Identification of harman as the antibiotic compound produced by a tunicate-associated bacterium

Antibacterial and Antifungal Alkaloids from Asian Angiosperms: Distribution, Mechanisms of Action, Structure-Activity, and Clinical Potentials

The emergence of multidrug-resistant bacteria and fungi requires the development of antibiotics and antifungal agents. This review identified natural products isolated from Asian angiosperms with antibacterial and/or antifungal activities and analyzed their distribution, molecular weights, solubility, and modes of action. All data in this review were compiled from Google Scholar, PubMed, Science Direct, Web of Science, ChemSpider, PubChem, and a library search from 1979 to 2022. One hundred and forty-one antibacterial and/or antifungal alkaloids were identified during this period, mainly from basal angiosperms. The most active alkaloids are mainly planar, amphiphilic, with a molecular mass between 200 and 400 g/mol, and a polar surface area of about 50 Å2, and target DNA and/or topoisomerase as well as the cytoplasmic membrane. 8-Acetylnorchelerythrine, cryptolepine, 8-hydroxydihydrochelerythrine, 6-methoxydihydrosanguinarine, 2'-nortiliacorinine, pendulamine A and B, rhetsisine, sampangine, tiliacorine, tryptanthrin, tylophorinine, vallesamine, and viroallosecurinine yielded MIC ≤ 1 µg/mL and are candidates for the development of lead molecules.

Synthesis of harmine-nitric oxide donor derivatives as potential antitumor agents

To further improve the anti-tumor activity of Harmine (HM), we took the hybridization approach and synthesized harmine derivatives-furoxan hybrids containing nitric oxide (NO) releasing parts by connecting NO donors with anti-tumor active fragments to harmine. Then, the synthesized compounds were evaluated for their in vitro cytotoxicity against five human cancer cell lines. Among them, compound 10 was found to have the strongest antiproliferative activity against HepG2 (IC₅₀ = 1.79 µM). In addition, compound 10 produced high levels of NO in vitro, verifying that the release of NO was closely correlated to the antiproliferative activity. In addition, Compound 10 also showed good plasma stability. Finally, we also preliminarily investigated the acute toxicity of compound 10 in mice and assessed the absorption of compound 10 by Caco-2 cell permeability assay. In brief, the remarkable biological characteristics of the new harmine derivatives-furoxan hybrids may make them promising candidates for human cancer intervention.

Ayahuasca as a Decoction Applied to Human: Analytical Methods, Pharmacology and Potential Toxic Effects

Ahyahuasca is a term commonly used to describe a decoction prepared by cooking the bark or crushed stems of the liana Banisteriopsis caapi (contains β-carbolines) alone or in combination with other plants, most commonly leaves of the shrub Psychotria viridis (contains N,N-dimethyltryptamine-DMT). More than 100 different plants can serve as sources of β-carbolines and DMT, which are the active alkaloids of this decoction, and therefore it is important to know the most accurate composition of the decoction, especially when studying the pharmacology of this plant. The aim was to summarize the latest sensitive methods used in the analysis of the composition of the beverage itself and the analysis of various biological matrices. We compared pharmacokinetic parameters in all of the studies where decoction of ayahuasca was administered and where its composition was known, whereby minimal adverse effects were observed. The therapeutic benefit of this plant is still unclear in the scientific literature, and side effects occur probably on the basis of pre-existing psychiatric disorder. We also described toxicological risks and clinical benefits of ayahuasca intake, which meant that the concentrations of active alkaloids in the decoction or in the organism, often not determined in publications, were required for sufficient evaluation of its effect on the organism. We did not find any post-mortem study, in which the toxicological examination of biological materials together with the autopsy findings would suggest potential lethality of this plant.

