Innate IRE1α-XBP1 activation by viral single-stranded RNA and its influence on lung cytokine production during SARS-CoV-2 pneumonia.

The utilization of host-cell machinery during SARS-CoV-2 infection can overwhelm the protein-folding capacity of the endoplasmic reticulum and activate the unfolded protein response (UPR). The IRE1α-XBP1 arm of the UPR could also be activated by viral RNA via Toll-like receptors. Based on these premises, a study to gain insight into the pathogenesis of COVID-19 disease was conducted using nasopharyngeal exudates and bronchioloalveolar aspirates. The presence of the mRNA of spliced XBP1 and a high expression of cytokine mRNAs were observed during active infection. TLR8 mRNA showed an overwhelming expression in comparison with TLR7 mRNA in bronchioloalveolar aspirates of COVID-19 patients, thus suggesting the presence of monocytes and monocyte-derived dendritic cells (MDDCs). In vitro experiments in MDDCs activated with ssRNA40, a synthetic mimic of SARS-CoV-2 RNA, showed induction of XBP1 splicing and the expression of proinflammatory cytokines. These responses were blunted by the IRE1α inhibitor MKC8866, the TLR8 antagonist CU-CPT9a, and knockdown of TLR8 receptor. In contrast, the IRE1α-XBP1 activator IXA4 enhanced these responses. Based on these findings, the TLR8/IRE1α system seems to play a significant role in the induction of the proinflammatory cytokines associated with severe COVID-19 disease and might be a druggable target to control cytokine storm.

Laurequinone, a Lead Compound against Leishmania.

Among neglected tropical diseases, leishmaniasis is one of the leading causes, not only of deaths but also of disability-adjusted life years. This disease, caused by protozoan parasites of the genus Leishmania, triggers different clinical manifestations, with cutaneous, mucocutaneous, and visceral forms. As existing treatments for this parasitosis are not sufficiently effective or safe for the patient, in this work, different sesquiterpenes isolated from the red alga Laurencia johnstonii have been studied for this purpose. The different compounds were tested in vitro against the promastigote and amastigote forms of Leishmania amazonensis. Different assays were also performed, including the measurement of mitochondrial potential, determination of ROS accumulation, and chromatin condensation, among others, focused on the detection of the cell death process known in this type of organism as apoptosis-like. Five compounds were identified that displayed leishmanicidal activity: laurequinone, laurinterol, debromolaurinterol, isolaurinterol, and aplysin, showing IC50 values against promastigotes of 1.87, 34.45, 12.48, 10.09, and 54.13 µM, respectively. Laurequinone was the most potent compound tested and was shown to be more effective than the reference drug miltefosine against promastigotes. Different death mechanism studies carried out showed that laurequinone appears to induce programmed cell death or apoptosis in the parasite studied. The obtained results underline the potential of this sesquiterpene as a novel anti-kinetoplastid therapeutic agent.

Chamigrane-Type Sesquiterpenes from Laurencia dendroidea as Lead Compounds against Naegleria fowleri.

Naegleria fowleri is an opportunistic protozoon that can be found in warm water bodies. It is the causative agent of the primary amoebic meningoencephalitis. Focused on our interest to develop promising lead structures for the development of antiparasitic agents, this study was aimed at identifying new anti-Naegleria marine natural products from a collection of chamigrane-type sesquiterpenes with structural variety in the levels of saturation, halogenation and oxygenation isolated from Laurencia dendroidea. (+)-Elatol (1) was the most active compound against Naegleria fowleri trophozoites with IC50 values of 1.08 µM against the ATCC 30808™ strain and 1.14 µM against the ATCC 30215™ strain. Furthermore, the activity of (+)-elatol (1) against the resistant stage of N. fowleri was also assessed, showing great cysticidal properties with a very similar IC50 value (1.14 µM) to the one obtained for the trophozoite stage. Moreover, at low concentrations (+)-elatol (1) showed no toxic effect towards murine macrophages and could induce the appearance of different cellular events related to the programmed cell death, such as an increase of the plasma membrane permeability, reactive oxygen species overproduction, mitochondrial malfunction or chromatin condensation. Its enantiomer (-)-elatol (2) was shown to be 34-fold less potent with an IC50 of 36.77 µM and 38.03 µM. An analysis of the structure-activity relationship suggests that dehalogenation leads to a significant decrease of activity. The lipophilic character of these compounds is an essential property to cross the blood-brain barrier, therefore they represent interesting chemical scaffolds to develop new drugs.

