Synthesis, in vitro anti-inflammatory and cytotoxic evaluation, and mechanism of action studies of 1-benzoyl-β-carboline and 1-benzoyl-3-carboxy-β-carboline derivatives

Discovery of novel harmine derivatives as GSK-3β/DYRK1A dual inhibitors for Alzheimer's disease treatment

Multitarget-directed ligands (MTDLs) have recently attracted significant interest due to their superior effectiveness in multifactorial Alzheimer's disease (AD). Combined inhibition of two important AD targets, glycogen synthase kinase-3β (GSK-3β) and dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A), may be a breakthrough in the treatment of AD. Based on our previous work, we have designed and synthesized a series of novel harmine derivatives, investigated their inhibition of GSK-3β and DYRK1A, and evaluated a variety of biological activities. The results of the experiments showed that most of these compounds exhibited good activity against GSK-3β and DYRK1A in vitro. ZLQH-5 was selected as the best compound due to the most potent inhibitory effect against GSK-3β and DYRK1A. Molecular docking studies demonstrated that ZLQH-5 could form stable interactions with the ATP binding pocket of GSK-3β and DYRK1A. In addition, ZLQH-5 showed low cytotoxicity against SH-SY5Y and HL-7702, good blood-brain barrier permeability, and favorable pharmacokinetic properties. More importantly, ZLQH-5 also attenuated the tau hyperphosphorylation in the okadaic acid SH-SY5Y cell model. These results indicated that ZLQH-5 could be a promising dual-target drug candidate for the treatment of AD.

Iodine-Catalyzed Synthesis of Benzo-β-carbolines through Desulfurative Cyclization of 2-(1H-Indol-3-ylsulfanyl)-phenylamines with Aryl Methyl Ketones

A novel transition metal-free strategy for the synthesis of benzene-fused β-carboline scaffolds has been developed. This protocol offers a rapid and direct pathway to access the benzene fused β-carboline from 2-(1H-indol-3-ylsulfanyl)-phenylamines and aryl methyl ketones using an efficient catalytic system of I2/DMSO. The present mild protocol proceeds through the sequential reactions of Kornblum oxidation, Pictet-Spengler cyclization, and desulfurization to afford the desired products in excellent yields up to 99%. Moreover, this method has a wide range of substrate tolerance and is operationally simple and applicable in gram-scale synthesis.

Design, synthesis and pharmacological evaluation of β-carboline derivatives as potential antitumor agent via targeting autophagy

A series of novel β-carboline derivatives was designed, synthesized and evaluated as potential anticancer agents. Among them, compound 6g showed the most potent antiproliferative activity against the 786-0, HT-29 and 22RV1 cell lines with IC₅₀ values of 2.71, 2.02, and 3.86 μM, respectively. The antitumor efficiency of compound 6gin vivo was also evaluated, and the results revealed that compound 6g significantly suppressed tumor development and reduced tumor weight in a mouse colorectal cancer homograft model. Further investigation on mechanisms of action demonstrated that compound 6g inhibited HCT116 cell growth by stimulating the ATG5/ATG7-dependent autophagic pathway. These molecules might be served as candidates for further development of colorectal cancer therapy agent.

A comprehensive overview of β-carbolines and its derivatives as anticancer agents

β-Carboline alkaloids are a family of natural and synthetic products with structural diversity and outstanding antitumor activities. This review summarizes research developments of β-carboline and its derivatives as anticancer agents, which focused on both natural and synthetic monomers as well as dimers. In addition, the structure-activity relationship (SAR) analysis of β-carboline monomers and dimers are summarized and mechanism of action of β-carboline and its derivatives are also presented. A few possible research directions, suggestions and clues for future work on the development of novel β-carboline-based anticancer agents with improved expected activities and lesser toxicity are also provided.

