Red Sea Sponge Research Articles

Pullenvalenes E-H: Triterpenyl-Aminoglycosides from an Australian Soil-Derived Fungus, Clonostachys sp.

Chemical profiling of soil-derived microbes collected under the auspices of the Australian citizen science initiative Soils for Science detected two fungi, Clonostachys sp. S4S-07771A07 and Coccidiodes sp. S4S-14879B01, capable of producing pullenvalenes, a rare class of triterpene glycoside. Cultivation profiling followed by scaled up cultivation and fractionation of the former yielded the known pullenvalenes A-D (1-4) and the new analogues E-H (5-8), with structures secured by detailed spectroscopic analysis and biogenetic considerations. This study reveals that the pullenvalenes 1-8 are produced by several genera of fungi (Clonostachys, Coccidiodes and Talaromyces) recovered from different geographic locations and substrates. We also draw attention to structural and biosynthetic similarities with the known Red Sea sponge metabolites neviotines A-D (9-12) and abudinols A-B (13-14), prompting speculation that the latter may be products of sponge-associated fungi.

Metagenomic mining of two Egyptian Red Sea sponges associated microbial community

The Red Sea is a promising habitat for the discovery of new bioactive marine natural products. Sponges associated microorganisms represent a wealthy source of compounds with unique chemical structures and diverse biological activities. Metagenomics is an important omics-based culture-independent technique that is used as an effective tool to get genomic and functional information on sponge symbionts. In this study, we used metagenomic analysis of two Egyptian Red Sea sponges Hyrtios erectus and Phorbas topsenti microbiomes to study the biodiversity and the biosynthetic potential of the Red Sea sponges to produce bioactive compounds. Our data revealed high biodiversity of the two sponges’ microbiota with phylum Proteobacteria as the most dominant phylum in the associated microbial community with an average of 31% and 70% respectively. The analysis also revealed high biosynthetic potential of sponge Hyrtios erectus microbiome through detecting diverse types of biosynthetic gene clusters (BGCs) with predicted cytotoxic, antibacterial and inhibitory action. Most of these BGCs were predicted to be novel as they did not show any similarity with any MIBiG database known cluster. This study highlights the importance of the microbiome of the collected Red Sea sponge Hyrtios erectus as a valuable source of new bioactive natural products.

Red Sea Sponge Extract Callyspongia siphonella and its Metabolites Induced Anticancer Activity in 2D and 3D Culture of Colon Cancer Cells.

Colorectal Cancer (CRC) significantly contributes to global cancer-related mortality and morbidity. Callyspongia siphonella (Callyspongia sp.), a Red Sea sponge, has shown promising activity as an anticancer extract and a source of anticancer-active compounds. This study sought to determine the effects of Callyspongia siphonella and its metabolites on HCT-116 colon cancer cells. Cell viability assays showed that Callyspongia sp. inhibited in a dose-dependent manner, the growth of HCT-116 cell lines with IC50 values of 64.8±17 ug/ml on 2D culture and 141.1±6.8 ug/ml on 3D culture. The purified compounds Sipholenol-A and Sipholenone-A have an IC50 of 48.9±2.2 uM and 47.1±1.2 uM respectively. Following Callyspongia sp. treatment of HCT-116, cell cycle analysis showed arrest at G2/M.flow cytometry analysis showed an increase in total apoptosis due to Callyspongia sp treatment. Moreover, mitochondria membrane potential has been reported to be depolarized due to Callyspongia sp. which is an extra sign of apoptosis. Further investigations are needed to explain the particular underlying mechanisms of Callyspongia sp. extract and its metabolites Sipholenol-A and Sipholenone-A to explore their therapeutic potential in treating colon cancer.

