Aristolactam BII of Saururus chinensis attenuates glutamate-induced neurotoxicity in rat cortical cultures probably by inhibiting nitric oxide production

Transition-Metal-Free Synthesis of 2-Substituted Benzo[cd]Indoles via the Reaction of 1-Halo-8-lithionaphthalenes with Nitriles

A simple and effective organolithium approach to the synthesis of 2-substituted benzo[cd]indoles from peri-dihalonaphthalenes and nitriles has been developed. The reaction proceeds via a surprisingly easy intramolecular aromatic nucleophilic substitution facilitated by the "clothespin effect". The discovered transformation provides good isolated yields, allows usage of an extensive range of nitriles, and demonstrates a good substituents tolerance. UV-absorption and NMR spectra of the obtained benzo[cd]indoles and their protonated forms demonstrated exclusive protonation to the indole nitrogen atom even in the presence of two NMe2 groups in positions 5 and 6 (i. e. "proton sponge" moiety).

DYRK1A inhibitors for disease therapy: Current status and perspectives

Dual-specificity tyrosine phosphorylation-regulated kinase 1 A (DYRK1A) is a conserved protein kinase that plays essential roles in various biological processes. It is located in the region q22.2 of chromosome 21, which is involved in the pathogenesis of Down syndrome (DS). Moreover, DYRK1A has been shown to promote the accumulation of amyloid beta (Aβ) peptides leading to gradual Tau hyperphosphorylation, which contributes to neurodegeneration. Additionally, alterations in the DRK1A expression are also associated with cancer and diabetes. Recent years have witnessed an explosive increase in the development of DYRK1A inhibitors. A variety of novel DYRK1A inhibitors have been reported as potential treatments for human diseases. In this review, the latest therapeutic potential of DYRK1A for different diseases and the novel DYRK1A inhibitors discoveries are summarized, guiding future inhibitor development and structural optimization.

A Serendipitous One-Pot Cyanation/Hydrolysis/Enamide Formation: Direct Access to 3-Methyleneisoindolin-1-ones

A direct, one-pot conversion of 2'-haloacetophenones to 3-methyleneisoindolin-1-one scaffolds using CuCN as the sole reagent without the need for moisture-free or anaerobic conditions is reported. This serendipitously discovered transformation with a broad substrate scope provides a significantly different route towards these important scaffolds. The scope of the method has also been further extended towards the synthesis of three special scaffolds, which are analogous to various bio-active drugs.

Identification of Aristolactam Derivatives That Act as Inhibitors of Human Immunodeficiency Virus Type 1 Infection and Replication by Targeting Tat-Mediated Viral Transcription

Despite the success of antiretroviral therapy (ART), efforts to develop new classes of antiviral agents have been hampered by the emergence of drug resistance. Dibenzo-indole-bearing aristolactams are compounds that have been isolated from various plants species and which show several clinically relevant effects, including anti-inflammatory, antiplatelet, and anti-mycobacterial actions. However, the effect of these compounds on human immunodeficiency virus type 1 (HIV-1) infection has not yet been studied. In this study, we discovered an aristolactam derivative bearing dibenzo[cd,f]indol-4(5H)-one that had a potent anti-HIV-1 effect. A structure-activity relationship (SAR) study using nine synthetic derivatives of aristolactam identified the differing effects of residue substitutions on the inhibition of HIV-1 infection and cell viability. Among the compounds tested, 1,2,8,9-tetramethoxy-5-(2-(piperidin-1-yl)ethyl)-dibenzo[cd,f]indol-4(5H)-one (Compound 2) exhibited the most potent activity by inhibiting HIV-1 infection with a half-maximal inhibitory concentration (IC₅₀) of 1.03 μmol/L and a half-maximal cytotoxic concentration (CC₅₀) of 16.91 μmol/L (selectivity index, 16.45). The inhibitory effect of the compounds on HIV-1 infection was linked to inhibition of the viral replication cycle. Mode-of-action studies showed that the aristolactam derivatives did not affect reverse transcription or integration; instead, they specifically inhibited Tat-mediated viral transcription. Taken together, these findings show that several aristolactam derivatives impaired HIV-1 infection by inhibiting the activity of Tat-mediated viral transcription, and suggest that these derivatives could be antiviral drug candidates.

