Design and synthesis of sirtinol analogs as human neutrophil elastase inhibitors.

Human neutrophil elastase (HNE) overexpression has a crucial role in most acute inflammation and alpha1-antitrypsin deficiency syndromes observed in humans, triggering neutrophil invasion and activation of macrophage inflammatory and proteolytic effects, leading to tissue damage. Manipulating HNE level homeostasis could potentially help treat neutrophilic inflammation. Previous studies have shown that sirtinol (1) has a specific influence on HNE and potently attenuates acute lung injury and hepatic injury mediated by lipopolysaccharide or trauma hemorrhage. Therefore, 1 was chosen as the model structure to obtain more potent anti-HNE agents. In the present study, we synthesized a series of sirtinol analogues and determined their inhibitory effects on HNE. Structure-activity relationship (SAR) studies showed that swapping the imine and methyl groups of the sirtinol scaffold with diazene and carboxyl groups, respectively, enhances the HNE inhibiting potency. Compound 29 exhibited the highest potency in the SAR study and showed dual inhibitory effects on HNE and proteinase 3 with IC50 values of 4.91 and 20.69 µM, respectively. Furthermore, 29 was confirmed to have dual impacts on inhibiting O2•- generation and elastase release in cell-based assays with IC50 values of 0.90 and 1.86 µM, respectively. These findings suggest that 29 is a promising candidate for developing HNE inhibitors in the treatment of neutrophilic inflammatory diseases.

Synthesis of bioactive evodiamine and rutaecarpine analogues under ball milling conditions.

Mechanochemical reactions achieved by processes such as milling and grinding are promising alternatives to traditional solution-based chemistry. This approach not only eliminates the need for large amounts of solvents, thereby reducing waste generation, but also finds applications in chemical and materials synthesis. The focus of this study is on the synthesis of quinazolinone derivatives by ball milling, in particular evodiamine and rutaecarpine analogues. These compounds are of interest due to their diverse bioactivities, including potential anticancer properties. The study examines the reactions carried out under ball milling conditions, emphasizing their efficiency in terms of shorter reaction times and reduced environmental impact compared to conventional methods. The ball milling reaction of evodiamine and rutaecarpine analogues resulted in yields of 63-78% and 22-61%, respectively. In addition, these compounds were tested for their cytotoxic activity, and evodiamine exhibited an IC50 of 0.75 ± 0.04 µg mL-1 against the Ca9-22 cell line. At its core, this research represents a new means to synthesise these compounds, providing a more environmentally friendly and sustainable alternative to traditional approaches.

3,4-Dicaffeoylquinic Acid from the Medicinal Plant Ilex kaushue Disrupts the Interaction Between the Five-Fold Axis of Enterovirus A-71 and the Heparan Sulfate Receptor.