Green synthesized extracts/Au complex of Phyllospongia lamellosa: Unrevealing the anti-cancer and anti-bacterial potentialities, supported by metabolomics and molecular modeling

The anti-cancer and anti-bacterial potential of the Red Sea sponge Phyllospongia lamellosa in its bulk (crude extracts) and gold nanostructure (loaded on gold nanaoparticles) were investigated. Metabolomics analysis was conducted, and subsequently, molecular modeling studies were conducted to explore and anticipate the P. lamellosa secondary metabolites and their potential target for their various bioactivities. The chloroformic extract (CE) and ethyl acetate extract (EE) of the P. lamellosa predicted to include bioactive lipophilic and moderately polar metabolites, respectively, were used to synthesize gold nanoparticles (AuNPs). The prepared AuNPs were characterized through transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and UV–vis spectrophotometric analyses. The cytotoxic activities were tested against MCF-7, MDB-231, and MCF-10A. Moreover, the anti-bacterial, antifungal, and anti-biofilm activity were assessed. Definite classes of metabolites were identified in CE (terpenoids) and EE (brominated phenyl ethers and sulfated fatty amides). Molecular modeling involving docking and molecular dynamics identified Protein-tyrosine phosphatase 1B (PTP1B) as a potential target for the anti-cancer activities of terpenoids. Moreover, CE exhibited the most powerful activity against breast cancer cell lines, matching our molecular modeling study. On the other hand, only EE was demonstrated to possess powerful anti-bacterial and anti-biofilm activity against Escherichia coli. In conclusion, depending on their bioactive metabolites, P. lamellosa-derived extracts, after being loaded on AuNPs, could be considered anti-cancer, anti-bacterial, and anti-biofilm bioactive products. Future work should be completed to produce drug leads.

Red Sea Sponge Callyspongia siphonella Extract Induced Growth Inhibition and Apoptosis in Breast MCF-7 and Hepatic HepG-2 Cancer Cell Lines in 2D and 3D Cell Cultures.

The increasing incidence of cancer diseases necessitates the urgent exploration of new bioactive compounds. One of the trends in drug discovery is marine sponges which is gaining significant support due to the abundant production of natural pharmaceutical compounds obtained from marine ecosystems. This study evaluates the anticancer properties of an organic extract from the Red Sea sponge Callyspongia siphonella (C. siphonella) on HepG-2 and MCF-7 cancer cell lines. C. siphonella was collected, freeze-dried, and extracted using a methanol-dichloromethane mixture. The extract was analyzed via Liquid Chromatography-Mass Spectrometry. Cytotoxic effects were assessed through cell viability assays, apoptosis detection, cell cycle analysis, mitochondrial membrane potential assays, scratch-wound healing assays, and 3D cell culture assays. Fifteen compounds were identified in the C. siphonella extract. The extract showed moderate cytotoxicity against MCF-7 and HepG-2 cells, with IC50 values of 35.6 ± 6.9 μg/mL and 64.4 ± 8 μg/mL, respectively, after 48 hours of treatment. It induced cell cycle arrest at the G2/M phase in MCF-7 cells and the S phase in HepG-2 cells. Apoptosis increased significantly in both cell lines, accompanied by reduced mitochondrial membrane potential. The extract inhibited cell migration, with notable reductions after 24 and 48 hours. In 3D cell cultures, the extract had IC50 values of 5.1 ± 2 μg/mL for MCF-7 and 166.4 ± 27 μg/mL for HepG-2 after 7 days of treatment, showing greater potency in MCF-7 spheres compared to HepG-2 spheres. The anticancer activity is attributed to the bioactive compounds. The C. siphonella extract's ability to induce apoptosis, disrupt mitochondrial membrane potential, and arrest the cell cycle highlights its potential as a novel anticancer agent. Additional research is required to investigate the underlying mechanism by which this extract functions as a highly effective anticancer agent.

Targeting antimalarial metabolites from the actinomycetes associated with the Red Sea sponge Callyspongia siphonella using a metabolomic method

