Synthesis and Biological Evaluation of Colchicine─Aryl/Alkyl Amine Hybrids as Potential Noncytotoxic Cholinesterase Inhibitors: Identification of SBN-284 as a Dual Inhibitor of Cholinesterases and NLRP3 Inflammasome.

Colchicine, one of the oldest anti-inflammatory natural products still used clinically, inhibits NF-κB signaling and NLRP3 inflammasome activation. Despite its cytotoxicity and narrow therapeutic range, colchicine continues to intrigue medicinal chemists exploring its anti-inflammatory potential. This study aimed to investigate the colchicine scaffold for its role in Alzheimer's disease by targeting neuroinflammation and cholinesterases. Molecular docking revealed that colchicine's hydrophobic trimethoxyphenyl framework can potentially bind to the peripheral anionic site of cholinesterases. Hybrid structures combining colchicine with aryl/alkyl amines were designed to bind both peripheral and catalytic sites of cholinesterases. We describe here the design, synthesis, and in vitro cytotoxicity evaluation of these colchicine-aryl/alkyl amine hybrids, along with their in silico interactions with the cholinesterase active site gorge. Nontoxic analogs demonstrating strong cholinesterase binding affinity were further evaluated for their anticholinesterase and antineuroinflammatory activities. The colchicine-donepezil hybrid, SBN-284 (3x), inhibited both acetylcholinesterase and butyrylcholinesterase as well as the NLRP3 inflammasome complex at low micromolar concentrations. It achieved this through noncompetitive inhibition, occupying the active site gorge and interacting with both peripheral and catalytic anionic sites of cholinesterases. Analog 3x was shown to cross the blood-brain barrier and exhibited no toxicity to neuronal cells, primary macrophages, or epithelial fR2 cells. These findings highlight the potential of this lead compound for further preclinical investigation as a promising anti-Alzheimer agent.

Design, synthesis, and pharmacological evaluation of indole-piperidine amides as Blood-brain barrier permeable dual cholinesterase and ß-secretase inhibitors.

Heterocyclic compounds play a crucial role in the discovery of therapeutics. Alzheimer's disease (AD) is an unfathomable sporadic neurodegenerative disorder that involves multiple pathological pathways. The failure of current single-target small molecules to address AD's underlying causes has prompted interest in discovering multi-target directed ligands (MTDLs) to slow down the disease's progression. Herein we report the synthesis and biological evaluation of indole-piperidine amides as MTDLs for AD. The 5,6-dimethoxy-indole N-(2-(1-benzylpiperidine) carboxamide (23a) inhibits hAChE and hBACE-1 with IC50 values of 0.32 and 0.39 µM, respectively. The MTDL 23a is a mixed-type inhibitor of both hAChE and hBACE-1 with Ki values of 0.26 µM and 0.46 µM, respectively. The MD simulation studies revealed that both AChE and BACE-1 experience minor conformational changes on binding with 23a. In the PAMPA-BBB assay, analog 23a demonstrated CNS permeability, indicating the possibility for future investigation in preclinical models of AD.

Discovery of blood-brain barrier permeable and orally bioavailable caffeine-based amide derivatives as acetylcholinesterase inhibitors.

Caffeine is one of the privileged natural products that shows numerous effects on the central nervous system. Herein, thirty-one caffeine-based amide derivatives were synthesized and evaluated in vitro for their anticholinesterase activity. The introduction of the amide group to the caffeine core augmented its anticholinesterase activity from an IC50 value of 128 to 1.32 µM (derivative, 6i). The SAR study revealed that N7 substitution on caffeine core is favorable over N1, and the presence of amide 'carbonyl' as a part of the linker contributes to the biological activity. The caffeine core of 6i exhibits interactions with the peripheral anionic site, whereas the N-benzyl ring fits nicely inside the catalytic anionic site. Analog 6i inhibits AChE in a mixed-type mode (Ki 4.58 µM) and crosses the BBB in an in-vitro PAMPA assay. Compound 6i has a descent metabolic stability in MLM (>70% remaining after 30 min) and favorable oral pharmacokinetics in Swiss albino mice.

Methoxy-naphthyl-Linked N-Benzyl Pyridinium Styryls as Dual Cholinesterase Inhibitors: Design, Synthesis, Biological Evaluation, and Structure-Activity Relationship.