While infections by enterovirus A71 (EV-A71) are generally self-limiting, they can occasionally lead to serious neurological complications and death. No licensed therapies against EV-A71 currently exist. Using anti-virus-induced cytopathic effect assays, 3,4-dicaffeoylquinic acid (3,4-DCQA) from Ilex kaushue extracts was found to exert significant anti-EV-A71 activity, with a broad inhibitory spectrum against different EV-A71 genotypes. Time-of-drug-addition assays revealed that 3,4-DCQA affects the initial phase (entry step) of EV-A71 infection by directly targeting viral particles and disrupting viral attachment to host cells. Using resistant virus selection experiments, we found that 3,4-DCQA targets the glutamic acid residue at position 98 (E98) and the proline residue at position 246 (P246) in the 5-fold axis located within the VP1 structural protein. Recombinant viruses harboring the two mutations were resistant to 3,4-DCQA-elicited inhibition of virus attachment and penetration into human rhabdomyosarcoma (RD) cells. Finally, we showed that 3,4-DCQA specifically inhibited the attachment of EV-A71 to the host receptor heparan sulfate (HS), but not to the scavenger receptor class B member 2 (SCARB2) and P-selectin glycoprotein ligand-1 (PSGL1). Molecular docking analysis confirmed that 3,4-DCQA targets the 5-fold axis to form a stable structure with the E98 and P246 residues through noncovalent and van der Waals interactions. The targeting of E98 and P246 by 3,4-DCQA was found to be specific; accordingly, HS binding of viruses carrying the K242A or K244A mutations in the 5-fold axis was successfully inhibited by 3,4-DCQA.The clinical utility of 3,4-DCQA in the prevention or treatment of EV-A71 infections warrants further scrutiny. IMPORTANCE The canyon region and the 5-fold axis of the EV-A71 viral particle located within the VP1 protein mediate the interaction of the virus with host surface receptors. The three most extensively investigated cellular receptors for EV-A71 include SCARB2, PSGL1, and cell surface heparan sulfate. In the current study, a RD cell-based anti-cytopathic effect assay was used to investigate the potential broad spectrum inhibitory activity of 3,4-DCQA against different EV-A71 strains. Mechanistically, we demonstrate that 3,4-DCQA disrupts the interaction between the 5-fold axis of EV-A71 and its heparan sulfate receptor; however, no effect was seen on the SCARB2 or PSGL1 receptors. Taken together, our findings show that this natural product may pave the way to novel anti-EV-A71 therapeutic strategies.

An Anthranilate Derivative Inhibits Glutamate Release and Glutamate Excitotoxicity in Rats.

The neurotransmitter glutamate plays an essential role in excitatory neurotransmission; however, excessive amounts of glutamate lead to excitotoxicity, which is the most common pathogenic feature of numerous brain disorders. This study aimed to investigate the role of butyl 2-[2-(2-fluorophenyl)acetamido]benzoate (HFP034), a synthesized anthranilate derivative, in the central glutamatergic system. We used rat cerebro-cortical synaptosomes to examine the effect of HFP034 on glutamate release. In addition, we used a rat model of kainic acid (KA)-induced glutamate excitotoxicity to evaluate the neuroprotective potential of HFP034. We showed that HFP034 inhibits 4-aminopyridine (4-AP)-induced glutamate release from synaptosomes, and this inhibition was absent in the absence of extracellular calcium. HFP034-mediated inhibition of glutamate release was associated with decreased 4-AP-evoked Ca2+ level elevation and had no effect on synaptosomal membrane potential. The inhibitory effect of HFP034 on evoked glutamate release was suppressed by blocking P/Q-type Ca2+ channels and protein kinase C (PKC). Furthermore, HFP034 inhibited the phosphorylation of PKC and its substrate, myristoylated alanine-rich C kinase substrate (MARCKS) in synaptosomes. We also observed that HFP034 pretreatment reduced neuronal death, glutamate concentration, glial activation, and the levels of endoplasmic reticulum stress-related proteins, calpains, glucose-regulated protein 78 (GRP 78), C/EBP homologous protein (CHOP), and caspase-12 in the hippocampus of KA-injected rats. We conclude that HFP034 is a neuroprotective agent that prevents glutamate excitotoxicity, and we suggest that this effect involves inhibition of presynaptic glutamate release through the suppression of P/Q-type Ca2+ channels and PKC/MARCKS pathways.

Chlorogenic Acid Decreases Glutamate Release from Rat Cortical Nerve Terminals by P/Q-Type Ca2+ Channel Suppression: A Possible Neuroprotective Mechanism.

