Synthesis and antiviral activity of β-carboline derivatives bearing a substituted carbohydrazide at C-3 against poliovirus and herpes simplex virus (HSV-1)

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 β-carboline (βC) 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.

Bioinspired total synthesis and biological activity of Pegaharine A

BACKGROUND

Phytopathogens cause various diseases by parasitizing crops, reducing crop yield and resulting in substantial economic losses in agricultural production. A novel type isolated from the perennial herbaceous Peganum harmala L. seeds, β-carboline alkaloids pegaharine A (PA), has become a hot topic in developing plant-originated green pesticides owing to their significant physiological activities.

RESULTS

A scalable bioinspired total synthesis of PA is accomplished in the present work. The systematical biological assay study showed that PA exhibited moderate inhibitory activity against nine tested plant pathogenic fungi and showed significant inhibitory activity in vitro against the three tested plant pathogenic bacteria. Most noteworthy is the inhibitory rates of PA on Xanthomonas oryzae pv. oryzae (Xoo), X. oryzae pv. oryzicola (Xoc) and X. axonopodis pv. citri (Xac) of 93.6%, 92.1% and 86.1%, respectively, which are better than the control drug, bismerthiazol (63.4%, 61.2% and 53.7% at 100 μg mL-1 concentration). Furthermore, the EC50 value of PA against Xoo, Xoc and Xac was 52.2, 60.0 and 65.1 μg mL-1 , respectively, superior to 72.9, 64.2 and 70.1 μg mL-1 of the control drug. Moreover, the anti-Xoo mechanistic studies revealed that PA exerted its antibacterial effects by increasing the permeability of the bacterial membrane, reducing the extracellular polysaccharide content and inducing morphological changes in bacterial cells.

CONCLUSION

A novel β-carboline alkaloid, PA, was prepared by biomimetic total synthesis. Its significant antibacterial activity was closely related to the permeation of bacterial cell membranes, which was confirmed by anti-Xoo mechanistic studies. More importantly, the structure could be regarded as a model for developing novel bactericides. © 2023 Society of Chemical Industry.

The Genus Cladosporium: A Prospective Producer of Natural Products

Cladosporium, a genus of ascomycete fungi in the Dematiaceae family, is primarily recognized as a widespread environmental saprotrophic fungus or plant endophyte. Further research has shown that the genus is distributed in various environments, particularly in marine ecosystems, such as coral reefs, mangroves and the polar region. Cladosporium, especially the marine-derived Cladosporium, is a highly resourceful group of fungi whose natural products have garnered attention due to their diverse chemical structures and biological activities, as well as their potential as sources of novel leads to compounds for drug production. This review covers the sources, distribution, bioactivities, biosynthesis and structural characteristics of compounds isolated from Cladosporium in the period between January 2000 and December 2022, and conducts a comparative analysis of the Cladosporium isolated compounds derived from marine and terrestrial sources. Our results reveal that 34% of Cladosporium-derived natural products are reported for the first time. And 71.79% of the first reported compounds were isolated from marine-derived Cladosporium. Cladosporium-derived compounds exhibit diverse skeletal chemical structures, concentrating in the categories of polyketides (48.47%), alkaloids (19.21%), steroids and terpenoids (17.03%). Over half of the natural products isolated from Cladosporium have been found to have various biological activities, including cytotoxic, antibacterial, antiviral, antifungal and enzyme-inhibitory activities. These findings testify to the tremendous potential of Cladosporium, especially the marine-derived Cladosporium, to yield novel bioactive natural products, providing a structural foundation for the development of new drugs.

Current development of β-carboline derived potential antimalarial scaffolds

β-Carboline alkaloids are an eminent class of nitrogen-based natural alkaloids and therapeutic molecules which exert various pharmacological activities through diverse mechanisms. A lot of attention has recently been directed towards this moiety in order to develop effective antimalarial drugs. "Malaria", an acute febrile illness caused by diverse Plasmodium parasites, is a continuing and escalating problem that devastates economically less developed countries by significantly increased morbidity and mortality rates. The mounting parasite resistance towards the antimalarial drugs and augmenting the 'habitat of the insect vector' are creating a catastrophe, indicating an urgent need for new efficacious therapeutics to combat this tropical disease. This article comprehensively encapsulates the clinical and preclinical antimalarial scaffolds comprising β-carboline moiety in their structure. Herein, various classes of natural and semi-synthetic analogues of β-carbolines reported in the last decade (2011-2021) have been extensively studied and illustrated. This review will help the readers to develop an insight into the β-carboline based antimalarials and molecular mechanisms lying behind their mode of action, which is anticipated to be beneficial for the future development of new β-carboline based therapeutics.