Rapid Screening of Polyol Polyketides from Marine Dinoflagellates.

Dinoflagellate-derived polyketides are typically large molecules (>1000 Da) with complex structures, potent bioactivities, and high toxicities. Their discovery suffers three major bottlenecks: insufficient bioavailability, low-yield cultivation of producer organisms, and production of multiple highly related analogues by a single strain. Consequently, the biotechnological production of therapeutics or toxicological standards of dinoflagellate-derived polyketides is also hampered. Strategies based on sensitive and selective techniques for chemical prospection of dinoflagellate extracts could aid in overcoming these limitations, as it allows selecting the most interesting candidates for discovery and exploitation programs according to the biosynthetic potential. In this work, we assess the combination of data-dependent liquid chromatography coupled with high-resolution tandem mass spectrometry (LC-HRMS2) and molecular networking to screen polyol polyketides. To demonstrate the power of this approach, we selected dinoflagellate Amphidinium carterae since it is commonly used as a biotechnological model and produces amphidinols, a family of polyol-polyene compounds with antifungal and antimycoplasmal activity. First, we screened families of compounds with multiple hydroxyl groups by examining MS2 profiles that contain sequential neutral losses of water. Then, we clustered MS2 spectra by molecular networking to facilitate the dereplication and discovery of amphidinols. Finally, we used the MS2 fragmentation behavior of well-characterized luteophanol D as a model to propose a structural hypothesis of nine novel amphidinols. We envision that this strategy is a valuable approach to rapidly monitoring toxin production of known and unknown polyol polyketides in dinoflagellates, even in small culture volumes, and distinguishing strains according to their toxin profiles.

Lessons from bright-spots for advancing knowledge exchange at the interface of marine science and policy.

Evidence-informed decision-making is in increasing demand given growing pressures on marine environments. A way to facilitate this is by knowledge exchange among marine scientists and decision-makers. While many barriers are reported in the literature, there are also examples whereby research has successfully informed marine decision-making (i.e., 'bright-spots'). Here, we identify and analyze 25 bright-spots from a wide range of marine fields, contexts, and locations to provide insights into how to improve knowledge exchange at the interface of marine science and policy. Through qualitative surveys we investigate what initiated the bright-spots, their goals, and approaches to knowledge exchange. We also seek to identify what outcomes/impacts have been achieved, the enablers of success, and what lessons can be learnt to guide future knowledge exchange efforts. Results show that a diversity of approaches were used for knowledge exchange, from consultative engagement to genuine knowledge co-production. We show that diverse successes at the interface of marine science and policy are achievable and include impacts on policy, people, and governance. Such successes were enabled by factors related to the actors, processes, support, context, and timing. For example, the importance of involving diverse actors and managing positive relationships is a key lesson for success. However, enabling routine success will require: 1) transforming the ways in which we train scientists to include a greater focus on interpersonal skills, 2) institutionalizing and supporting knowledge exchange activities in organizational agendas, 3) conceptualizing and implementing broader research impact metrics, and 4) transforming funding mechanisms to focus on need-based interventions, impact planning, and an acknowledgement of the required time and effort that underpin knowledge exchange activities.

Structure and Computational Basis for Backbone Rearrangement in Marine Oxasqualenoids.