The multifaceted nature of Alzheimer's disease (AD) indicates the need for multitargeted agents as potential therapeutics. Both cholinesterases (ChEs), acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), play a vital role in disease progression. Thus, inhibiting both ChEs is more beneficial than only one for effectively managing AD. The present study provides a detailed lead optimization of the e-pharmacophore-generated pyridinium styryl scaffold to discover a dual ChE inhibitor. A structure-activity relationship analysis indicated the importance of three structural fragments, methoxy-naphthyl, vinyl-pyridinium, and substituted-benzyl, in a dual ChE inhibitor pharmacophore. The optimized 6-methoxy-naphthyl derivative, 7av (SB-1436), inhibits EeAChE and eqBChE with IC50 values of 176 and 370 nM, respectively. The kinetic study has shown that 7av inhibits AChE and BChE in a non-competitive manner with ki values of 46 and 115 nM, respectively. The docking and molecular dynamics simulation demonstrated that 7av binds with the catalytic and peripheral anionic sites of AChE and BChE. Compound 7av also significantly stops the self-aggregation of Aß. The data presented herein indicate the potential of 7av for further investigation in preclinical models of AD.

Design, Synthesis, and Pharmacological Evaluation of Embelin-Aryl/alkyl Amine Hybrids as Orally Bioavailable Blood-Brain Barrier Permeable Multitargeted Agents with Therapeutic Potential in Alzheimer's Disease: Discovery of SB-1448.

The complex and multifaceted nature of Alzheimer's disease has brought about a pressing demand to develop ligands targeting multiple pathways to combat its outrageous prevalence. Embelin is a major secondary metabolite of Embelia ribes Burm f., one of the oldest herbs in Indian traditional medicine. It is a micromolar inhibitor of cholinesterases (ChEs) and ß-site amyloid precursor protein cleaving enzyme 1 (BACE-1) with poor absorption, distribution, metabolism, and excretion (ADME) properties. Herein, we synthesize a series of embelin-aryl/alkyl amine hybrids to improve its physicochemical properties and therapeutic potency against targeted enzymes. The most active derivative, 9j (SB-1448), inhibits human acetylcholinesterase (hAChE), human butyrylcholinesterase (hBChE), and human BACE-1 (hBACE-1) with IC50 values of 0.15, 1.6, and 0.6 µM, respectively. It inhibits both ChEs noncompetitively with ki values of 0.21 and 1.3 µM, respectively. It is orally bioavailable, crosses blood-brain barrier (BBB), inhibits Aß self-aggregation, possesses good ADME properties, and protects neuronal cells from scopolamine-induced cell death. The oral administration of 9j at 30 mg/kg attenuates the scopolamine-induced cognitive impairments in C57BL/6J mice.

Design, synthesis, and structure-activity relationship of caffeine-based triazoles as dual AChE and BACE-1 inhibitors.

Natural products have significantly contributed to drug discovery for neurodegenerative diseases. Caffeine is one of the well-known central nervous system(CNS)-active natural products. Besides its CNS stimulant properties, it is a mild inhibitor of acetylcholinesterase (AChE) and possesses memory-enhancing properties. The present work aimed to improve the AChE inhibition activity of the caffeine. The rationally designed caffeine-based triazoles were synthesized and evaluated in vitro for cholinesterase and ß-site amyloid precursor protein cleaving enzyme-1 (BACE-1) inhibitory activities. The attachment of triazole to the caffeine enhances its AChE inhibition activity from half-maximal inhibitory concentration (IC50 ) of 129 µM to 0.49 µM (derivative, 6l). The caffeine core interacts with the peripheral anionic site, whereas the benzyl triazole occupies the catalytic anionic site located at the bottom of the active site gorge. The structure-activity relationship revealed that the four-atom ester linker is superior to shorter linkers for connecting the caffeine core to the triazole. The 2,6-difluorobenzyl triazole-linked caffeine derivative, 6d, exhibits dual inhibition of AChE and BACE-1 with IC50 values of 1.43 and 10.9 µM, respectively. The derivative 6d inhibits AChE via a mixed-type mode with an inhibition rate constant (Ki ) value of 2.35 µM, which was corroborated by docking studies. The triazole 6d has an acceptable stability profile in human liver microsomes (t1/2 = 54 min) and was found to possess CNS permeability when evaluated using the parallel artificial membrane permeability blood-brain barrier assay. The results presented herein warrant investigating caffeine-based triazoles in preclinical models of Alzheimer's disease.