Synthesis of 3-Alkylideneisoindolin-1-ones via Sonogashira Cyclocarbonylative Reactions of 2-Ethynylbenzamides

Cyclocarbonylative Sonogashira reactions of ortho-ethynylbenzamides have been investigated. The process is carried out under CO pressure, in the presence of a very small amount of PdCl₂(PPh₃)₂ (0.4 mol %) as a catalytic precursor and without the need for a Cu salt as the co-catalyst. 2-Ethynylbenzamide reacted successfully with iodoarenes bearing electron-withdrawing and electron-donating groups, giving rise to different classes of compounds depending on the solvent used. On the contrary, N-(4-chlorophenyl)-2-ethynylbenzamide afforded exclusively polyfunctionalized isoindolinones with high stereoselectivity toward (E) isomers.

Simultaneous determination of four amides in Saururus chinensis by matrix solid phase dispersion and high-performance liquid chromatography method

A rapid and simple analytical method was established for the determination of four amides (N-p-trans-coumaroyltyramine, aristolactam AII, sauristolactam and aristolactam BII) in Saururus chinensis by matrix solid phase dispersion (MSPD) and high-performance liquid chromatography-diode array detector (HPLC-DAD). In the optimized MSPD, 0.2 g S. chinensis powder was blended with 0.4 g silica gel, and 5 mL methanol was selected as elution solvent. The MSPD extraction achieved higher extraction recovery of four amides, and required less sample, solvent and preparation time, comparing with the conventional methods (Soxhlet and ultrasonic extraction). The assay was performed on a TSK gel ODS-100Z column (4.6 mm × 250 mm, 5 μm) at 30 °C. Acetonitrile and 0.4% acetic acid aqueous solution was used as mobile phase by gradient elution at the flow rate of 1.0 mL/min. The detection wavelength was 280 nm. All the analytes showed good linear regression (R² ≥ 0.9998) within the concentration ranges. The validated method showed good precision and stability with relative standard deviations (RSDs) ≤ 3.18%. The recoveries were in the range of 96.57–99.65%, with RSDs less than 2.74%.

Total synthesis of aristolactam alkaloids via synergistic C-H bond activation and dehydro-Diels-Alder reactions

A concise total synthesis of aristolactam alkaloids by a synergistic combination of C–H bond activation and dehydro-Diels–Alder reactions is described.

A concise total synthesis of aristolactam alkaloids by a synergistic combination of C–H bond activation and dehydro-Diels–Alder reactions is described. To achieve the synthesis two new synthetic methodologies, namely the oxidative cyclization of benzamides with vinyl sulfone leading to 3-methyleneisoindolin-1-ones via a ruthenium-catalyzed C–H bond activation, and a dehydro-Diels–Alder reaction followed by the fluoride ion mediated desulfonylation of 3-methyleneisoindolin-1-ones with benzynes, were developed. The method presented allows the opportunity for the construction of all the rings of aristolactams from easily available starting materials.

Evaluation of antioxidant and anticancer activities of chemical constituents of the Saururus chinensis root extracts

Evaluation of antioxidant and anticancer activities were screened by various Saururus chinensis root extracts. Four solvents (ethyl acetate, methanol, ethanol, and water) extracts were investigated for their total flavonoids, phenol contents and their antioxidant activity of DPPH (2,2-diphenyl-1-picrylhydrazyl), NO (nitric oxide), H₂O₂ (hydrogen peroxide), ABTS 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonicacid)diammonium assays, FRAP (ferric reducing ability of plasma) assays and anticancer activity. The total phenolic and flavonoid content of extracts were determined by using FC (Folin–Ciocalteu) and AlCl₃ colorimetric assay method. Total flavonoid content in these plants ranged from 24.7 to 72.1 mg g⁻¹ and amount of free phenolic compounds was between 11.2 and 67.1 mg g⁻¹ extract. The all extracts have significant levels of phenolics and flavonoids content. Anticancer activity was screened for MCF-7 breast cancer cell line. Ethanol extract shows significant of antioxidant activity and water extract shows significant of anticancer activity compared with standard (BHT) butylated hydroxy toluene. These ethanol and water extracts could be considered as a natural source for using antioxidant, and anticancer agents compared to commercial available synthetic drugs.

KBH-1, an herbal composition, improves hepatic steatosis and leptin resistance in high-fat diet-induced obese rats

Background

KBH-1 is an herbal mixture of Saururus chinensis, Curcuma longa and Polygala tenuifolia. Each herb has been reported to have various pharmaceutical activities; however, the synergistic effect of this herbal composition on obesity has not yet been determined. We investigated the alleviation effect of KBH-1 and its possible molecular mechanism in obesity-induced hepatic steatosis and leptin resistance in the hypothalamus.

