Antimicrobial activity of marine algal extracts

Total, hydrophilic and lipophilic extracts of 21 marine algae species (2 species of Chlorophyta, 11 of Phaeophyceae and 8 of Rhodophyta) collected along the coast of Russian Far East were screened for antimicrobial activities (against Staphylococcus aureus, Escherichia coli and Candida albicans). Among the macroalgal extracts analyzed, 95% were active against at least one of studied microorganisms, while 80% of extracts were active against two or more test strains. Broad-spectrum activity against three studied microorganisms was observed in the 35% of extracts from tested species of marine seaweeds. The results of our survey did not show clear taxonomic trends in the activities of the total extracts and their hydrophilic fractions against the studied microorganisms. Nevertheless, lipophilic red algal extracts had both the highest values and broadest spectrum of bioactivity among all survey algal extracts. More over, lipophilic extracts from red algal exhibited the highest activity against fungus C. albicans among tested algal extracts

Antimicrobial activity of marine algal extracts

Total, hydrophilic and lipophilic extracts of 21 marine algae species (2 species of Chlorophyta, 11 of Phaeophyceae and 8 of Rhodophyta) collected along the coast of Russian Far East were screened for antimicrobial activities (against Staphylococcus aureus, Escherichia coli and Candida albicans). Among the macroalgal extracts analyzed, 95% were active against at least one of studied microorganisms, while 80% of extracts were active against two or more test strains. Broad-spectrum activity against three studied microorganisms was observed in the 35% of extracts from tested species of marine seaweeds. The results of our survey did not show clear taxonomic trends in the activities of the total extracts and their hydrophilic fractions against the studied microorganisms. Nevertheless, lipophilic red algal extracts had both the highest values and broadest spectrum of bioactivity among all survey algal extracts. More over, lipophilic extracts from red algal exhibited the highest activity against fungus C. albicans among tested algal extracts

Phytoceramides from the Marine Sponge <i>Monanchora clathrata</i>: Structural Analysis and Cytoprotective Effects

In our research on sphingolipids from marine invertebrates, a mixture of phytoceramides was isolated from the sponge Monanchora clathrata (Western Australia). Total ceramide, ceramide molecular species (obtained by RP-HPLC, high-performance liquid chromatography on reversed-phase column) and their sphingoid/fatty acid components were analyzed by NMR (nuclear magnetic resonance) spectroscopy and mass spectrometry. Sixteen new (1b, 3a, 3c, 3d, 3f, 3g, 5c, 5d, 5f, 5g, 6b–g) and twelve known (2b, 2e, 2f, 3b, 3e, 4a–c, 4e, 4f, 5b, 5e) compounds were shown to contain phytosphingosine-type backbones i-t17:0 (1), n-t17:0 (2), i-t18:0 (3), n-t18:0 (4), i-t19:0 (5), or ai-t19:0 (6), N-acylated with saturated (2R)-2-hydroxy C21 (a), C22 (b), C23 (c), i-C23 (d), C24 (e), C25 (f), or C26 (g) acids. The used combination of the instrumental and chemical methods permitted the more detailed investigation of the sponge ceramides than previously reported. It was found that the cytotoxic effect of crambescidin 359 (alkaloid from M. clathrata) and cisplatin decreased after pre-incubation of MDA-MB-231 and HL-60 cells with the investigated phytoceramides. In an in vitro paraquat model of Parkinson’s disease, the phytoceramides decreased the neurodegenerative effect and ROS (reactive oxygen species) formation induced by paraquat in neuroblastoma cells. In general, the preliminary treatment (for 24 or 48 h) of the cells with the phytoceramides of M. clathrata was necessary for their cytoprotective functions, otherwise the additive damaging effect of these sphingolipids and cytotoxic compounds (crambescidin 359, cisplatin or paraquat) was observed

Cytoprotective Activity of p-Terphenyl Polyketides and Flavuside B from Marine-Derived Fungi against Oxidative Stress in Neuro-2a Cells

The influence of p-terphenyl polyketides 1–3 from Aspergillus candidus KMM 4676 and cerebroside flavuside B (4) from Penicillium islandicum (=Talaromyces islandicus) against the effect of neurotoxins, rotenone and paraquat, on Neuro-2a cell viability by MTT and LDH release assays and intracellular ROS level, as well as DPPH radical scavenging activity, was investigated. Pre-incubation with compounds significantly diminished the ROS level in rotenone- and paraquat-treated cells. It was shown that the investigated polyketides 1–3 significantly increased the viability of rotenone- and paraquat-treated cells in two of the used assays but they affected only the viability of paraquat-treated cells in the LDH release assay. Flavuside B statistically increased the viability of paraquat-treated cells in both MTT and LDH release assays, however, it increased the viability of rotenone-treated cells in the LDH release assay. Structure–activity relationships for p-terphenyl derivatives, as well as possible mechanisms of cytoprotective action of all studied compounds, were discussed

