Simultaneous production of biofuel, and removal of heavy metals using marine alga Turbinaria turbinata as a feedstock in NEOM Region, Tabuk.

Depletion of fossil fuel and pollution by heavy metals are two major global issues. The cell wall of algae consists of polymers of polysaccharides such as cellulose, hemicellulose, alginate, starch, and many others that are readily hydrolyzed to monosaccharides and hence are amenable to fermentation into bioethanol. Moreover, algae contain lipids that may undergo trans-esterification to biodiesel, and can be absorbed by heavy metals. In this study, extraction of lipids from Turbinaria turbinata (common brown alga) from the beach of Sharma, NEOM, Tabuk, Saudi Arabia by different solvents hexane, methanol, and hexane: methanol (1:1), and trans-esterification was performed to obtain biodiesel and investigated by GC.MS. The alga residue after fats extractions by different solvents was used in bioremediation synthetic wastewater containing 50 ppm of As-3, Co+2, Cu+2, Fe+2, Mn+2, and Zn+2. The residue of defatted alga was hydrolyzed by 2% H2SO4 and then fermented to obtain bioethanol. The combination of hexane: methanol (1:1) gave the greatest amount of petroleum hydrocarbons, which contain Tetradecane, 5-methyl, Octacosane, Pentatriacontane, and a small amount of Cyclotrisiloxane, Hexamethyl. The most effective removal % was obtained with alga residue defatted by hexane: methanol (1:1), and methanol, 100% removal of As-3, 83% Co+2, 95% Cu+2, 97.25% Fe+2, Mn+2 79.69%, Zn+2 90.15% with 2 g alga /L at 3 hours. The lowest value of sugar was obtained with hexane: methanol residue but gave the highest bioethanol efficiency. Thus, it is possible to use Turbinaria turbinata, or brown alga as a feedstock to produce bio-diesel, and bioethanol, and to remove heavy metals from wastewater, which may have a great economic and environmental significance.

Halomicroarcula laminariae sp. nov. and Halomicroarcula marina sp. nov., extremely halophilic archaea isolated from salted brown alga Laminaria and coastal saline-alkali lands.

Four extremely halophilic archaeal strains, LYG-108T, LYG-24, DT1T and YSSS71, were isolated from salted Laminaria produced in Lianyungang and saline soil from the coastal beach at Jiangsu, PR China. The four strains were found to be related to the current species of Halomicroarcula (showing 88.1-98.5% and 89.3-93.6% similarities, respectively) as revealed by phylogenetic analysis based on 16S rRNA and rpoB' genes. These phylogenies were fully supported by the phylogenomic analysis, and the overall genome-related indexes (average nucleotide identity, DNA-DNA hybridization and average amino acid identity) among these four strains and the Halomicroarcula species were 77-84 %, 23-30 % and 71-83 %, respectively, clearly below the threshold values for species demarcation. Additionally, the phylogenomic and comparative genomic analyses revealed that Halomicroarcula salina YGH18T is related to the current species of Haloarcula rather than those of Halomicroarcula, Haloarcula salaria Namwong et al. 2011 is a later heterotypic synonym of Haloarcula argentinensis Ihara et al. 1997, and Haloarcula quadrata Oren et al. 1999 is a later heterotypic synonym of Haloarcula marismortui Oren et al. 1990. The major polar lipids of strains LYG-108T, LYG-24, DT1T and YSSS71 were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulphate, sulphated mannosyl glucosyl diether and additional glycosyl-cardiolipins. All these results showed that strains LYG-108T (=CGMCC 1.13607T=JCM 32950T) and LYG-24 (=CGMCC 1.13605=JCM 32949) represent a new species of the genus Halomicroarcula, for which the name Halomicroarcula laminariae sp. nov. is proposed; strains DT1T (=CGMCC 1.18928T=JCM 35414T) and YSSS71 (=CGMCC 1.18783=JCM 34915) also represent a new species of the genus Halomicroarcula, for which the name Halomicroarcula marina sp. nov. is proposed.

Identification of a genomic region linked with sex determination of Undaria pinnatifida (Alariaceae) through genomic resequencing and genetic linkage analyses of a segregating gametophyte family.