Malaria is a persistent illness that is still a public health issue. On the other hand, marine organisms are considered a rich source of anti‑infective drugs and other medically significant compounds. Herein, we reported the isolation of the actinomycete associated with the Red Sea sponge Callyspongia siphonella. Using "one strain many compounds" (OSMAC) approach, a suitable strain was identified and then sub-cultured in three different media (M1, ISP2 and OLIGO). The extracts were evaluated for their in-vitro antimalarial activity against Plasmodium falciparum strain and subsequently analyzed by Liquid chromatography coupled with high-resolution mass spectrometry (LC-HR-MS). In addition, MetaboAnalyst 5.0 was used to statistically analyze the LC-MS data. Finally, Molecular docking was carried out for the dereplicated metabolites against lysyl-tRNA synthetase (PfKRS1). The phylogenetic study of the 16S rRNA sequence of the actinomycete isolate revealed its affiliation to Streptomyces genus. Antimalarial screening revealed that ISP2 media is the most active against Plasmodium falciparum strain. Based on LC-HR-MS based metabolomics and multivariate analyses, the static cultures of the media, ISP2 (ISP2-S) and M1 (M1-S), are the optimal media for metabolites production. OPLS-DA suggested that quinone derivatives are abundant in the extracts with the highest antimalarial activity. Fifteen compounds were identified where eight of these metabolites were correlated to the observed antimalarial activity of the active extracts. According to molecular docking experiments, saframycin Y3 and juglomycin E showed the greatest binding energy scores (-6.2 and -5.13) to lysyl-tRNA synthetase (PfKRS1), respectively. Using metabolomics and molecular docking investigation, the quinones, saframycin Y3 (5) and juglomycin E (1) were identified as promising antimalarial therapeutic candidates. Our approach can be used as a first evaluation stage in natural product drug development, facilitating the separation of chosen metabolites, particularly biologically active ones.

Metagenomic and metatranscriptomic exploration of the Egyptian Red Sea sponge Theonella sp. associated microbial community.

Marine sponges associated microorganisms are considered to be prolific source of bioactive natural products. Omics-based techniques such as metagenomics and metatranscriptomics have been used as effective tools to discover natural products. In this study, we used integrated metagenomic and metatranscriptomic analysis of three samples of the Egyptian Red Sea sponge Theonella sp. microbiome to obtain a complete picture of its biosynthetic activity to produce bioactive compounds. Our data revealed high biodiversity of the Egyptian sponge microbiota represented by 38 bacterial phyla with Candidate Phylum Poribacteria as the most abundant phyla with an average of 27.5% of the microbial community. The analysis also revealed high biosynthetic activity of the sponge microbiome through detecting different types of biosynthetic gene clusters (BGCs) with predicted antibacterial, cytotoxic and inhibitory bioactivity and the majority of these clusters were found to be actively transcribed. The complete BGCs of the cytotoxic theonellamide and misakinolide were detected and found to be actively transcribed. The majority of the detected BGCs were predicted to be novel as they did not show any similarity with any known cluster in the MIBiG database.

A comparison of mesophotic and shallow sponge holobionts resilience to predicted future temperature elevation

Climate change is predicted to have detrimental impacts on sessile invertebrates, including sponges. Mesophotic ecosystems have been suggested to play a major role as refugia for coral reef sponge species, however knowledge regarding the ability of mesophotic sponges to cope with thermal stress is scarce. In this study we compared the response of the sponge Diacarnus erythraeanus, a widespread Red Sea sponge, from the shallow and mesophotic reef, to moderate and acute temperature elevation (2°C and 6°C, respectively) for short and long term periods (two and 35 days, respectively) by measuring physiological parameters (respiration, oxygen removal, pumping rates, and photosynthetic efficiency), and the microbiome composition change. The results indicated that mesophotic and shallow populations of D. erythraeanus are highly tolerant to both moderate and acute heat stress, demonstrating a high survival rate (100%) across the experimental treatments, with no visible signs of bleaching or necrosis. Exposure to heat stress resulted in significant alterations in the physiological parameters of sponges, including higher respiration rate and lower photosynthetic efficiency. These alterations were accompanied by correspondingly significant microbial adjustments, thus emphasizing the essential role of the microbiome in the host’s ability to persist when facing essential environmental stress. Moreover, while shallow and mesophotic sponges showed similar physiological tolerance to heat stress, their microbial response differed: while the microbiome diversity of the mesophotic sponges remained stable throughout the experiment, the shallow one significantly changed. This result suggests that their underlying coping mechanisms might differ between mesophotic and shallow populations. Since the associated-microbiome is largely regulated by the sponge-host genetics, difference in microbial adjustments to stress between populations, could indicate genetic variability between hosts. Therefore, while the results of this study support the hypothesis that mesophotic coral reefs could serve as thermal refugia for some sponge species, it raises the question regarding the validity of MCEs as a refuge for shallow populations. Finally, it emphasizes the crucial need to elucidate the underlying mechanisms governing the sponge-microbiome interactions, specifically in the context of the anticipated climate change scenarios.

New 3,4-seco-3,19-Dinor- and Spongian-Based Diterpenoid Lactones from the Marine Sponge Spongia sp.