Six novel oxasqualenoids (polyether triterpenes) were isolated from the red alga Laurencia viridis. Laurokanols A-E (1-5) comprise an unreported tricyclic core with a [6,6]-spiroketal system. Yucatecone (6) shows a biogenetically intriguing epimerization at C14. Quantum mechanical calculations were used to corroborate their structures and to explain key steps involved in the biogenetic mechanisms proposed for the formation of oxasqualenoids.

Antiamoebic effects of sesquiterpene lactones isolated from the zoanthid Palythoa aff. clavata.

Opportunistic parasitic protozoa of genus Acanthamoeba are responsible to cause severe infections in humans such as Acanthamoeba Keratitis or Amoebic Granulomatous Encephalitis. Current treatments are usually toxic and inefficient and there is a need to access new therapeutic agents. The antiamoebic effects of nephthediol (1) and fourteen germacranolide and eudesmanolide sesquiterpene lactones (2-5, 7-12) isolated from the indigenous zoanthid Palythoa aff. clavata collected at the coast of Lanzarote, Canary Islands were studied against Acanthamoeba castellanii Neff, and the clinical strains A. polyphaga and A. griffini. 4-epi-arbusculin A (11) presented the lowest IC50 value (26,47 ± 1,69 µM) against A. castellanii Neff and low cytotoxicity against murine macrophages, followed by isobadgerin (2), which also showed to be active against A. castellanii Neff cysts. The studies on the mode of action of compounds 2 and 11 revealed these sesquiterpene lactones induce mechanisms of PDC on A. castellanii Neff.

Isolation and Structural Elucidation of New Amphidinol Analogues from Amphidinium carterae Cultivated in a Pilot-Scale Photobioreactor.

The demand for valuable products from dinoflagellate biotechnology has increased remarkably in recent years due to their many prospective applications. However, there remain many challenges that need to be addressed in order to make dinoflagellate bioactives a commercial reality. In this article, we describe the technical feasibility of producing and recovering amphidinol analogues (AMs) excreted into a culture broth of Amphidinium carterae ACRN03, successfully cultured in an LED-illuminated pilot-scale (80 L) bubble column photobioreactor operated in fed-batch mode with a pulse feeding strategy. We report on the isolation of new structurally related AMs, amphidinol 24 (1, AM24), amphidinol 25 (2, AM25) and amphidinol 26 (3, AM26), from a singular fraction resulting from the downstream processing. Their planar structures were elucidated by extensive NMR and HRMS analysis, whereas the relative configuration of the C-32→C-47 bis-tetrahydropyran core was confirmed to be antipodal in accord with the recently revised configuration of AM3. The hemolytic activities of the new metabolites and other related derivatives were evaluated, and structure-activity conclusions were established. Their isolation was based on a straightforward and high-performance bioprocess that could be suitable for the commercial development of AMs or other high-value compounds from shear sensitive dinoflagellates.

Antimycobacterial Activity of Laurinterol and Aplysin from Laurencia johnstonii.

Marine environments represent a great opportunity for the discovery of compounds with a wide spectrum of bioactive properties. Due to their large variety and functions derived from natural selection, marine natural products may allow the identification of novel drugs based not only on newly discovered bioactive metabolites but also on already known compounds not yet thoroughly investigated. Since drug resistance has caused an increase in infections by Mycobacterium tuberculosis and nontuberculous mycobacteria, the re-evaluation of known bioactive metabolites has been suggested as a good approach to addressing this problem. In this sense, this study presents an evaluation of the in vitro effect of laurinterol and aplysin, two brominated sesquiterpenes isolated from Laurencia johnstonii, against nine M. tuberculosis strains and six nontuberculous mycobacteria (NTM). Laurinterol exhibited good antimycobacterial activity, especially against nontuberculous mycobacteria, being remarkable its effect against Mycobacterium abscessus, with minimum inhibitory concentration (MIC) values lower than those of the reference drug imipenem. This study provides further evidence for the antimycobacterial activity of some sesquiterpenes from L. johnstonii, which can be considered interesting lead compounds for the discovery of novel molecules to treat NTM infections.