Catalytic potential of a fungal indole prenyltransferase toward β-carbolines, harmine and harman, and their prenylation effects on antibacterial activity

The prenylation of compounds has attracted much attention, since it often adds bioactivity to non-prenylated compounds. We employed an enzyme assay with CdpNPT, an indole prenyltransferase from Aspergillus fumigatus with two naturally occurring β-carbolines, harmine (3) and harman (4) as prenyl acceptors, in the presence of dimethylallyl diphosphate (DMAPP) as the prenyl donor. The enzyme accepted these two prenyl acceptor substrates to produce 6-(3',3'-dimethylallyl)harmine (5) from 3 and 9-(3',3'-dimethylallyl)harman (6) and 6-(3',3'-dimethylallyl)harman (7) from 4. The X-ray crystal structure analysis of the CdpNPT (38-440) truncated mutant complexed with 4, and docking simulation studies of DMAPP to the crystal structure of the CdpNPT (38-440) mutant, suggested that CdpNPT could employ the two-step prenylation mechanism to produce 7, while the enzyme produced 6 with either one- or two-step prenylation mechanisms. Furthermore, the antibacterial assays revealed that the 3',3'-dimethylallylation of 3 and 4, as well as harmol (1), at C-6 enhanced the activities against Staphylococcus aureus and Bacillus subtilis.

Discovery of novel β-carboline derivatives as selective AChE inhibitors with GSK-3β inhibitory property for the treatment of Alzheimer's disease

The natural product harmine, a representative β-carboline alkaloid from the seeds of Peganum harmala L. (Zygophyllaceae), possesses a broad spectrum of biological activities. In this study, a novel series of harmine derivatives containing N-benzylpiperidine moiety were identified for the treatment of Alzheimer's disease (AD). The results showed that all the derivatives possessed significant anti-acetylcholinesterase (AChE) activity and good selectivity over butyrylcholinesterase (BChE). In particular, compound ZLWH-23 exhibited potent anti-AChE activity (IC₅₀ = 0.27 μM) and selective BChE inhibition (IC₅₀ = 20.82 μM), as well as acceptable glycogen synthase kinase-3 (GSK-3β) inhibition (IC₅₀ = 6.78 μM). Molecular docking studies and molecular dynamics simulations indicated that ZLWH-23 could form stable interaction with AChE and GSK-3β. Gratifyingly, ZLWH-23 exhibited good selectivity for GSK-3β over multi-kinases and very low cytotoxicity towards SH-SY5Y, HEK-293T, HL-7702, and HepG2 cell lines. Importantly, ZLWH-23 displayed efficient reduction against tau hyperphosphorylation on Ser-396 site in Tau (P301L) 293T cell model. Collectively, harmine-based derivatives could be considered as possible drug leads for the development of AD therapies.

From natural products to HDAC inhibitors: An overview of drug discovery and design strategy

Histone deacetylases (HDACs) play a key role in the homeostasis of protein acetylation in histones and have recently emerged as a therapeutic target for numerous diseases. The inhibition of HDACs may block angiogenesis, arrest cell growth, and lead to differentiation and apoptosis in tumour cells. Thus, HDAC inhibitors (HDACi) have received increasing attention and many of which are developed from natural sources. In the past few decades, naturally occurring HDACi have been identified to have potent anticancer activities, some of which have demonstrated promising therapeutic effects on haematological malignancies. In this review, we summarized the discovery and modification of HDAC inhibitors from natural sources, novel drug design that uses natural products as parent nuclei, and dual target design strategies that combine HDAC with non-HDAC targets.

