Recent pharmacological developments in β-carboline alkaloid "harmaline"

Iranian traditional medicinal plants for management of chronic heart failure: A review

Chronic heart failure is a public health problem with a high prevalence worldwide and an important topic in clinical cardiology. Despite of advances in the drug treatment strategy for heart failure, the number of deaths from this condition continues to rise. It will be a renewed focus on preventing heart failure using proven and perhaps novel drugs. Management will also focus on comorbid conditions that may influence the progression of the disease. Traditional medicine has a potential to introduce different approaches for treatment of some disorders. We here reviewed top medicinal plants, according to traditional medicine to experimental studies, and their potency for the treatment of chronic heart failure based on the evidence of their functions.

Application of Indole-Alkaloid Harmaline Induces Physical Damage to Photosystem II Antenna Complexes in Adult Plants of Arabidopsis thaliana (L.) Heynh

Finding herbicides with new and multiple modes of action is a solution to stop the increase in resistant weed species. Harmaline, a natural alkaloid with proven phytotoxic potential, was tested on Arabidopsis adult plants by watering and spraying; watering resulted as the more effective treatment. Harmaline altered several photosynthetic parameters, reducing the efficiency of the light- (Φ_II) and dark-adapted (F_v/F_m) PSII, suggesting physical damages in photosystem II, although dissipation of the energy in excess under the form of heat was not compromised as demonstrated by the significant increase in Φ_NPQ. Metabolomic alterations, such as osmoprotectant accumulation and reduction in sugars' content, also indicate a reduction of photosynthetic efficiency and suggest early senescence and water status alteration induced by harmaline. Data suggest that harmaline might be considered a new phytotoxic molecule interesting for further studies.

Lethal and Sublethal Toxicity of Beta-Carboline Alkaloids from Peganum harmala (L.) against Aedes albopictus Larvae (Diptera: Culicidae)

Plant-derived agents are powerful bio-pesticides for the eco-friendly control of mosquito vectors and other blood-sucking arthropods. The larval toxicity of beta-carboline alkaloids against the Asian tiger mosquito, Aedes albopictus (Skuse) (Diptera: Culicidae), was investigated under laboratory conditions. The total alkaloid extracts (TAEs) and beta-carboline alkaloids (harmaline, harmine, harmalol, and harman) from Peganum harmala seeds were isolated and tested in this bioassay. All alkaloids were tested either individually or as binary mixtures, using the co-toxicity coefficient (CTC) and Abbott's formula analysis. The results revealed considerable toxicity of the tested alkaloids against A. albopictus larvae. When all larval instars were exposed to the TAEs at 48 h post-treatment, the mortality of all larval instars varied in a concentration-dependent manner. The second-instar larvae were the most susceptible to different concentrations of TAEs, and the fourth-instar larvae were more tolerant to TAEs than the second-instar larvae. Especially, the third-instar larvae exposed to all alkaloids also showed that all doses resulted in an increased mortality of the third-instar larvae at 48 h post-treatment, and the toxicities of the tested alkaloids in a descending order were TAEs > harmaline > harmine > harmalol, with the LC₅₀ values of 44.54 ± 2.56, 55.51 ± 3.01, 93.67 ± 4.53, and 117.87 ± 5.61 μg/mL at 48 h post-treatment, respectively. In addition, all compounds were also tested individually or in a 1:1 ratio (dose LC₂₅/LC₂₅) as binary mixtures to assess the synergistic toxicity of these binary combinations against the third-instar larvae at 24 and 48 h post-treatment, respectively. The results demonstrated that when tested as a binary mixture, all compounds (especially TAEs, harmaline, and harmine) showed their synergistic effects, exceeding the toxicity of each compound alone. Interestingly, the obtained data further revealed that the TAEs at sublethal doses (LC₁₀ and LC₂₅) could significantly delay the larval development and decrease the pupation and emergence rates of A. albopictus. This phenomenon could be helpful in order to develop more effective control strategies for different notorious vector mosquitoes.

Harmaline exerts potentially anti-cancer effects on U-87 human malignant glioblastoma cells in vitro

BACKGROUND

Harmaline is a β-carboline alkaloid that can be extracted from the seeds of Peganum harmala. Harmaline has been shown to exhibit a potent cytotoxic effect against tumor cells. In this study, the anti-glioblastoma activity of harmaline was investigated in vitro.

METHODS AND RESULTS

Cell viability, apoptosis, and cell cycle arrest were assessed in U-87 cells treated with harmaline at different doses. Reactive oxygen species (ROS) generation and the mRNA expression of apoptosis-associated genes were assessed. The anti-metastatic effect of harmaline on U-87 cells was evaluated by gelatin zymography assay where matrix metalloproteinase [MMP]-2/-9 enzymatic activity was measured, and the scratch assay was used to assess migratory responses. Flow cytometry demonstrated that harmaline could suppress the proliferation and induce sub-G1 cell cycle arrest and apoptotic cell death in glioblastoma cells. Harmaline treatment was also associated with an upregulation of the cell cycle-related genes, p21 and p53, and pro-apoptotic Bax, as well as the induction of ROS. The zymography assay indicated that the essential steps of metastasis were potently suppressed by harmaline through inhibiting the expression of MMP-2 and - 9. In addition, the migration of U-87 cells was significantly reduced after harmaline treatment.

