Synthesis and evaluation of diphyllin β-hydroxyl amino derivatives as novel V-ATPase inhibitors

Natural diphyllin glycosides were identified as potent vacuolar H⁺ -ATPase (V-ATPase) inhibitors. A series of diphyllin β-hydroxyl amino derivatives were designed and synthesized as novel diphyllin derivatives. Most of these derivatives displayed potent cytotoxicity against six cancer cell lines with IC₅₀ values in the submicromolar to nanomolar concentration range. Compounds 2b, 2c, 2l, 2m, and 2n showed similar V-ATPase inhibitory potency to Bafilomycin A1. Compound 2l exhibited potent activity of modulation of lysosomal pH and cytoplasmic pH.

The Insights and Perspectives of Nitric Oxide-mediated Biofilm Eradication

Biofilms are among the most important causes of nosocomial and recurrent infections as biofilms confer antibiotic resistance to pathogenic bacteria and protect them from the host's immune system. Thus, it is imperative to investigate effective therapeutic agents to counteract biofilms. As an important signaling molecule, nitric oxide (NO) plays a crucial role in various biological and pathological processes. NO could disperse biofilm and restore the drug sensitivity by reducing intracellular cyclic-diguanosine monophosphate (c-di-GMP) levels. This review highlights recent advances on antibacterial and antibiofilm effects of NO when NO was co-administered with other antimicrobial agents. A significant improvement in drug permeability and biofilm cell targeting and reduced cytotoxicity could be attained with this strategy. In this review, we briefly lay out challenges and propose future directions in this appealing avenue of research on NO-based therapy for biofilm eradication.

The Protective Effects of Dexmedetomidine against Hypoxia/Reoxygenation-Induced Inflammatory Injury and Permeability in Brain Endothelial Cells Mediated by Sigma-1 Receptor

Cerebral ischemia-reperfusion injury (CIRI) mainly arises from the clinical treatment of ischemic stroke, induced by the blood-brain barrier (BBB) disruption and infiltrated inflammation. The Sigma-1 receptor (Sigma-1R) is a novel target for neuroprotection, and the α2-receptor agonist pain medication dexmedetomidine displays a neuroprotective effect through activating Sigma-1R. The present study aims to investigate the potential therapeutic effect of dexmedetomidine in a mouse stroke model and hypoxia/reoxygenation(OGD/R)-induced brain endothelial dysfunction. First, we found that Sigma-1R was significantly upregulated in middle cerebral artery occlusion (MCAO) mice by the administration of dexmedetomidine. In vivo experiments revealed that dexmedetomidine ameliorated hyperpermeability of the blood-brain barrier (BBB), lowered the expression level of Occludin, and impaired brain function as measured by neurological scores in MCAO mice. In vitro assays show that dexmedetomidine alleviated OGD/R-caused cytotoxicity, hyperpermeability, abnormal expression of Occludin, and inflammatory factors in human brain microvascular endothelial cells (HBMVECs). Moreover, blockage of Sigma-1R by its antagonist BD1047 abolished the neuroprotective property of dexmedetomidine in both animal and cell culture experiments. On the basis of these findings, we conclude that dexmedetomidine therapy shows neuroprotection in MCAO mice. Mechanistically, dexmedetomidine alleviated hypoxia/reoxygenation-induced cerebral endothelial dysfunction by activating the Sigma-1R-mediated signaling pathway.

11-year follow-up outcomes of catheter ablation of para-hisian accessory pathways

Funding Acknowledgements

Type of funding sources: None.

Background

Ablation of para-hisian accessory pathways (APs) remains challenging due to anatomic characteristics and few studies have focused on the causes for recurrence of radiofrequency ablation of para-hisian APs.

Objective

This retrospective single center study was aimed to explore the risk factors for recurrence of para-hisian APs.

Methods

113 patients who had a para-hisian AP with an acute success were enrolled in the study. In the 11-year follow-up, 15 cases had a recurrent para-hisian AP. Therefore 98 patients were classified into success group while 15 patients were classified into recurrence group. Demographic and ablation characteristics were analyzed.

