inhibitors are capable of decreasing the KYNA levels in the rat brain by a maximum of 80%. KMO inhibitors effectively reduce the central nervous system (CNS) levels of 3-HK, while markedly boosting the brain concentration of KYNA. Emerging data suggest that the galantamine-memantine combination also lowers L-TRP, kynurenine, KYNA, and PIC levels in humans. Presently, there are only 2 pathophysiological mechanisms (cholinergic and glutamatergic) that are FDA approved for the treatment of cognitive dysfunction for which purpose the galantamine-memantine combination has been designed for clinical use against Alzheimer's disease. The alpha7 nicotinic-NMDA hypothesis targeted by the galantamine-memantine combination has been implicated in the pathophysiology of various CNS diseases. Similarly, KYNA is well capable of modulating the neuropathophysiology of these disorders. This is known as the KYNA-centric hypothesis, which may be implicated in the management of certain neuropsychiatric conditions. In line with this hypothesis, KYNA may be considered as the "conductor of the orchestra" for the major pathophysiological mechanisms underlying CNS disorders. Therefore, there is great opportunity to further explore and compare the biological effects of these therapeutic modalities in animal models with a special focus on their effects on KP metabolites in the CNS and with the ultimate goal of progressing to clinical trials for many neuropsychiatric diseases.

LC-HRMS/MS phytochemical profiling of Symphytum officinale L. and Anchusa ochroleuca M. Bieb. (Boraginaceae): Unveiling their multi-biological potential via an integrated approach

This study was aimed at providing a comprehensive phytochemical characterization and multi-biological assessment of Symphytum officinale L., a medicinal plant with a noteworthy traditional use, and Anchusa ochroleuca M. Bieb., a Boraginaceae species from the Romanian flora. The dichloromethane, methanol and 65 % ethanol extracts obtained from the roots and aerial parts of both plants revealed the presence of numerous phenolic acids, oxygenated fatty acids, pyrrolizidine alkaloids (PAs) and flavonoids, as assessed by LC-HRMS/MS analysis. Consistent with their higher total phenolic content, the polar aerial part extracts of S. officinale and root extracts of A. ochroleuca showed the most significant antioxidant activities, as evaluated by DPPH (173.22-216.98 mg TE/g) and ABTS (219.41-311.97 mg TE/g) radical scavenging, CUPRAC (387.18-626.40 mg TE/g), FRAP (199.36-299.86 mg TE/g) and total antioxidant capacity (2.28-2.68 mmol TE/g). Furthermore, both plants exhibited good tyrosinase (19.11-43.89 mg KAE/g) and α-glucosidase (2.45-12.54 mmol ACAE/g) inhibitory effects. The orthogonal projections to latent structures discriminant analysis (OPLS-DA) allowed the objective differentiation between the roots and aerial parts of the two investigated species based on their phytochemical and biological profiles. The partial least square (PLS) analysis showed that several individual phenolic acids, such as danshensu, rabdosiin and rosmarinic acid, significantly contributed to the antioxidant potential of both Boraginaceae species, whilst the relative levels of sucrose were positively correlated with the anti-enzymatic properties. Overall, S. officinale and A. ochroleuca could be regarded as rich sources of bioactive phytochemicals that could further lead to developing novel phyto-pharmaceutical commodities.

Synthesis and characterization of a new two photon excitable acid sphingomyelinase FRET probe

Recently, FRET probes for acid sphingomyelinase (ASM) have enabled the observation of enzyme activity in intact cells for the first time. Here we present an ASM FRET probe specifically optimized for 2-photon excitation. To facilitate probe characterization and comparison to the previous probe, we mixed the two intact probes with defined amounts of the probes' ceramide cleavage products and mounted them on lipid beads. Directly excited NBD FRET acceptor fluorescene proved to be a useful means of reference and showed that the new probe is brighter, albeit only moderately, than the previous one. The new probe was then used to detect inhibition by various ASM inhibitors microscopically for the first time. Also in cells, directly excited acceptor fluorescence proved to be a useful parameter in addition to FRET to visualize inhibition of ASM.