CONCLUSION

Our data suggest a basis for further research of harmaline which has potential cytotoxic activities in glioblastoma cells; inducing cell cycle arrest and apoptosis, repression of migration, possibly invasion, and metastasis.

Mode of action of Akkermansia muciniphila in the intestinal dialogue: role of extracellular proteins, metabolites and cell envelope components

Akkermansia muciniphila is a promising next-generation beneficial microbe due to its natural presence in the mucus layer of the gut, its symbiotic ability to degrade mucus, and its capacity to improve the intestinal barrier function. A. muciniphila is able to counteract weight gain and immuno-metabolic disturbances in several animal models. Many of these disorders, including obesity and auto-immune diseases, have been associated with decreased gut barrier function and consequent increased inflammation. Since A. muciniphila was found to normalize these changes and strengthen the gut barrier function, it is hypothesized that other beneficial effects of A. muciniphila might be caused by this restoration. In search for A. muciniphila's mode of action in enhancing the gut barrier function and promoting health, we reasoned that secreted components or cell envelope components of A. muciniphila are interesting candidates as they can potentially reach and interact with the epithelial barrier. In this review, we focus on the potential mechanisms through which A. muciniphila can exert its beneficial effects on the host by the production of extracellular and secreted proteins, metabolites and cell envelope components. These products have been studied in isolation for their structure, signaling capacity, and in some cases, also for their effects in preclinical models. This includes the protein known as Amuc_1100, which we here rename as pilus-associated signaling (PAS) protein , the P9 protein encoded by Amuc_1631, the short-chain fatty acids acetate and propionate, and cell envelope components, such as phosphatidylethanolamine and peptidoglycan.

Akkermansia muciniphila protects mice against an emerging tick-borne viral pathogen

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease caused by a phlebovirus in the Bunyaviridae family. Infection can result in systemic inflammatory response syndrome with a high fatality rate, and there are currently no treatments or vaccines available. The microbiota has been implicated in host susceptibility to systemic viral infection and disease outcomes, but whether the gut microbiota is implicated in severe fever with thrombocytopenia syndrome virus (SFTSV) infection is unknown. Here, we analysed faecal and serum samples from patients with SFTS using 16S ribosomal RNA-sequencing and untargeted metabolomics, respectively. We found that the gut commensal Akkermansia muciniphila increased in relative abundance over the course of infection and was reduced in samples from deceased patients. Using germ-free or oral antibiotic-treated mice, we found that A. muciniphila produces the β-carboline alkaloid harmaline, which protects against SFTSV infection by suppressing NF-κB-mediated systemic inflammation. Harmaline indirectly modulated the virus-induced inflammatory response by specifically enhancing bile acid-CoA: amino acid N-acyltransferase expression in hepatic cells to increase conjugated primary bile acids, glycochenodeoxycholic acid and taurochenodeoxycholic acid. These bile acids induced transmembrane G-protein coupled receptor-5-dependent anti-inflammatory responses. These results indicate the probiotic potential of A. muciniphila in mitigating SFTSV infection.

Photosensitizing properties and subcellular localisation of 3,4-dihydro-β-carbolines harmaline and harmalol

Harmaline (1) and harmalol (2) represent two 3,4-dihydro-β-carboline (DHβCs) most frequently reported in a vast number of living systems. Fundamental aspects including the photosensitizing properties, cellular uptake, as well as the cyto- and phototoxicity of 1 and 2 were investigated herein. The molecular basis underlying the investigated processes are elucidated. Data reveal that both alkaloids show a distinctive pattern of extracellular DNA photodamage. Compound 1 induces a DNA photodamage profile dominated by oxidised purines and sites of base loss (AP sites), whereas 2 mostly induces single-strand breaks (SSBs) in addition to a small extent of purine oxidative damage. In both cases, DNA oxidative damage would occur through type I mechanism. In addition, a concerted hydrolytic attack is suggested as an extra mechanism accounting for the SSBs formation photoinduced by 2. Subcellular internalisation, cyto- and phototoxicity of 1 and 2 and the corresponding full-aromatic derivatives harmine (3) and harmol (4) also showed quite distinctive patterns in a structure-dependent manner. These results are discussed in the framework of the potential biological, biomedical and/or pharmacological roles reported for these alkaloids.

Graphical abstract

The subtle structural difference (i.e., the exchange of a methoxy group for a hydroxyl substituent at C(7)) between harmaline and harmalol, gives rise to distinctive photosensitizing and subcellular localisation patterns.

