Synthesis and dopaminergic neuroprotective activity of the proposed structure of bassiamide A, a caffeamide alkaloid derived from Bassia indica Wight.

Herein, we describe the synthesis of the proposed structure of the caffeamide alkaloid bassiamide A. The amide moiety of bassiamide A was readily formed via an amide coupling reaction between caffeic acid and the known N-(3-aminopropyl)-3-methylbutanamide. However, the spectral data of the synthesized bassiamide A did not agree with that of a previous study. The structure of the synthesized bassiamide A was confirmed using combined two-dimensional NMR analysis. Extended analyses of the bioactivity of the synthesized bassiamide A revealed its efficacy in protecting dopaminergic neurons from MPP+-induced neurotoxicity in C. elegans. Additionally, treatment with bassiamide A notably ameliorated the impaired food-sensing ability and locomotion of C. elegans, suggesting a protective effect on the functionality of dopaminergic neurons.

An Efficient One-Pot Synthesis of Pyrido[2,3-c]coumarins via Serial Catalysis and Its Application in Concise Formal Synthesis of Santiagonamine.

Versatile and high-yielding one-pot synthesis of polysubstituted pyrido[2,3-c]coumarins from N-Boc-N-coumarinyl propargylamine derivatives was achieved via serial catalysis using AgSbF6. Using this approach, the concise formal synthesis of santiagonamine was successfully accomplished. This simple and versatile method could be used to increase the potential of the pyrido[2,3-c]coumarin scaffold for diverse synthetic and biological applications.

Oleracone F Alleviates Cognitive Impairment and Neuropathology in APPswe/PSEN1dE9 Mice by Reducing the Expression of Vascular Cell Adhesion Molecule and Leukocyte Adhesion to Brain Vascular Endothelial Cells.

Alzheimer's disease (AD) is the most common neurodegenerative disease and the blood-brain barrier dysfunction has been suggested as a key pathological feature of the disease. Our research group successfully established a synthetic protocol for oleracones, a novel series of flavonoids isolated from the plant extract of Portulaca oleracea L. (PO). PO extract was reported to have anti-inflammatory and antioxidant effects, enhancing cognitive function. Thus, we investigated the effects and mechanism of oleracones on cognition using AD model transgenic mice (Tg; APPswe/PSEN1dE9). Oleracone F treatment significantly improved memory dysfunction in Tg mice. Oleracone F decreased the number, burden, and immunoreactivity of amyloid plaques and amyloid precursor protein (APP) protein levels in the brains of Tg mice compared to wild-type mice. Oleracone F also alleviated inflammation observed in Tg mice brains. In vitro studies in human microvascular endothelial cells (HBMVECs) demonstrated that oleracones D, E, and F blocked the elevations in VCAM-1 protein induced by tumor necrosis factor-α (TNF-α), hindering leukocyte adhesion to HBMVECs. Taken together, our results suggest that oleracones ameliorated cognitive impairment by blocking TNF-α-induced increases in VCAM-1, thereby reducing leukocyte infiltration to the brain and modulating brain inflammation.

Synthesis of a natural quinoline alkaloid isolated from the deep-sea-derived fungus and its potential as a therapeutic for Parkinson's disease.

2-(Quinoline-8-carboxamido)benzoic acid (2-QBA; 1) is a natural quinoline alkaloid isolated from the deep-sea-derived fungus Aspergillus sp. SCSIO06786. Alkaloid 1 was synthesized by an amidation reaction of 8-quinolinecaroxylic acid with methyl anthranilate, followed by hydrolysis. The neuroprotective properties of 1 were evaluated using a Caenorhabditis elegans Parkinson's disease model, which revealed that 1 significantly ameliorated 1-methyl-4-phenylpyridinium (MPP+)-induced dopaminergic neurodegeneration in a dose-dependent manner. MPP+-induced behavioral defects in worms, including impaired locomotion and basal slowing ability, were restored by treatment with 1. We further demonstrated that treatment with 1 modulates the formation of neurotoxic α-synuclein oligomers by suppressing α-synuclein expressions and enhancing proteasome activity. These results suggest that 1 is a promising therapeutic candidate for the treatment of Parkinson's disease.