Viral inhibitors derived from macroalgae, microalgae, and cyanobacteria: A review of antiviral potential throughout pathogenesis

Viruses are abiotic obligate parasites utilizing complex mechanisms to hijack cellular machinery and reproduce, causing multiple harmful effects in the process. Viruses represent a growing global health concern; at the time of writing, COVID-19 has killed at least two million people around the world and devastated global economies. Lingering concern regarding the virus' prevalence yet hampers return to normalcy. While catastrophic in and of itself, COVID-19 further heralds in a new era of human-disease interaction characterized by the emergence of novel viruses from natural sources with heretofore unseen frequency. Due to deforestation, population growth, and climate change, we are encountering more viruses that can infect larger groups of people with greater ease and increasingly severe outcomes. The devastation of COVID-19 and forecasts of future human/disease interactions call for a creative reconsideration of global response to infectious disease. There is an urgent need for accessible, cost-effective antiviral (AV) drugs that can be mass-produced and widely distributed to large populations. Development of AV drugs should be informed by a thorough understanding of viral structure and function as well as human biology. To maximize efficacy, minimize cost, and reduce development of drug-resistance, these drugs would ideally operate through a varied set of mechanisms at multiple stages throughout the course of infection. Due to their abundance and diversity, natural compounds are ideal for such comprehensive therapeutic interventions. Promising sources of such drugs are found throughout nature; especially remarkable are the algae, a polyphyletic grouping of phototrophs that produce diverse bioactive compounds. While not much literature has been published on the subject, studies have shown that these compounds exert antiviral effects at different stages of viral pathogenesis. In this review, we follow the course of viral infection in the human body and evaluate the AV effects of algae-derived compounds at each stage. Specifically, we examine the AV activities of algae-derived compounds at the entry of viruses into the body, transport through the body via the lymph and blood, infection of target cells, and immune response. We discuss what is known about algae-derived compounds that may interfere with the infection pathways of SARS-CoV-2; and review which algae are promising sources for AV agents or AV precursors that, with further investigation, may yield life-saving drugs due to their diversity of mechanisms and exceptional pharmaceutical potential.

Investigation of 3-sulfamoyl coumarins against cancer-related IX and XII isoforms of human carbonic anhydrase as well as cancer cells leads to the discovery of 2-oxo-2H-benzo[h]chromene-3-sulfonamide - A new caspase-activating proapoptotic agent

Herein we report the synthesis of a set of seventeen 3-sulfonamide substituted coumarin derivatives. Prepared compounds were tested in vitro for inhibition of four physiologically relevant isoforms of the metalloenzyme human carbonic anhydrase (hCA, EC 4.2.1.1). Several coumarin sulfonamides displayed low nanomolar K_I values against therapeutically relevant hCA II, IX, and XII, whereas they did not potently inhibit hCA I. Some of these compounds exerted a concentration-dependent antiproliferative action toward RT4 human bladder cancer and especially A431 human epidermoid carcinoma cell lines. In the meantime, the viability of non-tumorigenic hTERT immortalized human foreskin fibroblast cell line Bj-5ta was not significantly affected by the obtained derivatives. Interestingly, compound 10q (2-oxo-2H-benzo [h]chromene-3-sulfonamide) showed a profound and selective dose-dependent inhibition of A431 cell growth with low nanomolar IC₅₀ values. We demonstrated that 10q possessed a concentration-dependent apoptosis induction activity associated with caspase 3/7 activation in cancer cells. As carbonic anhydrase isoforms in question were not potently inhibited by this compound, its antiproliferative effects likely involve other mechanisms, such as DNA intercalation. Compound 10q clearly represents a viable lead for further development of new-generation anticancer agents.

Development of Diverse Range of Biologically Relevant Carbohydrate-Containing Molecules: Twenty Years of Our Journey*

There is an increasing demand for significant amount of carbohydrate-containing molecules owing to their complete chemical, biological, and pharmacological investigations to better understand their role in many important biological events. Clinical studies of a wide range of simple carbohydrates or their derivatives, glycohybrids, glycoconjugates, and neoglycoconjugates have been conducted worldwide for the successful treatment of various frontline diseases. Herein, a brief perspective of carbohydrate-based molecular scaffolding and my experience during the last 20 years in the area of synthetic carbohydrate chemistry, mainly for their impact in drug discovery & development, is presented.

Flavonoids from Pterogyne nitens as Zika virus NS2B-NS3 protease inhibitors

Although the widespread epidemic of Zika virus (ZIKV) and its neurological complications are well-known there are still no approved drugs available to treat this arboviral disease or vaccine to prevent the infection. Flavonoids from Pterogyne nitens have already demonstrated anti-flavivirus activity, although their target is unknown. In this study, we virtually screened an in-house database of 150 natural and semi-synthetic compounds against ZIKV NS2B-NS3 protease (NS2B-NS3p) using docking-based virtual screening, as part of the OpenZika project. As a result, we prioritized three flavonoids from P. nitens, quercetin, rutin and pedalitin, for experimental evaluation. We also used machine learning models, built with Assay Central® software, for predicting the activity and toxicity of these flavonoids. Biophysical and enzymatic assays generally agreed with the in silico predictions, confirming that the flavonoids inhibited ZIKV protease. The most promising hit, pedalitin, inhibited ZIKV NS2B-NS3p with an IC50 of 5 μM. In cell-based assays, pedalitin displayed significant activity at 250 and 500 µM, with slight toxicity in Vero cells. The results presented here demonstrate the potential of pedalitin as a candidate for hit-to-lead (H2L) optimization studies towards the discovery of antiviral drug candidates to treat ZIKV infections.

