Repurposing harmaline as a novel approach to reverse tmexCD1-toprJ1-mediated tigecycline resistance against klebsiella pneumoniae infections.

BACKGROUND: A novel plasmid-mediated resistance-nodulation-division (RND) efflux pump gene cluster tmexCD1-toprJ1 in Klebsiella pneumoniae tremendously threatens the use of convenient therapeutic options in the post-antibiotic era, including the "last-resort" antibiotic tigecycline. RESULTS: In this work, the natural alkaloid harmaline was found to potentiate tigecycline efficacy (4- to 32-fold) against tmexCD1-toprJ1-positive K. pneumoniae, which also thwarted the evolution of tigecycline resistance. Galleria mellonella and mouse infection models in vivo further revealed that harmaline is a promising candidate to reverse tigecycline resistance. Inspiringly, harmaline works synergistically with tigecycline by undermining tmexCD1-toprJ1-mediated multidrug resistance efflux pump function via interactions with TMexCD1-TOprJ1 active residues and dissipation of the proton motive force (PMF), and triggers a vicious cycle of disrupting cell membrane integrity and metabolic homeostasis imbalance. CONCLUSION: These results reveal the potential of harmaline as a novel tigecycline adjuvant to combat hypervirulent K. pneumoniae infections.

Cytotoxicity of alkaloids isolated from Peganum harmala seeds on HCT116 human colon cancer cells.

BACKGROUND: The present study aimed to elucidate the potential anticancer activity and mechanism of P. harmala's alkaloid extract, harmine (HAR), and harmaline (HAL) in HCT-116 colorectal cancer cells. METHODS AND RESULTS: P. harmala's alkaloid was extracted from harmala seeds. HCT-116 cells were treated with P. harmala's alkaloid extract, HAR and HAL. Cytotoxicity was determined by MTT assay, apoptotic activity detected via flow cytometry and acridine orange (AO)/ethidium bromide (EB) dual staining, and cell cycle distribution analyzed with flow cytometry. The mRNA expression of Bcl-2-associated X protein (Bax) and glycogen synthase kinase-3 beta (GSK3ß) was measured by real-time PCR. Furthermore, the expression of Bax, Bcl-2, GSK3ß and p53 proteins, were determined by western blotting. The findings indicated that, P. harmala's alkaloids extract, HAR and HAL were significantly cytotoxic toward HCT116 cells after 24 and 48 h of treatment. We showed that P. harmala's alkaloid extract induce apoptosis and cell cycle arrest at G2 phase in the HCT116 cell line. Downregulation of GSK3ß and Bcl-2 and upregulation of Bax and p53 were observed. CONCLUSION: The findings of this study indicate that the P. harmala's alkaloid extract has anticancer activity and may be further investigated to develop future anticancer chemotherapeutic agents.

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

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

Evaluation of therapeutic role of harmaline: in vitro cytotoxicity targeting nucleic acids.

Use of small molecules as valuable drugs against diseases is still an indefinable purpose due to the lack of in-detail knowledge regarding proper bio-target identification, specificity aspects, mode-mechanism of binding and proper in vitro study. Harmaline, an important beta-carboline alkaloid, shows effective anti-proliferative action against different types of human cancers and is also found to be a nucleic acid targeting natural molecule. This review sought to address the different signal pathways of apoptosis by harmaline in different cancer cell lines and simultaneously to characterize the structure activity aspects of the alkaloid with different motifs of nucleic acid to show its preference, biological efficacy and genotoxicity. The results open up new insights for the design and development of small molecule-based nucleic acid therapeutic agents.

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

Harmaline (1) and harmalol (2) represent two 3,4-dihydro-ß-carboline (DHßCs) 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. 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.

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

BACKGROUND: Harmaline is a ß-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.

Epicranial Direct Current Stimulation Suppresses Harmaline Tremor in Rats.