Bioactive Tryptophan-Based Copper Complex with Auxiliary β-Carboline Spectacle Potential on Human Breast Cancer Cells: In Vitro and In Vivo Studies

Biocompatible tryptophan-derived copper (1) and zinc (2) complexes with norharmane (β-carboline) were designed, synthesized, characterized, and evaluated for the potential anticancer activity in vitro and in vivo. The in vitro cytotoxicity of both complexes 1 and 2 were assessed against two cancerous cells: (human breast cancer) MCF7 and (liver hepatocellular cancer) HepG2 cells with a non-tumorigenic: (human embryonic kidney) HEK293 cells. The results exhibited a potentially decent selectivity of 1 against MCF7 cells with an IC50 value of 7.8 ± 0.4 μM compared to 2 (less active, IC50 ~ 20 μM). Furthermore, we analyzed the level of glutathione, lipid peroxidation, and visualized ROS generation to get an insight into the mechanistic pathway and witnessed oxidative stress. These in vitro results were ascertained by in vivo experiments, which also supported the free radical-mediated oxidative stress. The comet assay confirmed the oxidative stress that leads to DNA damage. The histopathology of the liver also ascertained the low toxicity of 1.

The effect of CA1 dopaminergic system on amnesia induced by harmane in mice

In the present study, the effects of bilateral injections of dopaminergic drugs into the hippocampal CA1 regions (intra-CA1) on harmane-induced amnesia were examined in mice. We used a single-trial step-down inhibitory avoidance task for the assessment of memory acquisition in adult male mice. Our data indicated that pre-training intra-peritoneal (i.p.) administration of harmane (12 mg/kg) impaired memory acquisition. Moreover, intra-CA1 administration of dopamine D1 receptor agonist, SKF38393 (0.25 µg/mouse), dopamine D1 receptor antagonist, SCH23390 (0.25 µg/mouse), dopamine D2 receptor agonist, quinpirole (0.125 and 0.25 µg/mouse) and dopamine D2 receptor antagonist, sulpiride (0.2 and 0.4 µg/mouse) decreased the learning of a single-trial inhibitory avoidance task. Furthermore, pre-training intra-CA1 injection of sub-threshold doses of SKF38393 (0.0625 µg/mouse) or sulpiride (0.1 µg/mouse) increased pre-training harmane (4 and 8 mg/kg, i.p.)-induced amnesia. On the other hand, pre-training intra-CA1 injection of a sub-threshold dose of SCH23390 (0.0625 µg/mouse) reversed amnesia induced by an effective dose of harmane (12 mg/kg; i.p.). In addition, Pre-training intra-CA1 injection of quinpirole (0.0625 µg/mouse) had no effect on memory impairment induced by harmane. These findings indicate the involvement of CA1 dopaminergic system on harmane-induced impairment of memory acquisition.

Design, Synthesis, and Biological Evaluation of Novel N-Acylhydrazone Bond Linked Heterobivalent β-Carbolines as Potential Anticancer Agents

Utilizing a pharmacophore hybridization approach, we have designed and synthesized a novel series of 28 new heterobivalent β-carbolines. The in vitro cytotoxic potential of each compound was evaluated against the five cancer cell lines (LLC, BGC-823, CT-26, Bel-7402, and MCF-7) of different origin—murine and human, with the aim of determining the potency and selectivity of the compounds. Compound 8z showed antitumor activities with half-maximal inhibitory concentration (IC₅₀) values of 9.9 ± 0.9, 8.6 ± 1.4, 6.2 ± 2.5, 9.9 ± 0.5, and 5.7 ± 1.2 µM against the tested five cancer cell lines. Moreover, the effect of compound 8z on the angiogenesis process was investigated using a chicken chorioallantoic membrane (CAM) in vivo model. At a concentration of 5 μM, compound 8z showed a positive effect on angiogenesis. The results of this study contribute to the further elucidation of the biological regulatory role of heterobivalent β-carbolines and provide helpful information on the development of vascular targeting antitumor drugs.

Synthesis and antitumor activity of novel N-substituted tetrahydro-β-carboline-imidazolium salt derivatives

The synthesis of a series of novel N-substituted tetrahydro-β-carboline-imidazolium salt derivatives is presented. The biological properties of the compounds were evaluated in vitro against a panel of human tumor cell lines. The results suggest that the benzimidazole ring and 1-(naphthalen-2-yl)ethan-1-one or 2-naphthylmethyl substituent at the imidazolyl-3-position were vital for modulating cytotoxic activity. Compound 41 was observed as a potent derivative with IC₅₀ values of 3.24-8.78 μM and exhibited cytotoxic activity selectively against HL-60, A-549 and MCF-7 cell lines. Meanwhile, high inhibitory activities selectively against HL-60 and MCF-7 cell lines were observed for compound 51. Moreover, compound 51 was able to induce G1 phase cell cycle arrest and apoptosis in MCF-7 cells. The cytotoxicity of compound 51 against human normal lung epithelial cell line BEAS-2B was further evaluated.

