Development of Novel ß-Carboline/Furylmalononitrile Hybrids as Type I/II Photosensitizers with Chemo-Photodynamic Therapy and Minimal Toxicity.

Chemo-photodynamic therapy is a treatment method that combines chemotherapy and photodynamic therapy and has demonstrated significant potential in cancer treatment. However, the development of chemo-photodynamic therapeutic agents with fewer side effects still poses a challenge. Herein, we designed and synthesized a novel series of ß-carboline/furylmalononitrile hybrids 10a-i and evaluated their chemo-photodynamic therapeutic effects. Most of the compounds were photodynamically active and exhibited cytotoxic effects in four cancer cells. In particular, 10f possessed type-I/II photodynamic characteristics, and its 1O2 quantum yield increased by 3-fold from pH 7.4 to 4.5. Most interestingly, 10f exhibited robust antiproliferative effects by tumor-selective cytotoxicities and hypoxic-overcoming phototoxicities. In addition, 10f generated intracellular ROS and induced hepatocellular apoptosis, mitochondrial damage, and autophagy. Finally, 10f demonstrated extremely low acute toxicity (LD50 = 1415 mg/kg) and a high tumor-inhibitory rate of 80.5% through chemo-photodynamic dual therapy. Our findings may provide a promising framework for the design of new photosensitizers for chemo-photodynamic therapy.

Synthesis and biological evaluation of novel 1,2,3,4-tetrahydro-ß-carboline derivatives as potential antibacterial agents.

The quest for novel antibacterial agents is imperative in the face of escalating antibiotic resistance. Naturally occurring tetrahydro-ß-carboline (THßC) alkaloids have been highlighted due to their significant biological derivatives. However, these structures have been little explored for antibacterial drugs development. In this study, a series of 1,2,3,4-THßC derivatives were synthesized and assessed for their antibacterial prowess against both gram-positive and gram-negative bacteria. The compounds exhibited moderate to good antibacterial activity, with some compounds showing superior efficacy against gram-positive bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA), to that of Gentamicin. Among these analogs, compound 3k emerged as a hit compound, demonstrating rapid bactericidal action and a significant post-antibacterial effect, with significant cytotoxicity towards human LO2 and HepG2 cells. In addition, compound 3k (10 mg/kg) showed comparable anti-MRSA efficacy to Ciprofloxacin (2 mg/kg) in a mouse model of abdominal infection. Overall, the present findings suggested that THßC derivatives based on the title compounds hold promising applications in the development of antibacterial drugs.

3-Tetrazolyl-ß-carboline derivatives as potential neuroprotective agents.

3-Tetrazolyl-ß-carbolines were prepared by the Pictet-Spengler approach using a tryptophan analogue as building block, in which the carboxylic acid was replaced by the bioisosteric tetrazole group. Knowing that ß-carbolines are often associated with psychopharmacological effects, the study of the 3-tetrazolyl-ß-carbolines as potential neuroprotective agents against Parkinson's disease was investigated. The evaluation of neuroprotective effects against 1-methyl-4-phenylpyridin-1-ium (MPP+)-induced cytotoxicity allowed to identify compounds with relevant neuroprotective activity. One derivative, 3-(1-benzyl-1H-tetrazol-5-yl)-1-(p-dimethylaminophenyl)-ß-carboline, stood out for its low cytotoxicity and excellent performance, preventing cell death induced by this neurotoxin. The most promising compounds were also evaluated for their neuroprotective properties against iron (III)-induced cytotoxicity. However, only one 3-tetrazolyl-ß-carboline derivative slightly reduced iron-induced cytotoxicity. Overall, the neuroprotective properties of 3-tetrazolyl-ß-carbolines have been demonstrated and this finding may contribute to the development of new therapies for Parkinson's disease.

3-Amide-ß-carbolines block the cell cycle by targeting CDK2 and DNA in tumor cells potentially as anti-mitotic agents.