INTRODUCTION: Essential tremor (ET) is the most common neurologic movement disorder worldwide. It is characterized by a postural tremor, mostly in the upper extremities, causing difficulties in daily activities that may lead to social exclusion. Some patients with ET do not respond well to or do not tolerate medication. Thus, deep brain stimulation can be offered. In a recent study, we proposed a novel neuromodulation technique called epicranial current stimulation (ECS) that works in a minimally invasive way by placing the electrodes subcutaneously under the skin and directly over the skull. In this study, we investigated the feasibility of using epicranial direct current stimulation (EDCS) to suppress tremor in a rat harmaline ET model. MATERIALS AND METHODS: In experiment 1, seven Sprague Dawley rats were implanted with ECS electrodes placed over the motor cortex (MC) and the cerebellum to investigate whether stimulating between them could suppress tremor. In experiments 2 and 3, eight rats were implanted with ECS electrodes placed over the MC, cerebellum, and the rostral skull to separate the effects on tremor caused by stimulating each target. During each experiment, the rats were injected with harmaline, which induced tremor that was quantified using an accelerometer. EDCS was then applied through the different electrode configurations to evaluate their tremor suppression effectiveness. RESULTS: Results from experiment 1 showed that MCcathode-Cerebellaranode suppressed tremor compared with stimulation-OFF but MCanode-Cerebellarcathode did not. Furthermore, experiments 2 and 3 showed that it was the cerebellar anodal electrode that was driving tremor suppression. CONCLUSION: Cerebellar EDCS suppressed harmaline tremor in rats in a polarity-dependent manner. EDCS could be a promising neuromodulation method for patients with ET.

Hispidin, Harmaline, and Harmine as potent inhibitors of bovine xanthine oxidase: Gout treatment, in vitro, ADMET prediction, and SAR studies.

Alkaloids and phenols are potent inhibitors family for many enzymes used in many therapies. We aim to evaluate in vitro and in silico, the inhibition effect of Hispidin, Harmaline, and Harmine as pure molecules to bovine milk xanthine oxidase (BXO), Molecular docking and SAR study with GOLD was done to explain the mechanism of action related to its inhibition, ADMET parameters were checked to confirm their pharmacokinetics (PK) using preADMET 2.0 server, we classified our inhibitors by applying five drug-likeness rules, the best-ranked inhibitors were chosen based on the approved ADMET properties, drug-likeness qualifications, and the best PLPchem score generated by GOLD. The in vitro results show important inhibition activity to BXO comparing to the control with an IC50 of 39.72 ± 3.60 µM, 51.00 ± 1.0 µM, and 48.52 ± 1.76 µM for Hispidin, Harmaline, and Harmine respectively. The in silico results show that Hispidin was the best inhibitor model with approved ADMET properties and qualification in all drug-likeness rules; Harmaline was saved second-best model to BXO with suitable ADMET properties and qualified in most drug-likeness rules. Eventually, Harmine was ranked third potent inhibitor model with acceptable ADMET properties, drug-likeness rules, and PLPchem score. The tested inhibitors could be significant in drug discovery, especially in treating gout disease; therefore, drug development, including clinical trials, should be done with promising results.

Harmaline isolated from Peganum harmala suppresses growth of esophageal squamous cell carcinoma through targeting mTOR.

Harmaline is a naturally occurring ß-carboline alkaloid that is isolated from Peganum harmala. It has shown efficacy in treating Parkinson's disease and has been reported to exhibit antimicrobial and anticancer properties. However, the molecular mechanism of harmaline in the context of esophageal squamous cell carcinoma (ESCC) has not been characterized. Here, we report that harmaline attenuates ESCC growth by directly targeting the mammalian target of rapamycin (mTOR). Harmaline strongly reduced cell proliferation and anchorage-independent cell growth. Additionally, harmaline treatment induced G2/M phase cell-cycle arrest through upregulation of p27. The results of in vitro and cell-based assays showed that harmaline directly inhibited the activity of mTOR kinase and the phosphorylation of its downstream pathway components. Depletion of mTOR using an shRNA-mediated strategy in ESCC cell lines indicated that reduced mTOR protein expression levels are correlated with decreased cell proliferation. Additionally, we observed that the inhibitory effect of harmaline was dependent upon mTOR expression. Notably, oral administration of harmaline suppressed ESCC patient-derived tumor growth in vivo. Taken together, harmaline is a potential mTOR inhibitor that might be used for therapeutically treating ESCC.

Identification of compounds inhibiting prion replication and toxicity by removing PrPC from the cell surface.