Naturally derived indole alkaloids targeting regulated cell death (RCD) for cancer therapy: from molecular mechanisms to potential therapeutic targets

Regulated cell death (RCD) is a critical and active process that is controlled by specific signal transduction pathways and can be regulated by genetic signals or drug interventions. Meanwhile, RCD is closely related to the occurrence and therapy of multiple human cancers. Generally, RCD subroutines are the key signals of tumorigenesis, which are contributed to our better understanding of cancer pathogenesis and therapeutics. Indole alkaloids derived from natural sources are well defined for their outstanding biological and pharmacological properties, like vincristine, vinblastine, staurosporine, indirubin, and 3,3′-diindolylmethane, which are currently used in the clinic or under clinical assessment. Moreover, such compounds play a significant role in discovering novel anticancer agents. Thus, here we systemically summarized recent advances in indole alkaloids as anticancer agents by targeting different RCD subroutines, including the classical apoptosis and autophagic cell death signaling pathways as well as the crucial signaling pathways of other RCD subroutines, such as ferroptosis, mitotic catastrophe, necroptosis, and anoikis, in cancer. Moreover, we further discussed the cross talk between different RCD subroutines mediated by indole alkaloids and the combined strategies of multiple agents (e.g., 3,10-dibromofascaplysin combined with olaparib) to exhibit therapeutic potential against various cancers by regulating RCD subroutines. In short, the information provided in this review on the regulation of cell death by indole alkaloids against different targets is expected to be beneficial for the design of novel molecules with greater targeting and biological properties, thereby facilitating the development of new strategies for cancer therapy.

Structures and Biological Activities of Alkaloids Produced by Mushrooms, a Fungal Subgroup

Alkaloids are a wide family of basic N-containing natural products, whose research has revealed bioactive compounds of pharmacological interest. Studies on these compounds have focused more attention on those produced by plants, although other types of organisms have also been proven to synthesize bioactive alkaloids, such as animals, marine organisms, bacteria, and fungi. This review covers the findings of the last 20 years (2002–2022) related to the isolation, structures, and biological activities of the alkaloids produced by mushrooms, a fungal subgroup, and their potential to develop drugs and agrochemicals. In some cases, the synthesis of the reviewed compounds and structure−activity relationship studies have been described.

Basolateral amygdala cannabinoid CB1 receptors mediate the antinociceptive activity of harmaline in adolescent male mice

Evidence suggests a clear role for the amygdala endocannabinoid system in pain processing. Harmaline has been also known as the main nociceptive agent extracted from the Peganum harmala plant. In this study, the role of basolateral amygdala (BLA) cannabinoid CB1 receptors in pain sensitivity of harmaline-treated mice were assessed using tail-flick and hot plate methods in adolescent male NMRI mice. Intraperitoneal administration of two higher doses of harmaline (6 and 8 mg/kg) increased tail-flick latency, suggesting an antinociceptive activity. The same result was observed for the higher dose of harmaline in the hot plate test. Intra-BLA microinjection of CB1 receptor agonist ACPA (1 and 1.5 ng/mouse) or (1.5 ng/mouse) enhanced the ineffective dose-response of harmaline on pain threshold in the tail-flick or hot plate tests, respectively. Microinjection of two higher doses of CB1 receptor antagonist AM251 (0.5 and 1 ng/mouse) attenuated the antinociceptive activity of harmaline (8 ng/mouse) in both tail-flick and hot plate tests. Meanwhile, ACPA and AM251 did not alter latency to withdraw from the noxious stimulus in both tests, by themselves. It should be noted that the analgesic dose of the drugs alone or in combination did not affect locomotor activity. The obtained results highlight that BLA CB1 receptors mediate the antinociceptive activity of harmaline.

Design, synthesis, and biological evaluation of β-carboline 1,3,4-oxadiazole based hybrids as HDAC inhibitors with potential antitumor effects

A series of novel β-carboline 1,3,4-oxadiazole based hybrids were designed, synthesized, and tested for cytotoxicity and HDAC inhibition. Among the target compounds, compound ZDLT-1 displayed high inhibitory activity for class I HDACs 1, 2, and 3, and potent anti-proliferative activity against HCT116 cells with an IC₅₀ value of 0.173 ± 0.018 μM, it also exhibited better inhibitory activity with an IC₅₀ value of 6 nM for HDAC6 than SAHA (IC₅₀ = 15 nM). Furthermore, the pharmacological experiment of Hoechst staining, colony formation, cell apoptosis assay, and wound healing scratch assay indicated that compound ZDLT-1 was a potent cytotoxic agent against HCT116 cells with cell apoptosis induction. Further, in silico prediction of physicochemical properties, drug-likeness, and ADME parameters suggested that compound ZDLT-1 is a promising anticancer agent. Taken together, the high potency cytotoxicity and class I HDACs inhibitory activity of compound ZDLT-1, which with the β-carboline 1,3,4-oxadiazole based hybrids as potent anticancer agents could be nominated for further modification and optimization.