Different from the traditional knowledge about kelp, three sexual phenotypes (female, male, and monoecious) exist in the haploid gametophytes of Undaria pinnatifida. However, the sex-determining mechanisms remain unknown. Genetic linkage mapping is an efficient tool to identify sex-linked regions. In the present study, we resequenced a segregating gametophyte family based on the male genome of U. pinnatifida. A high-density genetic linkage map was constructed using 9887 SNPs, with an average distance of 0.41 cM between adjacent SNPs. On the basis of this genetic map and using the composite interval mapping method, we identified 62 SNPs significantly linked with the sexual phenotype. They were located at a position of 67.67 cM on the linkage group 23, corresponding to a physical range of 14.67 Mbp on the HiC_Scaffold_23 of the genome. Reanalysis of the previous specific length amplified fragment sequencing data according to the reference genome led to the identification of a sex-linked genomic region that encompassed the above-mentioned 14.67 Mbp region. Hence, this overlapped genomic range was likely the sex-determining region. Within this region, 129 genes were retrieved and 39 of them were annotated with explicit function, including the potential male sex-determining gene-encoding high mobility group (HMG) domain protein. Relative expression analysis of the HMG gene showed that its expression was higher in male gametophytes during the vegetative phase and monoecious gametophytes during both the vegetative and gametogenesis phases, but significantly lower in male gametophytes during the gametogenesis phase. These results provide a foundation for deciphering the sex-determining mechanism of U. pinnatifida.

Halorussus halobius sp. nov., Halorussus marinus sp. nov. and Halorussus pelagicus sp. nov., isolated from salted brown alga Laminaria.

Four halophilic archaeal strains, designated HD8-83T, LYG-36T, DLLS-82 and RC-68T, were isolated from the salted brown alga Laminaria of three different origins (Dalian, Lianyungang, Dalian and Rongcheng) in PR China. All strains had pleomorphic rod cells that were motile, lysed in distilled water, stained Gram-negative, and formed red-pigmented colonies on agar plate (except for DLLS-82, which formed white colonies). Based on phylogenetic analyses of the 16S rRNA genes, strain HD8-83T was closely related to Halorussus litoreus HD8-51T (97.9 % similarity), strain LYG-36T and DLLS-82 to Halorussus rarus TBN4T (94.4 % and 94.7 % similarities, respectively), and strain RC-68T to Halorussus salinus YJ-37-HT (96.9 % similarity). Results of phylogenetic analyses based on rpoB' genes and 728 concatenated single-copy orthologous clusters also showed that these strains formed three different branches and clustered tightly with the Halorussus members. The average nucleotide identity, average amino acid identity and in silico DNA-DNA hybridization values between strains LYG-36T and DLLS-82 were 98.9, 98 and 92.4%, showing that they were different strains of the same species. While those values between the isolates and other Halorussus members were below 84.7, 82.9 and 28.9 %, respectively. Based on the phenotypic, chemotaxonomic and phylogenetic properties, strains HD8-83T, LYG-36T, DLLS-82 and RC-68T represent three novel species of the genus Halorussus for which the names Halorussus halobius sp. nov. (type strain: HD8-83T=CGMCC 1.15334T=JCM 31110T), Halorussus marinus sp. nov. (type strain: LYG-36T=CGMCC 1.13606T=JCM 32952T; reference strain: DLLS-82=CGMCC 1.13604=JCM 32951) and Halorussus pelagicus sp. nov. (type strain: RC-68T=CGMCC 1.13609T=JCM 32953T) are proposed.

Functional identification of the 4-deoxy-L-erythro-5-hexoseulose uronate reductase from a brown alga, Saccharina japonica.

We previously reported the alginate lyase, SjAly, from a brown alga, Saccharina japonica, providing the first experimental evidence for a functional alginate-degradation enzyme in brown algae. 4-deoxy-L-erythro-5-hexoseulose uronate (DEHU), derived from an unsaturated monosaccharide, was identified as the minimum degradation product produced by SjAly-mediated lysis of alginate. DEHU was hitherto reported to be reduced to 2-keto-3-deoxy-gluconate (KDG) by a DEHU-specific reductase with NAD(P)H in alginate-assimilating organisms and its metabolism in alginate-producing organisms is unknown. Here, we report the functional identification of a DEHU reductase, SjRed, in S. japonica. Among the 14 tested compounds, only DEHU was used as a substrate and was converted to KDG in the presence of NADPH. Optimum temperature, pH, and KCl concentration required for SjRed activity were determined to be 25 °C, 7.2, and 100 mM, respectively. SjRed consists of 341 amino acid residues and is proposed to be a member of the aldo-keto reductase superfamily. Sequencing of SjRed revealed that it is composed of at least three exons. These results indicate the existence of an enzyme that reduces DEHU to KDG in S. japonica. This is the first report on the functional identification of a DEHU-reductase in alginate-producing organisms.