Synthesis of Evodileptin B, a Natural Anthranilate Derivative Isolated from Evodia lepta, and Evaluation of Its Therapeutic Potential against Parkinson's Disease.

Evodileptin B (1) is a natural anthranilate derivative isolated from the ethanol extract of the aerial parts of Evodia lepta (Spreng.) Merr., a traditional medicinal plant of the family Rutaceae. We readily synthesized 1 via the amidation of phloretic with methyl anthranilate and evaluate its neuroprotective activity using a C. elegans Parkinson's disease (PD) model. The results showed that evodilpetin B ameliorated MPP+ -induced dopaminergic (DA) neurodegeneration in a dose-dependent manner. Evodileptin B treatment also significantly improved the DA neurotransmission-related behavioral defects such as reduced locomotory and food-sensing ability of worms under MPP+ exposure conditions, suggesting its potential application for the functional restoration of DA neurons. In addition, we found that 1 has an ability to regulate aggregation of α-synuclein by increasing proteasome activity in the human α-synuclein-expressing mutant worms. These results demonstrate that evodileptin B has strong neuroprotective properties and may be useful in the treatment of PD.

RKIP Induction Promotes Tumor Differentiation via SOX2 Degradation in NF2-Deficient Conditions.

Loss of NF2 (merlin) has been suggested as a genetic cause of neurofibromatosis type 2 and malignant peripheral nerve sheath tumor (MPNST). Previously, we demonstrated that NF2 sustained TGFß receptor 2 (TßR2) expression and reduction or loss of NF2 activated non-canonical TGFß signaling, which reduced Raf kinase inhibitor protein (RKIP) expression via TßR1 kinase activity. Here, we show that a selective RKIP inducer (novel chemical, Nf18001) inhibits tumor growth and promotes schwannoma cell differentiation into mature Schwann cells under NF2-deficient conditions. In addition, Nf18001 is not cytotoxic to cells expressing NF2 and is not disturb canonical TGFß signaling. Moreover, the novel chemical induces expression of SOX10, a marker of differentiated Schwann cells, and promotes nuclear export and degradation of SOX2, a stem cell factor. Treatment with Nf18001 inhibited tumor growth in an allograft model with mouse schwannoma cells. These results strongly suggest that selective RKIP inducers could be useful for the treatment of neurofibromatosis type 2 as well as NF2-deficient MPNST. IMPLICATIONS: This study identifies that a selective RKIP inducer inhibits tumor growth and promotes schwannoma cell differentiation under NF2-deficient conditions by reducing SOX2 and increasing SOX10 expression.

Effect of particle size on in vivo performances of long-acting injectable drug suspension.

Herein, entecavir-3-palmitate (EV-P), an ester prodrug of entecavir (EV), was employed as a model drug, and the effect of drug particle size on in vivo pharmacokinetic profiles and local inflammatory responses, and those associations were evaluated following intramuscular (IM) injection. EV-P crystals with different median diameters (0.8, 2.3, 6.3, 15.3 and 22.6 µm) were prepared using the anti-solvent crystallization method, with analogous surface charges (-10.7 ~ -4.7 mV), and crystallinity (melting point, 160-170 °C). EV-P particles showed size-dependent in vitro dissolution profiles under sink conditions, exhibiting a high correlation between the median diameter and Hixon-Crowell's release rate constant (r2 = 0.94). Following IM injection in rats (1.44 mg/kg as EV), the pharmacokinetic profile of EV exhibited marked size-dependency; 0.8 µm-sized EV-P particles about 1.6-, 3.6-, and 5.6-folds higher systemic exposure, compared to 6.3, 15.3, and 22.6 µm-sized particles, respectively. This pharmacokinetic pattern, depending on particle size, was also highly associated with histopathological responses in the injected tissue. The smaller EV-P particles (0.8 or 2.3 µm) imparted the larger inflammatory lesion after 3 days, lower infiltration of inflammatory cells, and thinner fibroblastic bands around depots after 4 weeks. Conversely, severe fibrous isolation with increasing particle size augmented the drug remaining at injection site over 4 weeks, impeding the dissolution and systemic exposure. These findings regarding the effects of formulation variable on the in vivo behaviors of long-acting injectable suspension, provide constructive knowledge toward the improved design in poorly water-soluble compounds.