The vast majority of therapeutic approaches tested so far for prion diseases, transmissible neurodegenerative disorders of human and animals, tackled PrPSc , the aggregated and infectious isoform of the cellular prion protein (PrPC ), with largely unsuccessful results. Conversely, targeting PrPC expression, stability or cell surface localization are poorly explored strategies. We recently characterized the mode of action of chlorpromazine, an anti-psychotic drug known to inhibit prion replication and toxicity by inducing the re-localization of PrPC from the plasma membrane. Unfortunately, chlorpromazine possesses pharmacokinetic properties unsuitable for chronic use in vivo, namely low specificity and high toxicity. Here, we employed HEK293 cells stably expressing EGFP-PrP to carry out a semi-automated high content screening (HCS) of a chemical library directed at identifying non-cytotoxic molecules capable of specifically relocalizing PrPC from the plasma membrane as well as inhibiting prion replication in N2a cell cultures. We identified four candidate hits inducing a significant reduction in cell surface PrPC , one of which also inhibited prion propagation and toxicity in cell cultures in a strain-independent fashion. This study defines a new screening method and novel anti-prion compounds supporting the notion that removing PrPC from the cell surface could represent a viable therapeutic strategy for prion diseases.

Accurate and affordable assessment of physiological and pathological tremor in rodents using the accelerometer of a smartphone.

Tremor is a common symptom for the most prevalent neurological disorders, including essential tremor, spinal cord injury, multiple sclerosis, or Parkinson's disease. Despite the devastating effects of tremor on life quality, available treatments are few and unspecific. Because of the need for specific and costly devices, tremor is rarely quantified by laboratories studying motor control without a genuine interest in trembling. We present a simple, reliable, and affordable method aimed at monitoring tremor in rodents, with an accuracy comparable to that of expensive, commercially available equipment. We took advantage of the accelerometer integrated in modern mobile phones working with operating systems capable of running downloaded apps. By fixing a smartphone to a cage suspended by rubber bands, we were able to detect faint vibrations of the cage. With a mouse in the cage, we showed that the acceleration signals on two horizontal axes were sufficient for the detection of physiological tremor and harmaline-induced tremor. We discuss the advantages and limitations of our method.NEW & NOTEWORTHY The majority of patients suffering from neurological disorders suffer from tremor that severely disrupts their life quality. Because of the high cost of specific scientific equipment, tremor is rarely quantified by laboratories working on motor behavior. For this reason, the potential anti-tremor effect of most compounds tested in animals remains unknown. We describe an affordable technique that will allow any laboratory to measure tremor accurately with a smartphone.

Binding affinity and in vitro cytotoxicity of harmaline targeting different motifs of nucleic acids: An ultimate drug designing approach.

The work focuses towards interaction of harmaline, with nucleic acids of different motifs by multispectroscopic and calorimetric techniques. Findings of this study suggest that binding constant varied in the order single-stranded (ss) poly(A) > double-stranded calf thymus (CT) DNA > double-stranded poly(G)·poly(C) > clover leaf tRNAPhe . Prominent structural changes of ss poly(A), CT DNA, and poly(G)· poly(C) with concomitant induction of optical activity in the bound achiral alkaloid molecule was observed, while with tRNAPhe , very weak induced circular dichroism perturbation was seen. The interaction was predominantly exothermic, enthalpy driven, and entropy favored with CT DNA and poly(G)·poly(C), while it was entropy driven with poly(A) and tRNAPhe . Intercalated state of harmaline inside poly(A), CT DNA, and poly(G)·poly(C) was shown by viscometry, ferrocyanide quenching, and molecular docking. All these findings unequivocally pointed out preference of harmaline towards ss poly(A) inducing self-structure formation. Furthermore, harmaline administration caused a significant decrease in proliferation of HeLa and HepG2 cells with GI50 of 28µM and 11.2µM, respectively. Nucleic acid fragmentation, cellular ultramorphological changes, decreased mitochondrial membrane potential, upregulation of p53 and caspase 3, generation of reactive oxygen species, and a significant increase in the G2 /M population made HepG2 more prone to apoptosis than are HeLa cells.

In Vivo Analysis of the Climbing Fiber-Purkinje Cell Circuit in SCA2-58Q Transgenic Mouse Model.