Bacillus species (BT42) isolated from Coffea arabica L. rhizosphere antagonizes Colletotrichum gloeosporioides and Fusarium oxysporum and also exhibits multiple plant growth promoting activity

BACKGROUND

Colletotrichum and Fusarium species are among pathogenic fungi widely affecting Coffea arabica L., resulting in major yield loss. In the present study, we aimed to isolate bacteria from root rhizosphere of the same plant that is capable of antagonizing Colletotrichum gloeosporioides and Fusarium oxysporum as well as promotes plant growth.

RESULTS

A total of 42 Bacillus species were isolated, one of the isolates named BT42 showed maximum radial mycelial growth inhibition against Colletotrichum gloeosporioides (78%) and Fusarium oxysporum (86%). BT42 increased germination of Coffee arabica L. seeds by 38.89%, decreased disease incidence due to infection of Colletotrichum gloeosporioides to 2.77% and due to infection of Fusarium oxysporum to 0 (p < 0.001). The isolate BT42 showed multiple growth-promoting traits. The isolate showed maximum similarity with Bacillus amyloliquefaciens.

CONCLUSION

Bacillus species (BT42), isolated in the present work was found to be capable of antagonizing the pathogenic effects of Colletotrichum gloeosporioides and Fusarium oxysporum. The mechanism of action of inhibition of the pathogenic fungi found to be synergistic effects of secondary metabolites, lytic enzymes, and siderophores. The major inhibitory secondary metabolite identified as harmine (β-carboline alkaloids).

A rapid and simple method for the determination of psychoactive alkaloids by CE-UV: application to Peganum Harmala seed infusions

The β-carboline alkaloids of the harmala (HAlks) group are compounds widely spread in many natural sources, but found at relatively high levels in some specific plants like Peganum harmala (Syrian rue) or Banisteriopsis caapi. HAlks are a reversible Mono Amino Oxidase type A Inhibitor (MAOI) and, as a consequence, these plants or their extracts can be used to produce psychotropic effects when are combined with psychotropic drugs based on amino groups. Since the occurrence and the levels of the HAlks in natural sources are subject to significant variability, more widespread use is not clinical but recreational or ritual, for example B. caapi is a known part of the Ayahuasca ritual mixture. The lack of simple methods to control the variable levels of these compounds in natural sources restricts the possibilities to dose in strict quantities and, as a consequence, limits its use with pharmacological or clinical purposes. In this work, we present a fast, simple, and robust method of quantifying simultaneously the six HAlks more frequently found in plants, i.e., harmine, harmaline, harmol, harmalol, harmane, and norharmane, by capillary electrophoresis instruments equipped with the more common detector UV. The method is applied to analyze these HAlks in P. Harmala seeds infusion which is a frequent intake form for these HAlks. The method is validated in three different instruments in order to evaluate the transferability and to compare the performances between them. In this case, harmaline, harmine, and harmol were found in the infusion samples. Copyright © 2016 John Wiley & Sons, Ltd.

Temporal stability of bacterial symbionts in a temperate ascidian

In temperate seas, both bacterioplankton communities and invertebrate lifecycles follow a seasonal pattern. To investigate whether the bacterial community associated with the Mediterranean ascidian Didemnum fulgens exhibited similar variations, we monitored its bacterial community structure monthly for over a year using terminal restriction fragment length polymorphism and clone library analyses based on a nearly full length fragment of the 16S rRNA gene. D. fulgens harbored a bacterial consortium typical of ascidians, including numerous members of the phylum Proteobacteria, and a few members of the phyla Cyanobacteria and Acidobacteria. The overall bacterial community in D. fulgens had a distinct signature from the surrounding seawater and was stable over time and across seasonal fluctuations in temperature. Bacterial symbionts were also observed around animal cells in the tunic of adult individuals and in the inner tunic of D. fulgens larvae by transmission electron microscopy. Our results suggest that, as seen for sponges and corals, some species of ascidians host stable and unique bacterial communities that are at least partially inherited by their progeny by vertical transmission.