1-Formyl-β-carboline Derivatives Block Newcastle Disease Virus Proliferation through Suppressing Viral Adsorption and Entry Processes

Newcastle disease virus (NDV) is one of the highly contagious pathogens causing devastating economic effects on the global poultry industry. In the present study, three 1-formyl-β-carboline derivatives (compounds 6, 7, and 9) were found to be potent inhibitors of different genotypes of NDV with IC₅₀ values within 10 μM, which are similar to ribavirin. The virus titers were decreased by the presence of 1-formyl-β-carboline derivatives in a dose-dependent manner, and the inhibition rate was found to exceed 90% at the concentration of 20 μM. These compounds mainly suppressed the adsorption and entry processes of NDV lifecycle. Through DARTS, CETSA, and RBC binding assay, these compounds were identified as novel HN inhibitors, which could directly interact with the NDV HN protein to affect the adsorption of NDV. Furthermore, they could inhibit the entry of NDV through suppressing the PI3K/Akt pathway rather than the ERK pathway. The PI3K/Akt pathway was proved to be involved in NDV entry. Our findings reveal a unique mechanism through which 1-formyl-β-carboline derivatives restrain NDV infection. Moreover, these compounds represent suitable scaffolds for designing novel HN inhibitors.

Design, synthesis and biological evaluation of harmine derivatives as potent GSK-3β/DYRK1A dual inhibitors for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a chronic and progressive neurodegenerative disease, characterized by irreversible cognitive impairment, memory loss and behavioral disturbances, ultimately leading to death. Glycogen synthase kinase 3β (GSK-3β) and dual-specificity tyrosine phosphorylation regulated kinase1A (DYRK1A) have gained a lot of attention for its role in tau pathology. To search for potential dual GSK-3β/DYRK1A inhibitors, we focused on harmine, a natural β-carboline alkaloid, which has been extensively studied for its various biological effects on the prevention of AD. In this study, a new series of harmine derivatives were designed, synthesized and evaluated as dual GSK-3β/DYRK1A inhibitors for their multiple biological activities. The in vitro results indicated that most of them displayed promising activity against GSK-3β and DYRK1A. Among them, compound ZDWX-25 showed potent inhibitory effects on GSK-3β and DYRK1A with IC50 values of 71 and 103 nM, respectively. Molecular modelling and kinetic studies verified that ZDWX-25 could interact with the ATP binding pocket of GSK-3β and DYRK1A. Western blot analysis revealed that ZDWX-25 inhibited hyperphosphorylation of tau protein in okadaic acid (OKA)-induced SH-SY5Y cells. In addition, ZDWX-25 showed good blood-brain barrier penetrability in vitro. More importantly, ZDWX-25 could ameliorate the impaired learning and memory in APP/PS1/Tau transgenic mice. These results indicated that the harmine-based compounds could be served as promising dual-targeted candidates for AD.

A methanol extract and N,N-dimethyltryptamine from Psychotria viridis Ruiz & Pav. inhibit Zika virus infection in vitro

Zika virus (ZIKV) is a public health problem due to its association with serious fetal and neurological complications and the lack of antiviral agents and licensed vaccines against this virus. Surveillance studies have alerted about the potential occurrence of a new South American epidemic episode due to the recent circulation of an African ZIKV strain detected in Brazil. Therefore, it is essential to discover antiviral agents, including natural substances, that are capable of neutralizing the action of ZIKV. Several Psychotria species have antimicrobial and anti-inflammatory properties. Thus, a methanol extract and dimethyltryptamine from Psychotria viridis were evaluated for their ability to inhibit ZIKV infection in vitro by measuring the effective concentration that protects 50% of cells and investigating their possible mechanisms of action. The tested samples showed antiviral activity against ZIKV. The extract showed virucidal activity, affecting viral and non-cellular elements, inactivating the virus before infection or when it becomes extracellular after the second cycle of infection. It was also observed that both extract and dimethyltryptamine could inhibit the virus at intracellular stages of the viral cycle. In addition to dimethyltryptamine, it is believed that other compounds also contribute to the promising virucidal effect observed for the methanol extract. To our knowledge, this is the first report of the activity of a methanolic extract and dimethyltryptamine from Psychotria viridis against cellular ZIKV infection. These two samples, extracted from natural sources, are potential candidates for use as antiviral drugs to inhibit ZIKV infections.