Blood-brain barrier permeable benzylpiperidin-4-yl-linked benzylamino benzamides as dual cholinesterase inhibitors.

Alzheimer's disease (AD) is a multifaceted neurodegenerative disorder involving various pathological events. The existing options for managing the disease utterly rely on cholinesterase (ChE) inhibitors. In recent years, the dual inhibition of ChEs as a potential AD therapeutics has substantially attracted the attention of medicinal chemists. Recently, we reported benzyl piperidinyl-linked methoxy-naphthamides as dual ChE inhibitors. Herein, we investigated the peripheral anionic binding site-binding methoxy-naphthamide fragment that yielded benzyl piperidinyl-linked benzyl aminobenzamide as another class of dual ChE inhibitors. The 3,5-dimethoxy benzyl aminobenzamide, 8c1, exhibits inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with half-maximal inhibitory concentration values of 0.61 and 2.04 µM, respectively. The enzyme kinetics and molecular modeling study indicated the noncompetitive and mixed-type mode of inhibition for AChE and BChE with ki values of 0.14 and 0.46 µM, respectively. The derivative 8c1 crosses the blood-brain barrier as indicated by the Pe value of 14.34 × 10-6 cm/s in the parallel artificial membrane permeability assay. Besides this, it also inhibits the self-aggregation of amyloid-ß. The results presented herein indicate the potential of benzamide 8c1 for further investigation in preclinical models of AD.

A Coumarin-Donepezil Hybrid as a Blood-Brain Barrier Permeable Dual Cholinesterase Inhibitor: Isolation, Synthetic Modifications, and Biological Evaluation of Natural Coumarins.

Plants have immensely contributed to the drug discovery for neurodegenerative diseases. Herein, we undertook the phytochemical investigation of Nardostachys jatamansi (D.Don) DC. rhizomes followed by semisynthetic modifications to discover cholinesterase (ChE) and beta-site amyloid precursor protein cleaving enzyme 1 (BACE-1) inhibitors. The 8-acetyl-7-hydroxycoumarin isolated from the bioactive extract moderately inhibits acetylcholinesterase (AChE) and BACE-1 with IC50 values of 22.1 and 17.7 µM, respectively. The semisynthetic trifluoromethyl substituted coumarin chalcone display a 5-fold improvement in BACE-1 inhibition (IC50 3.3 µM). Another semisynthetic derivative, a coumarin-donepezil hybrid, exhibits dual inhibition of both ChEs with IC50 values of 1.22 and 3.09 µM, respectively. Molecular modeling and enzyme kinetics revealed that the coumarin-donepezil hybrid is a non-competitive inhibitor of AChE. It crosses the blood-brain barrier and also inhibits Aß self-aggregation. The results presented herein warrant a detailed investigation of the coumarin-donepezil hybrid in preclinical models of Alzheimer's disease.

Role of basic aminoalkyl chains in the lead optimization of Indoloquinoline alkaloids.

Indoloquinoline (IQ) is an important class of naturally occurring antimalarial alkaloids, mainly represented by cryptolepine, isocryptolepine, and neocryptolepine. The IQ structural framework consists of four isomeric ring systems differing via the linkage of indole with quinoline as [3,2-b], [3,2-c], [2,3-c], and [2,3-b]. Structurally, IQs are planar and thus they bind strongly to the DNA which largely contributes to their biological properties. The structural rigidity and associated nonspecific cellular toxicity is a key shortcoming of the IQ structural framework for preclinical development. Thus, the lead optimization efforts were aimed at improving the therapeutic window and ADME properties of IQs. The structural modifications mainly involved attaching the basic aminoalkyl chains that positively modulates the vital physicochemical and topological parameters, thereby improves biological activity. Our analysis has found that the aminoalkylation consistently improved the selectivity index and provided acceptable in-vivo antimalarial/anticancer activity. Herein, we critically review the role of aminoalkylation in deciphering the antimalarial and cytotoxic activity of IQs.