Therapeutic Properties of Ayahuasca Components in Ischemia/Reperfusion Injury of the Eye

Ischemic eye diseases are major causes of vision impairment. Thus, potential retinoprotective effects of N’N-dimethyltryptamine (DMT) were investigated. To inhibit its rapid breakdown by monoamine-oxidase A (MAO-A) enzyme, DMT was co-administered with harmaline, a β-carboline in the Amazonian Ayahuasca brew. Using ligation, 60 min of ischemia was provoked in eyes of rats, followed by 7 days of reperfusion whilst animals received harmaline alone, DMT + harmaline, or vehicle treatment. After 1 week of reperfusion, electroretinographical (ERG) measurements, histological analysis, and Western blot were performed. Harmaline alone exhibited retinoprotection in ischemia–reperfusion (I/R) which was, surprisingly, counterbalanced by DMT in case of co-administration. As both MAO-A inhibition and DMT increase serotoninergic tone synergistically, communicated to be anti-ischemic, thus, involvement of other pathways was investigated. Based on our experiments, DMT and harmaline exert opposite effects on important ocular proteins such as PARP1, NFκB, MMP9, or HSP70, each having a critical role in a different mechanism of eye-ischemia-related pathologies, e.g., cell death, inflammation, tissue destruction, and oxidative stress. Since DMT is proclaimed to be a promising drug candidate, its potentially undesirable effect on eye-ischemia should be further investigated. Meanwhile, this experiment revealed the potential therapeutic effect of MAO-A inhibitor harmaline in I/R-related eye diseases.

UV-light-driven photooxidation of harmaline catalyzed by riboflavin: Product characterization and mechanisms

β-Carboline alkaloid harmaline (HA) is a candidate drug molecule that has been proven to have broad and significant biological activity. Herein, the effects of HA on the riboflavin (RF)-sensitized photooxidation under aerobic conditions were studied for the first time. The photooxidation reaction of HA catalyzed by RF is triggered by UV light at 365 nm and shows a time-dependent stepwise reaction process. Seven transformed products, including five undescribed compounds, oxoharmalines A-E (1-4 and 7), and two known compounds, N-(2-(6-Methoxy-2-oxoindolin-3-yl)ethyl)acetamide (5) and harmine (6), were isolated and identified from the reaction system, following as the gradual oxidation mechanisms. The rare polymerization and dehydrogenation processes in radical-mediated photocatalytic reactions were involved in the process. The transformed products 2-7 exhibited significant neuroprotective activity in a model of H₂O₂-introduced injury in SH-SY5Y cells, which suggested that the products of the interaction between HA and vitamins may be beneficial to health.

Pseudosterins A-C, Three 1-Ethyl-3-formyl-β-carbolines from Pseudostellaria heterophylla and Their Cardioprotective Effects

Pseudostellaria heterophylla is used in China not only as a functional food but also as an herb to tonify the spleen, enhance immunity, and treat palpitation. Our previous investigation showed that a fraction enriched in glycosides obtained from the roots of P. heterophylla possessed pronounced protective effects on H9c2 cells against CoCl₂-induced hypoxic injury. However, the active compounds responsible for the observed effects were still unknown. In the current investigation, pseudosterins A–C (1–3), three new alkaloids with a 1-ethyl-3-formyl-β-carboline skeleton, together with polydatin, have been isolated from the active fraction. Their structures were elucidated on the basis of spectroscopic analysis and quantum chemical calculations. The four compounds showed cardioprotective effects against sodium hydrosulfite-induced hypoxia-reoxygenation injury in H9c2 cells, with the three alkaloids being more potent. This is also the first report of alkaloids with a β-carboline skeleton isolated from P. heterophylla as cardioprotective agents.

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.

Peganum spp.: A Comprehensive Review on Bioactivities and Health-Enhancing Effects and Their Potential for the Formulation of Functional Foods and Pharmaceutical Drugs

The genus Peganum includes four species widely distributed in warm temperate to subtropical regions from the Mediterranean to Mongolia as well as certain regions in America. Among these species, Peganum harmala L., distributed from the Mediterranean region to Central Asia, has been studied and its phytochemical profile, traditional folk use, and application in pharmacological and clinical trials are well known. The review is aimed at presenting an insight into the botanical features and geographical distribution of Peganum spp. along with traditional folk uses. This manuscript also reviews the phytochemical profile of Peganum spp. and its correlation with biological activities evidenced by the in vitro and in vivo investigations. Moreover, this review gives us an understanding of the bioactive compounds from Peganum as health promoters followed by the safety and adverse effects on human health. In relation to their multipurpose therapeutic properties, various parts of this plant such as seeds, bark, and roots present bioactive compounds promoting health benefits. An updated search (until December 2020) was carried out in databases such as PubMed and ScienceDirect. Chemical studies have presented beta-carboline alkaloids as the most active constituents, with harmalol, harmaline, and harmine being the latest and most studied among these naturally occurring alkaloids. The Peganum spp. extracts have shown neuroprotective, anticancer, antimicrobial, and antiviral effects. The extracts are also found effective in improving respiratory disorders (asthma and cough conditions), dermatoses, and knee osteoarthritis. Bioactivities and health-enhancing effects of Peganum spp. make it a potential candidate for the formulation of functional foods and pharmaceutical drugs. Nevertheless, adverse effects of this plant have also been described, and therefore new bioproducts need to be studied in depth. In fact, the design of new formulations and nanoformulations to control the release of active compounds will be necessary to achieve successful pharmacological and therapeutic treatments.

