Specific inhibition of cyclin-dependent kinases and cell proliferation by harmine

Plant extracts as a source of antiviral agents against influenza A virus

The influenza virus, especially influenza A (IAV), has remained a constant global health threat due to its high morbidity rate and ability to undergo antigenic shifts and drifts, causing pandemics and epidemics. Due to the rapid evolution of IAV, novel therapeutics are urgently required to combat these viruses effectively, as they develop resistance against current therapeutics. Natural products have been the subject of debate for alternative IAV therapy, where the abundance of bioactive compounds offers numerous potentials for novel anti-IAV drug discovery. Therefore, this review discusses the antiviral effects of natural plant extracts against IAV. Examples are Silybum marianum, Scutellaria baicalensis, Angelica dahurica, Peganum harmala, Sambucus nigra, Echinacea purpurea, Panax ginseng, and Camellia sinensis. Most studies found that Si. marianum inhibits viral ribonucleic acid (RNA) synthesis. In contrast, Sc. baicalensis, A. dahurica, Sa. nigra, C. sinensis, and E. purpurea were effective in preventing the entry or binding of IAV into host cells. On the other hand, Sc. baicalensis and Pa. ginseng exert their anti-IAV effect via immunomodulation. Peganum harmala, on the contrary, exhibits a direct virucidal effect against IAV. These studies have shown promising results from using natural products against IAV, which may aid in formulating combinatorial compounds as anti-IAV therapy.

Anti-tumor potential of Harmine and its derivatives: recent trends and advancements

Harmine is a β-carboline alkaloid derived from Peganum harmala, showing a solid antitumor potential in different types of human cancer cells. Unfortunately, the clinical application of this natural alkaloid has been impeded till now by severe toxic side effects, especially neurotoxicity, besides its poor water solubility. Therefore, over the recent years, several semisynthetic derivatives of harmine have been prepared and studied concerning their abilities to inhibit tumor cell proliferation, survival, angiogenesis, migration, and invasion in diverse preclinical models. This review article summarizes the anticancer effects of harmine and its synthetic derivatives, demonstrating their high potential to be developed as novel anticancer drugs to supplement our current therapeutic arsenal in the fight against the globally increasing rate of malignant disorders.

Cyclin-dependent Kinase 5 and Neurodegenerative Diseases

Neurodegenerative diseases are a group of diseases characterized by the progressive loss of neurons, including Alzheimer's disease, Parkinson's disease, and Amyotrophic lateral sclerosis. These diseases have a high incidence and mortality rate globally, placing a heavy burden on patients and their families. The pathogenesis of neurodegenerative diseases is complex, and there are no effective treatments at present. Cyclin-dependent kinase 5 is a proline-directed serine/threonine protein kinase that is closely related to the development and function of the nervous system. Under physiological conditions, it is involved in regulating the process of neuronal proliferation, differentiation, migration, and synaptic plasticity. Moreover, there is increasing evidence that cyclin-dependent kinase 5 also plays an important role in the pathogenesis of neurodegenerative diseases. In this review, we address the biological characteristics of cyclin-dependent kinase 5 and its role in neurodegenerative diseases. In particular, this review highlights the underlying mechanistic linkages between cyclin-dependent kinase 5 and mitochondrial dysfunction, oxidative stress and neuroinflammation in the context of neurodegeneration. Finally, we also summarize the currently available cyclin-dependent kinase 5 inhibitors and their prospects for the treatment of neurodegenerative diseases. Taken together, a better understanding of the molecular mechanisms of cyclin-dependent kinase 5 involved in neurodegenerative diseases can lead to the development of new strategies for the prevention and treatment of these devastating diseases.

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

AIM

Exploring the efficacy of β-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-β-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.

Mechanistic Insights into Harmine-Mediated Inhibition of Human DNA Methyltransferases and Prostate Cancer Cell Growth

Mammalian DNA methyltransferases (DNMTs), including DNMT1, DNMT3A, and DNMT3B, are key DNA methylation enzymes and play important roles in gene expression regulation. Dysregulation of DNMTs is linked to various diseases and carcinogenesis, and therefore except for the two approved anticancer azanucleoside drugs, various non-nucleoside DNMT inhibitors have been identified and reported. However, the underlying mechanisms for the inhibitory activity of these non-nucleoside inhibitors still remain largely unknown. Here, we systematically tested and compared the inhibition activities of five non-nucleoside inhibitors toward the three human DNMTs. We found that harmine and nanaomycin A blocked the methyltransferase activity of DNMT3A and DNMT3B more efficiently than resveratrol, EGCG, and RG108. We further determined the crystal structure of harmine in complex with the catalytic domain of the DNMT3B-DNMT3L tetramer revealing that harmine binds at the adenine cavity of the SAM-binding pocket in DNMT3B. Our kinetics assays confirm that harmine competes with SAM to competitively inhibit DNMT3B-3L activity with a Ki of 6.6 μM. Cell-based studies further show that harmine treatment inhibits castration-resistant prostate cancer cell (CRPC) proliferation with an IC50 of ∼14 μM. The CPRC cells treated with harmine resulted in reactivating silenced hypermethylated genes compared to the untreated cells, and harmine cooperated with an androgen antagonist, bicalutamide, to effectively inhibit the proliferation of CRPC cells. Our study thus reveals, for the first time, the inhibitory mechanism of harmine on DNMTs and highlights new strategies for developing novel DNMT inhibitors for cancer treatment.

Microbial Interactions between Marine Microalgae and Fungi: From Chemical Ecology to Biotechnological Possible Applications

Chemical interactions have been shown to regulate several marine life processes, including selection of food sources, defense, behavior, predation, and mate recognition. These chemical communication signals have effects not only at the individual scale, but also at population and community levels. This review focuses on chemical interactions between marine fungi and microalgae, summarizing studies on compounds synthetized when they are cultured together. In the current study, we also highlight possible biotechnological outcomes of the synthetized metabolites, mainly for human health applications. In addition, we discuss applications for bio-flocculation and bioremediation. Finally, we point out the necessity of further investigating microalgae-fungi chemical interactions because it is a field still less explored compared to microalga-bacteria communication and, considering the promising results obtained until now, it is worthy of further research for scientific advancement in both ecology and biotechnology fields.