Design and synthesis of β-carboline derivatives with nitrogen mustard moieties against breast cancer

To discover the promising antitumor agents, a series of β-carboline derivatives with nitrogen mustard moieties were designed and synthesized. Most target derivatives showed antiproliferative activity against MCF-7 and MDA-MB-231 cells. Among them, (1-methyl-9H-pyrido[3,4-b]indol-3-yl)methyl (S)-3-(4-(bis(2-chloroethyl)amino)phenyl)-2-formamidopropanoate possessed the most potent antiproliferative activity with IC₅₀ values of 1.79 μM and 4.96 μM, respectively, which were significantly higher than that of the parent compounds, and the efficacy was comparable to that of the positive control doxorubicin. More importantly, it showed weak cytotoxicity against human normal breast cell line MCF-10A (IC₅₀ > 20 μM), exhibiting certain selectivity. Subsequently, further mechanism exploration indicated that it induced G2/M phase cell cycle arrest and apoptosis in MDA-MB-231 cells. The DCFH-DA fluorescent probe assay and comet assay showed that this compound could cause intracellular ROS accumulation and DNA damage. In addition, it exerted potent inhibitory effect on the migration, invasion and adhesion of MDA-MB-231 cells in vitro. In short, (1-methyl-9H-pyrido[3,4-b]indol-3-yl)methyl (S)-3-(4-(bis(2-chloroethyl)amino)phenyl)-2-formamidopropanoate was considered as a promising compound for anti-breast cancer.

Design and Synthesis of Fluorescent 1,3-Diaryl-β-carbolines and 1,3-Diaryl-3,4-dihydro-β-carbolines

The 1,3-diaryl-β-carboline derivatives, including 3,4-dihydro variants, were synthesized via a multiple-step approach. These compounds possess rigid and twisted configurations, which are expected to exhibit unique optical properties. The absorption and fluorescence properties of the newly synthesized compounds were investigated. These synthetic 1,3-diaryl-β-carbolines displayed strong emission in the range of 387-409 nm and exhibited absolute photoluminescence quantum yields of up to 74%. Density functional theory calculations were performed to better elucidate the geometric, electronic, and optical properties of these novel 1,3-diaryl-β-carbolines.

β-Carbolines as potential anticancer agents

β-Carbolines are indole alkaloids having a tricyclic pyrido[3,4-b]indole ring in their structure. Since the isolation of first β-carboline from Peganum harmala in 1841, the isolation and synthesis of various β-carboline derivatives surged in the following centuries. β-Carboline derivatives due to their widespread availability from natural sources, structural flexibility, quick reactivity and interaction with varied anticancer targets such as DNA (intercalation, groove binding, etc.), enzymes (GPX4, topoisomerases, kinases, etc.) and proteins (tubulin, ABCG2/BRCP1, etc.) have established themselves as promising lead compounds for the synthesis of various anticancer active agents. The current review covers the synthesis and isolation, anticancer activity, mechanism of action and SAR of various β-carboline containing molecules, its derivatives and congeners.

Neuropharmacological potentials of β-carboline alkaloids for neuropsychiatric disorders

Neuropsychiatric disorders are diseases of the central nervous system (CNS) which are characterised by complex pathomechanisms that including homeostatic failure, malfunction, atrophy, pathology remodelling and reactivity anomaly of the neuronal system where treatment options remain challenging. β-Carboline (βC) alkaloids are scaffolds of structurally diverse tricyclic pyrido[3,4-b]indole alkaloid with vast occurrence in nature. Their unique structural features which favour interactions with enzymes and protein receptor targets account for their potent neuropharmacological properties. However, our current understanding of their biological mechanisms for these beneficial effects, especially for neuropsychiatric disorders is sparse. Therefore, we present a comprehensive review of the scientific progress in the last two decades on the prospective pharmacology and physiology of the βC alkaloids in the treatment of some neuropsychiatric conditions such as depression, anxiety, Alzheimer's disease, Parkinson's disease, brain tumour, essential tremor, epilepsy and seizure, licking behaviour, dystonia, agnosia, spasm, positive ingestive response as demonstrated in non-clinical models. The current evidence supports that βC alkaloids offer potential therapeutic agents against most of these disorders and amenable for further drug design.