ß-Carboline alkaloids are natural and synthetic products with outstanding antitumor activity. C3 substituted and dimerized ß-carbolines exert excellent antitumor activity. In the present research, 37 ß-carboline derivatives were synthesized and characterized. Their cytotoxicity, cell cycle, apoptosis, and CDK2- and DNA-binding affinity were evaluated. ß-Carboline monomer M3 and dimer D4 showed selective activity and higher cytotoxicity in tumor cells than in normal cells. Structure-activity relationships (SAR) indicated that the amide group at C3 enhanced the antitumor activity. M3 blocked the A549 (IC50 = 1.44 ± 1.10 µM) cell cycle in the S phase and inhibited A549 cell migration, while D4 blocked the HepG2 (IC50 = 2.84 ± 0.73 µM) cell cycle in the G0/G1 phase, both of which ultimately induced apoptosis. Furthermore, associations of M3 and D4 with CDK2 and DNA were proven by network pharmacology analysis, molecular docking, and western blotting. The expression level of CDK2 was downregulated in M3-treated A549 cells and D4-treated HepG2 cells. Moreover, M3 and D4 interact with DNA and CDK2 at sub-micromolar concentrations in endothermic interactions caused by entropy-driven adsorption processes, which means that the favorable entropy change (ΔS > 0) overcomes the unfavorable enthalpy change (ΔH > 0) and drives the spontaneous reaction (ΔG < 0). Overall, these results clarified the antitumor mechanisms of M3 and D4 through disrupting the cell cycle by binding DNA and CDK2, which demonstrated the potential of M3 and D4 as novel antiproliferative drugs targeting mitosis.

Single-dose Tadalafil Reduces Opening Urethral Pressure: A Randomized, Double-blind, Placebo-controlled, Crossover Trial in Healthy Women.

INTRODUCTION AND HYPOTHESIS: Phosphodiesterase enzymes are widely distributed in female urogenital tissues. Yet, the understanding of their physiological roles and the impact of phosphodiesterase inhibitors on lower urinary tract symptoms in women remains limited. Current hypotheses are conflicting: one suggests that vasodilation might expand the periurethral vascular plexus, leading to increased urethral pressure, whereas the other proposes a relaxation of urethral musculature, resulting in decreased pressure. To further clarify this, we investigated the effect of tadalafil on the opening urethral pressure and voiding function in healthy women. METHODS: We conducted a randomized, double-blind, placebo-controlled crossover trial involving 24 healthy women. Participants were randomly assigned to receive a single dose of tadalafil (40 mg) or placebo during their initial visit and then switched to the alternative treatment during their second visit. Opening urethral pressure was measured with urethral pressure reflectometry during both resting and squeezing conditions of the pelvic floor. Subsequently, voiding parameters were recorded. RESULTS: Compared with placebo, a single dose of tadalafil significantly reduced opening urethral pressure during both resting (-6.8 cmH20; 95% confidence interval [CI], -11.8 to -1.9; p = 0.009) and squeezing conditions (-8.8 cmH20; 95% CI, -14.6 to -3.1; p = 0.005). Voiding parameters did not show significant differences (average flow rate: -0.8 ml/s [95% CI, -2.0 to 0.4; p = 0.2]; maximum flow rate: -1.7 ml/s [95% CI, -4.8 to 1.5; p = 0.3]). CONCLUSIONS: A single dose of 40 mg tadalafil moderately reduced urethral pressure in healthy women, without affecting voiding parameters. The clinical implications of this are yet to be determined.

Anticancer Potential of ß-Carboline Alkaloids: An Updated Mechanistic Overview.

his comprehensive review is designed to evaluate the anticancer properties of ß-carbolines derived from medicinal plants, with the ultimate goal of assessing their suitability and potential in cancer treatment, management, and prevention. An exhaustive literature survey was conducted on a wide array of ß-carbolines including, but not limited to, harmaline, harmine, harmicine, harman, harmol, harmalol, pinoline, tetrahydroharmine, tryptoline, cordysinin C, cordysinin D, norharmane, and perlolyrine. Various analytical techniques were employed to identify and screen these compounds, followed by a detailed analysis of their anticancer mechanisms. Natural ß-carbolines such as harmaline and harmine have shown promising inhibitory effects on the growth of cancer cells, as evidenced by multiple in vitro and in vivo studies. Synthetically derived ß-carbolines also displayed noteworthy anticancer, neuroprotective, and cognitive-enhancing effects. The current body of research emphasizes the potential of ß-carbolines as a unique source of bioactive compounds for cancer treatment. The diverse range of ß-carbolines derived from medicinal plants can offer valuable insights into the development of new therapeutic strategies for cancer management and prevention.