Effects of Monoamino-Oxidase-A (MAO-A) Inhibition on Skeletal Muscle Inflammation and Wasting through Pancreatic Ductal Adenocarcinoma in Triple Transgenic Mice

Cancer cachexia describes a syndrome of muscle wasting and lipolysis that is still largely untreatable and negatively impacts prognosis, mobility, and healthcare costs. Since upregulation of skeletal muscle monoamine-oxidase-A (MAO-A), a source of reactive oxygen species, may contribute to cachexia, we investigated the effects of the MAO-inhibitor harmine-hydrochloride (HH, intraperitoneal, 8 weeks) on muscle wasting in a triple-transgenic mouse model of pancreatic ductal adenocarcinoma (PDAC) and wild type (WT) mice. Gastrocnemius and soleus muscle cryo-cross-sections were analyzed for fiber type-specific cross-sectional area (CSA), fraction and capillarization using ATPase- and lectin-stainings. Transcripts of pro-apoptotic, -atrophic, and -inflammatory signals were determined by RT-qPCR. Furthermore, we evaluated the integrity of neuromuscular junction (NMJ, pre-/post-synaptic co-staining) and mitochondrial ultrastructure (transmission electron microscopy). MAO-A expression in gastrocnemius muscle was increased with PDAC vs. WT (immunohistochemistry: p < 0.05; Western blot: by trend). PDAC expectedly reduced fiber CSA and upregulated IL-1β in both calf muscles, while MuRF1 expression increased in soleus muscle only. Although IL-1β decreased, HH caused an additional 38.65% (p < 0.001) decrease in gastrocnemius muscle (IIBX) fiber CSA. Moreover, soleus muscle CSA remained unchanged despite the downregulation of E3-ligases FBXO32 (p < 0.05) and MuRF1 (p < 0.01) through HH. Notably, HH significantly decreased the post-synaptic NMJ area (quadriceps muscle) and glutathione levels (gastrocnemius muscle), thereby increasing mitochondrial damage and centronucleation in soleus and gastrocnemius type IIBX fibers. Moreover, although pro-atrophic/-inflammatory signals are reversed, HH unfortunately fails to stop and rather promotes PDAC-related muscle wasting, possibly via denervation or mitochondrial damage. These differential adverse vs. therapeutic effects warrant studies regarding dose-dependent benefits and risks with consideration of other targets of HH, such as the dual-specificity tyrosine phosphorylation regulated kinases 1A and B (DYRK1A/B).

Natural Alkaloids as Multi-Target Compounds towards Factors Implicated in Alzheimer's Disease

Alzheimer's disease (AD) is the most common cause of dementia in elderly people; currently, there is no efficient treatment. Considering the increase in life expectancy worldwide AD rates are predicted to increase enormously, and thus the search for new AD drugs is urgently needed. A great amount of experimental and clinical evidence indicated that AD is a complex disorder characterized by widespread neurodegeneration of the CNS, with major involvement of the cholinergic system, causing progressive cognitive decline and dementia. The current treatment, based on the cholinergic hypothesis, is only symptomatic and mainly involves the restoration of acetylcholine (ACh) levels through the inhibition of acetylcholinesterase (AChE). Since the introduction of the Amaryllidaceae alkaloid galanthamine as an antidementia drug in 2001, alkaloids have been one of the most attractive groups for searching for new AD drugs. The present review aims to comprehensively summarize alkaloids of various origins as multi-target compounds for AD. From this point of view, the most promising compounds seem to be the β-carboline alkaloid harmine and several isoquinoline alkaloids since they can simultaneously inhibit several key enzymes of AD's pathophysiology. However, this topic remains open for further research on detailed mechanisms of action and the synthesis of potentially better semi-synthetic analogues.

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.

Simple naturally occurring β-carboline alkaloids – role in sustainable theranostics

This review is a brief treatise on some simple β-carboline alkaloids that are abundantly available in plants, animals and foodstuff. These alkaloids are well known for their pharmacological action as well as their allelopathic behaviour. The focus of this review is on sustainable use of naturally occurring compounds in safeguarding human health and protecting our environment at large i.e. the prospective applications of these molecules for Sustainable Theranostics. The review commences with an initial introduction to the β-carboline alkaloids, followed by an outlay of their geographical distribution and natural abundance, then the basic structure and building units of the simplest β-carboline alkaloids have been mentioned. This is followed by a discussion on the important methods of extraction from natural sources both plants and animals. Then the foundation for the use of these alkaloids in Sustainable Theranostics has been built by discussing their interesting photophysics, interactions with important biological molecules and an extensive survey of their therapeutic potential and allelopathic behaviour. Finally the review ends with a silver lining mentioning the future prospective applications of these alkaloids with special relevance to sustainability issues.

Cdk5-p25 as a key element linking amyloid and tau pathologies in Alzheimer's disease: Mechanisms and possible therapeutic interventions

Despite the fact that the small atypical serine/threonine cyclin-dependent kinase 5 (Cdk5) is expressed in a number of tissues, its activity is restricted to the central nervous system due to the neuron-only localization of its activators p35 and p39. Although its importance for the proper development and function of the brain and its role as a switch between neuronal survival and death are unmistakable and unquestionable, Cdk5 is nevertheless increasingly emerging, as supported by a large number of publications on the subject, as a therapeutic target of choice in the fight against Alzheimer's disease. Thus, its aberrant over activation via the calpain-dependent conversion of p35 into p25 is observed during the pathogenesis of the disease where it leads to the hyperphosphorylation of the β-amyloid precursor protein and tau. The present review highlights the pivotal roles of the hyperactive Cdk5-p25 complex activity in contributing to the development of Alzheimer's disease pathogenesis, with a particular emphasis on the linking function between Aβ and tau that this kinase fulfils and on the fact that Cdk5-p25 is part of a deleterious feed forward loop giving rise to a molecular machinery runaway leading to AD pathogenesis. Additionally, we discuss the advances and challenges related to the possible strategies aimed at specifically inhibiting Cdk5-p25 activity and which could lead to promising anti-AD therapeutics.

Morita–Baylis–Hillman reaction of 3-formyl-9H-pyrido[3,4-b]indoles and fluorescence studies of the products

β-Carboline is a privileged class of the alkaloid family and is associated with a broad spectrum of biological properties. 3-Formyl-9H-pyrido[3,4-b]indole is a such potent precursor belonging to this family which can be tailored for installing diversity at various positions of β-carboline to generate unique molecular hybrids of biological importance. The present work is a step towards this and assimilates the results related to the exploration of 3-formyl-9H-β-carbolines for the synthesis of β-carboline C-3 substituted MBH adducts followed by evaluation of their fluorescent characteristic. The effect of contact time, solvent system, concentration and substituents was also studied during investigation of fluorescence properties of these derivatives.