Three-dimensional imaging of the intracellular assembly of a functional viral RNA replicase complex.

Positive-strand RNA viruses, which can be devastating pathogens in humans, animals and plants, replicate their genomes on intracellular membranes. Here, we describe the three-dimensional ultrastructural organization of a tombusvirus replicase in yeast, a valuable model for exploring virus-host interactions. We visualized the intracellular distribution of a viral replicase protein using metal-tagging transmission electron microscopy, a highly sensitive nanotechnology whose full potential remains to be developed. These three-dimensional images show how viral replicase molecules are organized when they are incorporated into the active domains of the intracellular replication compartment. Our approach provides a means to study protein activation mechanisms in cells and to identify targets for new antiviral compounds.

Antiprotozoal activities of marine polyether triterpenoids.

Chagas disease and leishmaniasis are tropical neglected diseases caused by kinetoplastids protozoan parasites of Trypanosoma and Leishmania genera, and a public health burden with high morbidity and mortality rates in developing countries. Among difficulties with their epidemiological control, a major problem is their limited and toxic treatments to attend the affected populations; therefore, new therapies are needed in order to find new active molecules. In this work, sixteen Laurencia oxasqualenoid metabolites, natural compounds 1-11 and semisynthetic derivatives 12-16, were tested against Leishmania amazonensis, Leishmania donovani and Trypanosoma cruzi. The results obtained point out that eight substances possess potent activities, with IC50 values in the range of 5.40-46.45 µM. The antikinetoplastid action mode of the main metabolite dehydrothyrsiferol (1) was developed, also supported by AFM images. The semi-synthetic active compound 28-iodosaiyacenol B (15) showed an IC50 5.40 µM against Leishmania amazonensis, turned to be non-toxic against the murine macrophage cell line J774A.1 (CC50 > 100). These values are comparable with the reference compound miltefosine IC50 6.48 ±â€¯0.24 and CC50 72.19 ±â€¯3.06 µM, suggesting that this substance could be scaffold for development of new antikinetoplastid drugs.

Antiamoebic Activities of Indolocarbazole Metabolites Isolated from Streptomyces sanyensis Cultures.

Indolocarbazoles are a family of natural alkaloids characterized by their potent protein kinase and topoisomerase I inhibitory activity. Among them, staurosporine (1) has exhibited promising inhibitory activity against parasites. Based on new insights on the activity and mechanism of action of STS in Acanthamoeba parasites, this work reports the isolation, identification, and the anti-Acanthamoeba activity of the minor metabolites 7-oxostaurosporine (2), 4'-demethylamino-4'-oxostaurosporine (3), and streptocarbazole B (4), isolated from cultures of the mangrove strain Streptomyces sanyensis. A clear correlation between the antiparasitic activities and the structural elements and conformations of the indolocarbazoles 1-4 was observed. Also, the study reveals that 7-oxostaurosporine (2) affects membrane permeability and causes mitochondrial damages on trophozoites of A. castellanii Neff.

Evaluation of Oxasqualenoids from the Red Alga Laurencia viridis against Acanthamoeba.

Acanthamoeba genus is a widely distributed and opportunistic parasite with increasing importance worldwide as an emerging pathogen in the past decades. This protozoan has an active trophozoite stage, a cyst stage, and is dormant and very resistant. It can cause Acanthamoeba keratitis, an ocular sight-threatening disease, and granulomatous amoebic encephalitis, a chronic, very fatal brain pathology. In this study, the amoebicidal activity of sixteen Laurencia oxasqualenoid metabolites and semisynthetic derivatives were tested against Acanthamoeba castellanii Neff. The results obtained point out that iubol (3) and dehydrothyrsiferol (1) possess potent activities, with IC50 values of 5.30 and 12.83 µM, respectively. The hydroxylated congeners thyrsiferol (2) and 22-hydroxydehydrothyrsiferol (4), active in the same value range at IC50 13.97 and 17.00 µM, are not toxic against murine macrophages; thus, they are solid candidates for the development of new amoebicidal therapies.