The glutamatergic neurotransmitter system has received substantial attention in research on the pathophysiology and treatment of neurological disorders. The study investigated the effect of the polyphenolic compound chlorogenic acid (CGA) on glutamate release in rat cerebrocortical nerve terminals (synaptosomes). CGA inhibited 4-aminopyridine (4-AP)-induced glutamate release from synaptosomes. This inhibition was prevented in the absence of extracellular Ca2+ and was associated with the inhibition of 4-AP-induced elevation of Ca2+ but was not attributed to changes in synaptosomal membrane potential. In line with evidence observed through molecular docking, CGA did not inhibit glutamate release in the presence of P/Q-type Ca2+ channel inhibitors; therefore, CGA-induced inhibition of glutamate release may be mediated by P/Q-type Ca2+ channels. CGA-induced inhibition of glutamate release was also diminished by the calmodulin and Ca2+/calmodilin-dependent kinase II (CaMKII) inhibitors, and CGA reduced the phosphorylation of CaMKII and its substrate, synapsin I. Furthermore, pretreatment with intraperitoneal CGA injection attenuated the glutamate increment and neuronal damage in the rat cortex that were induced by kainic acid administration. These results indicate that CGA inhibits glutamate release from cortical synaptosomes by suppressing P/Q-type Ca2+ channels and CaMKII/synapsin I pathways, thereby preventing excitotoxic damage to cortical neurons.

Topical application of anthranilate derivatives ameliorates psoriatic inflammation in a mouse model by inhibiting keratinocyte-derived chemokine expression and neutrophil infiltration.

Psoriasis is an inflammatory autoimmune skin disorder possessing a complex etiology related to genetic and environmental triggers. Keratinocytes show a potential role for the origin of psoriasis. In this study, we estimated the efficiency of 2 anthranilate derivatives-(E)-4-( N-{2-[1-(hydroxyimino)ethyl]phenyl}sulfamoyl)phenyl pivalate (HFP031) and butyl 2-[2-(2-fluorophenyl)acetamido]benzoate (HFP034)-on psoriasis amelioration in a mouse model. The results showed that topical treatment with both compounds could attenuate epidermal thickness and scaling in an imiquimod (IMQ)-induced psoriasis mouse model via decreased expression of cytokines and chemokines [C-X-C chemokine ligand (CXCL)1 and CXCL2], leading to the reduction of neutrophilic abscess in the skin. The in vivo cutaneous absorption of HFP034 was 7.6-fold greater than that of HFP031. Both compounds caused negligible irritation on healthy mouse skin. In addition, we examined the effect of the anthranilate derivatives on chemokine expression in IMQ-treated HaCaT keratinocytes. Our results elucidated a mechanism for anti-inflammatory activity of HFP034 that involved the elevation of intracellular cAMP concentration, suppression of NF-κB activity, and attenuation of neutrophil chemoattractant expression. These results suggest that HFP034 could increase the cutaneous concentration of cAMP to suppress neutrophil infiltration into the skin. Topically applied HFP034 may demonstrate a potential for future clinical application as a novel therapy for psoriasis treatment.-Lin, Z.-C., Hsieh, P.-W., Hwang, T.-L., Chen, C.-Y., Sung, C. T., Fang, J.-Y. Topical application of anthranilate derivatives ameliorates psoriatic inflammation in a mouse model by inhibiting keratinocyte-derived chemokine expression and neutrophil infiltration.

ß-Nitrostyrene derivatives attenuate LPS-mediated acute lung injury via the inhibition of neutrophil-platelet interactions and NET release.

Acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS) are high-mortality and life-threatening diseases that are associated with neutrophil activation and accumulation within lung tissue. Emerging evidence indicates that neutrophil-platelet aggregates (NPAs) at sites of injury increase acute inflammation and contribute to the development of ALI. Although numerous studies have increased our understanding of the pathophysiology of ALI, there is still a lack of innovative and useful treatments that reduce mortality, emphasizing that there is an urgent need for novel treatment strategies. In this study, a new series of small compounds of ß-nitrostyrene derivatives (BNSDs) were synthesized, and their anti-inflammatory bioactivities on neutrophils and platelets were evaluated. The new small compound C7 modulates neutrophil function by inhibiting superoxide generation and elastase release. Compound C7 elicits protective effects on LPS-induced paw edema and acute lung injury via the inhibition of neutrophil accumulation, proinflammatory mediator release, platelet aggregation, myeloperoxidase activity, and neutrophil extracellular trap (NET) release. NET formation was identified as the bridge for the critical interactions between neutrophils and platelets by confocal microscopy and flow cytometry. This research provides new insights for elucidating the complicated regulation of neutrophils and platelets in ALI and sheds further light on future drug development strategies for ALI/ARDS and acute inflammatory diseases.