Discovery of novel 6-hydroxybenzothiazole urea derivatives as dual Dyrk1A/α-synuclein aggregation inhibitors with neuroprotective effects

A role of Dyrk1A in the progression of Down syndrome-related Alzheimer's disease (AD) is well supported. However, the involvement of Dyrk1A in the pathogenesis of Parkinson's disease (PD) was much less studied, and it is not clear whether it would be promising to test Dyrk1A inhibitors in relevant PD models. Herein, we modified our previously published 1-(6-hydroxybenzo[d]thiazol-2-yl)-3-phenylurea scaffold of Dyrk1A inhibitors to obtain a new series of analogues with higher selectivity for Dyrk1A on the one hand, but also with a novel, additional activity as inhibitors of α-synuclein (α-syn) aggregation, a major pathogenic hallmark of PD. The phenyl acetamide derivative b27 displayed the highest potency against Dyrk1A with an IC50 of 20 nM and high selectivity over closely related kinases. Furthermore, b27 was shown to successfully target intracellular Dyrk1A and to inhibit SF3B1 phosphorylation in HeLa cells with an IC50 of 690 nM. In addition, two compounds among the Dyrk1A inhibitors, b1 and b20, also suppressed the aggregation of α-synuclein (α-syn) oligomers (with IC50 values of 10.5 μM and 7.8 μM, respectively). Both compounds but not the Dyrk1A reference inhibitor harmine protected SH-SY5Y neuroblastoma cells against α-syn-induced cytotoxicity, with b20 exhibiting a higher neuroprotective effect. Compound b1 and harmine were more efficient in protecting SH-SY5Y cells against 6-hydroxydopamine-induced cell death, an effect that was previously correlated to Dyrk1A inactivation in cells but not yet verified using chemical inhibitors. The presented dual inhibitors exhibited a novel activity profile encouraging for further testing in neurodegenerative disease models.

Discovery of Hydroxybenzothiazole Urea Compounds as Multitargeted Agents Suppressing Major Cytotoxic Mechanisms in Neurodegenerative Diseases

Multiple factors are causally responsible and/or contribute to the progression of Alzheimer's and Parkinson's diseases. The protein kinase Dyrk1A was identified as a promising target as it phosphorylates tau protein, α-synuclein, and parkin. The first goal of our study was to optimize our previously identified Dyrk1A inhibitors of the 6-hydroxy benzothiazole urea chemotype in terms of potency and selectivity. Our efforts led to the development of the 3-fluorobenzyl amide derivative 16b, which displayed the highest potency against Dyrk1A (IC₅₀ = 9.4 nM). In general, the diversification of the benzylamide moiety led to an enhanced selectivity over the most homologous isoform, Dyrk1B, which was a meaningful indicator, as the high selectivity could be confirmed in an extended selectivity profiling of 3b and 16b. Eventually, we identified the novel phenethyl amide derivative 24b as a triple inhibitor of Dyrk1A kinase activity (IC₅₀ = 119 nM) and the aggregation of tau and α-syn oligomers. We provide evidence that the novel combination of selective Dyrk1A inhibition and suppression of tau and α-syn aggregations of our new lead compound confers efficacy in several established cellular models of neurotoxic mechanisms relevant to neurodegenerative diseases, including α-syn- and 6-hydroxydopamine-induced cytotoxicities.

GZ17-6.02 and Pemetrexed Interact to Kill Osimertinib-Resistant NSCLC Cells That Express Mutant ERBB1 Proteins

We determined the molecular mechanisms by which the novel therapeutic GZ17-6.02 killed non-small cell lung cancer (NSCLC) cells. Erlotinib, afatinib, and osimertinib interacted with GZ17-6.02 to kill NSCLC cells expressing mutant EGFR proteins. GZ17-6.02 did not interact with any EGFR inhibitor to kill osimertinib-resistant cells. GZ17-6.02 interacted with the thymidylate synthase inhibitor pemetrexed to kill NSCLC cells expressing mutant ERBB1 proteins or mutant RAS proteins or cells that were resistant to EGFR inhibitors. The drugs interacted to activate ATM, the AMPK, and ULK1 and inactivate mTORC1, mTORC2, ERK1/2, AKT, eIF2α; and c-SRC. Knockdown of ATM or AMPKα₁ prevented ULK1 activation. The drugs interacted to cause autophagosome formation followed by flux, which was significantly reduced by knockdown of ATM, AMPKα₁, and eIF2α, or by expression of an activated mTOR protein. Knockdown of Beclin1, ATG5, or [BAX + BAK] partially though significantly reduced drug combination lethality as did expression of activated mTOR/AKT/MEK1 or over-expression of BCL-XL. Expression of dominant negative caspase 9 weakly reduced killing. The drug combination reduced the expression of HDAC2 and HDAC3, which correlated with lower PD-L1, IDO1, and ODC levels and increased MHCA expression. Collectively, our data support consideration of combining GZ17-6.02 and pemetrexed in osimertinib-resistant NSCLC.

Alkaloids of Peganum harmala L. and their Pharmacological Activity

Peganum harmala L. contains 17 alkaloids of quinazoline and indole structure types. Of these, harmaline, harmine, harmalol and L-peganin (vazicin) are pharmacologically active. It was established that of the alkaloids contained in the seeds, 50-95% is dominated by harmaline, harmine is dominated in the roots (67-74% of the total of extractive substances), and in the aerial part, the main mass is peganin (up to 78% of the total of alkaloids). Beta-carboline alkaloids of Peganum harmala L. inhibit monoamine oxidase, thereby exerting a neuroprotective effect. This article is devoted to the results of studies of the neurotropic action of harmine hydrochloride, when compared with the activity of the reference drug “Amitriptyline”. It was shown that the use of harmine hydrochloride helps to reduce the level of anxiety in animals under conditions of experimental psychoemotional chronic stress with prolonged administration. In the study of acute and chronic toxicity, it was determined that harmine hydrochloride belongs to the category of moderately toxic substances (hazard class II). According to the results of molecular docking, the presence of strong bonds in harmine hydrochloride with the serotonin 5-HT2C receptor, dopamine D2 receptor, as well as monoamine oxidase A and B was revealed, which indicates the implementation of the mechanism of neurotropic action of harmine hydrochloride at the level of synaptic neurotransmission of monoamines (dopamine, serotonin and others). It was also established that harmine hydrochloride eliminates haloperidol-induced catalepsy in rats, reduces oligokinesia and rigidity in the Parkinson’s test, has antihypoxic activity in the hypobaric hypoxia test, and exhibits pronounced antidepressant activity in the Porsolt’s test. In the course of the study of pharmacokinetics and bioavailability, it was revealed that with the administration of harmine hydrochloride, the quantitative content is quickly achieved and the concentration of the active substance in the blood significantly increases. The relative bioavailability of harmine hydrochloride is 112.7%.