Antitumoral Effect of Laurinterol on 3D Culture of Breast Cancer Explants.

Macroalgae represent an important source of bioactive compounds with a wide range of biotechnological applications. Overall, the discovery of effective cytotoxic compounds with pharmaceutical potential is a significant challenge, mostly because they are scarce in nature or their total synthesis is not efficient, while the bioprospecting models currently used do not predict clinical responses. Given this context, we used three-dimensional (3D) cultures of human breast cancer explants to evaluate the antitumoral effect of laurinterol, the major compound of an ethanolic extract of Laurencia johnstonii. To this end, we evaluated the metabolic and histopathological effects of the crude extract of L. johnstonii and laurinterol on Vero and MCF-7 cells, in addition to breast cancer explants. We observed a dose-dependent inhibition of the metabolic activity, as well as morphologic and nuclear changes characteristic of apoptosis. On the other hand, a reduced metabolic viability and marked necrosis areas were observed in breast cancer explants incubated with the crude extract, while explants treated with laurinterol exhibited a heterogeneous response which was associated with the individual response of each human tumor sample. This study supports the cytotoxic and antitumoral effects of laurinterol in in vitro cell cultures and in ex vivo organotypic cultures of human breast cancer explants.

Antitumor activity of Lepidium latifolium and identification of the epithionitrile 1-cyano-2,3-epithiopropane as its major active component.

Consumption of Brassica (Cruciferae) vegetables is associated with a reduced risk of cancer, but identification of the active components and insights into the underlying molecular events are scarce. Here we found that an extract of Lepidium latifolium, a cruciferous plant native to southern Europe, Mediterranean countries and Asia, showed in vitro cytotoxic activity, inducing caspase-dependent apoptosis, in a variety of human tumor cells, and the plant juice showed in vivo antitumor activity in a HT-29 human colon cancer xenograft mouse model. The epithionitrile 1-cyano-2,3-epithiopropane (CETP) was identified as the major active cancer cell-killing principle of L. latifolium. Synthetic and plant-derived CETP displayed similar proapoptotic activities as assessed by biochemical and morphological analyses. Analysis of the antiproliferative capacity of CETP on a wide number of cancer cell lines from the NCI-60 cell line panel followed by COMPARE analysis, showed an activity profile different from known anticancer agents. Flow cytometry and biochemical analyses revealed that CETP-induced apoptosis involved mitochondria, as assessed by loss of mitochondrial transmembrane potential and generation of reactive oxygen species, while overexpression of Bcl-XL and Bcl-2 prevented CETP-induced apoptosis. Inhibition of reactive oxygen species by glutathione and N-acetyl cysteine reduced the apoptotic response induced by CETP. FADD dominant negative form, blocking Fas/CD95 signaling, and a specific caspase-8 inhibitor also inhibited CETP-induced killing. Taken together, our data suggest that the cancer cell-killing action of CETP, involving both intrinsic and extrinsic apoptotic signaling pathways, underlies the antitumor activity of L. latifolium plant, which could be of potential interest in cancer treatment.

Anti-Acanthamoeba Activity of Brominated Sesquiterpenes from Laurencia johnstonii.

Focused on our interest to develop novel antiparasistic agents, the present study was aimed to evaluate the biological activity of an extract of Laurencia johnstonii collected in Baja California Sur, Mexico, against an Acantamoeba castellanii Neff strain. Bioassay-guided fractionation allowed us to identify the amoebicidal diastereoisomers α-bromocuparane (4) and α-isobromocuparane (5). Furthermore, bromination of the inactive laurinterol (1) and isolaurinterol (2) yielded four halogenated derivatives, (6)⁻(9), which improved the activity of the natural sesquiterpenes. Among them, the most active compound was 3α-bromojohnstane (7), a sesquiterpene derivative which possesses a novel carbon skeleton johnstane.

Marine Microalgae: Promising Source for New Bioactive Compounds.