Continuing chemical investigation of the Red Sea sponge Spongia sp. led to the isolation of four new 3,4-seco-3,19-dinorspongian diterpenoid lactones, secodinorspongins A-D (1-4), along with a classical spongian diterpenoid lactone, sponginolide (5). The chemical structures, including the absolute configurations of these compounds, were elucidated using the extensive spectroscopic study composed of 1D and 2D NMR data analyses, and a comparison between calculated-electronic-circular-dichroism (ECD) and experimental-circular-dichroism (CD) spectra. A plausible biosynthetic pathway of 1-4 was also proposed. Furthermore, the cytotoxicity, antibacterial and anti-inflammatory activities of 1-5 were evaluated. Compound 1 was found to exhibit inhibitory activity against the growth of Staphylococcus aureus (S. aureus), and 4 and 5 exhibited suppression of superoxide-anion generation and elastase release in fMLF/CB-induced human neutrophils.

Screening and Molecular Docking of Bioactive Metabolites of the Red Sea Sponge Callyspongia siphonella as Potential Antimicrobial Agents.

Marine sponges create a wide range of bioactive secondary metabolites, as documented throughout the year. Several bioactive secondary metabolites were isolated from different members of Callyspongia siphonella species. This study aimed for isolation and structural elucidation of major metabolites in order to investigate their diverse bioactivities such as antimicrobial and anti-biofilm activities. Afterwards, a molecular docking study was conducted, searching for the possible mechanistic pathway of the most bioactive metabolites. Extraction, fractionation, and metabolomics analysis of different fractions was performed in order to obtain complete chemical profile. Moreover, in vitro assessment of different bioactivities was performed, using recent techniques. Additionally, purification, structural elucidation of high features using recent chromatographic and spectroscopic techniques was established. Finally, AutoDock Vina software was used for the Pharmacophore-based docking-based analysis. As a result, DCM (dichloromethane) fraction exerted the best antibacterial activity using disc diffusion method; particularly against S. aureus with an inhibition zone of 6.6 mm. Compound 11 displayed a considerable activity against both MRSA (Methicillin-resistant Staphyllococcus aureus) and Staphyllococcus aureus with inhibition ratios of 50.37 and 60.90%, respectively. Concerning anti-biofilm activity, compounds 1 and 2 displayed powerful activity with inhibition ratios ranging from 39.37% to 70.98%. Pharmacophore-based docking-based analysis suggested elongation factor G (EF-G) to be a probable target for compound 11 (siphonellinol C) that showed the best in vitro antibacterial activity, offering unexplored potential for new drugs and treatment candidates.

Neuroprotective Effect of Red Sea Marine Sponge Xestospongia testudinaria Extract Using In Vitro and In Vivo Diabetic Peripheral Neuropathy Models.

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes. Oxidative stress plays an important role in the pathophysiology of DPN. Red Sea marine sponge Xestospongia testudinaria extract has a promising neuroprotective effect, presumably owing to its antioxidant and anti-inflammatory properties. Thus, this study aimed to investigate the neuroprotective effect of the sponge X. testudinaria extract on in vitro and in vivo models of DPN. Mice dorsal root ganglia (DRG) were cultured with high glucose (HG) media and used as an in vitro model of DPN. Some of the DRGs were pre-treated with 2 mg/mL of X. testudinaria. The X. testudinaria extract significantly improved the HG-induced decreased neuronal viability and the neurite length. It improved the oxidative stress biomarkers in DRG cultures. The DPN model was induced in vivo by an injection of streptozotocin at a dose of 150 mg/kg in mice. After 35 days, 0.75 mg/kg of the X. testudinaria extract improved the hot hyperalgesia and the DRG histology. Although the sponge extract did not reduce hyperglycemia, it ameliorated the oxidative stress markers and pro-inflammatory markers in the DRG. In conclusion, the current study demonstrates the neuroprotective effect of Red Sea sponge X. testudinaria extract against experimentally induced DPN through its antioxidant and anti-inflammatory mechanisms.

Network Pharmacological Analysis of the Red Sea Sponge Hyrtios erectus Extract to Reveal Anticancer Efficacy of Corresponding Loaded Niosomes.