Improving health benefits with considering traditional and modern health benefits of Peganum harmala

Background

Medicinal plants are potential source of natural products that play an important role in preventing different human diseases. P. harmala is used traditionally as emmenagogue and an abortifacient agent in the Middle East, North of Africa and West of China. It belongs to the family of Zygophyllaceae and it is a wild growing flowering plant. Its seeds are main medicinal part of the plant.

Methods

The current searching was done by the keywords in main indexing systems including PubMed/MEDLINE, Scopus, and Institute for Scientific Information Web of Science as well as the search engine of Google Scholar. The keywords were wild rue, traditional medicine, Harman, health benefits, and pharmaceutical science.

Results

The most important uses of P. harmala in traditional pharmaceutical sciences are in cardiovascular, gasterointestinal, nervous, endocrine, neoplasm and tumors, pain relieving, organisms, diabetes, respiratory, disinfectant, anti-pyretic, skin and hair, rheumatism, arthritis and inflammation, and ulcers. Pharmacological effects of P. harmala are in cardiovascular system, nervous system, antimicrobial effects, antineoplasm, nervous system, endocrine, gastrointestinal effects, osteocytes, endocrine and respiratory system. Phenolic compounds are the main reason of antioxidant capacity.

Conclusions

Due to its pharmacological activities, P. harmala is a high potential medicinal herb and the suggestion is to increases by doing research in efficacy and safety.

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.

Evaluation of the effect of Peganum harmala extracts on the in vitro viability of Leishmania tropica promastigotes in comparison to Glucantime

Cutaneous leishmaniasis is a skin disease that pretends with skin lesions, mainly ulcers, on exposed parts of the body. It's caused mainly by parasites belonging to the genus Leishmania, such as L. tropica. Medicinal plants, which have sparked recent researches attention, consider one of the richest sources of active compounds against the Leishmania parasite including Peganum harmala. This study was conducted to investigate the antileishmanial effect of different extracts of Peganum harmala grown in Syria, particularly the methanolic extract of seeds and roots as well as its alkaloid fractions on Leishmania tropica promastigotes growth in vitro. After culturing promastigotes and incubating with extracts for 72 h, the surviving promastigotes were counted. The half maximal (50%) inhibitory concentration (IC₅₀) was determined. The experiments were repeated at least three times. The in vitro experiment has demonstrated a concentration-dependent decrease of parasites number caused by the extracts with an IC₅₀ value of 18.61 ± 0.87 µg/mL and 16.41 ± 0.71 µg/mL for the methanolic extract of seeds and roots respectively. While the IC₅₀ of the alkaloid fractions of seeds and roots were 4.97 ± 0.43 μg/mL and 9.23 ± 0.86 μg/mL respectively. There was a significant difference between all extracts and Glucantime which had IC₅₀ = 32.62 ± 0.66 µg/mL.

Discovery of Harmaline as a Potent Inhibitor of Sphingosine Kinase-1: A Chemopreventive Role in Lung Cancer

The sphingosine kinase-1/sphingosine-1-phosphate pathway is linked with the cancer progression and survival of the chemotherapy-challenged cells. Sphingosine kinase-1 (SphK1) has emerged as an attractive drug target, but their inhibitors from natural sources are limited. In this study, we have chosen harmaline, one of the β-carboline alkaloids, and report its mechanism of binding to SphK1 and subsequent inhibition. Molecular docking combined with fluorescence binding studies revealed that harmaline binds to the substrate-binding pocket of SphK1 with an appreciable binding affinity and significantly inhibits the kinase activity of SphK1 with an IC50 value in the micromolar range. The cytotoxic effect of harmaline on non-small-cell lung cancer cells by MTT assay was found to be higher for H1299 compared to A549. Harmaline induces apoptosis in non-small-cell lung carcinoma cells (H1299 and A549), possibly via the intrinsic pathway. Our findings suggest that harmaline could be implicated as a scaffold for designing potent anticancer molecules with SphK1 inhibitory potential.

A Fast and Reliable UHPLC-MS/MS-Based Method for Screening Selected Pharmacologically Significant Natural Plant Indole Alkaloids

Many substances of secondary plant metabolism have often attracted the attention of scientists and the public because they have certain beneficial effects on human health, although the reason for their biosynthesis in the plant remains unclear. This is also the case for alkaloids. More than 200 years have passed since the discovery of the first alkaloid (morphine), and several thousand substances of this character have been isolated since then. Most often, alkaloid-rich plants are part of folk medicine with centuries-old traditions. What is particularly important to monitor for these herbal products is the spectrum and concentrations of the present active substances, which decide whether the product has a beneficial or toxic effect on human health. In this work, we present a fast, reliable, and robust method for the extraction, preconcentration, and determination of four selected alkaloids with an indole skeleton, i.e., harmine, harmaline, yohimbine, and ajmalicine, by ultra-high performance liquid chromatography coupled with tandem mass spectrometry. The applicability of the method was demonstrated for tobacco and Tribulus terrestris plant tissue, the seeds of Peganum harmala, and extract from the bark of the African tree Pausinystalia johimbe.