Cytotoxic Indolocarbazoles from Actinomadura melliaura ATCC 39691

Actinomadura melliaura ATCC 39691, a strain isolated from a soil sample collected in Bristol Cove, California, is a known producer of the disaccharide-substituted AT2433 indolocarbazoles (6-9). Reinvestigation of this strain using new media conditions led to >40-fold improvement in the production of previously reported AT2433 metabolites and the isolation and structure elucidation of the four new analogues, AT2433-A3, A4, A5, and B3 (1-4). The availability of this broader set of compounds enabled a subsequent small antibacterial/fungal/cancer SAR study that revealed disaccharyl substitution, N-6 methylation, and C-11 chlorination as key modulators of bioactivity. The slightly improved anticancer potency of the newly reported N-6-desmethyl 1 (compared to 6) contrasts extensive SAR of monoglycosylated rebeccamycin-type topoisomerase I inhibitors where N-6 alkylation has contributed to improved potency and ADME. Complete 2D NMR assignments for the known metabolite BMY-41219 (5) and (13)C NMR spectroscopic data for the known analogue AT2433-B1 (7) are also provided for the first time.

Selective inhibition of toxic cyanobacteria by β-carboline-containing bacterium Bacillus flexus isolated from Saudi freshwaters

A bacterial strain SSZ01 isolated from a eutrophic lake in Saudi Arabia dominated by cyanobacterial blooms, showed an antialgal activity against cyanobacteria species. Based on the analysis of the 16S rDNA gene sequence, the isolated strain (SSZ01) most likely belonged to the genus Bacillus with a 99% similarity to Bacillus flexus strain EMGA5. The thin layer chromatography (TLC) analysis of the ethyl acetate extract of this bacterium revealed that this strain can produce harmine and norharmane compared to different β-carboline analog standards. Harmine and norharmane were also detected in considerable amounts in bacterial growth medium, indicating a potential excretion of these compounds into the aquatic environment. The crude extract of Bacillus flexus as well as pure materials of harmine and norharmane inhibited the growth of tested species of cyanobacteria. However, the bacterial crude extract has a higher toxicity against tested species of cyanobacteria than harmine and norharmane. In addition, harmine was more toxic to cyanobacteria than norharmane. On the other hand, neither pure compounds of harmine and norharmane nor crude bacterial extract showed any antialgal activity against tested species of green algae. The results of the present study suggest that B. flexus SSZ01 or its crude extract containing harmine and norharmane could be a candidate for the selective control of cyanobacterial blooms without affecting other algal species.

The second skin: ecological role of epibiotic biofilms on marine organisms

In the aquatic environment, biofilms on solid surfaces are omnipresent. The outer body surface of marine organisms often represents a highly active interface between host and biofilm. Since biofilms on living surfaces have the capacity to affect the fluxes of information, energy, and matter across the host’s body surface, they have an important ecological potential to modulate the abiotic and biotic interactions of the host. Here we review existing evidence how marine epibiotic biofilms affect their hosts’ ecology by altering the properties of and processes across its outer surfaces. Biofilms have a huge potential to reduce its host’s access to light, gases, and/or nutrients and modulate the host’s interaction with further foulers, consumers, or pathogens. These effects of epibiotic biofilms may intensely interact with environmental conditions. The quality of a biofilm’s impact on the host may vary from detrimental to beneficial according to the identity of the epibiotic partners, the type of interaction considered, and prevailing environmental conditions. The review concludes with some unresolved but important questions and future perspectives.

Detection of bioactive exometabolites produced by the filamentous marine cyanobacterium Geitlerinema sp

Marine cyanobacteria are noted for their ability to excrete metabolites with biotic properties. This paper focuses on such exometabolites obtained from the culture of the marine filamentous cyanobacterium Geitlerinema sp. strain, their purification and subsequent analyses. By this means the recoveries of the active compounds, a prerequisite for properly determining their concentration, are quantified here for the first time. We demonstrate a new procedure using Amberlite XAD-1180 resin in combination with the eluent isopropanol for extraction of the culture media and gas chromatography as simplified chemical analysis. This procedure reduced necessary bacteria cultivation time (from 150 to 21 days) at low volumes of culture media (300 mL) required for identification of two selected bioactive compounds: 4,4'-dihydroxybiphenyl and harmane.