Insertion of metal carbenes into the anilinic N-H bond of unprotected aminobenzenesulfonamides delivers low nanomolar inhibitors of human carbonic anhydrase IX and XII isoforms

Herein we report the synthesis of a set of thirty-four primary sulfonamides generated via formal N-H-insertion of metal carbenes into anilinic amino group of sulfanilamide and its meta-substituted analog. Obtained compounds were tested in vitro as inhibitors of four physiologically significant isoforms of the metalloenzyme human carbonic anhydrase (hCA, EC 4.2.1.1). Many of the synthesized sulfonamides displayed low nanomolar K_i values against therapeutically relevant hCA II, IX, and XII, whereas they did not potently inhibit hCA I. Provided the promising activity profiles of the substances towards tumor-associated hCA IX and XII isozymes, single-concentration MTT test was performed for the entire set. Disappointingly, most of the discovered hCA inhibitors did not significantly suppress the growth of cancer cells either in normoxia or CoCl₂ induced hypoxic conditions. The only two compounds exerting profound antiproliferative effect turned out to be modest hCA inhibitors. Their out of the range activity in cells is likely attributive to the presence of Michael acceptor substructure which can potentially act either through the inhibition of Thioredoxin reductases (TrxRs, EC 1.8.1.9) or nonspecific covalent binding to cell proteins.

High-Throughput Differential Scanning Fluorimetry of GFP-Tagged Proteins

Differential scanning fluorimetry is useful for a wide variety of applications including characterization of protein function, structure-activity relationships, drug screening, and optimization of buffer conditions for protein purification, enzyme activity, and crystallization. A limitation of classic differential scanning fluorimetry is its reliance on highly purified protein samples. This limitation is overcome through differential scanning fluorimetry of GFP-tagged proteins (DSF-GTP). DSF-GTP specifically measures the unfolding and aggregation of a target protein fused to GFP through its proximal perturbation effects on GFP fluorescence. As a result of this unique principle, DSF-GTP can specifically measure the thermal stability of a target protein in the presence of other proteins. Additionally, the GFP provides a unique in-assay quality control measure. Here, we describe the workflow, steps, and important considerations for executing a DSF-GTP experiment in a 96-well plate format.

Research progress in biological activities of succinimide derivatives

Succinimides are well recognized heterocyclic compounds in drug discovery which produce diverse therapeutically related applications in pharmacological practices. Researches in medicinal chemistry field have isolated and synthesized succinimide derivatives with multiple medicinal properties including anticonvulsant, anti-inflammatory, antitumor and antimicrobial agents, 5-HT receptor ligands and enzyme inhibitors. Simultaneously, SAR (Structure-Activity Relationship) analysis has been gradually possessed, along with a great deal of derivatives have been derived for potential targets. In this article, we comprehensively summarize the biological activities and SAR for succinimide derivatives, along with the featuring bioactive molecules reported in patents, wishing to provide an overall retrospect and prospect on the succinimide analogues.

An insight on medicinal attributes of 1,2,4-triazoles

The present review aims to summarize the pharmacological profile of 1,2,4-triazole, one of the emerging privileged scaffold, as antifungal, antibacterial, anticancer, anticonvulsant, antituberculosis, antiviral, antiparasitic, analgesic and anti-inflammatory agents, etc. along with structure-activity relationship. The comprehensive compilation of work carried out in the last decade on 1,2,4-triazole nucleus will provide inevitable scope for researchers for the advancement of novel potential drug candidates having better efficacy and selectivity.

Network analysis, chemical characterization, antioxidant and enzyme inhibitory effects of foxglove (Digitalis cariensis Boiss. ex Jaub. & Spach): A novel raw material for pharmaceutical applications

The present study outlines the phenolic composition and pharmacological properties of different extracts of Digitalis cariensis Boiss. ex Jaub. & Spach root and aerial parts. The metabolic profiles of the studied extracts were characterized by UHPLC-MS. The in vitro antioxidant and enzyme (acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase, α-amylase, and α-glucosidase) inhibitory potential of the extracts were determined. Bioinformatics and docking investigations were also conducted to support the enzyme inhibition test and predict putative targets for potential pharmacological applications. Overall, the methanolic extract followed by the water extract of the D. cariensis root were found to be superior source of antioxidant compounds except for metal chelating ability, in which the water extract of the root (26.34 ± 1.54 mg EDTAE/g) and aerial parts (16.47 ± 0.88 mg EDTAE/g) have showed the highest activity. The tested extracts were potent against AChE (9.11 ± 0.27-9.79 ± 0.28 mg GEs/g extract), α-amylase (0.12 ± 0.01- 0.50 ± 0.01 mmol ACEs/g extract) and α-glucosidase (0.28 ± 0.01-17.29 ± 0.24 mmol ACEs/ g extract). Notable activity against tyrosinase was displayed by the methanolic extracts (Root-MeOH: 123.71 ± 2.70 and aerial parts - MeOH: 137.96 ± 1.07 mg KAE/g extract), while none of the extracts were potent against BChE. According to docking investigations, the observed anti-tyrosinase effect could be related, at least partially, to the presence of luteolin, rosmarinic acid and kaempferol in the extracts. Results amassed herein is the first report on the biological attributes of D. cariensis, which validate the pharmacological uses of this plant.