Synthesis of Proposed Structure of Aaptoline A, a Marine Sponge-Derived 7,8-Dihydroxyquinoline, and Its Neuroprotective Properties in C. elegans.

A concise and efficient synthesis of the proposed structure of aaptoline A, a 7,8-dihydroxyquinoline derived from a marine sponge, was accomplished in seven steps with a 52% overall yield. A key feature of the synthesis is the high-yielding Ag(I)-catalyzed cycloisomerization of the N-propargylaniline precursor to afford the quinoline carboxylate skeleton from acid-labile methyl aminobenzoate. However, the spectral data of the synthesized aaptoline A were not consistent with those of previous studies. The structure of the synthesized aaptoline A was confirmed by combined 2D NMR analysis. Additional studies on the bioactivity of the synthesized aaptoline A revealed that it has the ability to protect dopaminergic neurons against MPP+-induced neurotoxicity in C. elegans. In addition, impaired food-sensing ability and travel distance capability in C. elegans were significantly ameliorated by aaptoline A treatment, suggesting that aaptoline A can protect dopaminergic neurons both morphologically and functionally.

Antitumor Activity of Novel Signal Transducer and Activator of Transcription 3 Inhibitors on Retinoblastoma.

Signal transducer and activator of transcription 3 (STAT3) is a plausible therapeutic target in the treatment of retinoblastoma, the most common intraocular malignant tumor in children. STAT3, a transcription factor of several genes related to tumorigenesis, is activated in retinoblastoma tumors as well as other cancers. In this study, we investigated the structure-activity relationship of a library of STAT3 inhibitors, including a novel series of derivatives of the previously reported compound with a Michael acceptor (compound 1). We chose two novel STAT3 inhibitors, compounds 11 and 15, from the library based on their inhibitory effects on the phosphorylation and transcription activity of STAT3. These STAT3 inhibitors effectively suppressed the phosphorylation of STAT3 and inhibited the expression of STAT3-related genes CCND1, CDKN1A, BCL2, BCL2L1, BIRC5, MYC, MMP1, MMP9, and VEGFA Intraocularly administered STAT3 inhibitors decreased the degree of tumor formation in the vitreous cavity of BALB/c nude mice of an orthotopic transplantation model. It is noteworthy that compounds 11 and 15 did not induce in vitro and in vivo toxicity on retinal constituent cells and retinal tissues, respectively, despite their potent antitumor effects. We suggest that these novel STAT3 inhibitors be used in the treatment of retinoblastoma. SIGNIFICANCE STATEMENT: The current study suggests the novel STAT3 inhibitors with Michael acceptors possess antitumor activity on retinoblastoma, the most common intraocular cancer in children. Based on detailed structure-activity relationship studies, we found a 4-fluoro and 3-trifluoro analog (compound 11) and a monochloro analog (compound 15) of the parental compound (compound 1) inhibited STAT3 phosphorylation, leading to suppressed retinoblastoma in vitro and in vivo.

Neuroprotective effect of damaurone D in a C. elegans model of Parkinson's disease.

In this study, we evaluated the protective effects of damaurone D (DaD), a dihydropyranoaurone compound, on dopaminergic (DA) neurodegeneration in Caenorhabditis elegans. The results showed that DaD treatment could successfully increase the survival rate of the worms under MPP+ exposure. Additionally, DaD protected against the MPP+-induced neurodegeneration in all eight DA neurons of the worms. Similarly, diminished DA neuronal damage was observed in the DaD-fed transgenic mutant overexpressing tyrosine hydroxylase. In addition, the corresponding behavioral impairment induced by MPP+ was strongly improved in the DaD treated worms, implying DaD has protective properties for DA neuronal function. Then, we further investigated the effect of DaD on α-synuclein aggregation, a key pathogenesis of Parkinson's disease (PD). In this study, DaD reduced the fluorescence signals of transgenic mutants that carried YFP-fused α-synuclein. A similar reduction in expressions of α-synuclein was observed by Western blot. Interestingly, our result from the dot-blot assay demonstrated that the formation of oligomers was significantly attenuated by the DaD treatment. Furthermore, DaD improved the abnormal fat storage and shortened lifespan of the animals with the same genetic background which supports the beneficial action of DaD on the α-synuclein-induced DA neurodegeneration. These results demonstrate that DaD could protect against both chemical- and genetic-induced DA neurodegeneration possibly through the modulation of oxidative stress, DA metabolism, and α-synuclein toxicity. Based on our present findings, we suggest that DaD might have a potential therapeutic role in Parkinson's disease.

