Antimicrobial spiroketal macrolides and dichloro-diketopiperazine from Micromonospora sp. FIMYZ51.

Four compounds (1-4) featuring with an L-rhodinose and spiroketal, possess uncommon continuous hydroxy groups in the macrolide skeleton, and a dichloro-diketopiperazine (5) were isolated from a marine derived Micromonospora sp. FIMYZ51. The determination of the relative and absolute configurations of all isolates was achieved by extensive spectroscopic analyses, single-crystal X-ray diffraction analysis, and ECD calculations. According to structural characteristic and genomic sequences, a plausible biosynthetic pathway for compound 1-4 was proposed and a spirocyclase was inferred to be responsible for the formation of the rare spirocyclic moiety. Compounds 1-4 exhibited potent antifungal activities which is equal to itraconazole against Aspergillus niger. Compounds 1-5 exhibited different degree of inhibitory activities against opportunistic pathogenic bacteria of endocarditis (Micrococcus luteus) with MIC values ranging from 0.0625 µg/mL to 32 µg/mL. Compounds 2 and 3 showed moderate cytotoxicity against drug-resistant tumor cell lines (Namalwa and U266). The result not only provides active lead-compounds, but also reveal the potential of the spirocyclase gene resources from Micromonospora sp., which highlights the promising potential of the strain for biomedical applications.

Voacanga globosa Spirobisindole Alkaloids Exert Antiviral Activity in HIV Latently Infected Cell Lines by Targeting the NF-kB Cascade: In Vitro and In Silico Investigations.

Since the efficiency in the transcription of the HIV genome contributes to the success of viral replication and infectivity, we investigated the downregulating effects of the spirobisindole alkaloids globospiramine (1), deoxyvobtusine (2), and vobtusine lactone (3) from the endemic Philippine medicinal plant, Voacanga globosa, during HIV gene transcription. Alkaloids 1-3 were explored for their inhibitory activity on TNF-α-induced viral replication in two latently HIV-infected cell lines, OM10.1 and J-Lat. The induction of HIV replication from OM10.1 and J-Lat cells elicited by TNF-α was blocked by globospiramine (1) within noncytotoxic concentrations. Furthermore, globospiramine (1) was found to target the NF-ĸB activation cascade in a dose-dependent manner when the transcriptional step at which inhibitory activity is exerted was examined in TNF-α-induced 293 human cells using transient reporter (luciferase) gene expression systems (HIV LTR-luc, ĸB-luc, and mutant ĸB-luc). Interrogation through molecular docking against the NF-ĸB p50/p65 heterodimer and target sites of the subunits comprising the IKK complex revealed high binding affinities of globospiramine (1) against the S281 pocket of the p65 subunit (BE = -9.2 kcal/mol) and the IKKα activation loop (BE = -9.1 kcal/mol). These findings suggest globospiramine (1) as a molecular inspiration to discover new alkaloid-based anti-HIV derivatives.

Two antibacterial spiro compounds from the roots of Artemisia pallens wall: evidence from molecular docking.

Bioassay-guided isolation from acetone extract of the roots of Artemisia pallens Wall yielded two spiro compounds (1 and 2). The structures of these compounds were determined on the basis of spectroscopic techniques such as IR, MS, 1 D and 2 D- NMR. The acetone extract, fractions and the isolated two compounds were investigated for their antibacterial activity against two gram negative (E. coli, P. aeruginosa) and two gram positive (S. aureus, B. subtilis) bacterial strains. Compound (2) showed the best spectra of activity with IC50 and MIC values between 2.48-3.08 and 12.78 - 21.77 µM and Compound (1) with 2.57-3.69 and 38.17 - 80.57 µM, respectively, for the four bacterial strains, whereas inactive against Mycobacterium tuberculosis. Molecular docking study could further help in understanding the various interactions between these compounds and DNA gyrase active site in detail and thereby could provide valuable insight into the mechanism of action.

Natural spirocyclic alkaloids and polyphenols as multi target dementia leads.