Insight into Mechanism of Action of Anticancer Benzazoles

BACKGROUND

Targeting the DNA topoisomerase II enzyme (topo II) is a promising anticancer treatment approach. TopoII controls and modifies the topological states of DNA and plays key roles in DNA replication, transcription, and chromosome segregation. The DNA binding and cleavage domain is one of the active sites of this enzyme. It is known that topoisomerase inhibitors, also known as topoisomerase poisons, bind to the transient enzyme-DNA complex and inhibit the religation of DNA, generating single- and double-stranded breaks that harm the integrity of the genome. This ultimately leads to the accumulation of DNA strand breaks and cell death.

METHODS

Our previously synthesized benzazole derivatives were tested for their eukaryotic DNA topoisomerase II inhibitory activity in a cell-free system. Their interactions with the enzyme were studied by carrying out molecular docking studies using and comparing two different docking programs.

RESULTS

The results of the docking studies clarified binding modes of these compounds to the topoisomerase II enzyme.

CONCLUSION

This study also provides guidelines to design novel and more potent antitumor agents functioning as human topoisomerase II enzyme inhibitors.

The effect of 8 plant extracts and combinations on post-prandial blood glucose and insulin responses in healthy adults: a randomized controlled trial

BACKGROUND

Lower post-prandial glucose (PPG) and insulin (PPI) responses to foods are associated with reduced diabetes risk and progression. Several plant extracts have been proposed to reduce PPG or PPI by inhibiting enzymes or transporters involved in carbohydrate digestion and uptake. This study evaluates a range of such extracts, consumed with a carbohydrate load, for their effects on PPG, PPI and indicators of (gastrointestinal) tolerance.

METHODS

Interventions were extracts of mulberry fruit (MFE, 1.5 g), mulberry leaf (MLE, 1.0 g), white bean (WBE, 3.0 g), apple (AE, 2.0 g), elderberry (EE, 2.0 g), turmeric (TE, 0.18 g), AE + TE, and EE + TE. Each of these 8 individual extracts or combinations were added to a rice porridge containing ~ 50 g available carbohydrate (control). In a within-subject (randomised, balanced incomplete block) design, individual subjects received the control and a subset of 4 of the 8 extracts or combinations. Participants were 72 apparently healthy adults (mean [SD] age 31.2 [5.5] yr, body mass index 22.1 [2.0] kg/m2). The primary outcome was the percentage change in 2-h PPG (positive incremental area under the curve) relative to control. Secondary measures were the 2-h PPI response, 7-h breath hydrogen, measures of gastrointestinal discomfort, and urine glucose.

RESULTS

In the 65 subjects who completed the control and at least one intervention treatment, additions of AE, MFE and MLE produced statistically significant reductions in PPG vs control (p < 0.05; mean effect - 24.1 to - 38.1%). All extracts and combinations except TE and WBE significantly reduced PPI (p < 0.01; mean effect - 17.3% to - 30.4%). Rises in breath hydrogen > 10 ppm were infrequent, but statistically more frequent than control only for MLE (p = 0.02). Scores for gastrointestinal discomfort were extremely low and not different from control for any treatment, and no glucosuria was observed.

CONCLUSIONS

Additions of AE, MFE and MLE to rice robustly reduced PPG and PPI. EE significantly reduced only PPI, while TE and WBE showed no significant efficacy for PPG or PPI. Breath hydrogen responses to MLE suggest possible carbohydrate malabsorption at the dose used, but there were no explicit indications of intolerance to any of the extracts.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT04258501. Registered 6 February 2020 - Retrospectively registered.

Synthesis and Molecular Simulation Studies of Mandelic Acid Peptidomimetic Derivatives as Aminopeptidase N Inhibitors

BACKGROUND

The aminopeptidase N (APN) over-expressed in tumor cells plays a critical role in angiogenesis which makes the development of APN inhibitors an attractive strategy for cancer research.

AIMS AND OBJECTIVES

It is clinically significant to develop potential APN inhibitors for cancer treatment. Reported here are the design, synthesis, biological evaluation and molecular simulation of mandelic acid peptidomimetic derivatives as APN inhibitors.