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.

A natural compound harmine decreases melanin synthesis through regulation of the DYRK1A/NFATC3 pathway

BACKGROUND

Melanin plays important roles in determining human skin color and protecting human skin cells against harmful ultraviolet light. However, abnormal hyperpigmentation in some areas of the skin may become aesthetically unpleasing, resulting in the need for effective agents or methods to regulate undesirable hyperpigmentation.

OBJECTIVE

We investigated the effect of harmine, a natural harmala alkaloid belonging to the beta-carboline family, on melanin synthesis and further explored the signaling pathways involved in its mechanism of action.

METHODS

Human MNT-1 melanoma cells and human primary melanocytes were treated with harmine, chemical inhibitors, small interfering RNAs, or mammalian expression vectors. Cell viability, melanin content, and expression of various target molecules were assessed.

RESULTS

Harmine decreased melanin synthesis and tyrosinase expression in human MNT-1 melanoma cells. Inhibition of DYRK1A, a harmine target, decreased melanin synthesis and tyrosinase expression. Further studies revealed that nuclear translocation of NFATC3, a potential DYRK1A substrate, was induced via the harmine/DYRK1A pathway and that NFATC3 knockdown increased melanin synthesis and tyrosinase expression. Suppression of melanin synthesis and tyrosinase expression via the harmine/DYRK1A pathway was significantly attenuated by NFATC3 knockdown. Furthermore, harmine also decreased melanin synthesis and tyrosinase expression through regulation of NFATC3 in human primary melanocytes.

CONCLUSION

Our results indicate that harmine decreases melanin synthesis through regulation of the DYRK1A/NFATC3 pathway and suggest that the DYRK1A/NFATC3 pathway may be a potential target for the development of depigmenting agents.

Recent Update on the Anti-infective Potential of β-carboline Analogs

β-Carboline, a naturally occurring indole alkaloid, holds a momentous spot in the field of medicinal chemistry due to its myriad of pharmacological actions like anticancer, antiviral, antibacterial, antifungal, antileishmanial, antimalarial, neuropharmacological, anti-inflammatory and antithrombotic among others. β-Carbolines exhibit their pharmacological activity via diverse mechanisms. This review provides a recent update (2015-2020) on the anti-infective potential of natural and synthetic β-carboline analogs focusing on its antibacterial, antifungal, antiviral, antimalarial, antileishmanial and antitrypanosomal properties. In cases where enough details are available, a note on its mechanism of action is also added.

In vitro effects of harmine against Echinococcus granulosus protoscoleces by stimulating DNA damage

Cystic echinococcosis (CE), a parasitic larval cystic stage of a small taeniid-type tapeworm (Echinococcus granulosus), causes illness in intermediate hosts and has become a threat to global public health. Currently, chemical compounds recommended by the WHO targeting CE are albendazole and mebendazole, however, none of them shows enhanced efficacy. Novel molecular compounds are urgently required to treat this disease. Our group uncover a drug, termed harmine (HM), that may be capable of treating CE. In this study, we aim to evaluate the anti-parasitic efficacy and the mechanism of DNA damage of HM against E. granulosus. In vitro, the results indicated that, within two and three days of treatment, ABZ killed 30.4% and 35.3% of protoscoleces, whereas HM killed 52.7% and 100% of protoscoleces, respectively. Furthermore, the presence of abnormalities in the internal structure of protoscoleces was examined by ultrastructural images of TEM, and the result showed that there were scattered nucleoli and heterochromatin margination phenomenon by HM treatment. DNA damage of protoscoleces was examined by using the comet assay, and results showed the DNA of protoscoleces was damaged. Moreover, EgATM, EgP53, EgTopo2a and EgRad54 genes were used to support the DNA damage by HM treatment, and results showed that all four genes were upregulated expression. In further, the result of HM treatment was tested by using designed siRNA to inhibit the expression of EgTopo2a and EgRad54. The results demonstrated that the viability was 88.75 ± 2.11% after suppressing the expression of EgTopo2a, which was significantly higher than that for HM alone group (P < 0.01). The viability was 10.11 ± 2.60% after transfected with EgRad54 siRNA, which was significantly lower compared with the HM alone group (P < 0.01). Based on our preliminary data, HM demonstrated significant parasiticidal activity against E. granulosus in vitro without obvious toxicity towards its host cells, suggesting that HM can be a potential anti-echinococcosis drug. HM was found to induce DNA damages of CE by activating the EgATM-EgP53-EgTopo2a signaling pathway. We therefore surmise that DNA damage response may be one of the mechanisms of HM against the parasite.

GZ17-6.02 Interacts With [MEK1/2 and B-RAF Inhibitors] to Kill Melanoma Cells

We defined the lethal interaction between the novel therapeutic GZ17-6.02 and the standard of care combination of the MEK1/2 inhibitor trametinib and the B-RAF inhibitor dabrafenib in PDX isolates of cutaneous melanoma expressing a mutant B-RAF V600E protein. GZ17-6.02 interacted with trametinib/dabrafenib in an additive fashion to kill melanoma cells. Regardless of prior vemurafenib resistance, the drugs when combined interacted to prolong ATM S1981/AMPK T172 and eIF2α S51 phosphorylation and prolong the reduced phosphorylation of JAK2 Y1007, STAT3 Y705 and STAT5 Y694. In vemurafenib-resistant cells GZ17-6.02 caused a prolonged reduction in mTORC1 S2448, mTORC2 S2481 and ULK1 S757 phosphorylation; regardless of vemurafenib resistance, GZ17-6.02 caused a prolonged elevation in CD95 and FAS-L expression. Knock down of eIF2α, Beclin1, ATG5, ATM, AMPKα, CD95 or FADD significantly reduced the ability of GZ17-6.02 to kill as a single agent or when combined with the kinase inhibitors. Expression of activated mTOR, activated STAT3, activated MEK1 or activated AKT significantly reduced the ability of GZ17-6.02 to kill as a single agent or when combined with kinase inhibitors; protective effects that were significantly less pronounced in cells treated with trametinib/dabrafenib. Regardless of vemurafenib resistance, the drugs alone or in combination all reduced the expression of PD-L1 and increased the levels of MHCA, which was linked to degradation of multiple HDAC proteins. Our findings support the use of GZ17-6.02 in combination with trametinib/dabrafenib in the treatment of melanomas expressing mutant B-RAF V600E proteins.