In this study, the LC-HRMS-assisted chemical profiling of Hyrtios erectus sponge led to the annotation of eleven major compounds (1–11). H. erectus-derived crude extract (HE) was tested in vitro for its antiproliferative activity against three human cancer cell lines, Hep-G2 (human liver cancer cell line), MCF-7 (breast cancer cell line), and Caco-2 (colon cancer cell line), before and after encapsulation within niosomes. Hyrtios erectus extract showed moderate in vitro antiproliferative activities towards the studied cell lines with IC50 values 18.5 ± 0.08, 15.2 ± 0.11, and 13.4 ± 0.12, respectively. The formulated extract-containing niosomes (size 142.3 ± 10.3 nm, PDI 0.279, and zeta potential 22.8 ± 1.6) increased the in vitro antiproliferative activity of the entrapped extract significantly (IC50 8.5 ± 0.04, 4.1 ± 0.07, and 3.4 ± 0.05, respectively). A subsequent computational chemical study was performed to build a sponge–metabolite–targets–cancer diseases network, by focusing on targets that possess anticancer activity toward the three cancer types: breast, colon, and liver. Pubchem, BindingDB, and DisGenet databases were used to build the network. Shinygo and KEGG databases in addition to FunRich software were used for gene ontology and functional analysis. The computational analysis linked the metabolites to 200 genes among which 147 genes related to cancer and only 64 genes are intersected in the three cancer types. The study proved that the co-occurrence of compounds 1, 2, 3, 7, 8, and 10 are the most probable compounds possessing cytotoxic activity due to large number of connections to the intersected cytotoxic genes with edges range from 9-14. The targets possess the anticancer effect through Pathways in cancer, Endocrine resistance and Proteoglycans in cancer as mentioned by KEGG and ShinyGo 7.1 databases. This study introduces niosomes as a promising strategy to promote the cytotoxic potential of H. erectus extract.

Spongenolactones A-C, Bioactive 5,5,6,6,5-Pentacyclic Spongian Diterpenes from the Red Sea Sponge Spongia sp.

Three new 5,5,6,6,5-pentacyclic spongian diterpenes, spongenolactones A–C (1–3), were isolated from a Red Sea sponge Spongia sp. The structures of the new metabolites were elucidated by extensive spectroscopic analysis and the absolute configurations of 1–3 were determined on the basis of comparison of the experimental circular dichroism (CD) and calculated electronic circular dichroism (ECD) spectra. Compounds 1–3 are the first 5,5,6,6,5-pentacyclic spongian diterpenes bearing an β-hydroxy group at C-1. These metabolites were assayed for their cytotoxic, antibacterial, and anti-inflammatory activities. All three compounds were found to exert inhibitory activity against superoxide anion generation in fMLF/CB-stimulated human neutrophils. Furthermore, 1 showed a higher activity against the growth of Staphylococcus aureus in comparison to 2.

The Chemically Highly Diversified Metabolites from the Red Sea Marine Sponge Spongia sp.

A polyoxygenated and halogenated labdane, spongianol (1); a polyoxygenated steroid, 3β,5α,9α-trihydroxy-24S-ethylcholest-7-en-6-one (2); a rare seven-membered lactone B ring, (22E,24S)-ergosta-7,22-dien-3β,5α-diol-6,5-olide (3); and an α,β-unsaturated fatty acid, (Z)-3-methyl-9-oxodec-2-enoic acid (4) as well as five known compounds, 10-hydroxykahukuene B (5), pacifenol (6), dysidamide (7), 7,7,7-trichloro-3-hydroxy-2,2,6-trimethyl-4-(4,4,4-trichloro-3-methyl-1-oxobu-tylamino)-heptanoic acid methyl ester (8), and the primary metabolite 2’-deoxynucleoside thymidine (9), have been isolated from the Red Sea sponge Spongia sp. The stereoisomer of 3 was discovered in Ganoderma resinaceum, and metabolites 5 and 6, isolated previously from red algae, were characterized unprecedentedly in the sponge. Compounds 7 and 8 have not been found before in the genus Spongia. Compounds 1–9 were also assayed for cytotoxicity as well as antibacterial and anti-inflammatory activities.