MATERIALS AND METHODS

Analysis of the binding mode of bestatin to APN lead to the design and synthesis of mandelic acid peptidomimetic derivatives. APN inhibitory activities in vitro were evaluated by spectrophotometric method. The binding mode of the target compounds with the APN binding site was studied relying on docking studies, molecular dynamics simulation experiments and binding energies calculation.

RESULTS

The structures of target compounds were confirmed by IR, 1H-NMR and MS. All compounds exhibited different range of inhibitory ability with IC50 values lying in micromolar level. The compound 9m was found to be most potent as compared to other target derivatives. Molecular simulation revealed that ligand coordinating with the catalytic zinc ion is very important for inhibitory activities.

CONCLUSION

The compound 9m might represent a promising scaffold for the further development of novel anti-cancer drugs.

Structure-Activity Relationships of Natural and Synthetic Indole-Derived Scaffolds as α-Glucosidase Inhibitors: A Mini-Review

α-Glucosidase plays an important role in carbohydrate metabolism and is an attractive drug target for the treatment of diabetes, obesity and other related complications. Currently, acarbose, miglitol and voglibose have been approved by the FDA for the treatment of diabetes by oral α-glucosidase inhibitors. With the development of anti-diabetic drugs, the emergence of novel drugs with various chemotypes has overshadowed α-glucosidase inhibitors. Since the 1990s, the FDA has not approved new chemical entities against α-glucosidase, which has resulted in restricted clinical medication. Nevertheless, this type of inhibitors possess several unparalleled advantages over other drugs, especially mild side effects (non-systemic gastrointestinal side effects and occasional allergic reactions). Additionally, α-glucosidase inhibitors for monotherapy or in combination with other drugs have been proved to be a feasible approach for the treatment of diabetes. In the last decade, the discovery of natural or synthetic indole derivatives possessing the inhibitory activity of α-glucosidase has received great attention. Herein, we have summarized indoles as inhibitors of α-glucosidase activity, their mechanism of action, synthetic methodologies and structure-activity relationships. Moreover, we have compared the inhibitory potencies of all compounds under their corresponding positive control as well as oral absorption in silico evaluated by tPSA. This review will provide a medium on which future drug design and development for the treatment of diabetes may be modeled as many drug candidates with present great potential as effective anti-diabetic chemotherapy.

Review of recently used techniques and materials to improve the efficiency of orally administered proteins/peptides

OBJECTIVES

The main objective of present review is to explore and evaluate the effectiveness of recently developed methods to improve the bioavailability of orally administered biopharmaceutical drugs.

METHODS

A systematic search of sciencedirect, tandfonline and Google Scholar databases based on various sets of keywords was performed. All results were evaluated based on their abstracts, and irrelevant studies were neglected during further evaluation.

RESULTS

At present, biopharmaceuticals are used as injectable therapies as they are not absorbed adequately from the different routes of drug administration, particularly the oral one. Their insufficient absorption is attributed to their high molecular weight, degradation by proteolytic enzymes, high hydrophilicity and rigidity of the absorptive tissues. From industrial aspect incorporation of enzyme inhibitors (EIs) and permeation enhancers (PEs) and mucoadhesive polymers into conventional dosage forms may be the easiest way of formulation of orally administered macromolecular drugs, but the effectiveness of protection and absorption enhancement here is the most questionable. Conjugation may be problematic from regulatory aspect. Encapsulation into lipid-based vesicles sufficiently protects the incorporated macromolecule and improves intestinal uptake but have considerable stability issues. In contrast, polymeric nanocarriers may provide good stability but provides lower internalization efficacy in comparison with the lipid-based carriers.

CONCLUSION

It can be concluded that the combination of the advantages of mucoadhesive polymeric and lid-based carriers in hybrid lipid/polymer nanoparticles may result in improved absorption and might represent a potential means for the oral administration of therapeutic proteins in the near future. Graphical abstract Delivery systems for oral protein daministration.

Sulfonamido carboranes as highly selective inhibitors of cancer-specific carbonic anhydrase IX