In Vitro Effect of 9,9'-Norharmane Dimer against Herpes Simplex Viruses.

Herpes simplex virus (HSV) infections are highly widespread among humans, producing symptoms ranging from ulcerative lesions to severe diseases such as blindness and life-threatening encephalitis. At present, there are no vaccines available, and some existing antiviral treatments can be ineffective or lead to adverse effects. As a result, there is a need for new anti-HSV drugs. In this report, the in vitro anti-HSV effect of 9,9'-norharmane dimer (nHo-dimer), which belongs to the ß-carboline (ßC) alkaloid family, was evaluated. The dimer exhibited no virucidal properties and did not impede either the attachment or penetration steps of viral particles. The antiviral effect was only exerted under the constant presence of the dimer in the incubation media, and the mechanism of action was found to involve later events of virus infection. Analysis of fluorescence lifetime imaging data showed that the nHo-dimer internalized well into the cells when present in the extracellular incubation medium, with a preferential accumulation into perinuclear organelles including mitochondria. After washing the host cells with fresh medium free of nHo-dimer, the signal decreased, suggesting the partial release of the compound from the cells. This agrees with the observation that the antiviral effect is solely manifested when the alkaloid is consistently present in the incubation media.

Synthesis and Biological Activities of C1-Substituted Acylhydrazone ß-Carboline Analogues as Antifungal Candidates.

In our ongoing work to create potential antifungal agents, we synthesized and tested a group of C1-substituted acylhydrazone ß-carboline analogues 9a-o and 10a-o for their effectiveness against Valsa mali, Fusarium solani, Fusarium oxysporum, and Fusarium graminearum. Their compositions were analyzed using different spectral techniques, such as 1H/13C NMR and HRMS, with the structure of 9l being additionally confirmed through X-ray diffraction. The antifungal evaluation showed that, among all the target ß-carboline analogues, compounds 9n and 9o exhibited more promising and broad-spectrum antifungal activity than the commercial pesticide hymexazol. Several intriguing findings regarding structure-activity relationships (SARs) were examined. In addition, the cytotoxicity test showed that these acylhydrazone ß-carboline analogues with C1 substitutions exhibit a preference for fungi, with minimal harm to healthy cells (LO2). The reported findings provide insights into the development of ß-carboline analogues as new potential antifungal agents.

Identification of a ß-Carboline Alkaloid from Chemoselectively Derived Vanilla Bean Extract and Its Prevention of Lipid Droplet Accumulation in Human Hepatocytes (HepG2).

Targeting bioactive compounds to prevent lipid droplet accumulation in the liver, we explored an antioxidative extract from vanilla bean (Vainilla planifolia) after chemo-selective derivatization through heating and acid modification. The chemical analysis of vanilla bean extract through chemoselective derivatization resulted in the identification of sixteen compounds (34-50) using LC-MS/MS analysis. A ß-carboline alkaloid with a piperidine C-ring and a vanillin moiety at C-1 (34) was identified by molecular networking and diagnostic fragmentation filtering approaches. ß-carboline alkaloid 34 exhibited significant inhibitory activity of lipid droplet accumulation (LDAI) in oleic acid-loaded hepatocellular carcinoma HepG2 cells. The LDAI activity was associated with both activation of lipolysis and suppression of lipogenesis in the cells. The study indicates that crude plant extracts, following chemoselective derivatization, may contain bioactive compounds that could be beneficial in preventing hepatosteatosis and could serve as a source of lead compounds for drug development. This approach may be useful to investigate other mixtures of natural products and food resources.