Longevity effects of hispidol in Caenorhabditis elegans.

In this study, we investigated the longevity effects of hispidol, a 6,4'-dihydroxyaurone, using the Caenorhabditis elegans model system. Our lifespan assay data revealed that hispidol could prolong the lifespan of wild-type worms under normal culture condition. Moreover, hispidol increased the survival rate of the worms against a heat stress condition through up-regulated expressions of HSP-16.2. Similarly, hispidol protected worms from paraquat-induced oxidative stress. We also found that the hispidol elevated the activities of antioxidant enzymes, thereby attenuating the generation of intracellular reactive oxygen species. These results suggest that the enhancement of lifespan and stress resistance by the hispidol treatment might be attributed to its strong in vivo antioxidant capacity and regulation of stress proteins. Further tests on the aging-related factors revealed that hispidol could regulate the speed of pharyngeal pumping, indicating the association of dietary restriction with the hispidol-mediated longevity. However, there were no significant alterations in the body length of the worms between the groups. We then investigated the effects of hispidol on body movement and lipofuscin accumulation in aged worms. Interestingly, these healthspan parameters were strongly improved by the hispidol treatment. Our genetic studies showed no significant change in the lifespan of the daf-16 null mutants by hispidol supplementation. In addition, enhanced nuclear translocation of DAF-16 was observed in the hispidol-fed DAF-16::GFP fused transgenic mutants, suggesting the requirement of DAF-16/FOXO activation for the longevity effect of hispidol.

Preliminary Study on Novel Expedient Synthesis of 5-Azaisocoumarins by Transition Metal-Catalyzed Cycloisomerization.

A preliminary study to develop a novel synthetic method for 3-aryl-5-azaisocoumarins was performed herein. The cycloisomerization of N-pyranonyl propargylamines in the AgOTf-catalyzed system efficiently afforded the desired 3-aryl-5-azaisocoumarins in a highly regioselective manner. This unprecedented method is expected as an expedient alternative synthetic route to 5-azaisocoumarins because the regioselectivity problem is circumvented, and it is easier to introduce substituents on the pyridine ring compared to previously reported intramolecular lactonization approaches.

The first synthesis and immunomodulatory properties of p-hydroxyphenyl caffeate derived from Wedelia trilobata.

Herein, we report a concise and efficient method for the synthesis of p-hydroxyphenyl caffeate, a novel natural caffeic acid ester derivative isolated from Wedelia trilobata. The key feature of this synthesis is the Verley-Doebner modification of the Knoevenagel condensation of the p-hydroxyphenyl malonate intermediate. The synthesized p-hydroxyphenyl caffeate enhanced interleukin 2 production by murine lymph node T cells, and suppressed interleukin 13 production by murine epidermal T cells. This implies that p-hydroxyphenyl caffeate might be a novel immunomodulatory drug candidate, specifically targeting T helper 2 cell type responses in skin diseases such as atopic dermatitis and vitiligo. [Formula: see text].

A novel small molecule STAT3 inhibitor SLSI-1216 suppresses proliferation and tumor growth of triple-negative breast cancer cells through apoptotic induction.

Triple-negative breast cancer (TNBC) is the most aggressive type of breast cancer, characterized by the lack of expression of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. Owing to the absence of molecular targets, there are limited treatment options, and TNBC patients exhibit high mortality rates. Signal transducer and activator of transcription 3 (STAT3) is overexpressed and aberrantly activated in TNBC cells. Therefore, inhibition of STAT3-mediated signaling provides a potential strategy for the treatment of TNBC. In this study, A series of synthetic derivatives of SLSI-1 (a STAT3 inhibitor) were designed and evaluated for antitumor activity in TNBC cells. A novel derivative (SLSI-1216) exhibited the most potent anti-proliferative activity. SLSI-1216 effectively inhibited STAT3 activity and activation of STAT3, leading to the downregulation of AXL, a downstream target of STAT3 and epithelial-mesenchymal transition (EMT) progression. The inhibition of EMT by SLSI-1216 was associated with modulation of E-cadherin and N-cadherin. Furthermore, SLSI-1216 induced apoptosis by targeting STAT3 and effectively inhibited tumor growth in vivo. These findings suggest that SLSI-1216, as a potential inhibitor of STAT3, may be a promising therapeutic agent for TNBC.