Structural activity analysis, spectroscopic investigation, biological and chemical properties interpretation on Beta Carboline using quantum computational methods

In this methodological work, the structural activity analysis have been carried out on β-Carboline to study the anti cancer activity and the way of improving the biological activity. The molecular spectroscopic tools were used to evaluate all the experimental data like spectral results and data were validated by the computational, HyperChem and Osiris tools. The structural, biological and physico-chemical related analyses have been performed to interpret the properties. The GPCR ligand calculated to be 0.11 for generating pharmacokinetic process, Specified drug information for the compound, was congregated from all types of structural activity which was drawn by spectral and HyperChem data. The σ and π interaction band gap (6.18 eV) ensured the drug consistency. The Mulliken charge process distribution was mapped, the charge orientation assignment was checked; the acquired negative charge potential consignment for the cause of antibiotic impact was verified. The molecular orbital interaction study was carried out to identify the origination of degeneracy of interaction causing drug mechanism. Using NMR spectral pattern, the chemical reaction path was recognized and the nodal region dislocation was distinguished on chemical shift. The Electronegativity (χ) and Electrophilicity charge transfer found to be 3.83 and 0.215, confirmed charge complex transfer for activating drug process in the compound. The molecular nonbonding section was thoroughly observed in order to find the occupancy energy, was the key process to initiate drug activity. The bathochromic electronic shift was observed and the existence of CT complex was discussed. The hindering of toxicity was inspected on inevitable chirality of the compound by specifying VCD spectrum.

Recent update on anti-dengue drug discovery

Dengue is the most important arthropod-borne viral disease of humans, with more than half of the global population living in at-risk areas. Despite the negative impact on public health, there are no antiviral therapies available, and the only licensed vaccine, Dengvaxia^®, has been contraindicated in children below nine years of age. In an effort to combat dengue, several small molecules have entered into human clinical trials. Here, we review anti-DENV molecules and their drug targets that have been published within the past five years (2014-2018). Further, we discuss their probable mechanisms of action and describe a role for classes of clinically approved drugs and also an unclassified class of anti-DENV agents. This review aims to enhance our understanding of novel agents and their cognate targets in furthering innovations in the use of small molecules for dengue drug therapies.

Design, synthesis, fungicidal property and QSAR studies of novel β-carbolines containing urea, benzoylthiourea and benzoylurea for the control of rice sheath blight

BACKGROUND

Rice sheath blight is a globally important rice disease. Unfortunately, this critical disease has not been effectively controlled, and the intensive and continuous use of the same fungicide might increase the risk of resistance development in the pathogen. To discover new active agents against rice sheath blight, in this study, three series of β-carboline urea, benzoylurea and benzoylthiourea derivatives were designed, synthesized and evaluated for in vitro and in vivo fungicidal activity against Rhizoctonia solani.

RESULTS

All these compounds (EC₅₀ : 0.131-1.227 mmol L^-1 ) exhibited better fungicidal activity than harmine itself (EC₅₀ : 2.453 mmol L^-1 ). Significantly, compound 17c (EC₅₀ : 0.131 mmol L^-1 ) displayed the best efficacy in vitro and superior fungicidal activity compared with validamycin A (EC₅₀ : 0.397 mmol L^-1 ). Moreover, the in vivo bioassay also indicated that compound 17c could be effective for the control of rice sheath blight.

CONCLUSION

Based on the bioassay result and quantitative structure-activity relationship (QSAR) information, structure modification in β-carboline warrants further investigation and its benzoylurea derivative 17c, which showed the best fungicidal activities, could emerge as a potential fungicide against rice sheath blight. © 2018 Society of Chemical Industry.

Design, Synthesis and Bioactivity Evaluation of Novel β-carboline 1,3,4-oxadiazole Derivatives

A series of novel β-carboline 1,3,4-oxadiazole derivatives were designed and synthesized, and the in vitro cytotoxic activity against Sf9 cells and growth inhibitory activity against Spodoptera litura were evaluated. Bioassay results showed that most of these compounds exhibited excellent in vitro cytotoxic activity. Especially, compound 37 displayed the best efficacy in vitro (IC₅₀ = 3.93 μM), and was five-fold more potent than camptothecin (CPT) (IC₅₀ = 18.95 μM). Moreover, compounds 5 and 37 could induce cell apoptosis and cell cycle arrest and stimulate Sf-caspase-1 activation in Sf9 cells. In vivo bioassay also demonstrated that compounds 5 and 37 could significantly inhibit larvae growth of S. litura with decreasing the weight of larvae and pupae. Based on these bioassay results, compounds 5 and 37 emerged as lead compounds for the development of potential insect growth inhibitions.