ß-Carboline (FG-7142) modulates fear but not anxiety-like behaviour in zebrafish.

The ß-Carboline FG-7142 is a partial inverse agonist at the benzodiazepine allosteric site on the GABA-A receptor that induces anxiogenic, proconvulsant, and appetite-reducing effects in many species, including humans. Seizure-kindling effects have been well studied, however anxiogenic properties are relatively unexplored. This study aimed to investigate concentration-dependent effects of FG-7142 on anxiety-like behaviour and fear responses in zebrafish (Danio rerio) using the open-field test (OF) and novel object approach test (NOA). A U-shaped distribution was found with maximal responses in increased immobility and reduced distance moved at 10 µM in the NOA but not the OF. Follow up experiments demonstrated a lack of effect in repeated OF testing and no changes in opercular movements. Furthermore, the effect of FG-7142 was reversed with ethanol treatment. These results suggest that FG-7142 elicits a 'freezing' response in zebrafish via the introduction of novelty, suggesting fear-induction. These findings indicate that FG-7142 may act as an agent to promote acute fear responses in zebrafish.

1-Ethoxycarbonyl-beta-carboline inhibits the M2 polarization of tumor-associated macrophages: A study based on network pharmacology and molecular docking analyses.

AIM: Through network pharmacology, molecular docking, molecular dynamics in combination with experimentation, we explored the mechanism whereby 1-ethoxycarbonyl-beta-carboline (EBC) regulates the M2 polarization of tumor-associated macrophages. METHODS: Network pharmacology was adopted for analyzing the targets and signaling pathways related to the M2 polarization of EBC-macrophages, small molecular-protein docking was employed to analyze the possibility of EBC bonding to related protein, and molecular dynamics was introduced to analyze the binding energy between EBC and HDAC2. The M2 polarization of RAW264.7 macrophages was triggered in vitro by IL-4. After EBC intervention, the expressions of M1/M2 polarization-related cytokines were detected, and the mechanism of EBC action was explored in HDAC2-knockout RAW264.7 macrophages. A tumor-bearing mouse model was established in vitro to find the impact of EBC on tumor-associated M2 macrophages. RESULTS: As revealed by the network pharmacology, molecular docking and molecular dynamics analyses, EBC was associated with 51 proteins, including HDAC2, NF-κB and HDAC4. Molecular docking and dynamics analyses suggested that HDAC2 was the main target of EBC. In vitro experiments discovered that EBC could hinder the M2 polarization of RAW264.7 macrophages, which exerted insignificant effect on the M1-associated cytokines, but could lower the levels of M2-associated cytokines. After knocking out HDAC2, EBC could not further inhibit the M2 polarization of macrophages. At the mouse level, EBC could hinder the tumor growth and the tissue levels of M2 macrophages, whose effect was associated with HDAC2. CONCLUSION: Our study combining multiple methods finds that EBC inhibits the HDAC2-mediated M2 polarization of macrophages, thereby playing an anti-tumor role.

Novel access to α-carbolines with biological applications.

In recent years, the 9H-pyrido[2,3-b]indole nuclei, also named α-carboline which is found in many organic compounds such as natural products, pharmaceuticals, and materials, have intensively stimulated the research of new synthetic pathways. After a brief report published in 2015 describing novel accesses and biological applications of α-carbolines, this update reports between 2015 and 2023 on the emergence of original syntheses to this heterocyclic nucleus. Examples representing these processes are described and the biological activities of α-carbolines are mentioned when they have been prepared for therapeutic purposes.

[4 + 2] Cyclization or Lossen Rearrangement: Rhodium-Catalyzed Divergent Synthesis of Carboline Derivatives with Anticancer Activity.

An unusual rhodium-catalyzed C-H activation/Lossen rearrangement/oxa-Michael addition tandem cyclization has been achieved along with a tunable well-known C-H activation/[4 + 2] annulation, leading to regio-, chemo-, and diastereoselective access to diverse pentacyclic α-carbolines and ß-carboline-1-one derivatives in moderate to good yields with significant anticancer activity.