Rhodanthpyrone A and B play an anti-inflammatory role by suppressing the nuclear factor-κB pathway in macrophages.

Macrophage-associated inflammation is crucial for the pathogenesis of diverse diseases including metabolic disorders. Rhodanthpyrone (Rho) is an active component of Gentiana rhodantha, which has been used in traditional Chinese medicine to treat inflammation. Although synthesis procedures of RhoA and RhoB were reported, the biological effects of the specific compounds have never been explored. In this study, the anti-inflammatory activity and mechanisms of action of RhoA and RhoB were studied in lipopolysaccharide (LPS)-stimulated macrophages. Pretreatment with RhoA and RhoB decreased inducible nitric oxide synthase and cyclooxygenase-2 expressions in RAW 264.7 cells and in thioglycollate-elicited mouse peritoneal macrophages. In addition, it downregulated transcript levels of several inflammatory genes in LPS-stimulated RAW 264.7 cells, including inflammatory cytokines/chemokines (Tnfa, Il6, and Ccl2) and inflammatory mediators (Nos2 and Ptgs2). Macrophage chemotaxis was also inhibited by treatment with the compounds. Mechanistic studies revealed that RhoA and RhoB suppressed the nuclear factor (NF)-κB pathway, but not the canonical mitogen activated protein kinase pathway, in LPS-stimulated condition. Moreover, the inhibitory effect of RhoA and RhoB on inflammatory gene expressions was attenuated by treatment with an NF-κB inhibitor. Our findings suggest that RhoA and RhoB play an anti-inflammatory role at least in part by suppressing the NF-κB pathway during macrophage-mediated inflammation.

Novel Galiellalactone Analogues Can Target STAT3 Phosphorylation and Cause Apoptosis in Triple-Negative Breast Cancer.

Aberrant activation of signal transducer and activator of transcription 3 (STAT3) has been documented in various malignancies including triple-negative breast cancers (TNBCs). The STAT3 transcription factor can regulate the different important hallmarks of tumor cells, and thus, targeting it can be a potential strategy for treating TNBC, for which only limited therapeutic options are available. In this study, we analyzed the possible effect of (-)-galiellalactone and its novel analogues, SG-1709 and SG-1721, and determined whether these agents exerted their antineoplastic effects by suppressing the STAT3 signaling pathway in TNBC cells. The two analogues, SG-1709 and SG-1721, inhibited both constitutive as well as inducible STAT3 phosphorylation at tyrosine 705 more effectively than (-)-galiellalactone, which indicates that the analogues are more potent STAT3 blockers. Moreover, SG-1721 not only inhibited nuclear translocation and DNA binding of STAT3 but also induced apoptosis, and decreased expression of diverse oncogenic proteins. Interestingly, SG-1721 also exhibited an enhanced apoptotic effect when combined with radiotherapy. Furthermore, in vivo administration of SG-1721 significantly attenuated breast xenograft tumor growth via decreasing levels of p-STAT3. Therefore, SG-1721 may be a promising candidate for further application as a pharmacological agent that can target STAT3 protein in treating TNBC.

Recent Advances in Synthesis of 4-Arylcoumarins.

4-Arylcoumarins (4-aryl-2H-1-benzopyran-2-one), also known as neoflavones, comprise a minor subclass of naturally occurring flavonoids. Because of their broad-spectrum biological activities, arylcoumarins have been attracting the attention of the organic and medicinal chemistry communities, and are considered as an important privileged scaffold. Since the development of Pechmann condensation, a classical acid-catalyzed condensation between phenol and ß-keto-carboxylic acid, several versatile and efficient synthetic approaches for 4-arylcoumarins have been reported. This review summarizes recent advances in the synthesis of the 4-arylcoumarin scaffold by classifying them based on the final bond-formation type. In particular, synthetic methods executed under mild and highly efficient conditions, such as solvent-free reactions and transition metal catalysis, are highlighted.