Cerebellar Purkinje cells (PCs) and cerebellar pathways are primarily affected in many autosomal dominant cerebellar ataxias. PCs generate complex spikes (CS) in vivo when activated by climbing fiber (CF) which rise from the inferior olive. In this study, we investigated the functional state of the CF-PC circuitry in the transgenic mouse model of spinocerebellar ataxia type 2 (SCA2), a polyglutamine neurodegenerative genetic disease. In our experiments, we used an extracellular single-unit recording method to compare the PC activity pattern and the CS shape in age-matched wild-type mice and SCA2-58Q transgenic mice. We discovered no alterations in the CS properties of PCs in aging SCA2 mice. To examine the integrity of the olivocerebellar pathway, we applied harmaline, an alkaloid that acts directly on the inferior olive neurons. The pharmacological stimulation of olivocerebellar circuit by harmaline uncovered disturbances in SCA2-58Q PC activity pattern and in the complex spike shape when compared with age-matched wild-type cells. The abnormalities in the CF-PC circuitry were aggravated with age. We propose that alterations in CF-PC circuitry represent one of potential causes of ataxic symptoms in SCA2 and in other SCAs.

In vivo analysis of synaptic activity in cerebellar nuclei neurons unravels the efficacy of excitatory inputs.

KEY POINTS: Cerebellar nuclei (CN) neurons can be classified into four groups according to their action potential (AP) waveform, corresponding to four types of neurons previously characterized. Half of the APs are generated by excitatory events, suggesting that excitatory inputs play a key role in generating CN outputs. Analysis of post-synaptic potentials reveals that the probability of excitatory inputs generating an AP is 0.1. The input from climbing fibre collaterals is characterized by a pair of synaptic potentials with a distinct interpair interval of 4.5 ms. The probability of climbing fibre collaterals initiating an AP in CN neurons is 0.15. ABSTRACT: It is commonly agreed that the main function of the cerebellar system is to provide well-timed signals used for the execution of motor commands or prediction of sensory inputs. This function is manifested as a temporal sequence of spiking that should be expressed in the cerebellar nuclei (CN) projection neurons. Whether spiking activity is generated by excitation or release from inhibition is still a hotly debated issue. In an attempt to resolve this debate, we recorded intracellularly from CN neurons in anaesthetized mice and performed an analysis of synaptic activity that yielded a number of important observations. First, we demonstrate that CN neurons can be classified into four groups. Second, shape-index plots of the excitatory events suggest that they are distributed over the entire dendritic tree. Third, the rise time of excitatory events is linearly related to amplitude, suggesting that all excitatory events contribute equally to the generation of action potentials (APs). Fourth, we identified a temporal pattern of spontaneous excitatory events that represent climbing fibre inputs and confirm the results by direct stimulation and analysis on harmaline-evoked activity. Finally, we demonstrate that the probability of excitatory inputs generating an AP is 0.1 yet half of the APs are generated by excitatory events. Moreover, the probability of a presumably spontaneous climbing fibre input generating an AP is higher, reaching a mean population value of 0.15. In view of these results, the mode of synaptic integration at the level of the CN should be re-considered.

Antitrichomonal activity of Peganum harmala alkaloid extract against trichomoniasis in pigeon (Columba livia domestica).

1. This study was designed to evaluate the antitrichomonal effects of P. harmala alkaloid extract against T. gallinae, both in vitro and in vivo, as well as comparing it to that of metronidazole, conventional antitrichomonal medication and harmine and harmaline, the two alkaloids present in P. harmala. 2. T. gallinae were collected by the wet mount method from infected free-living pigeons. The in vitro assay was performed using multi-well plates containing test compounds in final concentrations of 5, 10, 15, 20, 30, 50 or 100 µg/ml. The in vivo assay was done on 60 experimentally infected pigeons dosed with metronidazole at 50 mg/kg body weight (BW) or alkaloids at 25 mg/kg BW. 3. The 24 h minimum inhibitory concentration (MIC) of alkaloid extract was 15 µg/ml while that of metronidazole was 50 µg/ml. Harmine and harmaline revealed 24 h MIC of 30 and 100 µg/ml, respectively. Treatment of infected pigeons with alkaloids led to a full recovery after 3 d but with metronidazole total eradication of trophozoites was not achieved. 4. In conclusion, data of the present study suggested P. harmala is a potent natural anti-trichomonal agent, effective against T. gallinae.

Short Communication: Evaluation of antimicrobial activities of Harmine, Harmaline, Nicotine and their complexes.