CYT-Rx20 Inhibits Cervical Cancer Cell Growth and Migration Through Oxidative Stress-Induced DNA Damage, Cell Apoptosis, and Epithelial-to-Mesenchymal Transition Inhibition.

OBJECTIVE: The ß-nitrostyrene family has been reported to possess anticancer properties. However, the anticancer activity of ß-nitrostyrenes on cervical cancer cells and the underlying mechanisms involved remain unexplored. In this study, a ß-nitrostyrene derivative CYT-Rx20 (3'-hydroxy-4'-methoxy-ß-methyl-ß-nitrostyrene) was synthesized, and its anticancer activity on cervical cancer cells and the mechanisms involved were investigated. METHODS: The effect of CYT-Rx20 on human cervical cancer cell growth was evaluated using cell viability assay. Reactive oxygen species (ROS) generation and annexin V staining were detected by flow cytometry. The protein expression levels of cleaved caspase-3, cleaved caspase-9, cleaved poly (ADPribose) polymerase, γH2AX, ß-catenin, Vimentin, and Twist were measured by Western blotting. DNA double-strand breaks were determined by γ-H2AX foci formation and neutral comet assay. Migration assay was used to determine cancer cell migration. Nude mice xenograft was used to investigate the antitumor effects of CYT-Rx20 in vivo. RESULTS: CYT-Rx20 induced cytotoxicity in cervical cancer cells by promoting cell apoptosis via ROS generation and DNA damage. CYT-Rx20-induced cell apoptosis, ROS generation, and DNA damage were reversed by thiol antioxidants. In addition, CYT-Rx20 inhibited cervical cancer cell migration by regulating the expression of epithelial-to-mesenchymal transition markers. In nude mice, CYT-Rx20 inhibited cervical tumor growth accompanied by increased expression of DNA damage marker γH2AX and decreased expression of mesenchymal markers ß-catenin and Twist. CONCLUSIONS: CYT-Rx20 inhibits cervical cancer cells in vitro and in vivo and has the potential to be further developed into an anti-cervical cancer drug clinically.

In vitro and in vivo studies of a potent capsid-binding inhibitor of enterovirus 71.

OBJECTIVES: Enterovirus 71 (EV-A71) is an important pathogen that can cause severe neurological symptoms and even death. Our aim was to identify potent anti-EV-A71 compounds and study their underlying mechanisms and in vivo activity. METHODS: We identified a potent imidazolidinone derivative (abbreviated to PR66) as an inhibitor of EV-A71 infection from the screening of compounds and subsequent structure-based modification. Time-course treatments and resistant virus selection of PR66 were employed to study the mode of mechanism of PR66. In vivo activity of PR66 was tested in the ICR strain of new-born mice challenged with EV-A71/4643/MP4. RESULTS: PR66 could impede the uncoating process during viral infection via interaction with capsid protein VP1, as shown by a resistant virus selection assay. Using site-directed mutagenesis, we confirmed that a change from valine to phenylalanine in the 179th amino acid residue of the cDNA-derived resistant virus resulted in resistance to PR66. PR66 increased the virion stability of WT viruses, but not the PR66-resistant mutant, in a particle stability thermal release assay. We further showed that PR66 had excellent anti-EV-A71 activity in an in vivo mouse model of disease, with a dose-dependent increase in survival rate and in protection against virus-induced hind-limb paralysis following oral or intraperitoneal administration. This was associated with reductions of viral titres in brain and muscle tissues. CONCLUSIONS: We demonstrated here for the first time that an imidazolidinone derivative (PR66) could protect against EV-A71-induced neurological symptoms in vivo by suppressing EV-A71 replication. This involved binding to and restricting viral uncoating.

HPW-RX40 restores anoikis sensitivity of human breast cancer cells by inhibiting integrin/FAK signaling.