Photophysical and spectroscopic features of 3,4-dihydro-β-carbolines: a combined experimental and theoretical approach

The spectroscopic and photophysical properties of 3,4-dihydro-β-carboline alkaloids in aqueous were revisited. Absorbing and emitting species present in aqueous solution in the entire pH range were reassigned by DFT calculations.

Nano-scaled MTCA-KKV: for targeting thrombus, releasing pharmacophores, inhibiting thrombosis and dissolving blood clots in vivo

BACKGROUND

In vitro (1R,3S)-1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxyl-Lys(Pro-Ala-Lys)-Arg-Gly-Asp-Val (MTCA-KKV) adheres activated platelets, targets P-selectin and GPIIb/IIIa. This led to the development of MTCA-KKV as thrombus targeting nano-medicine.

METHODS

MTCA-KKV was characterized by nano-feature, anti-thrombotic activity, thrombolytic activity, thrombus target and targeting release.

RESULTS

In vivo 0.01 μmol/kg of MTCA-KKV formed nano-particles less than 100 nm in diameter, targeted thrombus, released anti-thrombotic and thrombolytic pharmacophores, prevented thrombosis and dissolved blood clots.

CONCLUSION

Based on the profiles of targeting thrombus, targeting release, inhibiting thrombosis and dissolving blood clots MTCA-KKV is a promising nano-medicine.

Subchronic toxicity and concomitant toxicokinetics of long-term oral administration of total alkaloid extracts from seeds of Peganum harmala Linn: A 28-day study in rats

ETHNOPHARMACOLOGICAL RELEVANCE

The seeds of Peganum harmala Linn, in which the most abundant active compounds are harmaline and harmine, have been widely used as a traditional medicine in various countries to treat a broad spectrum of diseases including asthma, cough, depression, Parkinson's and Alzheimer's diseases. However, few studies on long-term or subchronic toxicity of seeds of P. harmala were reported after overdose.

AIM OF THE STUDY

To investigate the subchronic toxicity and concomitant toxicokinetics of total alkaloid extracts from seeds of P. harmala (TAEP) after oral administration for four weeks in rats.

MATERIALS AND METHODS

The subchronic toxicity and concomitant toxicokinetics of TAEP were evaluated after 28-day oral administration in rats at daily dose levels of 15, 45, and 150 mg/kg. The signs of toxicity and mortality were monitored and recorded daily. The body weight and average food consumption were measured weekly. The analyses of hematology, biochemistry, urine, relative organ weights and histopathology were conducted at the termination of treatment and recovery phase. For concomitant toxicokinetics study, the plasma toxicokinetic parameters, tissue distribution, and excretion of predominant ingredients harmaline and harmine in TAEP and metabolites harmalol and harmol were tested.

RESULTS

Following initial repeated exposure to high-dose (150 mg/kg/day) of TAEP excitotoxic reaction, such as tremor, was observed, but tolerated on the fourth day after multiple dosing. The significant alterations in blood glucose and lipid metabolism in liver were observed, but recovered after four weeks of drug withdrawal. The no-observed-adverse-effect level (NOAEL) of TAEP was considered to be 45 mg/kg/day under the present study conditions. There were no significant gender differences in most indexes of subchronic toxicity throughout the experimental period with the exception of food consumption and body weight. In concomitant toxicokinetics study, the alterations of dynamic characteristic for harmaline, harmine and metabolite harmol after multiple oral administration at three doses had been observed. Harmaline, harmine and metabolites harmalol and harmol were widely distributed in organs and there was no accumulation in the tissues examined. The reduction of harmaline and metabolite harmalol in brain after multiple dosing at dose of 150 mg/kg might be closely related to the tremor tolerance. The main excretory pathway for metabolites harmalol and harmol was urinary excretion via kidney.

CONCLUSIONS

The results revealed that TAEP at doses of 15 and 45 mg/kg/day in rats might be safe. Excitotoxic reaction such as tremor occurred initially at dose of 150 mg/kg/day, however, the toxicity was tolerant and reversible. In addition, harmaline and harmine in TAEP had a quick absorption into blood and metabolized to harmalol and harmol, and there was no drug accumulation in the detected tissues. Further studies should be investigated to clarify the mechanisms of tremor tolerance and neurotoxicity of TAEP.

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.

Heptapeptide-based modification leading to enhancing the action of MTCA on activated platelets, P-selectin, GPIIb/IIIa

AIM

The modification of platelet inhibitor to enhance its targeting capacity toward platelets is of clinical importance. Thus, (1R, 3S)-1-methyl-1, 2, 3, 4-tetrahydro-β-carboline-3-carboxylic acid (MTCA), a platelet inhibitor, was modified with Lys(Pro-Ala-Lys)-Arg-Gly-Asp-Val (KKV), platelet targeting peptide, to form MTCA-KKV.

MATERIALS & METHODS

MTCA and MTCA-KKV were synthesized to identify the effect of KKV modification on MTCA and platelets.

RESULTS

Atomic force microscopy imaged MTCA-KKV effectively accumulated on activated platelets. UV spectra showed that MTCA-KKV concentration dependently changed P-selectin and GPIIb/IIIa conformations. For platelet aggregation, the IC₅₀ of MTCA-KKV was approximately 1/10 folds of MTCA.