Dietary effects of harmine, a β-carboline alkaloid, on development, energy reserves and α-amylase activity of Plodia interpunctella Hübner (Lepidoptera: Pyralidae)

The physiological and developmental effects of harmine, a β-carboline alkaloid, on the insect pest Plodia interpunctella have been analyzed. When added at the larval diet, harmine induced a strong reduction of larvae weight, cannibalism between larvae, in addition to significant mortality. On the other hand, it caused a remarkable development disruption, manifested by both delay and reduction of pupation and adult emergence. Using spectrophotometric assays, we have shown that harmine ingestion provoked a severe reduction in protein, glycogen and lipid contents. Beside, when larvae fed harmine, the activity of the digestive enzyme α-amylase was strongly reduced. In conclusion, our experiments clearly show the susceptibility of P. interpunctella to harmine ingestion revealing the potent bioinsecticidal effect of harmine.

Antialgal, antibacterial and antifungal activity of two metabolites produced and excreted by cyanobacteria during growth

The antimicrobial activity of two cyanobacterial exometabolites, norharmane (9H-pyrido(3,4-b)indole) and 4,4'-dihydroxybiphenyl, was determined in suspension assays. Good anticyanobacterial activities (concentrations of 8-80 microg ml(-1)) and moderate antibacterial (16-160 microg ml(-1)) and antifungal (32-40 microg ml(-1)) activities were found for both compounds. The natural function as allelopathic chemicals and a possible applicability as antifouling agents or leads for the development of new antifouling chemicals are discussed.

Molecular cloning and expression profile of putative antilipopolysaccharide factor in Chinese shrimp(Fenneropenaeus chinensis)

A new antimicrobial protein gene of the anti-lipopolysaccharide factor family (tentatively named as ALFFc) has been cloned from hemocytes of the Chinese shrimp Fenneropenaeus chinensis by rapid amplification of 3' and 5' complementary DNA ends with polymerase chain reaction. The full-length complementary DNA of ALFFc consists of 600 bp with a 369-bp open reading frame, encoding 123 amino acids. The deduced peptide contains a putative signal peptide of 25 amino acids and mature peptide of 98 amino acids. The molecular mass of the deduced mature peptide is 13799.16 Da. It is highly cationic, with a theoretical pI of 10.3. The deduced amino acid sequence of ALFFc showed 56% homology with sequences of Tachypleus tridentatus and L. polyhemus. The tissue expression profile of this gene was studied by Northern blot, and ALFFc transcripts were mainly detected in hemocytes, gill, and intestine. RNA in situ hybridization showed that ALFFc was constitutively expressed in hemocytes. Capillary electrophoresis reverse transcriptase PCR was used to quantify the variation of messenger RNA transcription level during the artificial infection process with Vibrio anguillarum. Significant enhancement of ALFFc transcription appeared during the first 24 hours in response to Vibrio infection. These results provide useful information for understanding the function of ALFFc in shrimp.

In vitro activity of the β-carboline alkaloids harmane, harmine, and harmaline toward parasites of the species Leishmania infantum

Harmane, harmine, and harmaline were investigated for their in vitro antileishmanial activity toward parasites of the species Leishmania infantum. Harmane and Harmine displayed a moderate antiproliferative activity toward human monocytes and exerted a weak antileishmanial activity toward both the promastigote and the amastigote forms of the parasite. Their mechanism of action on the promastigote form of the parasite involved interactions with DNA metabolism leading to an accumulation of parasites in the S-G(2)M phases of the cell-cycle. Harmaline, at the contrary, was deprived from toxicity toward human cells and Leishmania promastigotes, however it exerted a strong antileishmanial activity toward the intracellular amastigote form of the parasite. This property was shown to partly result from the capacity of the molecule to prevent parasite internalization within macrophages by inhibiting Leishmania PKC activity.