Biological and structural investigation of tetrahydro-ß-carboline-based selective HDAC6 inhibitors with improved stability.

Our previously reported HDAC6 inhibitor (HDAC6i) Marbostat-100 (4) has provided many arguments for further clinical evaluation. By the substitution of the acidic hydrogen of 4 for different carbon residues, we were able to generate an all-carbon stereocenter, which significantly improves the hydrolytic stability of the inhibitor. Further asymmetric synthesis has shown that the (S)-configured inhibitors preferentially bind to HDAC6. This led to the highly selective and potent methyl-substituted derivative S-29b, which elicited a long-lasting tubulin hyperacetylation in MV4-11 cells. Finally, a crystal structure of the HDAC6/S-29b complex provided mechanistic explanation for the high potency and stereoselectivity of synthesized compound series.

Anticancer mechanisms of ß-carbolines.

ß-Carboline nucleus is therapeutically valuable in medicinal chemistry for the treatment of varied number of diseases, most importantly cancer. The potent and wide-ranging activity of ß-carboline has established them as imperative pharmacological scaffolds especially in the cancer treatment. Numerous derivatives such as Tetrahydro ß-carbolines, metal complexed ß-carbolines, mono, di and tri substituted ß-carbolines have been reported to possess dynamic anticancer activity. These different substituted ß-carboline derivatives had shown different mechanism of action and plays important role in anticancer drug discovery and development. The review is an update of the chemistry of ß-carbolines, both synthetic and natural origin acting through various targets against cancerous cells. In addition to this, studies of multitarget molecules designed by coupling ß-carbolines along with other mechanisms for treatment of neoplasm are also summarized.

Multimechanism biological profiling of tetrahydro-ß-carboline analogues as selective HDAC6 inhibitors for the treatment of Alzheimer's disease.

With the intensive research on the pathogenesis of Alzheimer's disease (AD), inhibition of HDAC6 appears to be a potential therapeutic approach for AD. In this paper, a series of tetrahydro-ß-carboline derivatives with hydroxamic acid group were fast synthesized. Among all, the most potent 15 selectively inhibited HDAC6 with IC50 of 15.2 nM and markedly increased acetylated alpha-tubulin levels. In cellular assay, 15 showed excellent neurotrophic effect by increasing the expression of GAP43 and Beta-3 tubulin markers. Besides, 15 showed neuroprotective effects in PC12 or SH-SY5Y cells against H2O2 and 6-OHDA injury through activation of Nrf2, catalase and Prx II, and significantly reduced H2O2-induced reactive oxygen species (ROS) production. In vivo, 15 significantly attenuated zebrafish anxiety-like behaviour and memory deficits in a SCOP-induced zebrafish model of AD. To sum up, multifunctional 15 might be a good lead to develop novel tetrahydrocarboline-based agents for the treatment of AD.

ß-Carboline-based light and pH dual stimuli-responsive ion transporters induce cancer cell death.

Light and pH dual-responsive ion transporters offer better applicability for cancer due to higher tunability and low cytotoxicity. Herein, we demonstrate the development of pH-responsive ß-carboline-based ionophores and photocleavable-linker appended ß-carboline-based proionophores to facilitate the controlled transport of Cl- across membranes, leading to apoptotic and autophagic cancer cell death.

Next generation antimitotic ß-carboline derivatives modulate microtubule dynamics and downregulate NF-κB, ERK 1/2 and phospho HSP 27.