Methods

We used HepG2 cells, primary neuronal cells and a high-fat diet (HFD)-induced obesity rat model to determine the effect of KBH-1 in vitro and in vivo on hepatic steatosis and leptin resistance accompanied by obesity. To identify the alleviation effect on lipid accumulation, HepG2 cells stimulated by FFA were stained with Oil Red O; in addition, immunoblotting and qPCR were performed to determine the effect of KBH-1 on the activation of proteins and nuclear enzymes in HepG2 cells and the steatotic liver of HFD-induced obesity rats. To examine the effect of KBH-1 on the leptin resistance of the hypothalamus and its possible molecular mechanism, we examined the effect of KBH-1 on the activation of the leptin resistance-related protein in primary cultured cortical neuron cells and the hypothalamus of an HFD-induced obesity rat model. In addition, we used HPLC analysis to identify the standard compound of KBH-1.

Results

KBH-1 not only suppressed the lipid deposition in HepG2 cells exposed to free fatty acids (FFA) but also significantly down-regulated major factors in lipogenesis and up-regulated major factors in lipolysis. Similarly, in a HFD-induced obesity model, KBH-1 improved hepatic steatosis by alleviating the effects on lipogenic genes and kinases. In addition, KBH-1 significantly improved the leptin-mediated signals impaired by obesity or FFA in the obesity model and primary cultured cortical neuron cells. In addition, KBH-1 was analyzed to include six standard compounds using HPLC analysis, among these compounds, onji-saponin B and curcumin were potently suppressed the level of triglycerides.

Conclusions

KBH-1 exhibits alleviating effects by improving hepatic steatosis and leptin resistance by up-regulating the activation of AMPK and suppressing the expression of PPARγ. These findings show the potential of KBH-1 as a functional food supplement or preventive agent in the treatment of obesity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1265-z) contains supplementary material, which is available to authorized users.

The chemistry of isoindole natural products

This review highlights the chemical and biological aspects of natural products containing an oxidized or reduced isoindole skeleton. This motif is found in its intact or modified form in indolocarbazoles, macrocyclic polyketides (cytochalasan alkaloids), the aporhoeadane alkaloids, meroterpenoids from Stachybotrys species and anthraquinone-type alkaloids. Concerning their biological activity, molecular structure and synthesis, we have limited this review to the most inspiring examples. Within different congeners, we have selected a few members and discussed the synthetic routes in more detail. The putative biosynthetic pathways of the presented isoindole alkaloids are described as well.

Limonoids from Dictamnus dasycarpus protect against glutamate-induced toxicity in primary cultured rat cortical cells

In our previous report, four limonoids, obacunone, limonin, fraxinellone, and calodendrolide, isolated from Dictamnus dasycarpus showed significant neuroprotective activity against glutamate toxicity in primary cultured rat cortical cells. This study investigated neuroprotective mechanism of these compounds using the same in vitro culture system. These four compounds showed significant neuroprotective activity at the concentration of 0.1 muM. They effectively inhibited calcium influx and overproduction of cellular nitric oxide and reactive oxygen species accompanied by glutamate-induced neurotoxicity. In addition, these compounds significantly preserved mitochondrial membrane potential and activities of antioxidative enzymes. Our results showed that obacunone, limonin, fraxinellone, and calodendrolide significantly protect primary culture cortical cells against glutamate-induced toxicity by preserving the antioxidant defense system. These compounds might offer potential drug development candidate for various neurodegenerative diseases involved with glutamate.

Saurolactam inhibits osteoclast differentiation and stimulates apoptosis of mature osteoclasts

The receptor activator of nuclear factor-kappaB ligand (RANKL) plays a critical role in the differentiation and bone resorptive activity of osteoclasts. Recently, the development of anti-resorptive agents from natural substances has become a subject of interest. Therefore, we evaluated the effects of 222 natural compounds on the RANKL-induced tartrate-resistance acid phosphatase (TRAP; a marker for osteoclast differentiation) activity and multinucleated osteoclast formation in RAW264.7 murine macrophage cells. We found that saurolactam was one of the compounds inhibiting the RANKL-induced osteoclastogenesis; it significantly inhibited the RANKL-induced TRAP activity and formation of multinucleated osteoclasts without any cytotoxicity. Interestingly, saurolactam prevented RANKL-induced activation of MAP kinases and NF-kappaB, and mRNA expression of osteoclast-related genes and transcription factors (c-Fos, Fra-2, and NFATc1). We also observed the inhibitory effect of saurolactam on the differentiation of mouse bone marrow-derived macrophages into osteoclasts. Furthermore, saurolactam inhibited the bone resorptive activity of mature osteoclasts with the induction of apoptotic signaling cascade and the inhibition of survival signaling pathways such as c-Src/PI3K/Akt, Ras/ERK, and JNK/c-Jun. In conclusion, although further studies are needed to determine the precise mechanism and biological efficacy of saurolactam in osteoclast-mediated bone disorders, our results demonstrate that saurolactam potentially inhibits osteoclast differentiation by preventing the activation of MAP kinases and transcription factors that consequently affect the regulation of genes required for osteoclastogenesis, and the bone resorptive activity of mature osteoclasts by inhibiting osteoclast survival-related signaling pathways and triggering the apoptotic signaling cascade.