Results

Gender difference was similar in two groups. The median age was 36.2 years old and was younger in recurrence group. Maximum ablation power was significantly higher in success group (29 ± 7.5 vs 22.9 ± 7.8, p < 0.01). Ablation time of final target sites was found to be markedly higher in success group (123.4 ± 53.1 vs 86.7 ± 58.3, p < 0.05). Ablation time less than 60 seconds was detected in 12 (12.2%) cases in success group and 7 (46.7%) cases in recurrence group (p < 0.01). Occurrence of junctional rhythm was significantly higher in recurrence group (25.5% vs 53.3%, p < 0.05). No severe conduction block, no pacemaker implantation and no stroke were reported. Junctional rhythm during ablation (OR = 3.833, 95%CI 1.083-13.572, p = 0.037) and ablation time <60s (OR = 5.487, 95%CI 1.411-21.340, p = 0.014) were independent risk factors for the recurrence of para-hisian AP.

Conclusions

Considering the long-term safety of ablation of para-hisian AP, proper extension of ablation time and increase of ablation power could be applied during operation.

[Histopathological features of squamous cell carcinoma of lung neoadjuvant immunotherapy focusing on responses]

Objective: To analyze the pathologic features of responses to neoadjuvant immunotherapy of squamous cell carcinoma (SCC) of the lung. Methods: The study included 31 patients with resected lung SCC post neoadjuvant immunotherapy. All patients were recruited from the neoadjuvant anti-PD-1 (Sintilimab) phase Ⅰb clinical trial (ChiCTR-OIC-17013726). The histopathological morphology and different degrees of pathologic response to immunotherapy were evaluated basing on irPRC standard. Results: According to the percentage of residual viable tumor (% RVT), pathologic responses of complete pathologic response (cPR), major pathologic response (MPR) and non-MPR were noted in 19% (n=6), 29% (n=9), and 52% (n=16) of patients respectively. In addition, extensive immune activation phenomena (immune cell infiltration, including infiltration of lymphocytes, plasma cells, foamy macrophages, lymphocyte aggregation and tertiary lymphoid structures formation) and tissue repair features (giant cells, granuloma formation, proliferative fibrosis and neovascularization) were observed in tumor regression bed. Conclusions: Neoadjuvant immunotherapy has favorable effect on lung SCC. Pathologic assessment of resected lung cancer specimens after neoadjuvant immunotherapy shows unique histopathological features consistent with its mechanism.

N-Demethylsinomenine, an active metabolite of sinomenine, attenuates chronic neuropathic and inflammatory pain in mice

Chronic pain is a significant public health problem that afflicts nearly 30% of the global population, but current pharmacotherapies are insufficient. Previous report indicated that N-demethylsinomenine, an active metabolite of sinomenine, is efficacious against postoperative pain. The present study investigated whether N-demethylsinomenine is effective for chronic painful conditions or whether repeated treatment alters its effect. Both chronic constriction injury (CCI) surgery and complete Freund’s adjuvant (CFA) intraplantar injection induced significant and reliable mechanical allodynia at least for 7 days. Acute treatment with N-demethylsinomenine (10–40 mg/kg, i.p.) dose-dependently attenuated the mechanical allodynia both in CCI-induced neuropathic pain and CFA-induced inflammatory pain in mice. The potency of N-demethylsinomenine for reducing CFA-induced mechanical allodynia was slightly higher than sinomenine. During the period of repeated treatment, N-demethylsinomenine maintained its anti-allodynic effect against both neuropathic and inflammatory pain without producing carry-over effect. Pretreatment with bicuculline, a selective γ-aminobutyric acid type A (GABA_A) receptor antagonist, almost completely blocked the anti-allodynia of N-demethylsinomenine (40 mg/kg) both in CCI and CFA-treated mice. Our findings indicated that N-demethylsinomenine exhibits GABA_A receptor-mediated anti-allodynic effects in mouse models of neuropathic and inflammatory pain, suggesting it may be a useful novel pharmacotherapy for the control of chronic pain.

Acetylation of NDUFV1 induced by a newly synthesized HDAC6 inhibitor HGC rescues dopaminergic neuron loss in Parkinson models

It has been shown that histone deacetylase (HDAC) inhibitors hold considerable therapeutic potentials for treating neurodegeneration-related diseases including Parkinson disease (PD). Here, we synthesized an HDAC inhibitor named as HGC and examined its neuroprotective roles in PD models. Our results showed that HGC protects dopaminergic neurons from 1-methyl-4-phenylpyridinium (MPP⁺)-induced insults. Furthermore, in 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced PD model mice, HGC application rectifies behavioral defects, improves tyrosine hydroxylase-positive neurons in the midbrain, and maintains mitochondrial integrity and functions. Mechanistically, mass spectrometry data revealed that HGC stimulates acetylation modification at lysine 28 of NDUFV1. Inhibition of HDAC6 by HGC is responsible for this acetylation modification. Functional tests showed that, as well as HGC, NDUFV1 exhibits beneficial roles against MPP⁺ injuries. Moreover, knockdown of NDUFV1 abolishes the neuroprotective roles of HGC. Taken together, our data indicate that HGC has a great therapeutic potential for treating PD and NDUFV1 might be a target for developing drugs against PD.