CONCLUSION

KKV modification led to forming MTCA-KKV that is superior to MTCA in terms of accumulating on activated platelets, targeting P-selectin and GPIIb/IIIa and inhibiting platelet aggregation. MTCA-KKV could be a promising lead for further investigation.

Antibiofilm activities of norharmane and its derivatives against Escherichia coli O157:H7 and other bacteria

BACKGROUND

Bacterial biofilms exhibit reduced sensitivity to conventional antibiotics and host defence systems and contribute to the persistence of chronic bacterial infections.

HYPOTHESIS

The antibiofilm approach using plant alkaloids provides an alternative to antibiotic strategies.

STUDY DESIGN

In this study, the antibiofilm activities of various plant alkaloids were investigated against enterohemorrhagic Escherichia coli O157:H7 and Pseudomonas aeruginosa. In the subsequent investigation, the effects of five norharmane derivatives were investigated.

RESULT

Harmaline significantly inhibited biofilm formation by E. coli O157:H7, P. aeruginosa PAO1, P. aeruginosa PA14, and Klebsiella oxytoca, and norharmane (β-carboline) was found to have antibiofilm activity. It was also found that functional groups at the C-1 and C-7 positions of norharmane could play important roles in its antibiofilm activity. Confocal and electron microscopic observations confirmed biofilm inhibition by harmaline and norharmane, and both reduced fimbriae production and swarming and swimming motilities. Furthermore, harmaline and norharmane attenuated the virulence of E. coli O157:H7 in a Caenorhabditis elegans nematode model.

CONCLUSION

These findings strongly suggest that harmaline and norharmane could have potential use in antibiofilm strategy against persistent bacterial infections.

Exposure Characteristics of the Analogous β-Carboline Alkaloids Harmaline and Harmine Based on the Efflux Transporter of Multidrug Resistance Protein 2

Harmaline and harmine occur naturally in plants and are distributed endogenously in human and animal tissues. The two β-carboline alkaloids possess potential for treating Alzheimer's disease, Parkinson's disease, depression and other central nervous system diseases. However, studies have showed that the two compounds have similar structures but with quite different bioavailability. The aim of this study was to elucidate the exposure difference and characterize the in vitro transport, metabolism, and pharmacokinetic properties of harmaline and harmine. The results showed that the harmaline and harmine transport across the Caco-2 and MDCK cell monolayers was varied as the time, concentration, pH and temperature changed. The absorption of harmaline and harmine was significantly decreased when ES (OATPs inhibitor), TEA (OCTs/OCTNs substrate), NaN₃ (adenosine triphosphate inhibitor), or sodium vanadate (ATPase Na⁺/K⁺-dependent inhibitor) was added. However, when given MK571 and probenecid (the typical MRP2 inhibitor), the P_appAB of harmine was increased (1.62- and 1.27-folds), and the efflux ratio was decreased from 1.59 to 0.98 and from 1.59 to 1.19, respectively. In addition, the uptake ratio of harmine at 1 μM was >2.65 in the membrane vesicles expressing human MRP2. Furthermore, harmine could slightly up-regulate the expression of MRP2, which implying harmine might be the substrate of MRP2. Particularly, the CL_int-value for harmine was ~1.49-folds greater than that of harmaline in human liver microsomes. It was worth noting that the F-value of harmine was increased 1.96-folds after harmine co-administration with probenecid. To summarize, comprehensive analysis indicated that harmaline and harmine were absorbed by transcellular passive diffusion and a pH- and Na⁺-dependent mechanism might be mediated by OATPs and OCTs/OCTNs. MRP2 but MDR1 or BCRP might be involved in the transport of harmine. Furthermore, harmine was more unstable and easily metabolized than harmaline. All these findings suggested that harmine not only appears be an MRP2 substrate, but also possesses weak metabolic stability, and eventually leads to a low oral bioavailability. Taken together, the elucidated absorption, transport, metabolism as well as pharmacokinetic characteristics of harmaline and harmine provide useful information for designing delivery systems, pharmacological applications and avoiding drug-drug interactions.

Recent insights into synthetic β-carbolines with anti-cancer activities

Cancer, an uncontrolled and rapid proliferation of abnormal cells, has become one of the leading cause of death worldwide. The development of resistance among the numerous drugs in clinical use has provided strong impetus for the identification and development of novel cancer therapeutics. β-carbolines constitute an important class of pharmacologically active scaffolds known to exert their anticancer activities via diverse mechanisms. The purpose of present review article is to update the readers on the current developments in β-carbolines with an emphasis on synthetic strategies, structure-activity relationships, mechanism of action and in vivo studies wherever possible.

A review on traditional uses, phytochemistry, pharmacology, pharmacokinetics and toxicology of the genus Peganum

ETHNOPHARMACOLOGICAL RELEVANCE

The plants of the genus Peganum have a long history as a Chinese traditional medicine for the treatment of cough, hypertension, diabetes, asthma, jaundice, colic, lumbago, and many other human ailments. Additionally, the plants can be used as an amulet against evil-eye, dye and so on, which have become increasingly popular in Asia, Iran, Northwest India, and North Africa.