The U rhynchophylla, U tomentosa, Isatis indigotica Fortune, Voacanga Africana, herbal constituents, fungal extracts from Aspergillus duricaulis culture media, include spirooxindoles, polyphenols or bridged spirocyclic alkaloids. Their constituents exhibit specific and synergistic multiple neuroprotective properties including inhibiting of Aß fibril induced cytotoxicity, NMDA receptor inhibition in mice models of Alzheimer's disease (AD). The pioneering research from Woodward to Waldmann has advanced the synthesis of spirocyclic alkaloids. Furthermore, the elucidation of the genetic analysis, biochemical pathways that links strictosidine to the alkaloids akuammicine, stemmadenine, tabersonine, catharanthine, will now enable the biotechnological generation, also stimulate synthesis of related bridged spirocyclic alkaloids for medicinal investigations. From the value of spirocyclic structures as multi target dementia leads, we hypothesise that simpler Lipinski-like natural/synthetic alkaloid analogues may likewise be discovered that provide neurocognitive enhancing activities against dementia and AD.

Prolonged Treatment with Centella asiatica Improves Memory, Reduces Amyloid-ß Pathology, and Activates NRF2-Regulated Antioxidant Response Pathway in 5xFAD Mice.

BACKGROUND: The medicinal herb Centella asiatica has been long been used for its neuroprotective and cognitive enhancing effects. We have previously shown that two weeks of treatment with a water extract of Centella asiatica (CAW) improves cognition and activates the endogenous antioxidant response pathway without altering amyloid-ß (Aß) plaque burden. OBJECTIVE: Here, we assess the effect of long-term treatment of CAW in the 5xFAD mouse model of Aß accumulation. METHODS: Four-month-old 5xFAD mice were treated with CAW in their drinking water (2 g/L) for three months at which point they underwent cognitive testing as well as analysis of Aß plaque levels and antioxidant and synaptic gene expression. In order to confirm the involvement of the antioxidant regulatory transcription factor NRF2 on the effects of CAW on synaptic plasticity, neurons isolated from 5xFAD mice were also treated with CAW and the targeted inhibitor ML385. RESULTS: Three months of treatment with CAW improved spatial and contextual memory as well as executive function in 5xFAD mice. This improvement was accompanied by increased antioxidant gene expression and a decrease in Aß plaque burden relative to untreated 5xFAD animals. In isolated neurons, treatment with ML385 blocked the effects of CAW on dendritic arborization and synaptic gene expression. CONCLUSION: These results suggest that prolonged CAW exposure could be beneficial in Alzheimer's disease and that these effects likely involve NRF2 activation. Moreover, these findings suggest that targeting NRF2 itself may be a relevant therapeutic strategy for improving synaptic plasticity and cognitive function in Alzheimer's disease.

The Main Alkaloids in Uncaria rhynchophylla and Their Anti-Alzheimer's Disease Mechanism Determined by a Network Pharmacology Approach.

Alzheimer's disease (AD) is a growing concern in modern society, and effective drugs for its treatment are lacking. Uncaria rhynchophylla (UR) and its main alkaloids have been studied to treat neurodegenerative diseases such as AD. This study aimed to uncover the key components and mechanism of the anti-AD effect of UR alkaloids through a network pharmacology approach. The analysis identified 10 alkaloids from UR based on HPLC that corresponded to 90 anti-AD targets. A potential alkaloid target-AD target network indicated that corynoxine, corynantheine, isorhynchophylline, dihydrocorynatheine, and isocorynoxeine are likely to become key components for AD treatment. KEGG pathway enrichment analysis revealed the Alzheimers disease (hsa05010) was the pathway most significantly enriched in alkaloids against AD. Further analysis revealed that 28 out of 90 targets were significantly correlated with Aß and tau pathology. These targets were validated using a Gene Expression Omnibus (GEO) dataset. Molecular docking studies were carried out to verify the binding of corynoxine and corynantheine to core targets related to Aß and tau pathology. In addition, the cholinergic synapse (hsa04725) and dopaminergic synapse (hsa04728) pathways were significantly enriched. Our findings indicate that UR alkaloids directly exert an AD treatment effect by acting on multiple pathological processes in AD.

Benzannulated 5,5-spiroketal sesquiterpenes from the roots of Angelica Pubescens.