Synthesis and preliminary evaluation of novel alkyl diamine linked bivalent β-carbolines as angiogenesis inhibitors

A series of novel bivalent β-carbolines were synthesized and evaluated as potent angiogenesis inhibitors.

Harmaline-induced amnesia: Possible role of the amygdala dopaminergic system

In this study, we examined the effect of bilateral intra-basolateral amygdala (intra-BLA) microinjections of dopamine receptor agents on amnesia induced by a β-carboline alkaloid, harmaline in mice. We used a step-down method to assess memory and then, hole-board method to assess exploratory behaviors. The results showed that pre-training intra-BLA injections of dopamine D1 receptor antagonist and agonist (SCH23390 (0.5μg/mouse) and SKF38393 (0.5μg/mouse), respectively) impaired memory acquisition. In contrast, pre-training intra-BLA injections of dopamine D2 receptor antagonist and agonist (sulpiride and quinpirole, respectively) have no significant effect on memory acquisition. Pre-training intra-peritoneal (i.p.) injection of harmaline (1mg/kg) decreased memory acquisition. However, co-administration of SCH 23390 (0.01μg/mouse) with different doses of harmaline did not alter amnesia. Conversely, pre-training intra-BLA injection of SKF38393 (0.1μg/mouse), sulpiride (0.25μg/mouse) or quinpirole (0.1μg/mouse) reversed harmaline (1mg/kg, i.p.)-induced amnesia. Furthermore, all above doses of drugs had no effect on locomotor activity. In conclusion, the dopamine D1 and D2 receptors of the BLA may be involved in the impairment of memory acquisition induced by harmaline.

Synthesis and biological evaluation of piperazine group-linked bivalent β-carbolines as potential antitumor agents

A series of bivalent β-carbolines with a piperazine group spacer between 3-methylene units were synthesized and their cytotoxic activities in vitro were evaluated. Compounds 7e and 7g exhibited potent cytotoxic activity.

BPIC: A novel anti-tumor lead capable of inhibiting inflammation and scavenging free radicals

Inflammation has a critical role in the tumor progression, free radical damage can worse the status of patients in cancer condition. The anti-cancer agents capable of inhibiting inflammation and scavenging free radicals attract a lot of our interest. Aimed at the discovery of such anti-tumor agent, a novel intercalator, benzyl 1-[4-hydroxy-3-(methoxycarbonyl)-phenyl-9H-pyrido[3,4-b]indole-3-carboxylate (BPIC) was presented. The docking investigation of BPIC and doxorubicin towards the DNA (PDB ID: 1NAB) gave equal score and similar feature. The anti-proliferation assay of 8 cancer cells identified S180 cells had equal sensitivity to BPIC and doxorubicin. The anti-tumor assay defined the efficacy of BPIC been 2 folds higher than that of doxorubicin. At 1μmol/kg of dose BPIC effectively inhibited xylene-induced ear edema and decreased the plasma TNF-α and IL-8 of the mice. BPIC scavenged ∙OH, ∙O2(-) and NO free radicals in a concentration dependent manner and NO free radicals had the highest sensitivity. BPIC could be a novel anti-tumor lead capable of simultaneously inhibiting inflammation and scavenging free radicals.

Synthesis, antileishmanial and antitrypanosomal activities of N-substituted tetrahydro-β-carbolines

A series of N-substituted tetrahydro-β-carbolines were synthesized and screened for antileishmanial activity through an in vitro assay that involves promastigotes and axenic amastigotes of Leishmania donovani, the causative agent for visceral leishmaniasis. The thiophen-2-yl analogs 9b and 11f and naphthyl analog 11h were found to show significant activity against promastigotes with IC50 values of 12.7, 9.1 and 22.1 μM, respectively. Analogs 9b and 11h were also effective against axenic amastigotes with IC50 values of 62.8 and 87.6 μM, respectively. The antileishmanial activity of analogs was then tested in human macrophage cell line infected with L. donovani amastigotes and 2-naphthyl linked analog 11h was found to be effective with IC50 value of 28.3 μM. Several analogs also displayed antitrypanosomal activity against Trypanosoma brucei, the causative agent for human African trypanosomiasis. Compounds 11e, 11f and 11h were more effective than others with IC50 values of 1.0, 8.9 and 10.2 μM, respectively. All synthesized analogs were not cytotoxic towards mammalian cell lines including Vero (monkey kidney fibroblasts), HEPG2 (human hepatoma cells), LLC-PK1 (pig kidney epithelial cells) and THP-1 (human macrophages).