Synthesis and evaluation of novel hybrids β-carboline-4-thiazolidinones as potential antitumor and antiviral agents

A series of novel hybrids β-carboline-4-thiazolidinones were synthesized and evaluated for their in vitro antitumor activity against human cancer cell lines and for antiviral activity towards Herpes simplex virus type-1 (HSV-1). From the N'-(2-ylidene-4-thiazolidinone)-β-carboline-3-carbohydrazide series (9-11), compounds 9c and 11d were the most active, showing growth inhibition 50% (GI₅₀) values less than 5 μM for all cell lines tested. Compound 9c, bearing the 4-dimethylaminophenyl group at C-1 of β-carboline was selected for further investigation concerning cell death and cell cycle profile, focusing on the human renal adenocarcinoma cell line 786-0. Treatments with 25 μM of compound 9c induced cell death after 15 h of treatment, characterized by phosphatidylserine exposure and loss of membrane integrity. Moreover, treatment with 12.5 μM promoted a sub-G1 arrest, which indicates cell death. Derivatives of the N-(2-substituted-aryl-4-thiazolidinone)-β-carboline-3-carboxamide series (18-23) showed a potent activity and high selectivity for glioma (U251) and ovarian (OVCAR-3) cancer cell lines. Also, some β-carboline-4-thiazolidinone hybrids showed potent antiviral activity against Herpes simplex virus type-1. The N-(2-substituted-aryl-4-thiazolidinone)-carboxamide moiety in 18, 19 and 22 confer a potent anti-HSV-1 activity for these derivatives, which presented EC₅₀ values of 0.80, 2.15 and 2.02 μM, respectively. The assay results showed that the nature of 4-thiazolidinone moiety and of the substituent attached at the 3- and 1- position of β-carboline nucleus influenced the antitumor and antiviral activities.

Tetrahydro-β-carboline-3-carboxyl-thymopentin: a nano-conjugate for releasing pharmacophores to treat tumor and complications

To improve the therapeutic efficacy of cancer patients a novel conjugate of thymopentin (TP5) and (1S,3S)-1-methyl-tetrahydro-β-carboline-3-carboxylic acid (MTC) was presented. In water and mouse plasma MTCTP5 forms the nanoparticles of 14-139 nm in diameter, the suitable size for delivery in blood circulation. In mouse plasma MTCTP5 releases MTC, while in the presence of trypsin MTCTP5 releases MTC and TP5. On mouse and rat models the MTCTP5 dose dependently slows down the tumor growth, inhibits inflammatory response and blocks thrombosis. The anti-tumor activity as well as the anti-inflammation activity and anti-thrombotic activity of MTCTP5 are 100 fold and 10 fold higher than those of MTC, respectively, which are attributed to the fact that it down-regulates the plasma levels of TNF-α and IL-8 of the treated animals. The immunology enhancing activities in vitro and in vivo of MTCTP5 are similar to those of TP5, which is attributed to the fact that MTCTP5 up-regulates the plasma levels of IL-2 and CD4 as well as down-regulates the plasma level of CD8 of the treated animals. The plasma alanine transaminase, aspartate transaminase and creatinine assays indicate that MTCTP5 therapy does not injure the liver and the kidney of the animals. The survival time of MTCTP5 treated mice is significantly longer than that of TP5 treated mice.

Mitochondrial Dysfunction Induced by N-Butyl-1-(4-Dimethylamino)Phenyl-1,2,3,4-Tetrahydro-β-Carboline-3-Carboxamide Is Required for Cell Death of Trypanosoma cruzi

BACKGROUND

Chagas' disease is caused by the protozoan Trypanosoma cruzi and affects thousands of people worldwide. The available treatments are unsatisfactory, and new drugs must be developed. Our group recently reported the trypanocidal activity of the synthetic compound N-butyl-1-(4-dimethylamino)phenyl-1,2,3,4-tetrahydro-β-carboline-3-carboxamide (C4), but the mechanism of action of this compound was unclear.

METHODOLOGY/PRINCIPAL FINDINGS

We investigated the mechanism of action of C4 against epimastigote and trypomastigote forms of T. cruzi. The results showed alterations in mitochondrial membrane potential, alterations in cell membrane integrity, an increase in the formation of reactive oxygen species, phosphatidylserine exposure, a reduction of cell volume, DNA fragmentation, and the formation of lipid inclusions.