Anoikis is defined as apoptosis, which is induced by inappropriate cell-matrix interactions. Cancer cells with anoikis resistance tend to undergo metastasis, and this phenomenon has been reported to be associated with integrin and FAK activity. HPW-RX40 is a derivative of 3,4-methylenedioxy-ß-nitrostyrene, which is known to prevent platelet aggregation by inhibition of integrin. In the present study, we investigated the effect of HPW-RX40 on an anoikis-resistant human breast cancer cell line MDA-MB-231. HPW-RX40 inhibited cell aggregation and induced cell death in suspending MDA-MB-231 cells, but had only little effect on the monolayer growth of adherent cells. Analysis of caspase activation and poly (ADP-ribose) polymerase (PARP) cleavage confirmed anoikis in HPW-RX40-treated suspending cancer cells. HPW-RX40 also affected the Bcl-2 family proteins in detached cancer cells. Furthermore, HPW-RX40 inhibited detachment-induced activation of FAK and the downstream phosphorylation of Src and paxillin, but did not affect this pathway in adherent cancer cells. We also found that the expression and activation of ß1 integrin in MDA-MB-231 cells were reduced by HPW-RX40. The combination of HPW-RX40 with an EGFR inhibitor led to enhanced anoikis and inhibition of the FAK pathway in breast cancer cells. Taken together, our results suggest that HPW-RX40 restores the anoikis sensitivity in the metastatic breast cancer cells by inhibiting integrin and subsequent FAK activation, and reveal a potential strategy for prevention of tumor metastasis.

Synthesis and pharmacological characterization of 2-aminobenzaldehyde oxime analogs as dual inhibitors of neutrophil elastase and proteinase 3.

Proteinase 3 (Pr3), and human neutrophil elastase (HNE) are two major neutrophilic serine proteases (NsPs) expressed in neutrophil azurophil granules. Emerging data suggest that excessive release of proteases mediates tissue damage, and therefore prolonged neutrophil accumulation has an important role in the pathogenesis of many diseases. Thus, HNE and Pr3 inhibitors may prove to be targets for the generation of agents in the treatment of neutrophilic inflammatory disease. Sivelestat is the only commercially available selective HNE inhibitor. Therefore, sivelestat was chosen as the model structure in an attempt to obtain more potent anti-NsPs agents. In the present study, a series 2-aminobenzaldehyde oxime and 2-aminobenzoate analogs were synthesized and their inhibitory effects on NsPs (CatG, Pr3, and HNE) were determined, respectively. The results of structure-activity relationships studies concluded that a hydroxyl oxime moiety plays an important role in ligand-enzyme affinity through hydrogen bonding. As compound 6 had more potency and showed dual inhibitory effects on NE and Pr3, both in vitro and in vivo experiments were carried out to evaluate its selectivity, effects in cell-based assays, and efficacy in models of inflammation and damage. Compound 6 had the potential to reduce paw edema induced by LPS and HNE, as well as acute lung injury, and may be approved as a candidate for the development of new agents in the treatment of neutrophilic inflammatory diseases.

Ursolic acid inhibits the synaptic release of glutamate and prevents glutamate excitotoxicity in rats.