Two Red Sea Sponge Extracts (Negombata magnifica and Callyspongia siphonella) Induced Anticancer and Antimicrobial Activity

Bioactive compounds extracted from marine organisms showed several biological activities. The present study is an extension of our earlier studies where we assessed the antiproliferative and pro-apoptotic activities of ethanol, methylene chloride, ethyl acetate, acetone, and chloroform crude extracts of sponges: Negombata magnifica (NmE) and Callyspongia siphonella (CsE) against cancer cells. Herein, we are extending our previous findings on both sponge species depending on an alternative methanol extraction method with more advanced molecular biochemical insights as additional proof for anticancer and antimicrobial activity of N. magnifica and C. siphonella. Therefore, sponge specimens were collected during winter 2020 from the Dahab region at the Gulf of Aqaba. Each sponge was macerated with methanol to obtain the crude extracts; NmE and CsE. GC–MS analysis presented a total of 117 chemical compounds; 37 bioactive, 11 represented previously as constituents for a natural organism, and 69 had no biological activities. NmE dose-dependently inhibited the growth of HepG2, MCF-7, and Caco-2 carcinoma cell lines compared to CsE, which unfortunately has no antiproliferative activity against the same cancer cells. NmE was found to induce G0/G1 cell cycle arrest in HepG2 cells with its inhibition for CDK6, Cyclins D1, and E1 in HepG2, MCF-7, and Caco-2 cells. NmE also activated ROS production in HepG2 cells and induced apoptosis in HepG2, MCF-7, and Caco-2 cells via an increase in pro-apoptotic protein Bax, caspase-3, and cleavage PARP, and a decrease in anti-apoptotic protein BCL2. Unlike its anticancer potential, CsE exhibited clear superior results as an antimicrobial agent with a wider range against six microbial strains, whereas NmE showed a positive antibacterial activity against only two strains.

Anti-Cancer and Anti-Inflammatory Potential of the Green Synthesized Silver Nanoparticles of the Red Sea Sponge Phyllospongia lamellosa Supported by Metabolomics Analysis and Docking Study.

Background: The Red Sea sponges have been endorsed as a plentiful source of bioactive compounds with promising anti-cancer and anti-inflammatory activities; therefore, exploring their potential as a source of anti-cancer metabolites has stimulated a growing research interest. Purpose: To investigate the anti-cancer and anti-inflammatory potential of the Red Sea sponges, in their bulk and silver nanostructure. Metabolomics analysis of the selected sponge followed by molecular docking studies, will be conducted to explore and predict the secondary metabolites that might provide its capability of inhibiting cancer. Materials and Methods: We prepared a chloroform extract (CE) and ethyl acetate extract (EE) of the Red Sea sponge Phyllospongia lamellosa synthesized silver nanoparticles. The prepared silver nanoparticles were characterized through UV–vis spectrophotometric, transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR) analyses. Testing for their anti-cancer activities was performed against MCF-7, MDB-231, and MCF-10A cells. Anti-inflammatory activity against COX-1 and 2 was assessed. Furthermore, liquid chromatography–mass spectrometry (LC–MS)-based metabolomics analysis and molecular docking were also applied.

Influencing the Actin Dynamics in Plant Cells by Jasplakinolide, Chondramides, Phalloidin, Cytochalasins, and Latrunculins.

This chapter presents an overview of the most common F-actin influencing substances, used to study actin dynamics in living plant cells for studies on morphogenesis, motility, organelle movement, apoptosis, or abiotic stress. These substances can be divided into two major subclasses-F-actin-stabilizing and F-actin-polymerizing substances like jasplakinolide and chondramides and F-actin-severing compounds like cytochalasins and latrunculins. Jasplakinolide, which may have anti-cancer activities, was originally isolated from a marine sponge and can now be synthesized and has become commercially available, which is responsible for its wide distribution as membrane-permeable F-actin-stabilizing and F-actin-polymerizing agent. Recently an acyclic derivate of jasplakinolide was isolated. Cytochalasins, derived from fungi, show an F-actin-severing function, and many derivatives are commercially available (A, B, C, D, E, H, J), also making it a widely used compound for F-actin disruption. The same can be stated for latrunculins (A, B), derived from Red Sea sponges; however the mode of action is different by binding to G-actin and inhibiting incorporation into the filament. In the case of swinholide, isolated from red algae or the cyanobacterium Nostoc, a stable complex with actin dimers is formed, resulting in severing F-actin.For influencing F-actin dynamics in plant cells, only membrane permeable drugs are useful in a broad range. We, however, introduce also the phallotoxins and synthetic derivatives thereof, as they are widely used to visualize F-actin in fixed cells. A particular uptake mechanism has been shown for hepatocytes but has also been described in siphonal giant algae. The focus is set on F-actin dynamics in plant cells where alterations in cytoplasmic streaming can be particularly well studied; moreover fluorescence methods for phalloidin- and antibody staining as well as techniques for immunoelectron microscopy are explained.