The Metabolite Profiling of <i>Aspergillus fumigatus</i> KMM4631 and Its Co-Cultures with Other Marine Fungi

An Aspergillus fumigatus KMM 4631 strain was previously isolated from a Pacific soft coral Sinularia sp. sample and was found to be a source of a number of bioactive secondary metabolites. The aims of this work are the confirmation of this strain’ identification based on ITS, BenA, CaM, and RPB2 regions/gene sequences and the investigation of secondary metabolite profiles of Aspergillus fumigatus KMM 4631 culture and its co-cultures with Penicillium hispanicum KMM 4689, Amphichorda sp. KMM 4639, Penicillium sp. KMM 4672, and Asteromyces cruciatus KMM 4696 from the Collection of Marine Microorganisms (PIBOC FEB RAS, Vladivostok, Russia). Moreover, the DPPH-radical scavenging activity, urease inhibition, and cytotoxicity of joint fungal cultures’ extracts on HepG2 cells were tested. The detailed UPLC MS qTOF investigation resulted in the identification and annotation of indolediketopiperazine, quinazoline, and tryptoquivaline-related alkaloids as well as a number of polyketides (totally 20 compounds) in the extract of Aspergillus fumigatus KMM 4631. The metabolite profiles of the co-cultures of A. fumigatus with Penicillium hispanicum, Penicillium sp., and Amphichorda sp. were similar to those of Penicillium hispanicum, Penicillium sp., and Amphichorda sp. monocultures. The metabolite profile of the co-culture of A. fumigatus with Asteromyces cruciatus differed from that of each monoculture and may be more promising for the isolation of new compounds

Anti-Inflammatory Activity of 1,4-Naphthoquinones Blocking P2X7 Purinergic Receptors in RAW 264.7 Macrophage Cells

P2X7 receptors are ligand-gated ion channels activated by ATP and play a significant role in cellular immunity. These receptors are considered as a potential therapeutic target for the treatment of multiple inflammatory diseases. In the present work, using spectrofluorimetry, spectrophotometry, Western blotting and ELISA approaches, the ability of 1,4-naphthoquinone thioglucoside derivatives, compounds U-286 and U-548, to inhibit inflammation induced by ATP/LPS in RAW 264.7 cells via P2X7 receptors was demonstrated. It has been established that the selected compounds were able to inhibit ATP-induced calcium influx and the production of reactive oxygen species, and they also exhibited pronounced antioxidant activity in mouse brain homogenate. In addition, compounds U-286 and U-548 decreased the LPS-induced activity of the COX-2 enzyme, the release of pro-inflammatory cytokines TNF-α and IL-1β in RAW 264.7 cells, and significantly protected macrophage cells against the toxic effects of ATP and LPS. This study highlights the use of 1,4-naphthoquinones as promising purinergic P2X7 receptor antagonists with anti-inflammatory activity. Based on the data obtained, studied synthetic 1,4-NQs can be considered as potential scaffolds for the development of new anti-inflammatory and analgesic drugs

Marine Fungal Cerebroside Flavuside B Protects HaCaT Keratinocytes against Staphylococcus aureus Induced Damage

Cerebrosides are glycosylated sphingolipids, and in mammals they contribute to the pro-/anti-inflammatory properties and innate antimicrobial activity of the skin and mucosal surfaces. Staphylococcus aureus infection can develop, not only from minor scratches of the skin, but this pathogen can also actively promote epithelial breach. The effect of cerebroside flavuside B from marine sediment-derived fungus Penicillium islandicum (Aniva Bay, the Sea of Okhotsk) on viability, apoptosis, total caspase activity, and cell cycle in human epidermal keratinocytes HaCaT line co-cultivated with S. aureus, as well as influence of flavuside B on LPS-treated HaCaT cells were studied. Influence of flavuside B on bacterial growth and biofilm formation of S. aureus and its effect on the enzymatic activity of sortase A was also investigated. It was found S. aureus co-cultivated with keratinocytes induces caspase-depended apoptosis and cell death, arrest cell cycle in the G0/G1 phase, and increases in cellular immune inflammation. Cerebroside flavuside B has demonstrated its antimicrobial and anti-inflammatory properties, substantially eliminating all the negative consequences caused by co-cultivation of keratinocytes with S. aureus or bacterial LPS. The dual action of flavuside B may be highly effective in the treatment of bacterial skin lesions and will be studied in the future in in vivo experiments

Phanogracilins A–C, New Bibenzochromenones of Crinoid <i>Phanogenia gracilis</i> (Hartlaub, 1890)