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.

Bioinspired imidazo[1,2-a:4,5-c']dipyridines with dual antiproliferative and anti-migrative properties in human cancer cells: The SAR investigation

Herein, we report the design, synthesis and evaluation of novel bioinspired imidazo[1,2-a:4,5c']dipyridines. The structural optimization identified four anti-proliferative compounds. Compounds 11, 18, 19 and 20 exhibited excellent anticancer activities in vitro with IC₅₀ of 0.4-5 μM against three human cancer cell lines (MDA-MB-468, MDA-MB-435s and MDA-MB-231). These four compounds induced apoptosis in MDA-MB-231 cells in a dose-dependent manner, targeting different apoptotic proteins expression: 11 increased the expression of pro-apoptotic Bax protein while 18-20 reduced the level of anti-apoptotic Bcl-2 protein. Compounds 18 and 19 also reduced MDA-MB-231 cells proliferation as measured by Ki-67 staining. Furthermore, compounds were also tested for the ability to inhibit cell migration in the highly aggressive human MDA-MB-435s cell line. Six compounds of this series (8, 15, 18, 22, 23, 24) inhibited cell migration by 41-50% while four compounds (20, 25, 27, 30) inhibited the migration by 53-62% in wound-healing experiments. Interestingly, compound 20 presented both antiproliferative and anti-migration activities and might be a promising anti-metastatic agent for cancer treatment.

β-Carboline as a Privileged Scaffold for Multitarget Strategies in Alzheimer's Disease Therapy

The natural β-carboline alkaloids display similarities with neurotransmitters that can be favorably exploited to design bioactive and bioavailable drugs for Alzheimer's disease (AD) therapy. Several AD targets are currently and intensively being investigated, divided in different hypotheses: mainly the cholinergic, the amyloid β (Aβ), and the Tau hypotheses. To date, only symptomatic treatments are available involving acetylcholinesterase and NMDA inhibitors. On the basis of plethoric single-target structure-activity relationship studies, the β-carboline scaffold was identified as a powerful tool for fostering activity and molecular interactions with a wide range of AD-related targets. This knowledge can undoubtedly be used to design multitarget-directed ligands, a highly relevant strategy preferred in the context of multifactorial pathology with intricate etiology such as AD. In this review, we first individually discuss the AD targets of the β-carbolines, and then we focus on the multitarget strategies dedicated to the deliberate design of new efficient scaffolds.

Pharmacological effects of harmine and its derivatives: a review

Harmine is isolated from the seeds of the medicinal plant, Peganum harmala L., and has been used for thousands of years in the Middle East and China. Harmine has many pharmacological activities including anti-inflammatory, neuroprotective, antidiabetic, and antitumor activities. Moreover, harmine exhibits insecticidal, antiviral, and antibacterial effects. Harmine derivatives exhibit pharmacological effects similar to those of harmine, but with better antitumor activity and low neurotoxicity. Many studies have been conducted on the pharmacological activities of harmine and harmine derivatives. This article reviews the pharmacological effects and associated mechanisms of harmine. In addition, the structure-activity relationship of harmine derivatives has been summarized.

Design, Synthesis, Antiproliferative Evaluation, and Molecular Docking Studies of N-(3-Hydroxyindole)-Appended β-Carbolines/Tetrahydro-β-Carbolines Targeting Triple-Negative and Non-Triple-Negative Breast Cancer

The present manuscript pertains to the design and synthesis of a series of 3-hydroxyindole-substituted β-carbolines/tetrahydro-β-carbolines with an aim to explore their antiproliferative structure-activity relationship against breast cancer. The conjugate with an optimum combination of a flexible tetrahydro-β-carboline core, a tertiary alcoholic group along with a chloro substituent on the indole ring, proved to be the most active compound. It displayed IC50 values of 13.61 and 22.76 μM against MCF-7 (ER+) and MDA-MB-231 (ER-) cells, respectively. The docking studies were found to be consistent with experimental results owing to the stronger binding affinity of the synthesized conjugates via hydrophobic and H-bonding interactions.

GZ17-6.02 and Doxorubicin Interact to Kill Sarcoma Cells via Autophagy and Death Receptor Signaling

GZ17-6.02 (602) is presently under phase I clinical evaluation (NCT03775525). We defined the mechanisms by which it interacted with a standard of care therapeutic doxorubicin to kill sarcoma cells. Doxorubicin and 602 interacted to rapidly activate ATM and c-MET, inactivate mTOR, AKT, and p70 S6K, enhance the expression of Beclin1 and reduce the levels of K-RAS and N-RAS. This was followed later by the drugs interacting to reduce expression of MCL-1, BCL-XL, and HDAC6. Knock down of ATM prevented the drugs alone or in combination inactivating mTOR or activating ULK1. Knock down of c-MET significantly enhanced [doxorubicin + 602] lethality. Knock down of ATM and to a greater extent ULK1, Beclin1, or ATG5 significantly reduced killing by 602 alone or when combined with doxorubicin. Expression of an activated mTOR mutant suppressed killing, autophagosome formation and prevented autophagic flux. In the absence of Beclin1, knock down of CD95, or FADD, or over-expression of c-FLIP-s or BCL-XL abolished tumor cell killing. We conclude that 602 and doxorubicin interact to increase autophagosome formation and autophagic flux as well as causing elevated death receptor signaling resulting in mitochondrial dysfunction and tumor cell death.

Recent evolution on synthesis strategies and anti-leishmanial activity of β-carboline derivatives - An update

Leishmaniasis is the most widespread pathogenic disease in several countries. Currently, no effective vaccines are available, and the control of Leishmaniasis primarily relies on decade-old chemotherapy. The treatment for the Leishmaniasis is not up to the mark. Current therapy for Leishmaniasis is ancient and requires hospitalization for the administration. These medications are also highly toxic and resistant. β-carboline, a natural indole containing alkaloid, holds a vital position in the field of medicinal chemistry with a diversified pharmacological action. The current review focuses mainly on the anti-leishmanial effects of β-carboline analogs and their synthetic strategies, structural activity relationship studies (SAR). The past ten years alterations unveiled by β-carboline analogs present in phytoconstituents and various derivatives of synthesized analogs with the mechanism of action were briefly shortlisted and illustrated.