Two new tetrahydrobenzannulated 5,5-spiroketal sesquiterpenes (1 and 2) and three novel benzannulated 5,5-spiroketal sesquiterpenes (3-5) namely angepubesins A-E, together with a new heliannane-type benzannulated sesquiterpene namely angepubesin F (6) and two known monoterpenes (7 and 8), were isolated from the roots of Angelica Pubescens. Their structures were identified by various spectroscopic analyses (NMR, MS, UV, IR), in combination with 13C NMR calculation as well as MAE, CMAE, DP4 + and MAEΔΔδ values analyses. The absolute configurations of 1-6 were determined by modified Mosher's method, ECD calculation and single-crystal X-ray diffraction (Cu Kα). Furthermore, the inhibitory activities of these isolated compounds against nitric oxide (NO) production induced by lipopolysaccharide (LPS) in RAW264.7 macrophage cells were evaluated. The results showed that compounds 2-4, 6 and 7, especially 6, displayed markedly inhibitory effects on NO production in a concentration-dependent manner. Mechanical study revealed that compound 6 could significantly inhibit the expression of nitric oxide synthase (iNOS) protein at a concentration of 10 µM. In addition, compound 6 suppressed the activation of JAK-STAT and NF-κB pathways.

Genomics-directed activation of cryptic natural product pathways deciphers codes for biosynthesis and molecular function.

Natural products, which can be isolated from living organisms worldwide, have played a pivotal role in drug discovery since ancient times. However, it has become more challenging to identify a structurally novel molecule with promising biological activity for pharmaceutical development, mainly due to the limited methodologies for their acquisition. In this review, we summarize our recent studies that activate the biosynthetic potential of filamentous fungi by genetic engineering to harness the metabolic flow for the efficient production of unprecedented natural products. The recent revolution in genome sequencing technology enables the accumulation of vast amounts of information on biosynthetic genes, the blueprint of the molecular construction. Utilizing the established heterologous expression system, activation of the pathway-specific transcription factor coupled with a knockout strategy, and manipulating the global regulatory gene, the biosynthetic genes were exploited to activate biosynthetic pathways and decipher the encoded enzyme functions. We show that this methodology was beneficial for acquiring fungal treasures for drug discovery. These studies also enabled the investigation of the molecular function of natural products in fungal development.

Discovery of potentially biased agonists of mu-opioid receptor (MOR) through molecular docking, pharmacophore modeling, and MD simulation.

Opioids are well known for their potent analgesic efficacy and severe side effects. Studies have shown that analgesic effects are mediated by the downstream G-protein-dependent pathway of the µ-opioid receptor (MOR), and another ß-arrestin-dependent pathway mediates side effects such as respiratory depression, constipation and tolerance etc. TRV130 is a biased ligand for G-protein-dependent pathway, which has high analgesia and has fewer side effects than morphine. In this study, the structure similarity search was performed on the IBSSC database using Oliceridine (TRV130) and PZM21 as templates. The 3D structure-based pharmacophore model was built and combined molecular docking prediction mode was selected to filter out small molecules, Finally, based on affinity prediction, four candidate molecules were obtained. Molecular dynamics simulations explored the detailed interaction mechanism of proteins with small molecules under dynamics. These results suggest that these candidate molecules are potential MOR agonists.

Discovery of EST73502, a Dual µ-Opioid Receptor Agonist and σ1 Receptor Antagonist Clinical Candidate for the Treatment of Pain.

The synthesis and pharmacological activity of a new series of 4-alkyl-1-oxa-4,9-diazaspiro[5.5]undecane derivatives as potent dual ligands for the σ1 receptor (σ1R) and the µ-opioid receptor (MOR) are reported. A lead optimization program over the initial 4-aryl analogues provided 4-alkyl derivatives with the desired functionality and good selectivity and ADME profiles. Compound 14u (EST73502) showed MOR agonism and σ1R antagonism and a potent analgesic activity, comparable to the MOR agonist oxycodone in animal models of acute and chronic pain after single and repeated administration. Contrary to oxycodone, 14u produces analgesic activity with reduced opioid-induced relevant adverse events, like intestinal transit inhibition and naloxone-precipitated behavioral signs of opiate withdrawal. These results provide evidence that dual MOR agonism and σ1R antagonism may be a useful strategy for obtaining potent and safer analgesics and were the basis for the selection of 14u as a clinical candidate for the treatment of pain.

Discovery of DS34942424: An orally potent analgesic without mu opioid receptor agonist activity.

We identified (5'S)-10'-fluoro-6'-methyl-5',6'-dihydro-3'H-spiro[cyclopropane-1,4'-[2,6]diaza[2,5]methano[2,6]benzodiazonin]-7'(1'H)-one, 22b (DS34942424) with a unique and original bicyclic skeleton. 22b showed an orally potent analgesic in the acetic acid-induced writhing test and formalin test in ddY mice without sedation. Moreover, 22b did not exhibit mu opioid receptor agonist activity.