The present study evaluated the effect of ursolic acid, a natural pentacyclic triterpenoid, on glutamate release in rat cortical nerve terminals (synaptosomes) and its neuroprotection in a kainic acid-induced excitotoxicity rat model. In cortical synaptosomes, ursolic acid produced a concentration-dependent inhibition of evoked glutamate release with a half-maximum inhibition of release value of 9.5 µM, and calcium-free medium and the P/Q -type Ca2+ channel blocker, ω-agatoxin IVA, but not ω-conotoxin GVIA, an N-type Ca2+ channel blocker, prevented the ursoloic acid effect. The molecular docking study indicated that ursolic acid interacted with P/Q-type Ca2+ channels. Ursolic acid also significantly decreased the depolarization-induced activation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) and the subsequent phosphorylation of synapsin I, and the ursolic acid effect on evoked glutamate release was inhibited by the CaMKII inhibitor KN 62 in synaptosomes. In addition, in rats that were intraperitoneally injected with ursolic acid 30 min before kainic acid intraperitoneal injection, cortical neuronal degeneration was attenuated. This effect of ursolic acid in the improvement of kainic acid-induced neuronal damage was associated with the reduction of kainic acid-induced glutamate increase in the cortex of rats; this was characterized by the reduction of glutamate and glutaminase levels and elevation of glutamate dehydrogenase, glutamate transporter 1, glutamate-aspartate transporter, and glutamine synthetase protein levels. These results suggest that ursolic acid inhibits glutamate release from cortical synaptosomes by decreasing P/Q-type Ca2+ channel activity and subsequently suppressing CaMKII and exerts a preventive effect against glutamate neurotoxicity by controlling glutamate levels.

Novel Anti-Viral Properties of the Herbal Extract of Davallia mariesii against Influenza A Virus.

Gu-Sui-Bu, the dried rhizome of Davallia mariesii, is a traditional Chinese herbal remedy with a significant history of treating osteoporosis and inflammatory conditions. However, its potential as an anti-influenza agent and its underlying mechanisms of action remain unexplored. To obtain a more potent extract from D. mariesii and gain insights into its mechanism of action against influenza A virus (IAV), we utilized a partitioning process involving organic solvents and water, resulting in the isolation of butanolic subfractions of the D. mariesii extract (DMBE). DMBE exhibited a broad anti-viral spectrum, effectively inhibiting IAV, with an EC50 of 24.32 ± 6.19 µg/mL and a selectivity index of 6.05. We subsequently conducted a series of in vitro assays to evaluate the antiviral effects of DMBE and to uncover its mechanisms of action. DMBE was found to inhibit IAV during the early stages of infection by hindering the attachment of the virus onto and its penetration into host cells. Importantly, DMBE was observed to hinder IAV-mediated cell-cell fusion. It also inhibited neuraminidase activity, plaque size, and the expression levels of phospho-AKT. In summary, this study provides evidence for the effectiveness of D. mariesii as a complementary and alternative herbal remedy against IAV. Specifically, our data highlight DMBE's capabilities in inhibiting viral entry and the release of virions.

Design and synthesis of tryptophan containing dipeptide derivatives as formyl peptide receptor 1 antagonist.

Our previous studies identified an Fmoc-(S,R)-tryptophan-containing dipeptide derivative, 1, which selectively inhibited neutrophil elastase release induced by formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) in human neutrophils. In an attempt to improve pharmacological activity, a series of tryptophan-containing dipeptides were synthesized and their pharmacological activities were investigated in human neutrophils. Of these, five compounds 3, 6, 19a, 24a, and 24b exhibited potent and dual inhibitory effects on FMLP-induced superoxide anion (O2˙(-)) generation and neutrophil elastase release in neutrophils with IC50 values of 0.23/0.60, 1.88/2.47, 1.87/3.60, 0.12/0.37, and 1.32/1.03 µM, respectively. Further studies indicated that inhibition of superoxide production in human neutrophils by these dipeptides was associated with the selective inhibition of formyl peptide receptor 1 (FPR1). Furthermore, the results of structure-activity relationship studies concluded that the fragment N-benzoyl-Trp-Phe-OMe (3) was most suitable as a core structure for interaction with FPR1, and may be approved as a lead for the development of new drugs in the treatment of neutrophilic inflammatory diseases. As some of the synthesized compounds exhibited separable conformational isomers, and showed diverse bioactivities, the conformation analysis of these compounds is also discussed herein.

Melastoma malabathricum L. Suppresses Neutrophil Extracellular Trap Formation Induced by Synthetic Analog of Viral Double-Stranded RNA Associated with SARS-CoV-2 Infection.