Harmine, Harmaline, Nicotine and its various complexes synthesized have been characterized by physical, spectral and analytical methods and curtained for in-vitro antimicrobial activity against different bacterial and fungal species at two different concentrations i.e.100µ/100µl and 200µ/100µl dose level respectively. Analysis showed that Nicotine, Zinc-Nico, Cd-Nico, Hg-Nico, Ni-Nico, Cu-Nico, Co-Nico, Harmine, and Harmaline having conc. of 100ug/ 100ul had antibacterial activity on zero, 5, 4, 10, zero, 5, 7, zero, zero strain of bacteria having an average of zero (SD=0.0000), 15.2000 (SD=1.30384), 18.2500 (SD=3.30404), 20.2000 (SD=1.39841), zero (SD=0.0000), 14.6000 (SD=0.89443), 15.8571 (SD=1.34519), zero (SD=0.0000), zero (SD=0.0000) respectively. Zinc (II) chloride, Cadmium (II) Iodide, Mercury (II) chloride, Nickel (II) chloride, Copper (II) chloride, Cobalt (II) chloride, Mercury (II) chloride, Mercury (II) harmine, Mercury (II) harmaline at 100ug/100ul is valid for 7, 8, 9, 2, 7, 8, 9, 10, 8 strains of bacteria with an average of 7.1429 (SD=1.06904), 10.0000 (SD=5.01427), 14.8889 (SD=6.00925), 6.0000 (SD=0.0000), 8.5714 (SD=4.27618), 8.2500 (SD=0.88641), 14.8889 (SD=6.00925), 18.6000 (SD=2.45855), 18.5000 (SD=1.85164) respectively. The above given compounds at the conc. of 200 µ/100ul is valid for 10, 9, 10, 8, 8, 10, 10, 10, 10 strains of bacteria with an average of 8.1 (SD=1.66333), 11.7778 (SD=5.28625), 16.1000 (SD=6.36745), 6.5000 (SD=0.92582), 9.7500 (SD=4.43203), 9.9000 (SD=2.76687), 16.1000 (SD=6.36745), 22.0000 (SD=2.44949), 20.4000 (SD=2.75681) respectively. The above given compounds at conc. of 200 µ/100ul showed antibacterial action on 3, 8, 8, 10, 3, 9, 8, zero, 3 strains of bacteria with an average of 14(SD=0.000), 16.8750 (SD=1.35620), 18.2500 (SD=3.45378), 22.7000 (SD=1.82878), 14.3333 (SD=0.57735), 16.7778 (SD=1.71594), zero (SD=0.000), 12.0000 (SD=1.00000) respectively. Hence according to the average value of the zone of inhibition, maximum antibacterial activity at 100-200ug/100ul is of Hg-Nico and Mercury salt; Mercury (II) harmine having an average of 20.2000 (SD=1.39841)-22.7000 (SD=1.82878) and 18.6000 (SD=2.45855)-22.0000 (SD=2.44949). Minimum antibacterial activity at 100-200ug/100ul is Nicotine100, Nicotine-Nico100, Harmine 100,Harmaline 100, Harmine 200 having zero average (SD=0.000).

Harmaline and hispidin from Peganum harmala and Inonotus hispidus with binding affinity to Candida rugosa lipase: In silico and in vitro studies.

The inhibitory effect of phenolic compounds and alkaloids of Inonotus hispidus and Peganum harmala on Candida rugosa lipase was investigated, also, their antioxidant activities using DPPH, ABTS and phosphomolybdenum were studied in this paper. The phenolic extracts have shown a stronger antiradical activity than the alkaloids extracts. The enzymatic inhibition produced by these extracts is described here for the first time. The results have shown that the phenolic and the alkaloid extracts are good inhibitors of C. rugosa lipase. Thus, the inhibitor molecules (harmaline and hispidin) have been isolated from P. harmala and I. hispidus. Their structures were elucidated by (1)H NMR analysis. Molecular docking has been achieved using AutoDock Vina program to discuss the nature of interactions and the mechanism of inhibition. Therefore, these isolated molecules could be used in the treatment of candidiasis.

[Effects of Total Alkaloids of Harmaline on Learning and Memory in Vascular Dementia Rats].