Antihypertensive, vasorelaxant and inotropic effects of an ethanolic extract of the roots of Saururus chinensis

AIM OF THE STUDY

The present study was performed to evaluate the cardiovascular effects of ethanolic extract of the roots of Saururus chinensis (EERSC) in rats.

MATERIALS AND METHODS

The effects of EERSC on the vascular responses of isolated rat aorta, the cardiac functions in isolated rat heart, and the antihypertensive effects in spontaneously hypertensive rats (SHRs) were evaluated.

RESULTS

In isolated rat aortic preparations, EERSC exhibited a potent vasorelaxant effect with EC(50) value of 9.1 microg/ml. This relaxation was significantly inhibited by denudation of endothelial layer or by pretreatment with N(G)-nitro-l-arginine methyl ester. In addition, the raising extracellular K(+) (45 mM), or pretreatment with tetraethylammonium (10 mM) significantly inhibited EERSC-induced vasorelaxation in endothelium-denuded aortic rings. In isolated rat hearts, EERSC significantly reduced cardiac functions such as left ventricle pressure and heart rate. In an antihypertensive study with SHRs, long-term oral administrations of EERSC decreased blood pressure of SHRs (approximately 20 mmHg).

CONCLUSIONS

These results suggest that chronic treatment with EERSC exerts an antihypertensive effect in SHRs, and its direct vasorelaxant properties and negative inotropic actions may contribute to reduce the elevated blood pressure.

Total synthesis of aristolactams via a one-pot suzuki-miyaura coupling/aldol condensation cascade reaction

A direct one-pot synthesis of phenanthrene lactams, which employs a Suzuki-Miyaura coupling/aldol condensation cascade reaction of isoindolin-1-one with 2-formylphenylboronic acid, has been developed. The approach is used to efficiently produce a number of natural aristolactams, such as aristolactam BII (cepharanone B), aristolactam BIII, aristolactam FI (piperolactam A), N-methyl piperolactam A, and sauristolactam.

Pinusolide and 15-methoxypinusolidic acid attenuate the neurotoxic effect of staurosporine in primary cultures of rat cortical cells

BACKGROUND AND PURPOSE

Apoptosis is a fundamental process required for neuronal development but also occurs in most of the common neurodegenerative disorders. In an attempt to obtain an anti-apoptotic neuroprotective compound from natural products, we isolated the diterpenoids, pinusolide and 15-MPA, from B. orientalis and investigated their neuroprotective activity against staurosporine (STS) -induced neuronal apoptosis. In addition, we determined the anti-apoptotic mechanism of these compounds in rat cortical cells.

EXPERIMENTAL APPROACH

Primary cultures of rat cortical cells injured by STS were used as an in vitro assay system. Cells were pretreated with pinusolide or 15-MPA before exposure to STS. Anti-apoptotic activities were evaluated by the measurement of cytoplasmic condensation and nuclear fragmentation. The levels of cellular peroxide, malondialdehyde (MDA) and [Ca(2+)]i, as well as the activities of superoxide dismutase (SOD) and caspase-3/7, were measured.

KEY RESULTS

Pinusolide and 15-MPA, at a concentration of 5.0 ìM, reduced the condensed nuclei and rise in [Ca(2+)]i that accompanies apoptosis induced by 100 nM STS. Pinusolide and 15-MPA also protected the cellular activity of SOD, an antioxidative enzyme reduced by STS insult. Furthermore, the overproduction of reactive oxygen species and lipid peroxidation induced by STS was significantly reduced in pinusolide and 15-MPA treated cells. In addition, pinusolide and 15-MPA inhibited STS-induced caspase-3/7 activation.