CONCLUSION/SIGNIFICANCE

These finding suggest that mitochondria are a target of C4, the dysfunction of which can lead to different pathways of cell death.

Synthesis and antiviral and fungicidal activity evaluation of β-carboline, dihydro-β-carboline, tetrahydro-β-carboline alkaloids, and their derivatives

Six known β-carboline, dihydro-β-carboline, and tetrahydro-β-carboline alkaloids and a series of their derivatives were designed, synthesized, and evaluated for their anti-tobacco mosaic virus (TMV) and fungicidal activities for the first time. All of the alkaloids and some of their derivatives (compounds 3, 4, 14, and 19) exhibited higher anti-TMV activity than the commercial antiviral agent Ribavirin both in vitro and in vivo. Especially, the inactivation, curative, and protection activities of alkaloids Harmalan (62.3, 55.1, and 60.3% at 500 μg/mL) and tetrahydroharmane (64.2, 57.2, and 59.5% at 500 μg/mL) in vivo were much higher than those of Ribavirin (37.4, 36.2, and 38.5% at 500 μg/mL). A new derivative, 14, with optimized physicochemical properties, obviously exhibited higher activities in vivo (50.4, 43.9, and 47.9% at 500 μg/mL) than Ribavirin and other derivatives; therefore, 14 can be used as a new lead structure for the development of anti-TMV drugs. Moreover, most of these compounds exhibited good fungicidal activity against 14 kinds of fungi, especially compounds 4, 7, and 11.

Alkaloids from the mangrove-derived actinomycete Jishengella endophytica 161111

A new alkaloid, 2-(furan-2-yl)-6-(2S,3S,4-trihydroxybutyl)pyrazine (1), along with 12 known compounds, 2-(furan-2-yl)-5-(2S,3S,4-trihydroxybutyl)pyrazine (2), (S)-4-isobutyl-3-oxo-3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazine-6-carbaldehyde (3), (S)-4-isopropyl-3-oxo-3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazine-6-carbaldehyde (4), (4S)-4-(2-methylbutyl)-3-oxo-3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazine-6-carbaldehyde (5), (S)-4-benzyl-3-oxo-3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazine-6-carbaldehyde (6), flazin (7), perlolyrine (8), 1-hydroxy-β-carboline (9), lumichrome (10), 1H-indole-3-carboxaldehyde (11), 2-hydroxy-1-(1H-indol-3-yl)ethanone (12), and 5-(methoxymethyl)-1H-pyrrole-2-carbaldehyde (13), were isolated and identified from the fermentation broth of an endophytic actinomycetes, Jishengella endophytica 161111. The new structure 1 and the absolute configurations of 2–6 were determined by spectroscopic methods, J-based configuration analysis (JBCA) method, lactone sector rule, and electronic circular dichroism (ECD) calculations. Compounds 8–11 were active against the influenza A virus subtype H1N1 with IC₅₀ and selectivity index (SI) values of 38.3(±1.2)/25.0(±3.6)/39.7(±5.6)/45.9(±2.1) μg/mL and 3.0/16.1/3.1/11.4, respectively. The IC₅₀ and SI values of positive control, ribavirin, were 23.1(±1.7) μg/mL and 32.2, respectively. The results showed that compound 9 could be a promising new hit for anti-H1N1 drugs. The absolute configurations of 2–5, ¹³C nuclear magnetic resonance (NMR) data and the specific rotations of 3–6 were also reported here for the first time.

3D-QSAR and Docking Studies of a Series ofβ-Carboline Derivatives as Antitumor Agents of PLK1

An alignment-free, three dimensional quantitative structure-activity relationship (3D-QSAR) analysis has been performed on a series ofβ-carboline derivatives as potent antitumor agents toward HepG2 human tumor cell lines. A highly descriptive and predictive 3D-QSAR model was obtained through the calculation of alignment-independent descriptors (GRIND descriptors) using ALMOND software. For a training set of 30 compounds, PLS analyses result in a three-component model which displays a squared correlation coefficient (r2) of 0.957 and a standard deviation of the error of calculation (SDEC) of 0.116. Validation of this model was performed using leave-one-out,q2looof 0.85, and leave-multiple-out. This model gives a remarkably highr2pred(0.66) for a test set of 10 compounds. Docking studies were performed to investigate the mode of interaction betweenβ-carboline derivatives and the active site of the most probable anticancer receptor, polo-like kinase protein.