Antiageing properties of Damaurone D in Caenorhabditis elegans.

OBJECTIVES: This study was conducted to evaluate the longevity potential of damaurone D (DaD), a component of the damask rose, in the animal model Caenorhabditis elegans. METHODS: To investigate the effect of DaD on the longevity, lifespan assay was carried out. Fluorescence intensity of transgenic mutants was quantified to test the expression levels of stress proteins. A genetic study using single gene knockout mutants was designed to determine the target genes of DaD. KEY FINDINGS: DaD prolonged the mean lifespan of wild-type nematodes by 16.7% under normal conditions and also improved their stress endurance under thermal, osmotic, and oxidative stress conditions. This longevity-promoting effect could be attributed to in vivo antioxidant capacity and its up-regulating effects on the expressions of stress-response proteins such as SOD-3 and HSP-16.2. In addition, DaD treatment attenuated food intake, body length, lipofuscin accumulation and age-dependent decline of motor ability. Gene-specific mutant studies showed the involvement of genes such as daf-2, age-1, and daf-16. CONCLUSIONS: These results suggest that DaD has beneficial effects on the longevity, and thus it can be a valuable plant origin lead compound for the development of nutraceutical preparations targeting ageing and ageing-related diseases.

Design and in vivo evaluation of entecavir-3-palmitate microcrystals for subcutaneous sustained delivery.

The objectives of this study were to formulate microcrystals of entecavir-3-palmiate (EV-P), a palmitic acid ester of entecavir (EV), and evaluate the influence of particle size on its pharmacokinetic behavior following subcutaneous (SC) injection. Systemic toxicity and local tolerability of the hepatitis B anti-viral suspension were further evaluated in normal rats. EV-P microcrystals possessing median diameters of 2.1, 6.3, and 12.7 µm were fabricated using anti-solvent crystallization technique with polysorbate 20 and polyethylene glycol 4000 as steric stabilizer. Dissolution rate of EV-P microcrystals was controlled by adjusting the particle size, under sink condition. Pharmacokinetic profiles of 2.1 µm-sized and 6.3 µm-sized EV-P microcrystals were quite comparable (1.44 mg/kg as EV), over 46 days in rats. The absorption rate and extent of EV after SC injection of 12.7 µm-sized microcrystals were significantly retarded, due to its slower dissolution rate in aqueous media. No single-dose systemic toxicity was observed after SC injection of high dose of EV-P microcrystal suspension (30-300 mg/kg as EV). The microcrystals were tolerable in the injected site, showing mild inflammatory responses at a dose of 30 mg/kg. Therefore, the novel microcrystal system with median particle size of below 6.3 µm is expected to be a unique long-acting system of the anti-viral agent, improving patient's compliance with chronic disease.

Synthesis and Physicochemical Evaluation of Entecavir-Fatty Acid Conjugates in Reducing Food Effect on Intestinal Absorption.

The oral bioavailability of entecavir (EV), an anti-viral agent commonly prescribed to treat hepatitis B infections, is drastically reduced under a post-prandial state. This is primarily due to its low permeability in the gastrointestinal tract. To reduce the food effect on the intestinal absorption of the nucleotide analogue, four lipidic prodrugs were synthesized via the esterification of the primary alcohol of EV with fatty acids (hexanoic acid, octanoic acid, decanoic acid, and dodecanoic acid). EV-3-dodecanoate (or EV-C12) exhibited high solubility in a fed state simulated intestinal fluid (78.8 µg/mL), with the acceptable calculated logP value (3.62) and the lowest hydrolysis rate (22.5% for 12 h in simulated gastric fluid, pH 1.2). Therefore, it was chosen as a candidate to improve intestinal absorption of EV, especially under a fed state condition. Physical characterization using scanning electron microscopy, a differential scanning calorimeter, and X-ray powder diffraction revealed that EV-C12 had a rectangular-shaped crystalline form, with a melting point of about 170 °C. In a release test in biorelevant media, such as fasted and fed state-simulated intestinal and/or gastric fluid, more than 90% of the prodrug was released within 2 h in all media tested. These data suggest that this lipidic prodrug might have the potential to alleviate the negative food effect on the intestinal absorption of EV with increased therapeutic efficacy and patient compliance.