Acupuncture reduces pain in rats with osteoarthritis by inhibiting MCP2/CCR2 signaling pathway.

Acupuncture is an emerging alternative therapy that has been beneficial for the pain of osteoarthritis (OA). However, the underlying mechanism of protective effect remains unclear. MCP1/CCR2 axis can be stimulated in various periods of OA, and we hypothesize that acupuncture may treat OA by regulating the MCP1/CCR2 axis. This study aimed to explore the effect of acupuncture at points ST35 and ST36 on the effects of hyperalgesia and cartilage in OA rats including the expression of chemokines, nerve growth factor (NGF), and inflammatory-related proteins. OA was induced in male Sprague-Dawley rats by anterior cruciate ligament transection at the right knee. The first acupuncture intervention was performed on the seventh day after surgery and once a day for seven weeks. The knee-pain-related behaviors, histology, and related protein were examined in this study. We have found that electroacupuncture at ST35 and ST36 can significantly alleviate the hyperalgesia and cartilage degeneration as well as reducing nerve sprouting in OA knee joint. Moreover, acupuncture treatment may inhibit the MCP1/CCR2 axis as well as down-regulate inflaming factor and NGF in cartilage and synovial tissue. The data presented here indicate that acupuncture exerts a protective effect against hyperalgesia and cartilage degeneration, and the mechanism might involve in chemokines and NGF pathway.

Structure-based drug designing and immunoinformatics approach for SARS-CoV-2.

The prevalence of respiratory illness caused by the novel SARS-CoV-2 virus associated with multiple organ failures is spreading rapidly because of its contagious human-to-human transmission and inadequate globalhealth care systems. Pharmaceutical repurposing, an effective drug development technique using existing drugs, could shorten development time and reduce costs compared to those of de novo drug discovery. We carried out virtual screening of antiviral compounds targeting the spike glycoprotein (S), main protease (Mpro), and the SARS-CoV-2 receptor binding domain (RBD)-angiotensin-converting enzyme 2 (ACE2) complex of SARS-CoV-2. PC786, an antiviral polymerase inhibitor, showed enhanced binding affinity to all the targets. Furthermore, the postfusion conformation of the trimeric S protein RBD with ACE2 revealed conformational changes associated with PC786 drug binding. Exploiting immunoinformatics to identify T cell and B cell epitopes could guide future experimental studies with a higher probability of discovering appropriate vaccine candidates with fewer experiments and higher reliability.

Width-Consistent Mesoporous Silica Nanorods with a Precisely Controlled Aspect Ratio for Lysosome Dysfunctional Synergistic Chemotherapy/Photothermal Therapy/Starvation Therapy/Oxidative Therapy.

Although differently shaped mesoporous silica is widely studied, the formation of width-consistent mesoporous silica nanorods (MSNRs) with a precisely controlled aspect ratio (AR: length/width) is challenging and has not been reported. Herein, width-consistent (100 nm) MSNRs with ARs of 2, 3, 4, 6, 8, and 10 were obtained by increasing the concentrations while maintaining the molar ratio of cetyltrimethylammonium bromide (CTAB) and tetraethyl orthosilicate (TEOS). The results demonstrated that the as-prepared MSNR with an AR of 6 (AR6) possesses high cellular-uptake efficiency and drug-loading capacity. Thus, AR6-based cancer-cell-targeting nanosystems were designed. These nanosystems encapsulated doxorubicin (DOX) into the porous channel of AR6, adsorbed glucose oxidase (GOx), and then formed a polydopamine (PDA) layer for Siramesine (Siram, a lysosome dysfunctional drug) adsorption and folic acid modification. In this design, the PDA shell could prevent the leakage of loading components and keep the activity of GOx during delivery while achieving an on-demand drug release in the targeted location and photothermal therapy under near-infrared irradiation. The increase in temperature was highly beneficial for elevating the catalytic efficiency of GOx, accelerating the consumption of intracellular glucose, and generating a relatively high level of cytotoxic H2O2, all of which enhanced starvation and oxidative therapies. Siram was employed to inhibit lysosomal metabolism and accompany GOx to reach a dual-enhanced starvation therapy effect. In addition, DOX entered the nucleus and altered DNA for chemotherapy. The results showed that the nanosystems have superior therapeutic efficacy against cancer cells and not much toxicity to normal cells. Therefore, this study provides a novel strategy for lysosome dysfunctional synergistic chemotherapy/photothermal therapy/starvation therapy/oxidative therapy based on MSNR.