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HGC is a potent inhibitor for HDACs, especially HDAC1/6

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HGC protects dopaminergic neurons and alleviates PD symptoms in PD models

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HDAC6/NDUFV1 axis is responsible for transducing its anti-PD activities

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HGC holds great therapeutic potentials for treating PD

K2S2O8-mediated regio- and stereo-selective thiocyanation of enamides with NH4SCN

A direct and straightforward thiocyanation of enamides with NH₄SCN under metal-free conditions has been accomplished. A variety of (E)-β-thiocyanoenamides are readily produced in a regio- and stereo-selective manner. The protocol features mild reaction conditions, good functional group tolerance and operational simplicity. The potential utility of this strategy was further demonstrated by transformation of thiocyanate into thiotetrazole-containing compounds and a Pd-catalyzed cross-coupling reaction to afford six- or seven-membered sulfur-containing heterocycles. Mechanistic insights into the reaction indicate that the reaction may proceed via a radical mechanism.

Tetrazine-mediated bioorthogonal removal of 3-isocyanopropyl groups enables the controlled release of nitric oxide in vivo

Bond cleavage bioorthogonal chemistry has been widely employed to restore or activate proteins or prodrugs. Nitric oxide (NO), as a free radical molecule, has joined the clinical arena of cancer therapy, since high levels of NO could produce a cancer cell growth inhibitory effect. However, the spatiotemporal controlled release of NO remains a great challenge, and bioorthogonal chemistry may open a new window. Herein, we described a class of O2-3-isocyanopropyl diazeniumdiolates 3a-f as new bioorthogonal NO precursors, which can be effectively uncaged via tetrazine-mediated bond cleavage reactions to liberate NO and acrolein in living cancer cells, exhibiting potent antiproliferative activity. Furthermore, 3a and tetrazine BTZ were respectively encapsulated into two liposomes. It was found that simultaneous administrations of the two liposomes could specifically release large amounts of NO in the implanted cancer cells in zebrafish, thus generating potent tumor suppression activity in vivo. Our findings indicate that the TZ-labile NO precursors could serve to expand the NO-based smart therapeutics and the scope of bioorthogonal chemistry utility in vivo in the near future.

Recent Advances in Multi-target Drugs Targeting Protein Kinases and Histone Deacetylases in Cancer Therapy

Protein Kinase Inhibitors (PKIs) and Histone Deacetylase Inhibitors (HDACIs) are two important classes of anticancer agents and have provided a variety of small molecule drugs for the treatment of various types of human cancers. However, malignant tumors are of a multifactorial nature that can hardly be "cured" by targeting a single target, and treatment of cancers hence requires modulation of multiple biological targets to restore the physiological balance and generate sufficient therapeutic efficacy. Multi-target drugs have attracted great interest because of their advantages in the treatment of complex cancers by simultaneously targeting multiple signaling pathways and possibly leading to synergistic effects. Synergistic effects have been observed in the combination of kinase inhibitors, such as imatinib, dasatinib, or sorafenib, with an array of HDACIs including vorinostat, romidepsin, or panobinostat. A considerable number of multi-target agents based on PKIs and HDACIs have been developed. In this review, we summarize the recent literature on the development of multi-target kinase-HDAC inhibitors and provide our view on the challenges and future directions on this topic.

Correction: Synthesis and biological evaluation of hybrids from farnesylthiosalicylic acid and hydroxylcinnamic acid with dual inhibitory activities of Ras-related signaling and phosphorylated NF-κB

Correction for 'Synthesis and biological evaluation of hybrids from farnesylthiosalicylic acid and hydroxylcinnamic acid with dual inhibitory activities of Ras-related signaling and phosphorylated NF-κB' by Yong Ling et al., Org. Biomol. Chem., 2014, 12, 4517-4530, DOI: 10.1039/C4OB00023D.