Carbonic anhydrase IX (CA IX) is a transmembrane enzyme overexpressed in hypoxic tumors, where it plays an important role in tumor progression. Specific CA IX inhibitors potentially could serve as anti-cancer drugs. We designed a series of sulfonamide inhibitors containing carborane clusters based on prior structural knowledge of carborane binding into the enzyme active site. Two types of carborane clusters, 12-vertex dicarba-closo-dodecaborane and 11-vertex 7,8-dicarba-nido-undecaborate (dicarbollide), were connected to a sulfonamide moiety via aliphatic linkers of varying lengths (1-4 carbon atoms; n = 1-4). In vitro testing of CA inhibitory potencies revealed that the optimal linker length for selective inhibition of CA IX was n = 3. A 1-sulfamidopropyl-1,2-dicarba-closo-dodecaborane (3) emerged as the strongest CA IX inhibitor from this series, with a K_i value of 0.5 nM and roughly 1230-fold selectivity towards CA IX over CA II. X-ray studies of 3 yielded structural insights into their binding modes within the CA IX active site. Compound 3 exhibited moderate cytotoxicity against cancer cell lines and primary cell lines in 2D cultures. Cytotoxicity towards multicellular spheroids was also observed. Moreover, 3 significantly lowered the amount of CA IX on the cell surface both in 2D cultures and spheroids and facilitated penetration of doxorubicin. Although 3 had only a moderate effect on tumor size in mice, we observed favorable ADME properties and pharmacokinetics in mice, and preferential presence in brain over serum.

Synthesis, pharmacological evaluation and structure-activity relationship of recently discovered enzyme antagonist azoles

Global people are suffering from the legion of diseases. Cytotoxic property of the chemical compound would not solely influence effective drug properties and reduce unnecessary side effects. Proteins/enzymes responsible for microbe proliferation or survival are specifically targeted and inhibited successfully making the cells to undergo apoptosis. Furthermore, isoforms of essential enzymes have distinct physiological functions; thereby inhibition of essential enzyme isoforms is an apt way to the clinical approach of disease neutralization. Drugs are designed so as to play significant roles such as signaling pathways in the oncogenic process including cell proliferation, invasion, and angiogenesis. The present review comprises collective information of the recent synthesis of various organic drug compounds in brief, which could inhibit particular enzyme. The review also covers the correlation of the structure of a drug molecule designed and its inhibitory activity. Also, the most significant enzyme inhibitors are highlighted and structural moieties/core units responsible for remarkable inhibitory values are emphasized.

In vitro and in vivo inhibitory effects of Carica papaya seed on α-amylase and α-glucosidase enzymes

The present study was aimed to investigate the in vitro and in vivo inhibitory effects of Carica papaya seeds on α-amylase and α-glucosidase enzymes, as this is known to be an antidiabetic mechanism. Analysis of the extracts of the seeds for phytochemicals revealed the presence of a significant amount of saponins, alkaloids, flavonoids, phenols, terpenoids, and steroids. The seed extracts of Carica papaya exhibited good antioxidant capacity using 2, 2-diphenyl-1-picryl hydroxyl (DPPH), thiobarbituric reactive substance (TBARS) and ferric reducing antioxidant power (FRAP) method. The results of the inhibitory studies of the extracts revealed that the hexane extract followed by the ethyl acetate extract was the most potent inhibitor of α-amylase and α-glucosidase enzyme when compared to other extracts using their IC₅₀ values. In the animal study, different doses (250, 500 and 1000 mg/kg/body weight) of the extracts of Carica papaya seed were administered orally for 120 min, to normal and streptozotocin-induced diabetic rats, and were compared with acarbose 100 mg/kg/body weight and control group for the effect on postprandial hyperglycemia. The extract of ethyl acetate (at doses of 250, 500 and 1000 mg/kg/body weight) significantly reduced postprandial glucose levels in these animals. The characterization of hexane and ethyl acetate extracts by GC-MS analysis revealed 20 bioactive compounds while the FTIR analysis confirmed the presence of this functional groups: -C=C, -C-Cl, -C-O, -O-H, -CH, -C=O, -C=C=C, -N=C=S, -O=C=O and -N-H in Carica papaya seed extracts. It was concluded that the inhibition of α-amylase and α-glucosidase enzymes and the prevention of oxidative stress in postprandial hyperglycemia could be some of the possible mechanisms by which they exert their anti-diabetic properties.

Development of potent inhibitors of the human microsomal epoxide hydrolase

Microsomal epoxide hydrolase (mEH) hydrolyzes a wide range of epoxide containing molecules. Although involved in the metabolism of xenobiotics, recent studies associate mEH with the onset and development of certain disease conditions. This phenomenon is partially attributed to the significant role mEH plays in hydrolyzing endogenous lipid mediators, suggesting more complex and extensive physiological functions. In order to obtain pharmacological tools to further study the biology and therapeutic potential of this enzyme target, we describe the development of highly potent 2-alkylthio acetamide inhibitors of the human mEH with IC₅₀ values in the low nanomolar range. These are around 2 orders of magnitude more potent than previously obtained primary amine, amide and urea-based mEH inhibitors. Experimental assay results and rationalization of binding through docking calculations of inhibitors to a mEH homology model indicate that an amide connected to an alkyl side chain and a benzyl-thio function as key pharmacophore units.