Metabolic profile and behavior of clethodim and spirotetramat in herbs during plant growth and processing under controlled conditions.

Herbs may contain pesticide residues which are an important discriminator of food security and food quality. The challenge of the research was to assess the fate of the herbicide clethodim (CLE) and the insecticide spirotetramat (SPI) applied in herbs (BBCH 11-21) during herb growth and processing under controlled greenhouse trial conditions. The metabolic profile of CLE and SPI and their degradation products in basil (Ocimum basilicum L.), peppermint (Mentha × piperita L.) and sage (Salvia officinalis L.) was also presented. The half-lives of CLE and SPI in herbs were 1.10-1.56 days and 0.51-0.83 days, respectively. The terminal residues of SPI (SPI-enol, SPI-ketohydroxy, SPI-monohydroxy and SPI-enol-glucoside) and CLE (CLE-sulfone and CLE-sulfoxide) in herbal matrices were measured below EU maximum residue limits. In this paper, we aimed to assess the impact of washing and dehydratation pretreatment and calculated processing factors (PFs) which can be applied to more accurate food safety assessments. The PF values of CLE and SPI after drying prior washing was below 1 indicating reduction of initial residues. Drying process without washing demonstrated increases of SPI concentrations (PF up to 1.50). The lowest PFs were obtained when raw herbal plants were washed before drying showing almost complete degradation of parent compound (93-99%).

Two new compounds, Talaromycin A and B, isolated from an endophytic fungus, Talaromyces aurantiacus.

Two new compounds Talaromycin A (1) and Talaromycin B (2) were isolated from a liquid culture of Talaromyces aurantiacus. The structures of 1 and 2 were elucidated by IR, MS, 1D and 2D NMR spectra and comparison of the experimental and calculated electronic circular dichroism spectra. Additional known compounds (3-6) were also isolated. These compounds were tested for monoamine oxidase, acetylcholinesterase and PI3K inhibitory activity, but showed only weak activity.

BBB-permeable aporphine-type alkaloids in Nelumbo nucifera flowers with accelerative effects on neurite outgrowth in PC-12 cells.

Blood-brain barrier (BBB)-permeable components in the methanolic extract of Nelumbo nucifera flowers showed accelerative effects on neurite outgrowth in PC-12 cells. Among the constituents isolated from N. nucifera flowers in our previous study, aporphine-type alkaloids, lirinidine, asimilobine, N-methylasimilobine, and pronuciferine, showed accelerative effects. Lirinidine, N-methylasimilobine, and an alkaloid-rich diethyl ether fraction at low concentrations increased the expression of mRNAs coding for TrkA, Vav3, and Rac1. In addition, good permeability of asimilobine and N-methylasimilobine was confirmed using an in vitro BBB model. Asimilobine and N-methylasimilobine are considered to be suitable as seed compounds of drugs for Alzheimer's disease, because of their activity and BBB permeability.

Maggot Extracts Alleviate Inflammation and Oxidative Stress in Acute Experimental Colitis via the Activation of Nrf2.

Ulcerative colitis (UC) is a common chronic remitting disease driven through altered immune responses with production of inflammatory cytokines. Oxidant/antioxidant balance is also suggested to be an important factor for the recurrence and progression of UC. Maggots are known as a traditional Chinese medicine also known as "wu gu chong." NF-E2-related factor-2 (Nrf2) transcription factor regulates the oxidative stress response and also represses inflammation. The aim of this study was to investigate the effects of maggot extracts on the amelioration of inflammation and oxidative stress in a mouse model of dextran sulfate sodium- (DSS-) induced colitis and evaluate if the maggot extracts could repress inflammation and oxidative stress using RAW 264.7 macrophages stimulated by lipopolysaccharide (LPS). In the present study, we found that the maggot extracts significantly prevented the loss of body weight and shortening of colon length in UC induced by DSS. Furthermore, DSS-induced expression of proinflammatory cytokines at both mRNA and protein levels in the colon was also attenuated by the maggot extracts. In addition, the maggot extracts could significantly suppress the expression of interleukin- (IL-) 1ß, IL-6, TNF-α, NFκB p65, p-IκB, p22-phox, and gp91-phox in LPS-stimulated RAW 264.7 cells and colonic tissues. The maggot extracts increased the level of Nrf2 and prevented the degradation of Nrf2 through downregulating the expression of Keap1, which resulted in augmented levels of HO-1, SOD, and GSH-Px and reduced levels of MPO and MDA. However, after administering an Nrf2 inhibitor (ML385) to block the Nrf2/HO-1 pathway, we failed to observe the protective effects of the maggot extracts in mice with colitis and RAW 264.7 cells. Taken together, our data for the first time confirmed that the maggot extracts ameliorated inflammation and oxidative stress in experimental colitis via modulation of the Nrf2/HO-1 pathway. This study sheds light on the possible development of an effective therapeutic strategy for inflammatory bowel diseases.