Targeting cell cycle by β-carboline alkaloids in vitro: Novel therapeutic prospects for the treatment of cancer

Cell cycle dysregulation is the mainstay of aberrant cell proliferation, which leads to tumor progression. Mutations in tumor cells initiate various dysregulated pathways and spontaneous over-proliferation with genomic/chromosomal instability. Despite advances in cancer therapy, it has remained a medicinal challenge to treat. Besides, the complexity of pathophysiological pathways behind cancer raises the need for novel multi-target agents, possessing fewer side effects. Alkaloid-based therapies have been explored so far to target cell division in cancer, including vinca alkaloids. As a class of hopeful β-carboline derivatives, growing evidence has indicated their auspicious roles in combating cancer by inhibiting topoisomerase (TOPO), kinesin Eg5, telomerase, cyclin-dependent kinase (CDK), IκB kinase (IKK), and polo-like kinase-1 (PLK1) in the transition phases of cell cycle. In this review, in vitro potential of β-carboline has been revealed through targeting cell division cycle at different phases. In conclusion, β-carboline alkaloids could be introduced as novel candidates in cancer therapy.

Harmine Ameliorates Cognitive Impairment by Inhibiting NLRP3 Inflammasome Activation and Enhancing the BDNF/TrkB Signaling Pathway in STZ-Induced Diabetic Rats

Diabetes mellitus (DM) is considered a risk factor for cognitive dysfunction. Harmine not only effectively improves the symptoms of DM but also provides neuroprotective effects in central nervous system diseases. However, whether harmine has an effect on diabetes-induced cognitive dysfunction and the underlying mechanisms remain unknown. In this study, the learning and memory abilities of rats were evaluated by the Morris water maze test. Changes in the nucleotide-binding oligomerization domain-containing protein (NOD)-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome and brain-derived neurotrophic factor (BDNF)/TrkB signaling pathway were determined in both streptozotocin (STZ)-induced diabetic rats and high glucose (HG)-treated SH-SY5Y cells by western blotting and histochemistry. Herein, we found that harmine administration significantly ameliorated learning and memory impairment in diabetic rats. Further study showed that harmine inhibited NLRP3 inflammasome activation, as demonstrated by reduced NLRP3, ASC, cleaved caspase-1, IL-1β, and IL-18 levels, in the cortex of harmine-treated rats with DM. Harmine was observed to have similar beneficial effects in HG-treated neuronal cells. Moreover, we found that harmine treatment enhanced BDNF and phosphorylated TrkB levels in both the cortex of STZ-induced diabetic rats and HG-treated cells. These data indicate that harmine mitigates cognitive impairment by inhibiting NLRP3 inflammasome activation and enhancing the BDNF/TrkB signaling pathway. Thus, our findings suggest that harmine is a potential therapeutic drug for diabetes-induced cognitive dysfunction.

Novel Polycondensed Partly Saturated β-Carbolines Including Ferrocene Derivatives: Synthesis, DFT-Supported Structural Analysis, Mechanism of Some Diastereoselective Transformations and a Preliminary Study of Their in vitro Antiproliferative Effects

Use of a Pictet-Spengler reaction of tryptamine and l-tryptophan methyl ester and subsequent reduction of the nitro group followed by further cyclocondensation with aryl aldehydes and formyl–substituted carboxylic acids, including ferrocene-based components, furnished a series of diastereomeric 6-aryl-substituted 5,6,8,9,14,14b-hexahydroindolo[2′,3′:3,4]pyrido[1-c]-quinazolines and 5,5b,17,18-tetrahydroindolo[2′,3′:3,4]pyrido[1,2-c]isoindolo[2,1-a]quinazolin-11-(15bH)-ones with the elements of central-, planar and conformational chirality. The relative configuration and the conformations of the novel polycyclic indole derivatives were determined by ¹H- and ¹³C-NMR methods supplemented by comparative DFT analysis of the possible diastereomers. The structure of one of the pentacyclic methyl esters with defined absolute configuration “S” was also confirmed by single crystal X-ray diffraction measurement. Accounting for the characteristic substituent-dependent diastereoselective formation of the products multistep mechanisms were proposed on the basis of the results of DFT modeling. Preliminary in vitro cytotoxic assays of the products revealed moderate-to-significant antiproliferative effects against PANC-1-, COLO-205-, A-2058 and EBC-1 cell lines that proved to be highly dependent on the stereostructure and on the substitution pattern of the pending aryl substituent.

Synthesis and Biological Validation of a Harmine-Based, Central Nervous System (CNS)-Avoidant, Selective, Human β-Cell Regenerative Dual-Specificity Tyrosine Phosphorylation-Regulated Kinase A (DYRK1A) Inhibitor

Recently, our group identified that harmine is able to induce β-cell proliferation both in vitro and in vivo, mediated via the DYRK1A-NFAT pathway. Since, harmine suffers from a lack of selectivity, both against other kinases and CNS off-targets, we therefore sought to expand structure-activity relationships for harmine's DYRK1A activity, to enhance selectivity for off-targets while retaining human β-cell proliferation activity. We carried out optimization of the 9-N-position of harmine to synthesize 29 harmine-based analogs. Several novel inhibitors showed excellent DYRK1A inhibition and human β-cell proliferation capability. An optimized DYRK1A inhibitor, 2-2c, was identified as a novel, efficacious in vivo lead candidate. 2-2c also demonstrates improved selectivity for kinases and CNS off-targets, as well as in vivo efficacy for β-cell proliferation and regeneration at lower doses than harmine. Collectively, these findings demonstrate that 2-2c is a much improved in vivo lead candidate as compared to harmine for the treatment of diabetes.