Nickel(ii)-catalyzed reductive silylation of alkenyl methyl ethers for the synthesis of alkyl silanes

A new one pot protocol has been developed for the reductive silylation of alkenyl methyl ethers using Et₃Si–BPin and HSiEt₃ with nickel(ii) catalyst. Styrene type methyl ethers, multi-substituted vinyl methyl ethers, heterocycles and unconjugated vinyl ethers are all tolerated to form alkyl silanes. Mechanistic study reveals that it is a cascade of a C–O bond silylation and vinyl double bond hydrogenation process. Internal nucleophilic substitution or oxidative addition pathways were both acceptable for C–O bond cleavage. The acquired intermediate alkenyl silanes then proceeded through an unconventional reduction process thus providing alkyl silanes.

A Ni(ii)-catalyzed tandem reaction including vinyl C–O bond silylation and olefin hydrogenation has been developed providing structurally diversified alkyl silanes.

Dietary exposure to fatty acid esters of monochloropropanediols and glycidol of 2- to 3-year-old children attending nursery schools from two areas in China using the duplicate-diet collection method

The dietary exposures to fatty esters of 3- and 2-monochloropropanediol (MCPD) and glycidol were estimated for children aged 2- to 3-year-old from two areas of China using duplicate diet collection method. The 24-h daily duplicate diet samples over three consecutive days were collected from 40 healthy children aged between 26 and 36 months. The analysis of these contaminates in food samples was measured by an indirect method that entails MCPD/glycidol cleavage from their esterified forms for GC-MS analysis. Over 71% of the mixed diet and dairy products samples were found to be contaminated with 3-MCPD and glycidyl esters. The estimated daily exposure to bound 3-MCPD (mean: 0.48-0.49 μg kg^-1 bw day^-1; P95: 1.00-1.11 μg kg^-1 bw day^-1) were well below the health guidance values and were considered of low safety concern. The daily exposure to bound 2-MCPD was estimated to be 0.031-0.038 μg kg^-1 bw day^-1 on average and 0.12-0.14 μg kg^-1 bw day^-1 for the P95 exposure. However, it was not possible to assess its risk due to the lack of health guidance value of 2-MCPD. The margin of exposure (MOE) estimates for the mean exposure to bound glycidol (0.10-0.12 μg kg^-1 bw day^-1) were far above 10000 and were considered of low safety concern. However, the margin of exposure estimates for the P95 bound glycidol exposure (0.41-0.45 μg kg^-1 bw day^-1) were below 10000 and indicated a health concern. Our data indicated that the mixed diet accounted for nearly 76% to 91% of bound MCPD and glycidol exposure. In addition, the follow-on formula was also an important source for the children aged 2-3 years.

Novel Phenylmethylenecyclohexenone Derivatives as Potent TrxR Inhibitors Display High Antiproliferative Activity and Induce ROS, Apoptosis, and DNA Damage

The natural product piperlonguminine (PL) has been shown to exert potential anticancer activity against several types of cancer via elevation of reactive oxidative species (ROS). However, the application of PL has been limited due to its poor water solubility and moderate activity. To improve PL's potency, we designed and synthesized a series of 17 novel phenylmethylenecyclohexenone derivatives and evaluated their pharmacological properties. Most of them exerted antiproliferative activities against four cancer cell lines with IC₅₀ values lower than PL. Among these, compound 10 e not only showed good water solubility and exerted the most potent antiproliferative activity against HGC27 cells (IC₅₀ =0.76 μM), which was 10-fold lower than PL (IC₅₀ =7.53 μM), but also exhibited lower cytotoxicity in human normal gastric epithelial cells GES-1 compared with HGC27 cells. Mechanistically, compound 10 e inhibited thioredoxin reductase (TrxR) activity, increased ROS levels, and diminished mitochondrial transmembrane potential (MTP) in HGC27 cells. Furthermore, 10 e also induced G₂ /M cell-cycle arrest, and triggered cancer cell apoptosis through the regulation of apoptotic proteins. Finally, 10 e promoted DNA damage in HGC27 cells via the activation of the H2AX(S139ph) and p53 signaling. In conclusion, 10 e, with prominent tumor selectivity and water solubility, could be a promising candidate for the treatment of cancer and, as such, warrants further investigation.