OBJECTIVE: To investigate the effects of total alkaloids of harmaline on learning and memory in vascular dementia rats, and its mechanism. METHODS: The model rats of vascular dementia were established with bilateral carotid artery ligation. After 30 days, the model rats were randomly divided into six groups: sham group, model group, nicergoline tablets 7 mg/kg group, and 25, 12.5 and 6.25 mg/kg dose groups of total alkaloids of harmaline, the rats were given medicine for 30 days. Learning and memory abilities were tested by Morris water maze, histomorphology in hippocampal CA1 area were observed by HE staining, BAX and BCL-2 protein expression in hippocampal CA1 area were detected by immunohistochemistry. RESULTS: Compared with model group, 25 mg/kg group of total alkaloids of harmaline shortened the incubation period in the third and fourth day significantly, 12.5 mg/kg group of total alkaloids of harmaline shortened the incubation period in the fourth day. 25 and 12.5 mg/kg groups of total alkaloids of harmaline significantly increased the times crossing the target. Total alkaloids of harmaline improved the neurons pathological changes of rat in the hippocampus CA1 area, 25 and 12.5 mg/kg of total alkaloids of harmaline downregulated the expression of apoptosis proteins BAX, upregulated the protein expression of BCL-2. CONCLUSION: Total alkaloids of harmaline can improve the learning and memory abilities in vascular dementia rats, which probably is related to inhibiting apoptosis of hippocampus cell.

Herbicidal effects of harmaline from Peganum harmala on photosynthesis of Chlorella pyrenoidosa: probed by chlorophyll fluorescence and thermoluminescence.

The herbicidal effects of harmaline extracted from Peganum harmala seed on cell growth and photosynthesis of green algae Chlorella pyrenoidosa were investigated using chlorophyll a fluorescence and thermoluminescence techniques. Exposure to harmaline inhibited cell growth, pigments contents and oxygen evolution of C. pyrenoidosa. Oxygen evolution was more sensitive to harmaline toxicity than cell growth or the whole photosystem II (PSII) activity, maybe it was the first target site of harmaline. The JIP-test parameters showed that harmaline inhibited the donor side of PSII. Harmaline decreased photochemical efficiency and electron transport flow of PSII but increased the energy dissipation. The charge recombination was also affected by harmaline. Amplitude of the fast phase decreased and the slow phase increased at the highest level of harmaline. Electron transfer from QA(-) to QB was inhibited and backward electron transport flow from QA(-) to oxygen evolution complex was enhanced at 10 µg mL(-1) harmaline. Exposure to 10 µg mL(-1) harmaline caused appearance of C band in thermoluminescence. Exposure to 5 µg mL(-1) harmaline inhibited the formation of proton gradient. The highest concentration of harmaline treatment inhibited S3QB(-) charge recombination but promoted formation of QA(-)YD(+) charge pairs. P. harmala harmaline may be a promising herbicide because of its inhibition of cell growth, pigments synthesis, oxygen evolution and PSII activities.

A Role for GABAA Receptor ß3 Subunits in Mediating Harmaline Tremor Suppression by Alcohol: Implications for Essential Tremor Therapy.

Background: Essential tremor patients may find that low alcohol amounts suppress tremor. A candidate mechanism is modulation of α6ß3δ extra-synaptic GABAA receptors, that in vitro respond to non-intoxicating alcohol levels. We previously found that low-dose alcohol reduces harmaline tremor in wild-type mice, but not in littermates lacking δ or α6 subunits. Here we addressed whether low-dose alcohol requires the ß3 subunit for tremor suppression. Methods: We tested whether low-dose alcohol suppresses tremor in cre-negative mice with intact ß3 exon 3 flanked by loxP, and in littermates in which this region was excised by cre expressed under the α6 subunit promotor. Tremor in the harmaline model was measured as a percentage of motion power in the tremor bandwidth divided by overall motion power. Results: Alcohol, 0.500 and 0.575 g/kg, reduced harmaline tremor compared to vehicle-treated controls in floxed ß3 cre- mice, but had no effect on tremor in floxed ß3 cre+ littermates that have ß3 knocked out. This was not due to potential interference of α6 expression by the insertion of the cre gene into the α6 gene since non-floxed ß3 cre+ and cre- littermates exhibited similar tremor suppression by alcohol. Discussion: As α6ß3δ GABAA receptors are sensitive to low-dose alcohol, and cerebellar granule cells express ß3 and are the predominant brain site for α6 and δ expression together, our overall findings suggest alcohol acts to suppress tremor by modulating α6ß3δ GABAA receptors on these cells. Novel drugs that target this receptor may potentially be effective and well-tolerated for essential tremor. Highlights: We previously found with the harmaline essential tremor model that GABAA receptors containing α6 and δ subunits mediate tremor suppression by alcohol. We now show that ß3 subunits in α6-expressing cells, likely cerebellar granule cells, are also required, indicating that alcohol suppresses tremor by modulating α6ß3δ extra-synaptic GABAA receptors.