GZ17-6.02 initiates DNA damage causing autophagosome-dependent HDAC degradation resulting in enhanced anti-PD1 checkpoint inhibitory antibody efficacy

Our studies examined the molecular mechanisms by which the novel cancer therapeutic GZ17-6.02 (NCT03775525) killed GI tumor cells. TZ17-6.02 activated ATM which was responsible for increased phosphorylation of nuclear γH2AX and AMPKα T172. ATM-AMPK signaling was responsible for the subsequent inactivation of mTORC1 and mTORC2, dephosphorylation of ULK1 S757, and increased phosphorylation of ULK1 S317 and of ATG13 S318, which collectively caused enhanced autophagosome formation. GZ17-6.02 interacted with 5-fluorouracil in an additive to greater than additive fashion to kill all of the tested GI tumor cell types. This was associated with greater ATM activation and a greater mammalian target of rapamycin inactivation and autophagosome induction. As a result, autophagy-dependent degradation of multiple histone deacetylase (HDAC) proteins and chaperone proteins occurred. Loss of HDAC expression was causal in reduced expression of programed death ligand 1 (PD-L1), ornithine decarboxylase, and indole amine 2,3-dioxygenase (IDO1) and in the elevated expression of major histocompatibility complex Class IA (MHCA). Treatment with GZ17-6.02 also resulted in enhanced efficacy of a subsequently administered anti-PD1 checkpoint inhibitory antibody. Thus, the primary mode of GZ17-6.02 action is to induce a DNA damage response concomitant with ATM activation, that triggers a series of interconnected molecular events that result in tumor cell death and enhanced immunogenicity.

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.

Medicinal Properties and Active Constituents of Dracocephalum kotschyi and Its Significance in Iran: A Systematic Review

OBJECTIVES

Dracocephalum has over 60 species and is found mainly in the temperate regions of Asia and Europe. One of these species, i.e., Dracocephalum kotschyi Boiss, is known to have a number of medicinal properties and active ingredients in many parts of the world. Despite being an endemic wild-flowering plant of great importance, the plant is currently considered endangered in Iran. Besides, there is paucity of information on the significance of the medicinal properties and active constituents of D. kotschyi among the Iranian people. On that account a systematic review of studies reporting on the medicinal properties and active ingredients and its significance to human and animal health was conducted and the existing knowledge gaps were identified.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used in the search for published articles on medicinal properties and active ingredients of D. kotschyi and its significance on humans and animals in Iran. The search was confined to scientific articles from repositories of popular data bases and search engines among them PubMed, Web of Science, Google Scholar, Science Direct, SpringerLink, and Scopus. The search narrowed down on scientific journals, books, and book chapters focusing on the medicinal properties of D. kotschyi in Iran for the period between 1970 and 2018.

RESULTS

A total of 1158 scientific articles were sourced from the various databases, out of which 38 met the search criteria and qualified for this review. The studies were conducted in only 9 of the 31 provinces of Iran, with a large proportion in Isfahan province, central Iran. The studies showed that all plant parts (roots, aerial parts, flowers, and leaves) had active constituents. Essential oils and aerial plant parts were the main components studied. Nevertheless, the most frequently reported constituents were xanthomicrol, limonene, luteolin, geranial, apigenin, and calycopterin. A number of medicinal properties were reported among them antioxidant, antibacterial, anticancerous, antinociceptive, antihyperlipidemic, antispasmodic, cytotoxic, and immunomodulatory effects. The plant was also reported to be a remedy for inflammatory pain, headaches, congestion, liver disorders, ulcer, fever, renal pain, dyspepsia, stomach ache, abdominal pain, joints pains, muscle spasm, congestion, bloating, and wound healing effects, among others.

CONCLUSION

This review has shown that D. kotschyi is an important medicinal plant with a large number of active constituents and great potential to safeguard human and animal health in Iran. However, over utilization of the D. kotschyi plant is already endangering its existence. Nevertheless, more studies need be conducted across the country.

Identification of biosynthetic genes for the β-carboline alkaloid kitasetaline and production of the fluorinated derivatives by heterologous expression

β-Carboline alkaloids exhibit a broad spectrum of pharmacological and biological activities and are widely distributed in nature. Genetic information on the biosynthetic mechanism of β-carboline alkaloids has not been accumulated in bacteria, because there are only a few reports on the microbial β-carboline compounds. We previously isolated kitasetaline, a mercapturic acid derivative of a β-carboline compound, from the genetically modified Kitasatospora setae strain and found a plausible biosynthetic gene cluster for kitasetaline. Here, we identified and characterized three kitasetaline (ksl) biosynthetic genes for the formation of the β-carboline core structure and a gene encoding mycothiol-S-conjugate amidase for the modification of the N-acetylcysteine moiety by using heterologous expression. The proposed model of kitasetaline biosynthesis shows unique enzymatic systems for β-carboline alkaloids. In addition, feeding fluorotryptophan to the heterologous Streptomyces hosts expressing the ksl genes led to the generation of unnatural β-carboline alkaloids exerting novel/potentiated bioactivities.

Harmine induces anticancer activity in breast cancer cells via targeting TAZ

Harmine (HM) is a β-carboline alkaloid found in multiple medicinal plants. It has been used in folk medicine for anticancer therapy; however, the molecular mechanism of HM on human breast cancer remains unclear. Transcriptional co-activator with PDZ-binding motif (TAZ), also known as WW domain-containing transcription regulator 1, serves an important role in the carcinogenesis and progression of breast cancer. The aim of the present study was to elucidate the potential anticancer activity and mechanism of HM in breast cancer, in vitro and in vivo. Cell proliferation was measured using a CCK-8 assay, apoptotic activity was detected by flow cytometry and DAPI staining, and cell migration was examined using a wound healing assay. The expression of proteins, including extracellular signal-regulate kinase (Erk), phosphorylated (p-) Erk, protein kinase B (Akt), p-Akt, B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax), were determined by western blotting. The mRNA expression of TAZ was detected using reverse transcription-quantitative polymerase chain reaction analysis. The expression of proteins in mouse tumor tissues were examined by immunohistochemistry. HM significantly suppressed cellular proliferation and migration, promoted apoptosis in vitro and inhibited tumor growth in vivo. In addition, HM significantly decreased the expression of TAZ, p-Erk, p-Akt and Bcl-2, but increased that of Bax. The overexpression of TAZ in breast cancer cells inhibited the antitumor effect of HM. In conclusion, HM was found to induce apoptosis and prevent the proliferation and migration of human breast cancer cell lines, possibly via the downregulation of TAZ.