Isoquinoline alkaloids from the roots of Zanthoxylum rigidum as multi-target inhibitors of cholinesterase, monoamine oxidase A and Aβ1-42 aggregation

Multifactorial neurodegenerative disorders such as Alzheimer's disease (AD) are considered a growing public health problem due the rising incidence and low effectiveness of current treatments [6]. Since pharmacotherapy based on a single target has been insufficient for drug development in complex diseases, the emerging multi-target approach is a promising strategy for the search of new anti-AD drug candidates. Herein described natural isoquinoline alkaloids were investigated for multi-target activity on key mechanisms associated with the AD's pathogenesis, i.e. cholinergic depletion, beta amyloid (Aβ) aggregation and oxidative stress. Alkaloid isolation from root extract of Zanthoxylum rigidum was carried out using multi-step chromatography and TLC-bioautography against acetylcholinesterase (AChE) giving eight purified isoquinoline alkaloids. Isolated compounds were tested for inhibitory activity against cholinesterase (AChE and BChE), monoamine oxidase (MAO-A and B) and Aβ aggregation. Our study revealed two benzophenanthridine alkaloids, nitidine (5) and avicine (7), as the most potent multi-target candidates. Both showed dual cholinesterase inhibition, being more active against AChE over BChE, with IC₅₀ values in sub-micromolar range in AChE. Kinetic analysis with cholinesterase showed, that both compounds are reversible-mixed inhibitors, where avicine (7) presented highest potency with K_i values of 0.063 µM (EeAChE), 0.511 µM (HrAChE) and 0.123 µM (EqBChE). In addition, these alkaloids presented moderate Aβ_1-42 anti-aggregation activity and MAO-A inhibition with IC₅₀ values between 0.5 and 2 µM. Our findings suggest that avicine (7) is a promising natural compound and multifunctional candidate representing a suitable starting point for the development of new therapeutic agents for Alzheimer's disease.

Targeting obesity with plant-derived pancreatic lipase inhibitors: A comprehensive review

The prevalence of obesity is alarmingly increasing in the last few decades and leading to many serious public health concerns worldwide. The dysregulated lipid homeostasis due to various genetic, environmental and lifestyle factors is considered one of the critical putative pathways mediating obesity. Nonetheless, the scientific advancements unleashing the molecular dynamics of lipid metabolism have provided deeper insights on the emerging roles of lipid hydrolysing enzymes, including pancreatic lipase. It is hypothesized that inhibiting pancreatic lipase would prevent the breakdown of triglyceride and delays the absorption of fatty acids into the systemic circulation and adipocytes. Whilst, orlistat is the only conventional pancreatic lipase enzyme inhibitor available in clinics, identifying the safe clinical alternatives from plants to inhibit pancreatic lipase has been considered a significant advancement. Consequently, plants which have shown significant potential to combat obesity are now revisited for its abilities to inhibit pancreatic lipase. In this regard, our review surveyed the potential of medicinal plants and its phytoconstituents to inhibit pancreatic lipase and to elicit anti-obesity effects. Thus, the review collate and critically appraise the potential of medicinal plants and phyto-molecules inhibiting pancreatic lipase enzyme and consequently modulating triglyceride absorption in gut, and discuss its implications in the development of novel therapeutic strategies to combat obesity.

Steroid enzyme and receptor expression and regulations in breast tumor samples - A statistical evaluation of public data

In spite of the significant progress of estrogen-dependent breast cancer (BC) treatment, aromatase inhibitor resistance is a major problem limiting the clinical benefit of this frontier endocrine-therapy. The aim of this study was to determine the differential expression of steroid-converting enzymes between tumor and adjacent normal tissues, as well as their correlation in modulating intratumoral steroid-hormone levels in post-menopausal estrogen-dependent BC. RNA sequencing dataset (n = 1097) of The-Cancer-Genome-Atlas (Breast Invasive Carcinoma) retrieved through the data portal of Genomic Data Commons was used for differential expressions and expression correlation analyses by Mann-Whitney U and Spearman's rank test, respectively. The results showed significant up-regulation of 17β-HSD7 (2.50-fold, p < 0.0001) in BC, supporting its effect in sex-hormone control. Besides, suppression of 11β-HSD1 expression (-8.29-fold, p < 0.0001) and elevation of 11β-HSD2 expression (2.04-fold, p < 0.0001) provide a low glucocorticoid environment diminishing BC anti-proliferation. Furthermore, 3α-HSDs were down-regulated (-1.59-fold, p < 0.01; -8.18-fold, p < 0.0001; -33.96-fold, p < 0.0001; -31.85-fold, p < 0.0001 for type 1-4, respectively), while 5α-reductases were up-regulated (1.41-fold, p < 0.0001; 2.85-fold, p < 0.0001; 1.70-fold, p < 0.0001 for type 1-3, respectively) in BC, reducing cell proliferation suppressers 4-pregnenes, increasing cell proliferation stimulators 5α-pregnanes. Expression analysis indicates significant correlations between 11β-HSD1 with 3α-HSD4 (r = 0.605, p < 0.0001) and 3α-HSD3 (r = 0.537, p < 0.0001). Significant expression correlations between 3α-HSDs were also observed. Our results systematically present the regulation of steroid-converting enzymes and their roles in modulating the intratumoral steroid-hormone levels in BC with a vivid 3D-schema, supporting novel therapy targeting the reductive 17β-HSD7 and proposing a new combined therapy targeting 11β-HSD2 and 17β-HSD7.