Identification of plant-based multitargeted leads for Alzheimer's disease: In-vitro and in-vivo validation of Woodfordia fruticosa (L.) Kurz.

BACKGROUND: Alzheimer's disease (AD) is a complex neurodegenerative disease with no availability of disease-modifying therapeutics. The complex etiology and recent failures in clinical trials indicate the need for multitargeted agents. PURPOSE: The present study aims to discover new plant-based multitargeted anti-AD leads. METHODS: A library of plant extracts was screened for inhibition of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and beta-site amyloid precursor protein cleaving enzyme 1 (BACE-1). The secondary metabolites of active extracts were also tested, followed by enzyme-kinetics and molecular modeling to understand the mechanism of inhibition. The most active extract was investigated for in-vivo anti-dementia activity in behavioral mice models. RESULTS: Among the library of 105 extracts, Woodfordia fruticosa (SBE-80) and Bergenia ciliata (SBE-65) extracts displayed significant inhibition of all three enzymes. Gallic acid, one of the constituents of both plants, shows moderate inhibition of AChE and BACE-1. Catechin-3-O-gallate (CG), another constituent of SBE-65, inhibits EeAChE, rHuAChE, and eqBChE with IC50's of 29.9, 1.77, and 8.4 µM, respectively; along with a mild-inhibition of BACE-1. Ellagic acid, the constituent of SBE-80, inhibits BACE-1 with an IC50 value of 16 µM. The W. fruticosa extract SBE-80 at the dose of 25 mg/kg QD × 9 (PO) displayed memory-enhancing activity in Morris Water Maze and Passive Avoidance Test in Swiss albino mice. Treatment with SBE-80 also inhibits AChE in-vivo; whereas, a non-significant decrease in the serum TBARS was observed. CONCLUSION: W. fruticosa is identified for the first time as an anti-AD lead candidate. The in-vitro and in-vivo data presented herein and the documented safety profile of W. fruticosa indicate its strong potential for preclinical development as a botanical drug for dementia/AD.

Strategies to target SARS-CoV-2 entry and infection using dual mechanisms of inhibition by acidification inhibitors.

Many viruses utilize the host endo-lysosomal network for infection. Tracing the endocytic itinerary of SARS-CoV-2 can provide insights into viral trafficking and aid in designing new therapeutic strategies. Here, we demonstrate that the receptor binding domain (RBD) of SARS-CoV-2 spike protein is internalized via the pH-dependent CLIC/GEEC (CG) endocytic pathway in human gastric-adenocarcinoma (AGS) cells expressing undetectable levels of ACE2. Ectopic expression of ACE2 (AGS-ACE2) results in RBD traffic via both CG and clathrin-mediated endocytosis. Endosomal acidification inhibitors like BafilomycinA1 and NH4Cl, which inhibit the CG pathway, reduce the uptake of RBD and impede Spike-pseudoviral infection in both AGS and AGS-ACE2 cells. The inhibition by BafilomycinA1 was found to be distinct from Chloroquine which neither affects RBD uptake nor alters endosomal pH, yet attenuates Spike-pseudovirus entry. By screening a subset of FDA-approved inhibitors for functionality similar to BafilomycinA1, we identified Niclosamide as a SARS-CoV-2 entry inhibitor. Further validation using a clinical isolate of SARS-CoV-2 in AGS-ACE2 and Vero cells confirmed its antiviral effect. We propose that Niclosamide, and other drugs which neutralize endosomal pH as well as inhibit the endocytic uptake, could provide broader applicability in subverting infection of viruses entering host cells via a pH-dependent endocytic pathway.

Identification of aplysinopsin as a blood-brain barrier permeable scaffold for anti-cholinesterase and anti-BACE-1 activity.