Synthesis and biological evaluation of novel N9-heterobivalent β-carbolines as angiogenesis inhibitors

A series of novel N⁹-heterobivalent β-carbolines has been synthesized. All the novel compounds were tested for their anticancer activity against six tumour cell lines in vitro. Among these molecules, compounds 5b, and 5w exhibited strong cytotoxic activities with IC₅₀ value of lower than 20 μM. Acute toxicities and antitumor efficacies of the selected compounds in mice were also evaluated, compounds 5b and 5w exhibited that tumour inhibition rate of over 40% in the Sarcoma 180 and Lewis lung cancer animal models. Preliminary structure-activity relationships (SARs) analysis indicated that: (1) C¹-methylation and C⁷-methoxylation were favorable for increased activities; (2) 3-Pyridyl or 2-thienyl group substituent into position-1 of the β-carboline core, and the aryl substituent into another β-carboline ring might be detrimental to cytotoxic effects of this class compounds. Investigation of the preliminary mechanism of action demonstrated that compound 5b had obvious angiogenesis inhibitory effects in the chicken chorioallantoic membrane (CAM) assay.

A transition metal-free approach towards synthesis of β-carboline tethered 1,3,4-oxadiazoles via oxidative C–O bond formation

An efficient protocol has been developed for one-pot synthesis of biologically interesting β-carboline substituted 1,3,4-oxadiazoles via an I₂-assisted oxidative C–O bond formation strategy.

An AcOH-mediated metal free approach towards the synthesis of bis-carbolines and imidazopyridoindole derivatives and assessment of their photophysical properties

A concise, atom-economical and environmentally sustainable tandem strategy has been formulated to access highly fluorescent (Φ_F up to 40%) target molecules via the formation of three C–N bonds in a single operation.

Development of Kinase-Selective, Harmine-Based DYRK1A Inhibitors that Induce Pancreatic Human β-Cell Proliferation

DYRK1A has been implicated as an important drug target in various therapeutic areas, including neurological disorders and oncology. DYRK1A has more recently been shown to be involved in pathways regulating human β-cell proliferation, thus making it a potential therapeutic target for both Type 1 and Type 2 diabetes. Our group, using a high-throughput phenotypic screen, identified harmine that is able to induce β-cell proliferation both in vitro and in vivo. Since harmine has suboptimal kinase selectivity, we sought to expand structure-activity relationships for harmine's DYRK1A activity, to enhance selectivity, while retaining human β-cell proliferation capability. We carried out the optimization of the 1-position of harmine and synthesized 15 harmine analogues. Six compounds showed excellent DYRK1A inhibition with IC50 in the range of 49.5-264 nM. Two compounds, 2-2 and 2-8, exhibited excellent human β-cell proliferation at doses of 3-30 μM, and compound 2-2 showed improved kinase selectivity as compared to harmine.

Development of novel 2,4-bispyridyl thiophene-based compounds as highly potent and selective Dyrk1A inhibitors. Part I: Benzamide and benzylamide derivatives

The protein kinase Dyrk1A modulates several processes relevant to the development or progression of Alzheimer's disease (AD), e. g. through phosphorylation of tau protein, amyloid precursor protein (APP) as well as proteins involved in the regulation of alternative splicing of tau pre-mRNA. Therefore, Dyrk1A has been proposed as a potential target for the treatment of AD. However, the co-inhibition of other closely related kinases of the same family of protein kinases (e.g. Dyrk1B and Dyrk2) or kinases from other families such as Clk1 limits the use of Dyrk1A inhibitors, as this may cause unpredictable side effects especially over long treatment periods. Herein, we describe the design and synthesis of a series of amide functionalized 2,4-bispyridyl thiophene compounds, of which the 4-fluorobenzyl amide derivative (31b) displayed the highest potency against Dyrk1A and remarkable selectivity over closely related kinases (IC50: Dyrk1A = 14.3 nM; Dyrk1B = 383 nM, Clk1 > 2 μM). This degree of selectivity over the frequently hit off-targets has rarely been achieved to date. Additionally, 31b inhibited Dyrk1A in intact cells with high efficacy (IC50 = 79 nM). Furthermore, 31b displayed a high metabolic stability in vitro with a half-life of 2 h. Altogether, the benzamide and benzylamide extension at the 2,4-bispyridyl thiophene core improved several key properties, giving access to compound suitable for future in vivo studies.

Potent Antitumor Effects of a Combination of Three Nutraceutical Compounds

Head and neck squamous cell carcinoma (HNSCC) is associated with low survival, and the current aggressive therapies result in high morbidity. Nutraceuticals are dietary compounds with few side effects. However, limited antitumor efficacy has restricted their application for cancer therapy. Here, we examine combining nutraceuticals, establishing a combination therapy that is more potent than any singular component, and delineate the mechanism of action. Three formulations were tested: GZ17-S (combined plant extracts from Arum palaestinum, Peganum harmala and Curcuma longa); GZ17-05.00 (16 synthetic components of GZ17-S); and GZ17-6.02 (3 synthetic components of GZ17S; curcumin, harmine and isovanillin). We tested the formulations on HNSCC proliferation, migration, invasion, angiogenesis, macrophage viability and infiltration into the tumor and tumor apoptosis. GZ17-6.02, the most effective formulation, significantly reduced in vitro assessments of HNSCC progression. When combined with cisplatin, GZ17-6.02 enhanced anti-proliferative effects. Molecular signaling cascades inhibited by GZ17-6.02 include EGFR, ERK1/2, and AKT, and molecular docking analyses demonstrate GZ17-6.02 components bind at distinct binding sites. GZ17-6.02 significantly inhibited growth of HNSCC cell line, patient-derived xenografts, and murine syngeneic tumors in vivo (P < 0.001). We demonstrate GZ17-6.02 as a highly effective plant extract combination and pave the way for future clinical application in HNSCC.

Engineered production of kitasetalic acid, a new tetrahydro-β-carboline with the ability to suppress glucose-regulated protein synthesis

β-Carboline alkaloids and related compounds show a broad spectrum of biological activities. We previously identified new members of the β-carboline alkaloid family by using an engineered Kitasatospora setae strain and a heterologous Streptomyces host expressing the plausible biosynthetic genes, including the hypothetical gene kse_70640 (kslB). Here, we elucidated the chemical structure of a new tetrahydro-β-carboline compound (named kitasetalic acid) that appeared in a heterologous Streptomyces host expressing the kslB gene alone. Kitasetalic acid suppressed the expression of glucose-regulated protein 78 (GRP78) without inducing cell death. This is the first report to show that a tetrahydro-β-carboline compound regulates the expression of the GRP78 protein in cancer cell lines.