The Effects of N-Butyl-1-(4-dimethylamino)phenyl-1,2,3,4-tetrahydro- β -carboline-3-carboxamide against Leishmania amazonensis Are Mediated by Mitochondrial Dysfunction

Leishmaniasis is a disease that affects millions of people worldwide. The drugs that are available for the treatment of this infection exhibit high toxicity and various side effects. Several studies have focused on the development of new chemotherapeutic agents that are less toxic and more effective against trypanosomatids. We investigated the effects of N-butyl-1-(4-dimethylamino)phenyl-1,2,3,4-tetrahydro-β-carboline-3-carboxamide (C4) and its possible targets against L. amazonensis. The results showed morphological and ultrastructural alterations, depolarization of the mitochondrial membrane, the loss of cell membrane integrity, and an increase in the formation of mitochondrial superoxide anions in L. amazonensis treated with C4. Our results indicate that C4 is a selective antileishmanial agent, and its effects appear to be mediated by mitochondrial dysfunction.

Beta-carboline-3-carboxamide derivatives as promising antileishmanial agents

Leishmaniasis has an overwhelming impact on global public health especially in tropical and subtropical countries and the currently available antileishmanial drugs have serious side effects and low efficacy. Natural and synthetic compounds have been tested in the past few years against Leishmania and the beta-carboline class of compounds have shown great results in antiparasitic chemotherapy. In the present study, three 1-substituted beta-carboline-3-carboxamides (3-5) and 1-substituted beta-carboline-3-carboxylic acid (2) were synthesized and screened for in vitro activity against L. amazonensis. Compound 5 (N-benzyl 1-(4-methoxy)phenyl-9H-beta-carboline-3-carboxamide) had the best activity against promastigote and axenic amastigote forms with IC(50) of 2·6 and 1·0 μM, respectively. Its CC(50) on macrophages cell line was higher than 2457·0 μM with an SI ratio of 930·2. Against intracellular amastigote forms, it had a dose-dependent relationship with a 50% growth inhibitory concentration of 1·0 μM. Through morphological and ultrastructure analysis of promastigote forms treated with compound 5, alterations on cell shape and number of flagella and nuclear membrane damage were observed. For this, compound 5 supports the idea for more in vitro and in vivo studies.

Synthesis and herbicidal activity evaluation of novel β-carboline derivatives

Based on the original structure of harmine, several novel 1,2,3,4-tetrahydro-β-carboline, β-carboline and 1-substituted-β-carboline derivatives bearing a substituted carbohydrazide group at C-3 were designed and synthesized to investigate the structure-activity relationship of their analogues. All of the compounds were characterized by infrared (IR), proton and carbon nuclear magnetic resonance (¹H-NMR, ¹³C-NMR), and mass spectroscopy (MS). The bioassay tests showed that N'-benzylidene-1-phenyl-β-carboline-3-carbohydrazide (C₂₅H₁₈N₄O, m.w. 390.4) (c2) and N'-(4-trifluoromethyl-benzylidene)-1-phenyl-β-carboline-3-carbohydrazide (C₂₆H₁₇N₄OF₃, m.w. 458) (d2) exhibited good inhibitory activity against dicotyledonous and monocotyledonous weeds, with EC₅₀ values of 4.83 µM and 14.25 µM, respectively.

Synthesis and antiviral activity of novel 1,3,4-thiadiazine derivatives

A series of novel 1,3,4-thiadiazine derivatives were synthesized via chemical optimization on phthiobuzone. Their anti-herpes simplex virus (HSV) activities in vitro were also tested. Several compounds exhibited more highly potent anti-HSV activity and much higher selectivity index (SI) values than those of phthiobuzone. The most potent anti-HSV compound was 4f, which showed marked inhibition against HSV-1 (IC₅₀=77.04 µg/ml) and HSV-2 (IC₅₀=30.00 µg/ml). Meanwhile it had low cytotoxicity (CC₅₀=1000.00 µg/ml), resulting in high (SI(HSV-1)=12.98, SI(HSV-2)=33.33, respectively). Furthermore, a computational study for prediction of absorption, distribution, metabolism, excretion (ADME) properties of compound 4f was performed by determination of topological polar surface area, absorption and Lipinski parameters.