AIM OF THE REVIEW

The present paper reviewed the ethnopharmacology, phytochemistry, analytical methods, biological activities, metabolism, pharmacokinetics, toxicology, and drug interaction of the genus Peganum in order to assess the ethnopharmacological use and to explore therapeutic potentials and future opportunities for research.

MATERIALS AND METHODS

Information on studies of the genus Peganum was gathered via the Internet (using Google Scholar, Baidu Scholar, Elsevier, ACS, Pudmed, Web of Science, CNKI and EMBASE) and libraries. Additionally, information was also obtained from some local books, PhD and MS's dissertations.

RESULTS

The genus Peganum has played an important role in traditional Chinese medicine. The main bioactive metabolites of the genus include alkaloids, flavonoids, volatile oils, etc. Scientific studies on extracts and formulations revealed a wide range of pharmacological activities, such as cholinesterase and monoamine oxidase inhibitory activities, antitumor, anti-hypertension, anticoagulant, antidiabetic, antimicrobial, insecticidal, antiparasidal, anti-leishmaniasis, antioxidant, and anti-inflammatory.

CONCLUSIONS

Based on this review, there is some evidence for extracts' pharmacological effects on Alzheimer's and Parkinson's diseases, cancer, diabetes, hypertension. Some indications from ethnomedicine have been confirmed by pharmacological effects, such as the cholinesterase, monoamine oxidase and DNA topoisomerase inhibitory activities, hypoglycemic and vasodilation effects of this genus. The available literature showed that most of the activities of the genus Peganum can be attributed to the active alkaloids. Data regarding many aspects of the genus such as mechanisms of actions, metabolism, pharmacokinetics, toxicology, potential drug interactions with standard-of-care medications is still limited which call for additional studies particularly in humans. Further assessments and clinical trials should be performed before it can be integrated into medicinal practices.

Structurally Diverse Alkaloids from the Seeds of Peganum harmala

Investigation of the alkaloids from Peganum harmala seeds yielded two pairs of unique racemic pyrroloindole alkaloids, (±)-peganines A-B (1-2); two rare thiazole derivatives, peganumals A-B (3-4); six new β-carboline alkaloids, pegaharmines F-K (5-10); and 12 known analogues. Their structures, including stereochemistry, were elucidated through spectroscopic analyses, quantum chemistry calculations, and single-crystal X-ray diffraction. Notably, the incorporation of pyrrole and indole moieties in peganines A-B, thiazole fragments in peganumals A-B, and a C-1 α,β-unsaturated ester motif in pegaharmine F (5) are all rare, and their presence in the genus Peganum were demonstrated for the first time. All isolates were tested for antiproliferative activities against the HL-60, PC-3, and SGC-7901 cancer cell lines, and compounds 9, 11, 12, and 13 exhibited moderate cytotoxicity against HL-60 cancer cell lines with IC₅₀ values in the range of 4.36-9.25 μM.

In(OTf)3 assisted synthesis of β-carboline C-3 tethered imidazo[1,2-a]azine derivatives

Synthesis of β-carboline based natural products and synthetic derivatives is one of the frontier areas of research owing to their medicinal properties.

Anti-Candida albicans natural products, sources of new antifungal drugs: A review

INTRODUCTION

Candida albicans is the most prevalent fungal pathogen in humans. Due to the development of drug resistance, there is today a need for new antifungal agents for the efficient management of C. albicans infections. Therefore, we reviewed antifungal activity, mechanisms of action, possible synergism with antifungal drugs of all natural substances experimented to be efficient against C. albicans for future.

METHODS

An extensive and systematic review of the literature was undertaken and all relevant abstracts and full-text articles analyzed and included in the review.

REVIEW

A total of 111 documents were published and highlighted 142 anti-C. albicans natural products. These products are mostly are reported in Asia (44.37%) and America (28.17%). According to in vitro model criteria, from the 142 natural substances, antifungal activity can be considered as important for 40 (28.20%) and moderate for 24 (16.90%). Sixteen products have their antifungal activity confirmed by in vivo gold standard experimentation. Microbial natural products, source of antifungals, have their antifungal mechanism well described in the literature: interaction with ergosterol (polyenes), inhibition 1,3-β-d-glucan synthase (Echinocandins), inhibition of the synthesis of cell wall components (chitin and mannoproteins), inhibition of sphingolipid synthesis (serine palmitoyltransferase, ceramide synthase, inositol phosphoceramide synthase) and inhibition of protein synthesis (sordarins). Natural products from plants mostly exert their antifungal effects by membrane-active mechanism. Some substances from arthropods are also explored to act on the fungal membrane. Interestingly, synergistic effects were found between different classes of natural products as well as between natural products and azoles.

CONCLUSION

Search for anti-C. albicans new drugs is promising since the list of natural substances, which disclose activity against this yeast is today long. Investigations must be pursued not only to found more new anti-Candida compounds from plants and organisms but also to carried out details on molecules from already known anti-Candida compounds and to more elucidate mechanisms of action.