Piperlonguminine and Piperine Analogues as TrxR Inhibitors that Promote ROS and Autophagy and Regulate p38 and Akt/mTOR Signaling

The natural products piperlongumine and piperine have been shown to inhibit cancer cell proliferation through elevation of reactive oxidative species (ROS) and eventually cell death, but only have modest cytotoxic potencies. A series of 14 novel phenylallylidenecyclohexenone analogues based on piperlongumine and piperine therefore were designed and synthesized, and their pharmacological properties were evaluated. Most of the compounds produced antiproliferative activities against five human cancer cells with IC50 values lower than those of piperlongumine and piperine. Among these, compound 9m exerted the most potent antiproliferative activity against drug-resistant Bel-7402/5-FU human liver cancer 5-FU resistant cells (IC50 = 0.8 μM), which was approximately 10-fold lower than piperlongumine (IC50 = 8.4 μM). Further, 9m showed considerably lower cytotoxicity against LO2 human normal liver epithelial cells compared to Bel-7402/5-FU. Mechanistically, compound 9m inhibited thioredoxin reductase (TrxR) activity, increased ROS levels, reduced mitochondrial transmembrane potential (MTP), and induced autophagy in Bel-7402/5-FU cells via regulation of autophagy-related proteins LC3, p62, and beclin-1. Finally, 9m activated significantly the p38 signaling pathways and suppressed the Akt/mTOR signaling pathways. In conclusion, 9m could be a promising candidate for the treatment of drug-resistant cancer cells and, as such, warrants further investigation.

Efficacy of novel methylenecyclohexenone derivatives as TrxR inhibitors in suppressing the proliferation and metastasis of human cancer cells

A series of mono- and di-methylenecyclohexenone derivatives, 3a-f and 4a-f, respectively, were designed and synthesized from piperlongumine (PL) and their in vitro and in vivo pharmacological properties were evaluated. A majority of the compounds exhibited a potent antiproliferative effect on five human cancer cell lines, especially those causing breast cancer. Compound 4f showed the highest antiproliferative potency among all of the compounds, almost a 10-fold higher inhibitory potency against thioredoxin reductase (TrxR) compared with PL in cells causing breast cancer. In addition, 4f was found to increase the levels of reactive oxygen species (ROS), thus leading to more potent antiproliferative effects. More importantly, the suppression assays of migration and invasion revealed that compound 4f could reverse the epithelial-mesenchymal transition induced by the transforming growth factor β1, and exhibit prominent anti-metastasis effects. Compound 4f also showed strong inhibition potency toward solid tumors of breast cancer in vivo. Our findings show that compound 4f is a promising therapeutic candidate in the treatment of breast cancer, which, however, needs further research to be proved.

Less mechanical loading attenuates osteoarthritis by reducing cartilage degeneration, subchondral bone remodelling, secondary inflammation, and activation of NLRP3 inflammasome

Aims

Osteoarthritis (OA) is a disabling joint disorder and mechanical loading is an important pathogenesis. This study aims to investigate the benefits of less mechanical loading created by intermittent tail suspension for knee OA.

Methods

A post-traumatic OA model was established in 20 rats (12 weeks old, male). Ten rats were treated with less mechanical loading through intermittent tail suspension, while another ten rats were treated with normal mechanical loading. Cartilage damage was determined by gross appearance, Safranin O/Fast Green staining, and immunohistochemistry examinations. Subchondral bone changes were analyzed by micro-CT and tartrate-resistant acid phosphatase (TRAP) staining, and serum inflammatory cytokines were evaluated by enzyme-linked immunosorbent assay (ELISA).

Results

Our radiographs showed that joint space was significantly enlarged in rats with less mechanical loading. Moreover, cartilage destruction was attenuated in the less mechanical loading group with lower histological damage scores, and lower expression of a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-5, matrix metalloproteinase (MMP)-3, and MMP-13. In addition, subchondral bone abnormal changes were ameliorated in OA rats with less mechanical loading, as reduced bone mineral density (BMD), bone volume/tissue volume (BV/TV), and number of osteophytes and osteoclasts in the subchondral bone were observed. Finally, the level of serum inflammatory cytokines was significantly downregulated in the less mechanical loading group compared with the normal mechanical loading group, as well as the expression of NACHT, LRR, and PYD domains-containing protein 3 (NLRP3), caspase-1, and interleukin 1β (IL-1β) in the cartilage.

Conclusion

Less mechanical loading alleviates cartilage destruction, subchondral bone changes, and secondary inflammation in OA joints. This study provides fundamental insights into the benefit of non-weight loading rest for patients with OA.

Cite this article: Bone Joint Res 2020;9(10):731–741.