Targeted CRISPR-Cas9-based gene knockouts in the model brown alga Ectocarpus.

Brown algae are an important group of multicellular eukaryotes, phylogenetically distinct from both the animal and land plant lineages. Ectocarpus has emerged as a model organism to study diverse aspects of brown algal biology, but this system currently lacks an effective reverse genetics methodology to analyse the functions of selected target genes. Here, we report that mutations at specific target sites are generated following the introduction of CRISPR-Cas9 ribonucleoproteins into Ectocarpus cells, using either biolistics or microinjection as the delivery method. Individuals with mutations affecting the ADENINE PHOSPHORIBOSYL TRANSFERASE (APT) gene were isolated following treatment with 2-fluoroadenine, and this selection system was used to isolate individuals in which mutations had been introduced simultaneously at APT and at a second gene. This double mutation approach could potentially be used to isolate mutants affecting any Ectocarpus gene, providing an effective reverse genetics tool for this model organism. The availability of this tool will significantly enhance the utility of Ectocarpus as a model organism for this ecologically and economically important group of marine organisms. Moreover, the methodology described here should be readily transferable to other brown algal species.

A Marine-Derived Anti-Inflammatory Scaffold for Accelerating Skin Repair in Diabetic Mice.

Reconstructing the typical analogue of extracellular matrix (ECM) in engineered biomaterials is essential for promoting tissue repair. Here, we report an ECM-mimetic scaffold that successfully accelerated wound healing through enhancing vascularization and regulating inflammation. We prepared an electrospun fiber comprising a brown alga-derived polysaccharide (BAP) and polyvinyl alcohol (PVA). The two polymers in concert exerted the function upon the application of PVA/BAP2 fiber in vivo; it started to reduce the inflammation and promote angiogenesis at the wound site. Our serial in vitro and in vivo tests validated the efficacy of PVA/BAP2 fiber. Particularly, PVA/BAP2 fiber accelerated the repair of a full-thickness skin wound in diabetic mice and induced optimal neo-tissue formation. Generally, our results suggest that, by mimicking the function of ECM, this fiber as an engineered biomaterial can effectively promote the healing efficiency of diabetic wounds. Our investigation may inspire the development of new, effective, and safer marine-derived scaffold for tissue regeneration.

Density Functional Theory (DFT)-Aided Structure Elucidation of Linear Diterpenes from the Irish Brown Seaweed Bifurcaria bifurcata.

Brown alga Bifurcaria bifurcata is an extraordinarily rich source of linear (acylic) diterpenes with enormous structural diversity. As part of our interest into secondary metabolites of the Irish seaweeds, here we report four new acyclic diterpenes (1-4) and seven known terpenoids (5-11) from the CHCl3 extract of B. bifurcata. The planar structures of the new metabolites were elucidated by means of 1D and 2D NMR, HRMS, and FT-IR spectroscopy. Since linear diterpenes are highly flexible compounds, the assignment of their stereochemistry by conventional methods, e.g., NOESY NMR, is difficult. Therefore, we employed extensive quantum-mechanical prediction of NMR chemical shifts and optical rotation analyses to identify the relative and absolute configurations of the new compounds 1-4. Several compounds moderately inhibited the human breast cancer cell line (MDA-MB-231) with IC50 values ranging from 10.0 to 33.5 µg/mL. This study not only demonstrates the vast capacity of the Irish B. bifurcata to produce highly oxygenated linear diterpenoids, but also highlights the potential of new methodologies for assignment of their stereogenic centers.

Salinibaculum litoreum gen. nov., sp. nov., isolated from salted brown alga Laminaria.