Three new bibenzochromenones named phanogracilins A–C (1–3) were isolated from the crinoid Phanogenia gracilis. The structure of 1 was established using X-ray crystallography as 5,5′,6,6′,8,8′-hexahydroxy-2,2′-dipropyl-4H,4′H-[7,9′-bibenzo[g]chromene]-4,4′-dione. This allowed us to assign reliably 2D NMR signals for compound 1 and subsequently for its isomer 2 that differed in the connecting position of two benzochromenone moieties (7,10′ instead of 7,9′), and compound for 3 that differed in the length of the aliphatic chain of one of the fragments. Compound 4 was derived from 1 in alkaline conditions, and its structure was elucidated as 5,5′,6′,8,8′-pentahydroxy-2,2′-dipropyl-4H,4′H-[7,9′-bibenzo[g]chromene]-4,4′,6,9-tetraone. Even though compounds 1–4 did not contain stereo centers, they possessed notable optical activity due to sterical hindrances, which limited the internal rotation of two benzochromenone fragments around C(7)–C(9′/10′) bonds. Isolated bibenzochromenones 1–4 were tested for their antiradical, neuroprotective and antimicrobial activities. Compounds 1, 3 and 4 demonstrated significant antiradical properties towards ABTS radicals higher than the positive control trolox. Compounds 1 and 4 exhibited moderate neuroprotective activity, increasing the viability of rotenone-treated Neuro-2a cells at a concentration of 1 µM by 9.8% and 11.8%, respectively. Compounds 1 and 3 at concentrations from 25 to 100 μM dose-dependently inhibited the growth of Gram-positive bacteria S. aureus and yeast-like fungi C. albicans, and they also prevented the formation of their biofilms. Compounds 2 and 4 exhibited low antimicrobial activity

Triterpene Glycosides from the Far Eastern Sea Cucumber Thyonidium (=Duasmodactyla) kurilensis (Levin): The Structures, Cytotoxicities, and Biogenesis of Kurilosides A3, D1, G, H, I, I1, J, K, and K1

Nine new mono-, di-, and trisulfated triterpene penta- and hexaosides, kurilosides A3 (1), D1 (2), G (3), H (4), I (5), I1 (6), J (7), K (8), and K1 (9) and two desulfated derivatives, DS-kuriloside L (10), having a trisaccharide branched chain, and DS-kuriloside M (11), having hexa-nor-lanostane aglycone with a 7(8)-double bond, have been isolated from the Far-Eastern deep-water sea cucumber Thyonidium (=Duasmodactyla) kurilensis (Levin) and their structures were elucidated based on 2D NMR spectroscopy and HR-ESI mass-spectrometry. Five earlier unknown carbohydrate chains and two aglycones (having a 16β,(20S)-dihydroxy-fragment and a 16β-acetoxy,(20S)-hydroxy fragment) were found in these glycosides. All the glycosides 1–9 have a sulfate group at C-6 Glc, attached to C-4 Xyl1, while the positions of the other sulfate groups vary in different groups of kurilosides. The analysis of the structural features of the aglycones and the carbohydrate chains of all the glycosides of T. kurilensis showed their biogenetic relationships. Cytotoxic activities of the compounds 1–9 against mouse neuroblastoma Neuro 2a, normal epithelial JB-6 cells, and erythrocytes were studied. The highest cytotoxicity in the series was demonstrated by trisulfated hexaoside kuriloside H (4), having acetoxy-groups at C(16) and C(20), the latter one obviously compensated the absence of a side chain, essential for the membranolytic action of the glycosides. Kuriloside I1 (6), differing from 4 in the lacking of a terminal glucose residue in the bottom semi-chain, was slightly less active. The compounds 1–3, 5, and 8 did not demonstrate cytotoxic activity due to the presence of hydroxyl groups in their aglycones

Neuroprotective Metabolites from Vietnamese Marine Derived Fungi of Aspergillus and Penicillium Genera

Low molecular weight secondary metabolites of marine fungi Aspergillus flocculosus, Aspergillus terreus and Penicillium sp. from Van Phong and Nha Trang Bays (Vietnam) were studied and a number of polyketides, bis-indole quinones and terpenoids were isolated. The structures of the isolated compounds were determined by 1D and 2D NMR and HR-ESI-MS techniques. Stereochemistry of some compounds was established based on ECD data. A chemical structure of asterriquinone F (6) was thoroughly described for the first time. Anthraquinone (13) was firstly obtained from a natural source. Neuroprotective influences of the isolated compounds against 6-OHDA, paraquat and rotenone toxicity were investigated. 4-Hydroxyscytalone (1), 4-hydroxy-6-dehydroxyscytalone (2) and demethylcitreoviranol (3) have shown significant increasing of paraquat- and rotenone-treated Neuro-2a cell viability and anti-ROS activity