In vitro antimicrobial combination testing of and evolution of resistance to the first-in-class spiropyrimidinetrione zoliflodacin combined with six therapeutically relevant antimicrobials for Neisseria gonorrhoeae.

OBJECTIVES: Resistance in Neisseria gonorrhoeae to all gonorrhoea therapeutic antimicrobials has emerged. Novel therapeutic antimicrobials are imperative and the first-in-class spiropyrimidinetrione zoliflodacin appears promising. Zoliflodacin could be introduced in dual antimicrobial therapies to prevent the emergence and/or spread of resistance. We investigated the in vitro activity of and selection of resistance to zoliflodacin alone and in combination with six gonorrhoea therapeutic antimicrobials against N. gonorrhoeae. METHODS: The international gonococcal reference strains WHO F (WT) and WHO O, WHO V and WHO X (strains with different AMR profiles) were examined. Zoliflodacin was evaluated alone or combined with ceftriaxone, cefixime, spectinomycin, gentamicin, tetracycline, cethromycin or sitafloxacin in chequerboard assays, time-kill curve analysis and selection-of-resistance studies. RESULTS: Zoliflodacin alone or in combination with all six antimicrobials showed rapid growth inhibition against all examined strains. The time-kill curve analysis indicated that tetracycline or cethromycin combined with zoliflodacin can significantly decrease the zoliflodacin kill rate in vitro. The frequency of selected zoliflodacin-resistance mutations was low when evaluated as a single agent and further reduced for all antimicrobial combinations. All resistant mutants contained the GyrB mutations D429N, K450T or K450N, resulting in zoliflodacin MICs of 0.5-4 mg/L. CONCLUSIONS: Zoliflodacin, alone or in combination with sexually transmitted infection therapeutic antimicrobials, rapidly kills gonococci with infrequent resistance emergence. Zoliflodacin remains promising for gonorrhoea oral monotherapy and as part of dual antimicrobial therapy with low resistance emergence potential. A Phase III trial evaluating efficacy and safety of zoliflodacin for uncomplicated gonorrhoea treatment is planned in 2019.

Design, Synthesis, and Biological Evaluation of Substituted 4,6-Dihydrospiro[[1,2,3]triazolo[4,5-b]pyridine-7,3'-indoline]-2',5(3H)-dione Analogues as Potent NS4B Inhibitors for the Treatment of Dengue Virus Infection.

A series of substituted 4,6-dihydrospiro[[1,2,3]triazolo[4,5-b]pyridine-7,3'-indoline]-2',5(3H)-dione analogues were synthesized and evaluated as potent dengue virus inhibitors. Throughout a structure-activity relationship exploration on the amide of the indolone moiety, a wide range of substitutions were found to be well tolerated for chemical optimization at this position. Among these compounds, 15 (JMX0254) displayed the most potent and broad inhibitory activities, effective against DENV-1 to -3 with EC50 values of 0.78, 0.16, and 0.035 µM, respectively, while compounds 16, 21, 27-29, 47, and 70 exhibited relatively moderate to high activities with low micromolar to nanomolar potency against all four serotypes. The biotinylated compound 73 enriched NS4B protein from cell lysates in pull-down studies, and the findings together with the mutation investigations further validated dengue NS4B protein as the target of this class of compounds. More importantly, compound 15 exhibited good in vivo pharmacokinetic properties and efficacy in the A129 mouse model, indicating its therapeutic potential against the dengue virus infection as a drug candidate for further preclinical development.