Platelet hyper-reactivity and neutrophil extracellular trap (NET) formation contribute to the development of thromboembolic diseases for patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This study investigated the pathophysiological effects of SARS-CoV-2 surface protein components and the viral double-stranded RNA (dsRNA) on platelet aggregation and NET formation. Traditional Chinese medicine (TCM) with anti-viral effects was also delineated. The treatment of human washed platelets with SARS-CoV-2 spike protein S1 or the ectodomain S1 + S2 regions neither caused platelet aggregation nor enhanced agonists-stimulated platelet aggregation. Moreover, NET formation can be induced by polyinosinic-polycytidylic acid (poly(I:C)), a synthetic analog of viral dsRNA, but not by the pseudovirus composed of SARS-CoV-2 spike, envelope, and membrane proteins. To search for TCM with anti-NET activity, the plant Melastoma malabathricum L. which has anticoagulant activity was partially purified by fractionation. One of the fractions inhibited poly(I:C)-induced NET formation in a dose-dependent manner. This study implicates that SARS-CoV-2 structural proteins alone are not sufficient to promote NET and platelet activation. Instead, dsRNA formed during viral replication stimulates NET formation. This study also sheds new insight into using the active components of Melastoma malabathricum L. with anti-NET activity in the battle of thromboembolic diseases associated with SARS-CoV-2 infection.

Cynarin, a caffeoylquinic acid derivative in artichoke, inhibits exocytotic glutamate release from rat cortical nerve terminals (synaptosomes).

The purpose of this study was to evaluate the effect of cynarin, a caffeoylquinic acid derivative in artichoke, on glutamate release elicited by 4-aminopyridine (4-AP) in rat cortical nerve terminals (synaptosomes). We observed that cynarin decreased 4-aminopyridine-elicited glutamate release, which was prevented by the removal of external free Ca2+ with ethylene glycol bis (ß-aminoethyl ether)-N,N,N,N-tetraacetic acid (EGTA) or the blockade of P/Q-type calcium channels with ω-agatoxin IVA. Molecular docking also revealed that cynarin formed a hydrogen bond with the P/Q-type Ca2+ channel, indicating a mechanism of action involving Ca2+ influx inhibition. Additionally, the inhibitory effect of cynarin on glutamate release is associated with a change in the available synaptic vesicles, as cynarin decreased 4-AP-elicited FM1-43 release or hypertonic sucrose-evoked glutamate release from synaptosomes. Furthermore, the suppression of protein kinase A (PKA) prevented the effect of cynarin on 4-AP-elicited glutamate release. 4-AP-elicited PKA and synapsin I or synaptosomal-associated protein of 25 kDa (SNAP-25) phosphorylation at PKA-specific residues were also attenuated by cynarin. Our data indicate that cynarin, through the suppression of P/Q-type Ca2+ channels, inhibits PKA activation and attenuates synapsin I and SNAP-25 phosphorylation at PKA-specific residues, thus decreasing synaptic vesicle availability and contributing to glutamate release inhibition in cerebral cortex terminals.

Protective role of casuarinin from Melastoma malabathricum against a mouse model of 5-fluorouracil-induced intestinal mucositis: Impact on inflammation and gut microbiota dysbiosis.