A novel Gram-stain-negative, aerobic and rod-shaped halophilic archaeon, designated HD8-45T, was isolated from the red brine of salted brown alga Laminaria produced at Dalian, PR China. According to the results of 16S rRNA gene and rpoB' gene sequence comparisons, strain HD8-45T showed the highest sequence similarity to the corresponding genes of Salinirussus salinus YGH44T (95.1 and 85.2 % similarities, respectively), Halovenus aranensis EB27T (91.2 and 86.0 % similarities, respectively). The low sequence similarity and the phylogeny implied the novel generic status of strain HD8-45T. Genomic relatedness analyses showed that strain HD8-45T were clearly distinguished from other species in the order Halobacteriales, with average nucleotide identity, amino acid identity and in silico DNA-DNA hybridization values not more than 75.1, 65.6 and 21.5 %. The polar lipid pattern contained phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, two major glycolipids and two minor glycolipids. The two major glycolipids and a minor glycolipid were chromatographically identical to disulfated mannosyl glucosyl diether, sulfated mannosyl glucosyl diether and mannosyl glucosyl diether, respectively. The major respiratory quinones were menaquinone MK-8 and MK-8(H2). The DNA G+C content was 62.0 mol% (Tm) and 61.9 mol% (genome). All these results showed that strain HD8-45T represents a novel species of a new genus in the order Halobacteriales, for which the name Salinibaculum litoreum gen. nov., sp. nov. is proposed. The type strain of Salinibaculum litoreum is HD8-45T (=CGMCC 1.15328T=JCM 31107T).

Halostella pelagica sp. nov. and Halostella litorea sp. nov., isolated from salted brown alga Laminaria.

Three rod-shaped halophilic archaeal strains, DL-M4T, LYG-109 and DLLS-108T, were isolated from the salted brown alga Laminaria produced in different marine areas of PR China. Cells of strains were motile, formed red-pigmented colonies on agar and lysed in distilled water. The three strains grew optimally with 2.6 M NaCl, with 0.05-0.3 M MgCl2, at 37 °C and at pH 7.0-7.5. The results of phylogenetic analyses based on the 16S rRNA and rpoB' genes differentiated these strains into two clusters belonging to the genus Halostella, which currently contains Halostella salina CBA1114T and Halostella limicola LT12T. Strains DL-M4T and LYG-109 formed a single cluster separate from the current two members of Halostella (94.4-95.7 and 90.0-90.9 % similarities, respectively) while strain DLLS-108T had Hsl. salina CBA1114T as its nearest neighbour (97.7-97.8 and 95.9 % similarities, respectively) and was separated from Hsl. limicola LT12T (94.4-95.8 and 93.4 % similarities, respectively). These clusters represented two distinct novel species as indicated by phenotypic characteristics, polar lipid compositions and whole-genome comparisons. Diverse phenotypic characteristics, morphology and growth characteristics, nutrition and miscellaneous biochemical tests differentiate strains DL-M4T, LYG-109, DLLS-108T from Hsl. limicola LT12T and Hsl. salina CBA1114T. Strains DL-M4T and LYG-109 contained phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and three unidentified glycolipids, while strain DLLS-108T contained these polar lipids and two unidentified phospholipids. The major respiratory quinones detected in the three isolates were menaquinone MK-8 and MK-8(H2). The average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values between the isolated strains and the current two members of Halostella were found to be 79.3-86.6 (ANI) and 22.9-49.8 % (isDDH). All these results showed that the three isolates represent two novel species of the genus Halostella for which the names Halostella pelagica sp. nov. [type strain dl-M4T (=CGMCC 1.13603T=JCM 32954T)] and Halostella litorea sp. nov. [type strain DLLS-108T(=CGMCC 1.13610T=JCM 32955T)] are proposed.

Oxygenated Acyclic Diterpenes with Anticancer Activity from the Irish Brown Seaweed Bifurcaria bifurcata.

Brown alga Bifurcaria bifurcata is a prolific source of bioactive acyclic (linear) diterpenes with high structural diversity. In the continuation of our investigations on Irish brown algae, we undertook an in-depth chemical study on the n-hexanes and chloroform subextracts of B. bifurcata that led to isolation of six new (1-6) and two known (7-8) acyclic diterpenes. Chemical structures of the compounds were elucidated by a combination of 1D and 2D NMR, HRMS, FT-IR, [α]D and vibrational circular dichroism (VCD) spectroscopy. Compounds 1-8, as well as three additional linear diterpenes (9-11), which we isolated from the same seaweed before, were tested against the human breast cancer cell line (MDA-MB-231). Several compounds moderately inhibited the growth of the MDA-MB-231 cell line with IC50 values ranging from 11.6 to 32.0 µg/mL. The present study carried out on the lipophilic extracts of the Irish B. bifurcata shows the enormous capacity of this seaweed to produce a large palette of acyclic diterpenes with diverse oxygenation and substitution patterns and promising bioactivities.