The study of marine natural products for their bioactive potential has gained strength in recent years. Oceans harbor a vast variety of organisms that offer a biological and chemical diversity with metabolic abilities unrivalled in terrestrial systems, which makes them an attractive target for bioprospecting as an almost untapped resource of biotechnological applications. Among them, there is no doubt that microalgae could become genuine "cell factories" for the biological synthesis of bioactive substances. Thus, in the course of inter-laboratory collaboration sponsored by the European Union (7th FP) into the MAREX Project focused on the discovery of novel bioactive compounds of marine origin for the European industry, a bioprospecting study on 33 microalgae strains was carried out. The strains were cultured at laboratory scale. Two extracts were prepared for each one (biomass and cell free culture medium) and, thus, screened to provide information on the antimicrobial, the anti-proliferative, and the apoptotic potential of the studied extracts. The outcome of this study provides additional scientific data for the selection of Alexadrium tamarensis WE, Gambierdiscus australes, Prorocentrum arenarium, Prorocentrum hoffmannianum, and Prorocentrum reticulatum (Pr-3) for further investigation and offers support for the continued research of new potential drugs for human therapeutics from cultured microalgae.

Distribution of DNA-condensing protein complexes in the adenovirus core.

Genome packing in adenovirus has long evaded precise description, since the viral dsDNA molecule condensed by proteins (core) lacks icosahedral order characteristic of the virus protein coating (capsid). We show that useful insights regarding the organization of the core can be inferred from the analysis of spatial distributions of the DNA and condensing protein units (adenosomes). These were obtained from the inspection of cryo-electron tomography reconstructions of individual human adenovirus particles. Our analysis shows that the core lacks symmetry and strict order, yet the adenosome distribution is not entirely random. The features of the distribution can be explained by modeling the condensing proteins and the part of the genome in each adenosome as very soft spheres, interacting repulsively with each other and with the capsid, producing a minimum outward pressure of ∼0.06 atm. Although the condensing proteins are connected by DNA in disrupted virion cores, in our models a backbone of DNA linking the adenosomes is not required to explain the experimental results in the confined state. In conclusion, the interior of an adenovirus infectious particle is a strongly confined and dense phase of soft particles (adenosomes) without a strictly defined DNA backbone.

Pinnatifidenyne-Derived Ethynyl Oxirane Acetogenins from Laurencia viridis.

Red algae of Laurencia continue to provide wide structural diversity and complexity of halogenated C15 acetogenin medium-ring ethers. Here, we described the isolation of three new C15 acetogenins (3-5), and one truncated derivative (6) from Laurencia viridis collected on the Canary Islands. These compounds are interesting variations on the pinnatifidenyne structure that included the first examples of ethynyl oxirane derivatives (3-4). The structures were elucidated by extensive study of NMR (Nuclear Magnetic Resonance) data, J-based configuration analysis and DFT (Density Functional Theory) calculations. Their antiproliferative activity against six human solid tumor cell lines was evaluated.

Synthesis and biological evaluation of crown ether acyl derivatives.

A set of crown ethyl acyl derivatives based on 18-crown-6 moiety was synthesized and evaluated for biological activity. In vitro antiproliferative profiling demonstrated significant activities against HBL-100, HeLa, SW1573 and WiDr human cell lines. The most active compound exhibited GI50 values in the range of 3.7-5.6µM. Antimicrobial evaluation showed that three polyaromatic compounds were active against Staphylococcus aureus (MIC90 values from 8.3µM to 50µM), whereas a (decyloxy)benzene substitution exhibited moderate activity against Candida albicans (MIC90 values 36µM). According to SAR evaluation, the size of the crown ether and the acyl side chain had a significant effect on the bioactivity. Aromatic moieties close to the acyl group led to improved bioactivity as exemplified by some of the tested compounds. These results provide further evidence on the potential of crown ethyl structure as a scaffold for developing new biological probes and lead candidates for drug development.