Synthesis and biological evaluation of novel bivalent β-carbolines as potential antitumor agents

A series of bivalent β-carbolines with a spacer between the 3-carboxyl oxygens was synthesized and their cytotoxic activities in vitro and antitumor efficacies in vivo were evaluated. Compound 22 exhibited potent antitumor activity against Lewis lung cancer in mice with a tumor inhibition rate of 64.2%.

Trinorditerpenes from the roots of Flueggea virosa

Two trinorditerpenes, flueggrenes A and B (1 and 2), have been isolated from the roots of Flueggea virosa. Their structures were established by extensive analyses of spectroscopic data. The isolates were evaluated for anti-HCV activity, as well as the inhibition of superoxide anion generation and elastase release in response to FMLP/cytochalasin B.

Triterpenoids and steroids from Ganoderma mastoporum and their inhibitory effects on superoxide anion generation and elastase release

The methanol extracts of the fruiting bodies of Ganoderma mastoporum collected in Vietnam was purified to afford eight compounds, including three triterpenoids and five steroids. The purified compounds were examined for their inhibitory effects against superoxide anion generation and elastase release. Among the tested compounds, ergosta-4,6,8(14),22-tetraen-3-one (3) exhibited the most significant inhibition towards superoxide anion generation and elastase release with IC50 values of 2.30 ± 0.38 and 1.94 ± 0.50 µg/mL, respectively.

Honokiol dimers and magnolol derivatives with new carbon skeletons from the roots of Magnolia officinalis and their inhibitory effects on superoxide anion generation and elastase release

Two honokiol dimers, houpulins A and B (1 and 2), and two magnolol derivatives, houpulins C and D (3 and 4), were isolated and characterized from an ethanol extract obtained from the roots of Magnolia officinalis. The chemical structures were determined based on spectroscopic and physicochemical analyses, which included 1D and 2D NMR, as well as mass spectrometry data. These four oligomers possess new carbon skeletons postulated to be biosynthesized from the coupling of three or four C₆-C₃ subunits. In addition, the new oligomers were evaluated for inhibition of superoxide anion generation and elastase release, and houpulin B (2) was identified as a new anti-inflammatory lead compound.

Synthesis and structure--activity relationships of N²-alkylated quaternary β-carbolines as novel antitumor agents

A series of novel N(2)-alkylated quaternary β-carbolines was synthesized by modification of position-1, 2, 7 and 9 of β-carboline nucleus with various alkyl and arylated alkyl substituents, and their cytotoxic activities in vitro and antitumor potencies in mice were evaluated. Compound 3m was found to be the most potent antitumor agent. SARs analysis revealed that (1) the substituents in position-2 and 9 of β-carboline nucleus played a vital role in modulation of antitumor activity; (2) the benzyl and 3-phenylpropyl substituents in position-2 and 9 of β-carboline ring were the optimal substituents giving rise to significant antitumor agent. These compounds might be a novel promising class of antitumor agents with clinical development potential.

Anti-inflammatory diterpenoids from Croton tonkinensis

Phytochemical investigation of the methanolic extract of Croton tonkinensis afforded two known kauranes (1, 2), eight new ent-kauranes (3-10), and 16 known ent-kaurane-type diterpenoids (12-27). In addition, 30 known compounds were identified by comparison of their physical and spectroscopic data with reported data. Among the isolated compounds, ent-18-acetoxykaur-16-en-15-one (20) displayed the most significant inhibition of superoxide anion generation and elastase release.