Bioactive Molecular Networking for Mapping the Antimicrobial Constituents of the Baltic Brown Alga Fucus vesiculosus.

The brown alga Fucus vesiculosus is common to the intertidal zones of the Baltic Sea, where it is exposed to high fouling pressures by microorganisms. Our previous studies showed, repeatedly, the consistent antimicrobial activity of F. vesiculosus crude extracts against human pathogens, while untargeted metabolomics analyses have revealed a variety of metabolites. In this study, we applied the UPLC-QToF-MS/MS-based "bioactive molecular networking" (BMN) concept on the most bioactive n-hexane and n-butanol subextracts of Baltic F. vesiculosus coupled with in silico dereplication tools to identify the compounds responsible for antimicrobial activity. The first antimicrobial cluster identified by BMN was galactolipids. Our targeted isolation efforts for this class led to the isolation of six monogalactosyldiacylglycerol (MGDG) derivatives (1-6) and one digalactosyldiacylglycerol (DGDG, 7). The MGDGs 5 and 6 and the DGDG 7 exhibited activity against Staphylococcus aureus. The second compound class with high bioactivity was phlorotannins. In particular, phlorethol-type phlorotannins showed high correlations with antimicrobial activity based on the BMN approach, and two phlorotannins (8-9) were isolated. This study shows that antimicrobial components of F. vesiculosus reside in the algal cell walls and membranes and that BMN provides a complementary tool for the targeted isolation of bioactive metabolites.

Halorussus litoreus sp. nov., isolated from the salted brown alga Laminaria.

A halophilic archaeal strain, designated HD8-51T, was isolated from the salted brown alga Laminaria. Cells of strain HD8-51T were motile, pleomorphic coccoid or ovoid, and formed red-pigmented colonies on agar plates. Strain HD8-51T grew optimally at 3.1 M NaCl, 0.03 M MgCl2, 30 °C and pH 7.0. Cells lysed in distilled water and the minimal NaCl concentration to prevent cell lysis was 0.85 M. Based on phylogenetic analyses of the 16S rRNA and rpoB' genes, strain HD8-51T was most closely related to members of the genus Halorussus (92.3-95.6 % and 89.2-91.7% similarities, respectively). The average nucleotide identity values and in silico DNA-DNA hybridization values between strain HD8-51T and Halorussus rarus TBN4T were 81.69 and 24.5 %, respectively. The major polar lipids of strain HD8-51T were phosphatidic acid (PA), phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), phosphatidylglycerol sulfate (PGS) and five glycolipids, sulfated galactosyl mannosyl glucosyl diether (S-TGD-1), galactosyl mannosyl glucosyl diether (TGD-1), sulfated mannosyl glucosyl diether (S-DGD-1), mannosyl glucosyl diether (DGD-1) and diglycosyl diether (DGD-2). The DNA G+C content was 65.9 mol%. Based on phenotypic, chemotaxonomic and phylogenetic properties, strain HD8-51T represents a novel species of the genus Halorussus, for which the name Halorussus litoreus sp. nov. is proposed. The type strain is HD8-51T (=CGMCC 1.15333T=JCM 31109T).

Winogradskyella algae sp. nov., a marine bacterium isolated from the brown alga.

An aerobic, Gram-negative, yellow-pigmented non-motile rod-shaped bacterium Kr9-9T was isolated from a brown alga specimen collected near the Kuril Islands. Based on the 16S rRNA gene sequence analysis strain Kr9-9T was assigned to the genus Winogradskyella, and its close phylogenetic neighbors were found to be Winogradskyella damuponensis KCTC 23552T, Winogradskyella sediminis LMG 28075T, and Winogradskyella rapida CCUG 59098T showing high similarities of 98.1%, 97.5%, and 97.1%, respectively. It contained MK-6 as the predominant menaquinone and iso-C15:0, anteiso-C15:0, iso-C16:0 3-OH followed by iso-C15:1 as the major fatty acids. Polar lipids included phosphatidylethanolamine, three unidentified aminolipids and an unidentified lipid. The DNA C+C content was 32.3 mol%. Based on the phylogenetic analysis and distinctive phenotypic characteristics, strain Kr9-9T is concluded to represent a novel species of the genus Winogradskyella, for which the name Winogradskyella algae sp. nov. is proposed. The type strain of the species is strain Kr9-9T (= KMM 8180T = KACC 19709T).