Fusaripyridines A and B; Highly Oxygenated Antimicrobial Alkaloid Dimers Featuring an Unprecedented 1,4-Bis(2-hydroxy-1,2-dihydropyridin-2-yl)butane-2,3-dione Core from the Marine Fungus Fusarium sp. LY019.

The fungal strain, Fusarium sp. LY019, was obtained from the Red Sea sponge Suberea mollis. Bioassay-directed partition of the antimicrobial fraction of the extract of the culture of the fungus provided two dimeric alkaloids, fusaripyridines A and B (1 and 2). The compounds possess a previously unreported moiety, 1,4-bis(2-hydroxy-1,2-dihydropyridin-2-yl)butane-2,3-dione. Further, the compounds display a highly oxygenated substitution pattern on the dihydropyridine moieties, representing an additional feature of the fusaripyridines. Fusaripyridines A and B are the first examples of natural products possessing 1,4-bis(2-hydroxy-1,2-dihydropyridin-2-yl)butane-2,3-dione backbone. Careful analyses of the one- and two-dimensional NMR and HRESIMS spectra of the compounds secured their structural mapping, while their absolute stereochemistry was established by analyses of their ECD spectra. The production of such dimeric alkaloids with an unprecedented moiety in the culture of Fusarium sp. LY019 supports further understanding of the biosynthetic competences of the cultured marine-derived fungi. Fusaripyridines A and B selectively inhibited the growth of Candida albicans with MIC values down to 8.0 µM, while they are moderately active against S. aureus, E. coli and HeLa cells.

Psammaceratin A: A Cytotoxic Psammaplysin Dimer Featuring an Unprecedented (2Z,3Z)-2,3-Bis(aminomethylene)succinamide Backbone from the Red Sea Sponge Pseudoceratina arabica.

Bioassay-guided partition of the extract of the Red Sea sponge Pseudoceratina arabica and HPLC purification of the active fraction gave a psammaplysin dimer, psammaceratin A (1), along with psammaplysin A (2). The dimer comprises two units of psammaplysin A (2) connected via the terminal amines with an unprecedented (2Z,3Z)-2,3-bis(aminomethylene)succinamide moiety, and it represents the first dimer to be identified among the psammaplysin family. Data from 1D- and 2D-NMR and HRMS supported the chemical structures of the compounds. Psammaceratin A (1) and psammaplysin A (2) exhibited significant growth inhibition of HCT 116, HeLa, and MBA-MB-231 cells down to 3.1 μM.

Arsenate reducing bacteria isolated from the marine sponge Theonella swinhoei: Bioremediation potential

Arsenic (As) contamination of freshwater resources constitutes a major environmental issue affecting over 200 million people worldwide. Although the use of microorganisms for the bioremediation of As has been well studied, only very few candidates have been identified to date. Here, we investigated bacteria associated with the Red Sea sponge Theonella swinhoei and their potential to reduce As in a low-salinity liquid medium. This Indo-Pacific common sponge has been shown to hyper-accumulate As, at an average concentration of 8600 mg/g-1 in an environment uncontaminated by arsenic or barium. Four isolated strains of bacteria exhibited arsenic reduction potential by transforming inorganic As in the form of arsenate (iAsV) to arsenite (iAsIII). Two of these isolates were identified as Alteromonas macleodii and Pseudovibrio ascidisceicola, and the other two isolates, both belonging to the same species, were identified as Pseudovibrio denitrificans. The four isolates were then cultured in a low-salinity iAsV-rich medium (5 mM) and As concentration was measured over time using a specifically designed high-performance liquid chromatograph coupled to a mass spectrometer (HPLC-MS). Out of the four isolates, A. macleodii and P. ascidisceicola grew successfully in a low-salinity liquid medium and reduced AsV to AsIII at an average rate of 0.094 and 0.083 mM/h, respectively, thereby demonstrating great potential for the bioremediation of As-contaminated groundwater.