Design, synthesis and in vitro and in vivo antitumor activities of novel bivalent β-carbolines

A series of bivalent β-carbolines with a spacer of three to ten methylene units between the indole nitrogen was synthesized and evaluated as antitumor agents. The results demonstrated that compounds 18c, 21b, 25a and 31b exhibited strong cytotoxic activities with IC(50) value of lower than 20 μM against four tumor cell lines. Acute toxicities and antitumor efficacies of the selected compounds in mice were also evaluated, compounds 18b, 21b, 26a and 31b exhibited potent antitumor activities with tumor inhibition rate of over 40% in animal models. Preliminary structure-activity relationships analysis indicated that (1) the spacer length affected antitumor potencies, and four to six methylene units were more favorable; (2) the introduction of appropriate substituent into position-1 of β-carboline facilitated antitumor potencies.

Constituents from Vigna vexillata and their anti-inflammatory activity

The seeds of Vigna genus are important food resources and there have already been many reports regarding their bioactivities. In our preliminary bioassay, the chloroform layer of methanol extracts of V. vexillata demonstrated significant anti-inflammatory bioactivity. Therefore, the present research is aimed to purify and identify the anti-inflammatory principles of V. vexillata. One new sterol (1) and two new isoflavones (2,3) were reported from the natural sources for the first time and their chemical structures were determined by the spectroscopic and mass spectrometric analyses. In addition, 37 known compounds were identified by comparison of their physical and spectroscopic data with those reported in the literature. Among the isolates, daidzein (23), abscisic acid (25), and quercetin (40) displayed the most significant inhibition of superoxide anion generation and elastase release.

Beta-carboline alkaloids derived from the ascidian Synoicum sp

Six β-carboline alkaloids (1-6) of the eudistomin Y class were isolated from the Korean ascidian Synoicum sp. These compounds were chemically converted to a known compound, eudistomin Y(1) (7) and six new derivatives, designated eudistomins Y(8)-Y(13) (8-13). Several of these natural and synthetic compounds exhibited moderate to significant antimicrobial activity, weak cytotoxic activity, and inhibitory activities toward sortase A, isocitrate lyase, and Na(+)/K(+)-ATPase. Structure-activity relationships were also deduced.

Access to pyrrolo-pyridines by gold-catalyzed hydroarylation of pyrroles tethered to terminal alkynes

In a simple procedure, the intramolecular hydroarylation of N-propargyl-pyrrole-2-carboxamides was accomplished with the aid of gold(III) catalysis. The reaction led to differently substituted pyrrolo[2,3-c]pyridine and pyrrolo[3,2-c]pyridine derivatives arising either from direct cyclization or from a formal rearrangement of the carboxamide group. Terminal alkynes are essential to achieve bicyclic pyrrolo-fused pyridinones by a 6-exo-dig process, while the presence of a phenyl group at the C–C triple bond promotes the 7-endo-dig cyclization giving pyrrolo-azepines.

Manganese dioxide mediated one-pot synthesis of methyl 9H-pyrido[3,4-b]indole-1-carboxylate: Concise synthesis of alangiobussinine

The carboline ring system is an important pharmacophore found in a number of biologically important targets. Development of synthetic routes for the preparation of these compounds is important in order to prepare a range of analogues containing the carboline heterocyclic moiety. A manganese dioxide mediated one-pot method starting with an activated alcohol and consisting of alcohol oxidation, Pictet–Spengler cyclisation, and oxidative aromatisation, offers a convenient process that allows access to β-carbolines. This one-pot process for the preparation of methyl 9H-pyrido[3,4-b]indole-1-carboxylate has subsequently been used as the key step in the synthesis of alangiobussinine and a closely related analogue.

Anti-inflammatory principles from Cordyceps sinensis

In order to explore the anti-inflammatory principles of the mycelia of Cordyceps sinensis, the crude extract and partially purified fractions were examined for their inhibition of superoxide anion generation and elastase release. Further chemical investigation of the bioactive fractions has resulted in the identification of 50 compounds, including five constituents, cordysinins A-E (1-5), reported from a natural source for the first time. In addition, compounds were examined for their anti-inflammatory activity. 1-(5-Hydroxymethyl-2-furyl)-β-carboline displayed the most significant inhibition of superoxide anion generation and elastase release with IC50 values of 0.45±0.15 and 1.68±0.32 μM, respectively.