Aplysinopsins are a group of marine-derived indole alkaloids that display diverse array of pharmacological effects. However, their effect on anti-Alzheimer targets has not been reported. Herein, we report the synthesis of aplysinopsin (1) and its effect on cholinesterases and beta-site amyloid-precursor protein cleaving enzyme 1 (BACE-1). It inhibits electric eel acetylcholinesterase (AChE), equine serum butyrylcholinesterase (BChE), and human BACE-1 with IC50 values of 33.9, 30.3, and 33.7 µM, respectively, and excellent BBB permeability (Pe 8.92 × 10-6 cm/s). To optimize its sub-micromolar activity, the first-generation analogs were prepared and screened. Two most active analogs 5b and (Z)-8g were found to effectively permeate the BBB (Pe > 5 × 10-6 cm/s). The N-sulphonamide derivative 5b display better cholinesterase inhibition, whereas the other analog (Z)-8g strongly inhibits BACE-1 (IC50 0.78 µM) activity. The analog 5b interacts primarily with PAS of AChE, and thus exhibit a mixed-type of inhibition. In addition, aplysinopsin along with new analogs inhibited the self-induced Aß1-42 aggregation. The data presented herein indicate that the aplysinopsin-scaffold holds a potential for further investigation as a multi-targeted anti-Alzheimer agent.

Clinical Variation Reduction in Propensity-matched Patients Treated for Malignant Pleural Effusion.

BACKGROUND: The potential advantages of clinical variation reduction are improved patient outcomes and cost reduction through optimizing and standardizing care. Malignant pleural effusion (MPE) is a common condition encountered by thoracic surgeons that has significant variation in cost and outcomes. The purpose of this investigation was to assess the opportunity of improving patient outcomes and reducing cost by using a standardized treatment algorithm based on evidenced-based care. METHODS: Patients treated for MPE using a standardized treatment algorithm at the study institution over a 2 year period were identified and propensity matched to MPE patients from 1 of 6 affiliated hospitals with comprehensive oncology and thoracic surgery services. Matched patients were treated at their physicians' discretion. Factors used in propensity matching were age, performance status, and tumor histology. The 2 cohorts were then compared for interventions, admissions and readmissions, morbidity, and pleural effusion-associated costs. Patients who desired only comfort or hospice care were excluded. RESULTS: From 2016 through 2018, 60 patients were treated using the standardized algorithm. These patients were propensity matched and the 2 cohorts compared. Patients treated with the algorithm experienced significantly fewer hospital admissions, readmissions, interventions, and costs while having a comparable procedural morbidity. CONCLUSIONS: An evidence-based treatment algorithm for MPE produces superior clinical outcomes to individualized therapy while significantly reducing the costs of care.

Discovery of methoxy-naphthyl linked N-(1-benzylpiperidine) benzamide as a blood-brain permeable dual inhibitor of acetylcholinesterase and butyrylcholinesterase.

The cholinesterase enzymes play a vital role in maintaining balanced levels of the neurotransmitter acetylcholine in the central nervous system. However, the overexpression of these enzymes results in hampered neurotransmission. Both the major forms of cholinesterase enzymes viz. acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) play a crucial role in blocking neurotransmission; therefore, in recent years, a strategy of dual cholinesterase inhibition is being explored. Herein, we developed an energy-optimized e-pharmacophore hypothesis AHHPRR from AChE-donepezil complex and screened a set of 15 scaffolds that were designed imaginarily. The ligand with N-(1-benzylpyridinium) benzamide framework has shown the highest fitness and volume score, which was chosen for synthesis and validation. A series of pyridinium benzamides were synthesized and screened for cholinesterase inhibition that led to the identification of 7b, a naphthalene containing N-(1-benzylpiperidine) benzamide as a potent dual AChE and BChE inhibitor with IC50 values of 0.176, and 0.47 µM, respectively. The kinetic study indicated that 7b inhibits AChE in a non-competitive manner with Ki value of 0.21 µM, and BChE in a mixed-fashion with Ki of 0.15 µM. The observed mode of inhibition was corroborated with molecular docking studies. The MD simulation studies pointed out that both AChE and BChE undergo low conformational changes in complex with 7b. The benzamide 7b displayed high BBB permeability in PAMPA assay, which indicates its potential for further exploration in preclinical studies for Alzheimer's disease.

Discovery of Helminthosporin, an Anthraquinone Isolated from Rumex abyssinicus Jacq as a Dual Cholinesterase Inhibitor.