Enzymatic extract from Ecklonia cava: Acute and subchronic oral toxicity and genotoxicity studies.

Ecklonia cava (EC) is known to have antioxidant, anti-inflammatory, antidiabetic, and anticancer properties. Despite its wide use and beneficial properties, comprehensive toxicological information regarding EC extract is currently limited. Therefore, the purpose of this study was to investigate acute toxicity, subchronic toxicity, and genotoxicity of enzymatic EC extract according to test guidelines published by Organization for Economic Cooperation and Development. The acute oral LD50 values of this EC extract administered to rats and dogs were estimated to be more than 3000 mg/kg BW. In an oral 13-week toxicity study, changes in body weights of rats exposed to the EC extract up to 3000 mg/kg BW were found to be normal. In addition, repeated doses of EC extract failed to influence any systematic parameters of treatment-related toxic symptoms such as food/water consumption, mortality, urinalysis, hematology, serum biochemistry, organ weight, or histopathology. These results indicated that the no-observed-adverse-effect level for the EC extract was 3000 mg/kg/day for male and female rats. Data obtained from Ames test, chromosome aberration assay, and micronucleus assay indicated that EC extract was not mutagenic or clastogenic. Taken together, these results support the safety of enzymatic EC extract as a potential therapeutic for human consumption against various diseases.

The Effect of Fucoidan from the Brown Alga Fucus evanescence on the Activity of α-N-Acetylgalactosaminidase of Human Colon Carcinoma Cells.

α-N-acetylgalactosaminidase (EC 3.2.1.49) (alpha-NaGalase) catalyzes the hydrolysis of N-acetamido-2-deoxy-α-d-galactoside residues from non-reducing ends of various complex carbohydrates and glycoconjugates. It is known that human cancer cells express an alpha-NaGalase, which accumulates in the blood plasma of patients. The enzyme deglycosylates the Gc protein-derived macrophage activating factor (GcMAF) and inhibits macrophage activity acting as an immunosuppressor. The high specific activity 0.033 ± 0.002 μmol mg−1 min−1 of the enzyme was found in human colon carcinoma cells DLD-1. The alpha-NaGalase of DLD-1 cells was isolated and biochemical characterized. The enzyme exhibits maximum activity at pH 5.2 and temperature 55 °C. The Km is 2.15 mM, Vmax⁻0.021 μmol min−1 mL−1, kcat⁻1.55 min−1 and kcat/Km⁻0.72 min−1 mM−1 at 37 °C, pH 5.2. The effects of fucoidan from the brown alga Fucus evanescence on the activity of alpha-NaGalase in human colon carcinoma DLD-1 cells and on the biosynthesis of this enzyme were investigated. It was shown that fucoidan did not inhibit free alpha-NaGalase, however, it reduced the expression of the enzyme in the DLD-1 cells at IC50 73 ± 4 μg mL−1.

Norisoprenoids from the Brown Alga Sargassum naozhouense Tseng et Lu.

A new C11-norisoprenoid derivative, sargassumone (1), has been isolated from Sargassum naozhouense together with six known norisoprenoids and a highly oxygenated cyclopentene: (2R,6S,8S,9S)-hexahydro-2,9-dihydroxy-4,4,8-trimethyl-6-acetyloxy-3(2H)-benzofuranone (2), (6S,8S,9R)-hexahydro-6,9-dihydroxy-4,4,8-trimethyl-2(2H)-benzofuranone (3), (6S,8S,9R)-hexahydro-6,9-dihydroxy-4,4,8-trimethyl-2(2H)-benzofuranone (4), loliolide (5), (+)-epiloliolide (6), spheciospongones A (7), and (+)-kjellmanianone (8). Compound 1 was identified on the basis of nuclear magnetic resonance (NMR) and mass spectrometry (MS) analysis, and the absolute stereochemistry was defined by NOESY spectroscopy, minimizing energy calculation, and circular dichroism (CD) spectra. The known compounds 2-8, isolated from S. naozhouense for the first time, were identified by comparison of their physical and spectroscopic data with those reported in the literature. Compound 6 was tested for its inhibitory activity against protein tyrosine phosphatase 1B (PTP1B), antioxidant activity with 1,1-diphyl-2-picrylhydrazyl (DPPH) free radicals, and antimicrobial activity against resistant clinical isolates of Candida albicans, methicillin-resistant Staphylococcus aureus (MRSA), and Escherichia coli.