CONCLUSIONS AND IMPLICATIONS

These results show that pinusolide and 15-MPA protect neuronal cells from STS-induced apoptosis, probably by preventing the increase in [Ca(2+)]i and cellular oxidation caused by STS, and indicate that they could be used to treat neurodegenerative diseases.

meso-Dihydroguaiaretic acid attenuates the neurotoxic effect of staurosporine in primary rat cortical cultures

The effect of meso-dihydroguaiaretic acid (MDGA) on the staurosporine-induced neuronal apoptosis and its potential mechanism were investigated using primary cultures of rat cortical cells as an assay system. Treatment of MDGA at the concentrations of 0.1, 1.0 and 10 microM significantly protected neuronal cells against Staurosporine-induced apoptosis. The neuroprotective activity of MDGA was the most potent at the concentration of 1.0 microM and was not increased at higher concentration. MDGA reduced apoptotic characteristics induced by STS; MDGA reduced the condensed nuclei in staurosporine-injured rat cortical cells. MDGA diminished the calcium influx that accompanies the staurosporine-induced apoptosis, and inhibited the subsequent overproduction of reactive oxygen species and peroxide to the level of control cells. It also preserved cellular activity of superoxide dismutase, an antioxidative enzyme reduced by staurosporine insult. In addition, MDGA significantly inhibited caspase-3/7 activation and cytochrome c release. Taken together, these results suggested that MDGA protected neuronal cells against staurosporine-induced apoptosis through the inhibition of Ca(2+) influx, cellular oxidation, cytochrome c release and caspase-3/7 activation.

Meso-dihydroguaiaretic acid and licarin A of Machilus thunbergii protect against glutamate-induced toxicity in primary cultures of a rat cortical cells

1 We previously reported that four lignans isolated from the bark of Machilus thunbergii Sieb. et Zucc. (Lauraceae) protected primary cultures of rat cortical neurons from neurotoxicity induced by glutamate. 2 Among the lignans, meso-dihydroguaiarectic acid (MDGA) and licarin A significantly attenuated glutamate-induced neurotoxicity when added prior to or right after the excitotoxic glutamate challenge. 3 The neuroprotective activities of two lignans appeared to be more effective in protecting neurons against neurotoxicity induced by NMDA than that induced by kainic acid. 4 MDGA and licarin A diminished the calcium influx that routinely accompanies with the glutamate-induced neurotoxicity, and inhibited the subsequent overproduction of cellular nitric oxide and peroxide to the level of control cells. They also preserved cellular activities of antioxidative enzymes such as superoxide dismutase, glutathione peroxidase and glutathione reductase reduced in the glutamate-injured neuronal cells. 5 Thus, our results suggest that MDGA and licarin A significantly protect primary cultured neuronal cells against glutamate-induced oxidative stress, via antioxidative activities.

ESP-102, a standardized combined extract of Angelica gigas, Saururus chinensis and Schizandra chinensis, significantly improved scopolamine-induced memory impairment in mice

We assessed the effects of oral treatments of ESP-102, a standardized combined extract of Angelica gigas, Saururus chinensis and Schizandra chinensis, on learning and memory deficit. The cognition-enhancing effect of ESP-102 was investigated in scopolamine-induced (1 mg/kg body weight, s.c.) amnesic mice with both passive avoidance and Morris water maze performance tests. Acute oral treatment (single administration prior to scopolamine treatment) of mice with ESP-102 (doses in the range of 10 to 100 mg/kg body weight) significantly reduced scopolamine-induced memory deficits in the passive avoidance performance test. Another noteworthy result included the fact that prolonged oral daily treatments of mice with much lower amounts of ESP-102 (1 and 10 mg/kg body weight) for ten days reversed scopolamine-induced memory deficits. In the Morris water maze performance test, both acute and prolonged oral treatments with ESP-102 (single administration of 100 mg/kg body weight or prolonged daily administration of 1 and 10 mg/kg body weight for ten days, respectively, significantly ameliorated scopolamine-induced memory deficits as indicated by the formation of long-term and/or short-term spatial memory. In addition, we investigated the effects of ESP-102 on neurotoxicity induced by amyloid-beta peptide (Abeta25-35) or glutamate in primary cultured cortical neurons of rats. Pretreatment of cultures with ESP-102 (0.001, 0.01 and 0.1 mug/ml) significantly protected neurons from neurotoxicity induced by either glutamate or Abeta25-35. These results suggest that ESP-102 may have some protective characteristics against neuronal cell death and cognitive impairments often observed in Alzheimer's disease, stroke, ischemic injury and other neurodegenerative diseases.