Natural products have extensively contributed toward the discovery of new leads for Alzheimer's disease. During our search for new inhibitors of cholinesterase enzymes from natural sources, the ethyl acetate (EtOAc) extract of Rumex abyssinicus Jacq was identified as a dual cholinesterase inhibitor with IC50 values of 2.7 and 11.4 µg/mL against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), respectively. The phytochemical investigation of the EtOAc extract has resulted in isolation of four anthraquinones, namely, helminthosporin, emodin, chrysophanol, and physcion, amongst which the helminthosporin has been isolated for the first time from Rumex sp. All isolated secondary metabolites have displayed significant inhibition of EeAChE with IC50 values of 2.63, 15.21, 33.7, and 12.16 µM, respectively. In addition, the helminthosporin was also found to inhibit BChE with an IC50 value of 2.99 µM. The enzyme kinetic study has indicated that helminthosporin inhibits AChE and BChE in a noncompetitive manner with k i values of 10.3 and 12.3 µM, respectively. The results of molecular modeling and propidium iodide displacement assay have revealed that helminthosporin occupies the peripheral anionic site of the active site gorge of AChE. In the PAMPA-BBB permeability assay, helminthosporin was found to possess high BBB permeability (P e = 6.16 × 10-6 cm/s). In a nutshell, helminthosporin has been identified as a brain permeable dual cholinesterase inhibitor, and thus its further synthetic exploration is warranted for optimization of its potency.

Malononitrile-activated synthesis and anti-cholinesterase activity of styrylquinoxalin-2(1H)-ones.

Herein, we report a base-free malononitrile activated condensation of 3-methylquinoxaline-2(1H)-one (3MQ) 1 with aryl aldehydes 3a-3ad for synthesis of styrylquinoxalin-2(1H)-ones (SQs) 4a-4ad with excellent yields. In this reaction, malononitrile activates the aldehyde via Knoevenagel condensation towards reaction with 3MQ 1 and gets liberated during the course of reaction to yield the desired SQs 4a-4ad. The SQs were evaluated for in vitro cholinesterase inhibition and 4n was found to display a mixed type of inhibition of AChE, which was supported by molecular modelling studies. This study has led to the discovery of a new chemotype for cholinesterase inhibition which might be useful in finding a remedy for Alzheimer's disease.

Synthesis and biological evaluation of indoloquinoline alkaloid cryptolepine and its bromo-derivative as dual cholinesterase inhibitors.

Alkaloids have always been a great source of cholinesterase inhibitors. Numerous studies have shown that inhibiting acetylcholinesterase as well as butyrylcholinetserase is advantageous, and have better chances of success in preclinical/ clinical settings. With the objective to discover dual cholinesterase inhibitors, herein we report synthesis and biological evaluation of indoloquinoline alkaloid cryptolepine (1) and its bromo-derivative 2. Our study has shown that cryptolepine (1) and its 2-bromo-derivative 2 are dual inhibitors of acetylcholinesterase and butyrylcholinesterase, the enzymes which are involved in blocking the process of neurotransmission. Cryptolepine inhibits Electrophorus electricus acetylcholinesterase, recombinant human acetylcholinesterase and equine serum butyrylcholinesterase with IC50 values of 267, 485 and 699 nM, respectively. The 2-bromo-derivative of cryptolepine also showed inhibition of these enzymes, with IC50 values of 415, 868 and 770 nM, respectively. The kinetic studies revealed that cryptolepine inhibits human acetylcholinesterase in a non-competitive manner, with ki value of 0.88 µM. Additionally, these alkaloids were also tested against two other important pathological events of Alzheimer's disease viz. stopping the formation of toxic amyloid-ß oligomers (via inhibition of BACE-1), and increasing the amyloid-ß clearance (via P-gp induction). Cryptolepine displayed potent P-gp induction activity at 100 nM, in P-gp overexpressing adenocarcinoma LS-180 cells and excellent toxicity window in LS-180 as well as in human neuroblastoma SH-SY5Y cell line. The molecular modeling studies with AChE and BChE have shown that both alkaloids were tightly packed inside the active site gorge (site 1) via multiple π-π and cation-π interactions. Both inhibitors have shown interaction with the allosteric "peripheral anionic site" via hydrophobic interactions. The ADME properties including the BBB permeability were computed for these alkaloids, and were found within the acceptable range.