Epoxyalcohol synthase of Ectocarpus siliculosus. First CYP74-related enzyme of oxylipin biosynthesis in brown algae.

Enzymes of CYP74 family play the central role in the biosynthesis of physiologically important oxylipins in land plants. Although a broad diversity of oxylipins is known in the algae, no CYP74s or related enzymes have been detected in brown algae yet. Cloning of the first CYP74-related gene CYP5164B1 of brown alga Ectocarpus siliculosus is reported in present work. The recombinant protein was incubated with several fatty acid hydroperoxides. Linoleic acid 9-hydroperoxide (9-HPOD) was the preferred substrate, while linoleate 13-hydroperoxide (13-HPOD) was less efficient. α-Linolenic acid 9- and 13-hydroperoxides, as well as eicosapentaenoic acid 15-hydroperoxide were inefficient substrates. Both 9-HPOD and 13-HPOD were converted into epoxyalcohols. For instance, 9-HPOD was turned primarily into (9S,10S,11S,12Z)-9,10-epoxy-11-hydroxy-12-octadecenoic acid. Both epoxide and hydroxyl oxygen atoms of the epoxyalcohol were incorporated mostly from [18O2]9-HPOD. Thus, the enzyme exhibits the activity of epoxyalcohol synthase (EsEAS). The results show that the EsEAS isomerizes the hydroperoxides into epoxyalcohols via epoxyallylic radical, a common intermediate of different CYP74s and related enzymes. EsEAS can be considered as an archaic prototype of CYP74 family enzymes.

Species delimitation and phylogeographic analyses in the Ectocarpus subgroup siliculosi (Ectocarpales, Phaeophyceae).

The genus Ectocarpus (Ectocarpales, Phaeophyceae) contains filamentous algae widely distributed in marine and estuarine habitats of temperate regions in both hemispheres. While E. siliculosus has become a model organism for genomics and genetics of the brown macroalgae, accurate species delineation, distribution patterns and diversity for the genus Ectocarpus remain problematic. In this study, we used three independent species delimitation approaches to generate a robust species hypothesis for 729 Ectocarpus specimens collected mainly along the European and Chilean coasts. These approaches comprised phylogenetic reconstructions and two bioinformatics tools developed to objectively define species boundaries (General Mixed Yule Coalescence Method and Automatic Barcode Gap Discovery). Our analyses were based on DNA sequences of two loci: the mitochondrial cytochrome oxidase subunit 1 and the nuclear internal transcribed spacer 1 of the ribosomal DNA. Our analyses showed the presence of at least 15 cryptic species and suggest the existence of incomplete lineage sorting or introgression between five of them. These results suggested the possible existence of different levels of reproductive barriers within this species complex. We also detected differences among species in their phylogeographic patterns, range and depth distributions, which may suggest different biogeographic histories (e.g., endemic species or recent introductions).

Extraction and Identification of Phlorotannins from the Brown Alga, Sargassum fusiforme (Harvey) Setchell.

Phlorotannins are a group of complex polymers of phloroglucinol (1,3,5-trihydroxybenzene), which are unique compounds from marine brown algae. In our present study, a procedure for extraction and enrichment of phlorotannins from S. fusiforme with highly antioxidant potentials was established. After comparison of different extraction methods, the optimal extraction conditions were established as follows. The freeze-dried seaweed powder was extracted with 30% ethanol-water solvent with a solid/liquid ratio of 1:5 at temperature of 25 °C for 30 min. After extraction, the phlorotannins were fractioned by different solvents, among which the ethyl acetate fraction exhibited both the highest total phlorotannin content (88.48 ± 0.30 mg PGE/100 mg extract) and the highest antioxidant activities. The extracts obtained from these locations were further purified and characterized using a modified UHPLC-QQQ-MS method. Compounds with 42 different molecular weights were detected and tentatively identified, among which the fuhalol-type phlorotannins were the dominant compounds, followed by phlorethols and fucophlorethols with diverse degree of polymerization. Eckol-type phlorotannins including some newly discovered carmalol derivatives were detected in Sargassum species for the first time. Our study not only described the complex phlorotannins composition in S. fusiforme, but also highlighted the challenges involved in structural elucidation of these compounds.