Advanced Approaches of Bioactive Peptide Molecules and Protein Drug Delivery Systems

Despite the fact that protein and peptide therapeutics are widely employed in the treatment of various diseases, their delivery is posing an unembellished challenge to the scientists. It was discovered that delivery of these therapeutic systems through oral route is easy with high patient compliance. However, proteolytic degradation and absorption through the mucosal epithelium are the barriers in this route. These issues can be minimized by the use of enzyme inhibitors, absorption enhancers, different carrier systems or either by direct modification. In the process of investigation, it was found that transdermal route is not posing any challenges of enzymatic degradation, but, still absorption is the limitation as the outer layer of skin acts as a barrier. To suppress the effect of the barrier and increase the rate of the absorption, various advanced technologies were developed, namely, microneedle technology, iontophoresis, electroporation, sonophoresis and biochemical enhancement. Indeed, even these molecules are targeted to the cells with the use of cell-penetrating peptides. In this review, delivery of the peptide and protein therapeutics using oral, transdermal and other routes is discussed in detail.

Isolation and characterization of bioactive compounds with antibacterial, antioxidant and enzyme inhibitory activities from marine-derived rare actinobacteria, Nocardiopsis sp. SCA21

A rare actinobacteria strain designated SCA21, producing bioactive metabolites was isolated from marine sediment of Havelock Island, Andaman and Nicobar Islands, India. Analysis of 16S rRNA sequences suggested that the strain SCA21 belonged to the genus Nocardiopsis. Chemical investigation of the fermentation broth led to the isolation of two pure bioactive compounds (1-2). Compound 1: 4-bromophenol, a bromophenol derivative; Compound 2: Bis (2-ethylhexyl) phthalate, a phthalate ester. The structure of compound 1 and 2 were elucidated by the detailed analysis of FT-IR, HR-ESI-MS, 1D and 2D NMR, along with literature data analysis. The isolated metabolites were evaluated for enzyme inhibition activity against α-glucosidase and α-amylase, free radical scavenging activity against DPPH and ABTS radicals, metal chelating and antibacterial activity against clinical pathogens. 1 and 2 exhibited remarkable enzyme inhibitory activities against α-glucosidase. However, Compound 2 was found less active against α-amylase. They showed significant free radical scavenging activity against DPPH and ABTS radicals. In addition, except the strain Salmonella typhi ATCC 25241 and Listeria cytogens ATCC 13932, 1 and 2 showed broad spectrum inhibitory activity against MRSA ATCC NR-46171, MRSA ATCC-46071, Klebsiella pneumonia ATCC 13883, Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 12600. In conclusion, to best of our knowledge these findings are the first report of isolation of 4-bromophenol and Bis (2-ethylhexyl) phthalate from genus Nocardiopsis, thus suggesting that rare actinomycetes are promising source of therapeutically important bioactive metabolites.

Novel 2-arylthiopropanoyl-CoA inhibitors of α-methylacyl-CoA racemase 1A (AMACR; P504S) as potential anti-prostate cancer agents

α-Methylacyl-CoA racemase (AMACR; P504S) catalyses an essential step in the degradation of branched-chain fatty acids and the activation of ibuprofen and related drugs. AMACR has gained much attention as a drug target and biomarker, since it is found at elevated levels in prostate cancer and several other cancers. Herein, we report the synthesis of 2-(phenylthio)propanoyl-CoA derivatives which provided potent AMACR inhibitory activity (IC₅₀ = 22-100 nM), as measured by the AMACR colorimetric activity assay. Inhibitor potency positively correlates with calculated logP, although 2-(3-benzyloxyphenylthio)propanoyl-CoA and 2-(4-(2-methylpropoxy)phenylthio)propanoyl-CoA were more potent than predicted by this parameter. Subsequently, carboxylic acid precursors were evaluated against androgen-dependent LnCaP prostate cancer cells and androgen-independent Du145 and PC3 prostate cancer cells using the MTS assay. All tested precursor acids showed inhibitory activity against LnCaP, Du145 and PC3 cells at 500 µM, but lacked activity at 100 µM. This is the first extensive structure-activity relationship study on the influence of side-chain interactions on the potency of novel rationally designed AMACR inhibitors.