Identification of embelin, a 3-undecyl-1,4-benzoquinone from Embelia ribes as a multitargeted anti-Alzheimer agent.

Beta-secreatse (BACE-1) and cholinesterases are clinically validated targets of Alzheimer's disease (AD), for which natural products have provided immense contribution. The multifaceted nature of AD signifies the need of multitargeted agents to tackle this disease. In the search of new natural products as dual BACE-1/cholinesterase inhibitors, a library of pure natural products was screened for inhibition of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and BACE-1. The screening efforts have identified 1,4-benzoquinone "embelin," a natural product derived from Embelia ribes displaying inhibition of all three enzymes, with IC50 values of 2.5, 5.4, and 2.1 µM, respectively. This screen has also identified isoquinoline alkaloids papaverine and L-tetrahydropalmatine as AChE inhibitors. Kinetic study has shown that embelin inhibits EeAChE and EqBChE with ki values of 4.59 and 0.57 µM, in an uncompetitive and noncompetitive manner, respectively. The interactions of embelin with allosteric peripheral anionic site of cholinesterases, has further supported the results of kinetic study. Embelin has also enhanced the activity of P-gp in LS-180 cells, the efflux pump which is involved in the clearance of amyloid-ß from AD brain. Further, the cell viability study in neuronal cell line has indicated the excellent therapeutic window of embelin. These results are indicative of the fact that embelin is a multitargeted agent playing role in stopping the formation of amyloid-ß oligomers (via inhibition of BACE-1), improves cholinergic-transmission (via inhibition of AChE/BChE) and increases amyloid-ß clearance (via P-gp induction).

Patient Outcomes After Stent Failure for the Treatment of Acute Esophageal Perforation.

BACKGROUND: Esophageal stent placement for acute esophageal perforation has become part of the treatment algorithm for many thoracic surgery programs. Despite high success rates, there are patients for which stent placement is not successful. This investigation summarizes the outcomes of a relatively large group of such patients. METHODS: Patients who underwent esophageal stent placement for an acute perforation but required conversion to another form of therapy were identified from a prospectively collected institutional database. Excluded were patients whose perforation was associated with a malignancy. Patient demographics, operative and nonoperative invasive procedures, morbidities, mortality, and 6-month follow-up after discharge were reviewed. RESULTS: Between 2008 and 2015, 26 patients who failed to seal their esophageal leak after stent placement were identified. Eighteen (69%) of these patients required an operative repair with primary closure of the perforation. Four (15%) primary repairs had a persistent leak controlled with subsequent stent placement. Four (15%) patients required an esophagectomy with cervical esophagostomy. Three patients (11%), because of comorbid conditions, were referred for hospice care. One patient (3%) refused operative repair and developed a chronic fistula that resolved with subsequent stent placement. CONCLUSIONS: Esophageal stent placement continues to be a safe and effective treatment for acute esophageal perforation. Patients whose perforation does not seal with initial stent placement can be treated with primary surgical repair or esophagectomy without increasing their morbidity or mortality or compromising their prognosis.

Discovery and Preclinical Development of IIIM-290, an Orally Active Potent Cyclin-Dependent Kinase Inhibitor.

Rohitukine (1), a chromone alkaloid isolated from Indian medicinal plant Dysoxylum binectariferum, has inspired the discovery of flavopiridol and riviciclib, both of which are bioavailable only via intravenous route. With the objective to address the oral bioavailability issue of this scaffold, four series of rohitukine derivatives were prepared and screened for Cdk inhibition and cellular antiproliferative activity. The 2,6-dichloro-styryl derivative IIIM-290 (11d) showed strong inhibition of Cdk-9/T1 (IC50 1.9 nM) kinase and Molt-4/MIAPaCa-2 cell growth (GI50 < 1.0 µM) and was found to be highly selective for cancer cells over normal fibroblast cells. It inhibited the cell growth of MIAPaCa-2 cells via caspase-dependent apoptosis. It achieved 71% oral bioavailability with in vivo efficacy in pancreatic, colon, and leukemia xenografts at 50 mg/kg, po. It did not have CYP/efflux-pump liability, was not mutagenic/genotoxic or cardiotoxic, and was metabolically stable. The preclinical data presented herein indicates the potential of 11d for advancement in clinical studies.