BACKGROUND: 5-FU-induced intestinal mucositis (FUIIM) is a common gastrointestinal side effect of chemotherapy, leading to gastric pain in clinical cancer patients. In a previous study, we demonstrated that neutrophil elastase (NE) inhibitors could alleviate FUIIM and manipulate the homeostasis of the gut microbiota. The root of Melastoma malabathricum, also called Ye-Mu-Dan, has been used as a traditional Chinese medicine for gastrointestinal disease. Water extract of the roots of M. malabathricum exhibits an inhibitory effect on NE, with an IC50 value of 9.13 µg/ml. PURPOSE: In this study, we aimed to isolate an anti-NE compound from the root of M. malabathricum and to determine the protective effect of the bioactive component on a mouse model of FUIIM with respect to tissue damage, inflammation, intestinal barrier dysfunction, and gut microbiota dysbiosis. METHODS: A water extract of the roots of M. malabathricum was prepared and its major bioactive compound, was identified using bioactivity-guided fractionation. The effects of samples on the inhibition of NE activity were evaluated using enzymatic assays. To evaluate the effects of the bioactive compound in an FUIIM animal model, male C57BL/6 mice treated with or without casuarinin (50 and 100 mg/kg/day, p.o.), and then received of 5-fluorouracil (50 mg/kg/day) intraperitoneally for 5 days to induce FUIIM. Histopathological staining was used to monitor the tissue damage, proliferation of intestinal crypts, and expression of tight junction proteins. The inflammation score was estimated by determining the levels of oxidative stress, neutrophil-related proteases, and proinflammatory cytokines in tissue and serum. The ecology of the gut microbiota was evaluated using 16S rRNA gene sequencing. RESULTS: Casuarinin had the most potent and selective effect against NE, with an IC50 value of 2.79 ± 0.07 µM. Casuarinin (100 mg/kg/day, p.o.) significantly improved 5-FU-induced body weight loss together with food intake reduction, and it also significantly reversed villus atrophy, restored the proliferative activity of the intestinal crypts, and suppressed inflammation and intestinal barrier dysfunction in the mouse model of FUIIM. Casuarinin also reversed 5-FU-induced gut microbiota dysbiosis, particularly the abundance of Actinobacteria, Candidatus Arthromitus, and Lactobacillus murinus, and the Firmicutes-to-Bacteroidetes ratio. CONCLUSION: This study firstly showed that casuarinin isolated from the root part of M. malabathricum could be used as a NE inhibitor, whereas it could improve FUIIM by modulating inflammation, intestinal barrier dysfunction, and gut microbiota dysbiosis. In summary, exploring anti-NE natural product may provide a way to find candidate for improvement of FUIIM.

Sequencing cyclic peptides by multistage mass spectrometry.

Some of the most effective antibiotics (e.g. Vancomycin and Daptomycin) are cyclic peptides produced by non-ribosomal biosynthetic pathways. While hundreds of biomedically important cyclic peptides have been sequenced, the computational techniques for sequencing cyclic peptides are still in their infancy. Previous methods for sequencing peptide antibiotics and other cyclic peptides are based on Nuclear Magnetic Resonance spectroscopy, and require large amount (miligrams) of purified materials that, for most compounds, are not possible to obtain. Recently, development of MS-based methods has provided some hope for accurate sequencing of cyclic peptides using picograms of materials. In this paper we develop a method for sequencing of cyclic peptides by multistage MS, and show its advantages over single-stage MS. The method is tested on known and new cyclic peptides from Bacillus brevis, Dianthus superbus and Streptomyces griseus, as well as a new family of cyclic peptides produced by marine bacteria.

Anthranilic acid-based inhibitors of phosphodiesterase: design, synthesis, and bioactive evaluation.

Our previous studies identified two 2-benzoylaminobenzoate derivatives 1, which potently inhibited superoxide (O(2)˙(-)) generation induced by formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) in human neutrophils. In an attempt to improve their activities, a series of anthranilic acid derivatives were synthesized and their anti-inflammatory effects and underlying mechanisms were investigated in human neutrophils. Of these, compounds 17, 18, 46, 49, and 50 showed the most potent inhibitory effect on FMLP-induced release of O(2)˙(-) in human neutrophils with IC(50) values of 0.20, 0.16, 0.15, 0.06, and 0.29 µM, respectively. SAR analysis showed that the activities of most compounds were dependent on the ester chain length in the A ring. Conversely, a change in the linker between the A and B ring from amide to sulfonamide or N-methyl amide, as well as exchanges in the benzene rings (A or B rings) by isosteric replacements were unfavorable. Further studies indicated that inhibition of O(2)˙(-) production in human neutrophils by these anthranilic acids was associated with an elevation in cellular cAMP levels through the selective inhibition of phosphodiesterase 4. Compound 49 could be approved as a lead for the development of new drugs in the treatment of neutrophilic inflammatory diseases.