AIM: Exploring the efficacy of ß-carboline-based molecular inhibitors in targeting microtubules for the development of novel anticancer therapeutics. MATERIALS AND METHODS: We synthesized a series of 1-Aryl-N-substituted-ß-carboline-3-carboxamide compounds and evaluated their cytotoxicity against human lung carcinoma (A549) cells using the MTT assay. Normal lung fibroblast cells (WI-38) were used to assess compound selectivity. The mechanism of action of MJ-211 was elucidated through Western blot analysis of key pro-apoptotic and cell cycle regulatory proteins. Additionally, the inhibitory effect of MJ-211 on multicellular 3D spheroid growth of A549 cells was evaluated. KEY FINDINGS: Lead compound MJ-211 exhibited remarkable cytotoxicity against A549 cells with an IC50 of 4.075 µM at 24 h treatment and IC50 of 1.7 nM after 72 h of treatment, while demonstrating selectivity towards normal WI-38 cells. MJ-211 activated pro-apoptotic factors Bim and p53, and suppressed Cyclin B1, Phospho HSP 27, BubR1, Mad 2, ERK1/2, and NF-κB, indicating its potent antimitotic and pro-apoptotic effects. MJ-211 significantly suppressed the migration of cells and inhibited the growth of A549 cell-derived multicellular 3D spheroids, highlighting its efficacy in a more physiologically relevant model. SIGNIFICANCE: Cytotoxic effect of MJ-211 against cancer cells, selectivity towards normal cells, and ability to modulate key regulatory proteins involved in apoptosis and cell cycle progression underscore its potential as a promising template for further anticancer lead optimization. Moreover, the inhibitory effect of MJ-211 on multicellular spheroid growth suggests its efficacy in combating tumor heterogeneity and resistance mechanisms, thereby offering a promising avenue for future anticancer drug development.

Novel thiosemicarbazide-based ß-carboline derivatives as α-glucosidase inhibitors: Synthesis and biological evaluation.

In the quest for potent α-glucosidase inhibitors to combat diabetes, a series of novel thiosemicarbazide-based ß-carboline derivatives (CTL1∼36) were synthesized and evaluated. CTL1∼36 exhibited remarkable inhibitory effects against α-glucosidase, with IC50 values ranging from 2.81 to 12.40 µM, significantly surpassing the positive control acarbose (IC50 = 564.28 µM). Notably, CTL26 demonstrated the most potent inhibition (IC50 = 2.81 µM) and was characterized as a non-competitive inhibitor. Through a combination assay with fluorescence quenching, 3D fluorescence spectra, CD spectra, and molecular docking, we elucidated that CTL26 formed a complex with α-glucosidase via hydrogen bondings and hydrophobic interactions, leading to α-glucosidase conformation changes that impaired enzymatic activity. In vivo studies revealed that oral administration of CTL26 (25 and 50 mg/kg/d) reduced fasting blood glucose levels, enhanced glucose tolerance, and ameliorated lipid abnormalities in diabetic mice. These findings positioned CTL26 as a promising candidate for the development of α-glucosidase inhibitors with anti-diabetic potential.

ß-Carboline derivatives are potent against Acute Myeloid Leukemia in vitro and in vivo.

BACKGROUND: ß-carboline alkaloids exert a distinguished ability to impair cell growth and induce cell death in a variety of cancers and the evaluation of such new therapeutic candidates may denote new possibilities for leukemia treatment. In this present study, we screened 12 ß-carboline derivatives containing different substituents at 1- and 3-positions of ß-carboline nucleus for their antineoplastic activities in a panel of leukemia cell lines. METHODS: The cytotoxic effects of the ß-carboline derivatives were evaluated in different leukemia cell lines as well as reactive oxygen species (ROS) generation, autophagy, and important signaling pathways. RESULTS: Treatment with the ß-carboline derivatives resulted in a potent antineoplastic activity leading to a reduced cell viability that was associated with increased cell death in a concentration-dependent manner. Interestingly, the treatment of primary mononuclear cells isolated from the peripheral blood of healthy donors with the ß-carboline derivatives showed a minor change in cell survival. The antineoplastic activity occurs by blocking ROS production causing consequent interruption of the PI3K/AKT and MAPK/ERK signaling and modulating autophagy processes. Notably, in vivo, AML burden was diminished in peripheral blood and bone marrow of a xenograft mouse model. CONCLUSIONS: Our results indicated that ß-carboline derivatives have an on-target malignant cell-killing activity and may be promising candidates for treating leukemia cells by disrupting crucial events that promote leukemia expansion and chemotherapy resistance.