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Polysiphonia morrowii is a well-known red alga that has promising pharmacological characteristics. The current study evaluates the protective effect of 3-bromo-4,5-dihydroxybenzaldehyde (BDB) isolated from P. morrowii on tumor necrosis factor (TNF)-α/interferon (IFN)-γ-stimulated inflammation and skin barrier deterioration in HaCaT keratinocytes. The anti-inflammatory effect of BDB in TNF-α/IFN-γ-stimulated HaCaT keratinocytes is evaluated by investigating nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways, inflammatory cytokines, and chemokines. Further, the interaction between BDB and the skin barrier functions in stimulated HaCaT keratinocytes is investigated. The findings of the study reveal that BDB dose-dependently increases cell viability while decreasing intracellular reactive oxygen species (ROS) production. BDB downregulates the expression of inflammatory cytokines, interleukin (IL)-6, -8, -13, IFN-γ, TNF-α, and chemokines, Eotaxin, macrophage-derived chemokine (MDC), regulated on activation, normal T cells expressed and secreted (RANTES), and thymus and activation-regulated chemokine (TARC) by modulating the MAPK and NF-κB signaling pathways in TNF-α/IFN-γ-stimulated HaCaT keratinocytes. Furthermore, BDB increases the production of skin hydration proteins and tight junction proteins in stimulated HaCaT keratinocytes by preserving skin moisturization and tight junction stability. These findings imply that BDB exhibits a protective ability against inflammation and deterioration of skin barrier via suppressing the expression of inflammatory signaling in TNF-α/IFN-γ-stimulated HaCaT keratinocytes.

During our sampling surveys of the tribes Polysiphonieae and Streblocladieae in Spain and Australia, three previously unrecorded species were collected. Based on molecular and morphological evidence they are proposed as new species. Polysiphonia delicata sp. nov. and Polysiphonia radiata sp. nov. belong to the Polysiphonieae and share the synapomorphy in this group, rhizoids in open connection to pericentral cells. They differ from other members of this group either by rbcL sequence divergences greater than 4.5% and/or by morphological characters. The third species is placed in Melanothamnus (tribe Streblocladieae), as Melanothamnus pseudoforcipatus sp. nov. In agreement with the morphological delineation of the genus, it has plastids lying only on the radial walls of pericentral cells. It can be separated from most other members of the genus by having naked segments between trichoblasts or branches and/or rbcL sequence divergences higher than 4%. In Galicia, Spain, both Polysiphonia species were mainly collected in marinas, while M. pseudoforcipatus was found at a site close to oyster aquaculture facilities. Polysiphonia delicata was also found in Victoria, Australia, and the potentially non-native status of these three species in relation to their known distribution is discussed.

Due to massive industrial development, organic and inorganic wastes are very common in most industrial effluents from the pharmaceutical industry. Even in low concentrations, they are very dangerous and harmful to humans and other living organisms. Antibiotics are frequently detected in surface waters, in soil, in wastewater from sewage treatment plants, and even in drinking water. The major environmental threat they pose has prompted to search for effective and environmentally friendly means of eliminating these toxins. The biogenic synthesis of nanomaterials using natural herbal extracts has attracted considerable attention due to their low-cost, environmentally friendly and non-toxic nature, and as a reversal of various physical and chemical processes. The ceria nanoparticles (CeO 2 NPs), nickel oxide nanoparticles (NiO NPs), and CeO 2 /NiO nanocomposites (CeO 2 /NiO NCS) were successfully prepared by simple biosynthetic routes using Polysiphonia urceolata algae extract as green surfactants and tested for toxic ofloxacin removal efficiency. The formed nanostructures were identified and characterized by various microscopic (FESEM-EDX, TEM, XRD, BET, and XPS) and spectroscopic (UV–Vis, FTIR, and TGA) methods. The adsorption/desorption of ofloxacin (OFX) on the surface of the nanomaterials was investigated under optimized conditions (initial dose 20 mg/L, agitation speed 250 rpm, pH 12, adsorbent dose 0.5 mg/L, and contact time 120 min). The removal efficiencies were 78%, 86%, and 94% for CeO 2 NPs, NiO NPs and CeO 2 /NiO NCS, respectively, where OFX removal was found to be spontaneous, followed by Freundlich isotherm and pseudo-second order kinetic reaction model. The OFX adsorption mechanism on the nanomaterials involved the surface complexation via specific electrostatic attraction and H-bonding. The biogenic nanomaterials were also tested for their antibacterial activity against Escherichia coli , Pseudomonas aeruginosa , Staphylococcus epidermidis and Staphylococcus aureus . The CeO 2 /NiO NCS exhibited the highest antibacterial activity with zone of inhibition (31.12 ± 0.59 mm) against S. epidermidis , followed by CeO 2 NPs and NiONPs with zones of inhibition (25.53 ± 1.2 mm) and (21.42 ± 0.6 mm) against P. aeruginosa and S. epidermidis , respectively. This study demonstrated the efficiency of the synthesized nanomaterials in removing toxins such as OFX from contaminated water and can serve as potential antibacterial and antioxidant agents. Notably, the heterogeneous nanomaterials demonstrated remarkable stability across a broad pH range, promising reusability and indicated tremendous potential of waste biomass reduction and OFX effluent treatment.

Some Melanothamnus species have been documented growing epiphytically on other algae in seaweed aquaculture farms as fouling organisms. Such turf-forming Polysiphonia-looking algae were collected from a small (<1.0 km2 area) Agarophyton tenuistipitata (Gracilariaceae, Gracilariales) farm on the east coast of the Bay of Bengal and examined for their taxonomy. DNA was extracted from silica gel-preserved specimens, and plastid-encoded rbcL, nuclear-encoded small subunit SSU, large subunit LSU, and universal plastid amplicon (UPA) were amplified and sequenced. Maximum likelihood (ML) and Bayesian inference were performed for the phylogenetic analysis. Four single-locus species delimitation methods (SDMs), namely, the generalized mixed Yule-coalescent (GMYC) method, a Poisson tree processes (PTP) model, the automatic barcode gap discovery (ABGD), and the assemble species by automatic partitioning (ASAP) method, were performed to segregate the putative species from other taxa in the Polysiphonia sensu lato clades. Our results revealed that rbcL had 1.4% interspecific genetic divergence, whereas LSU, UPA, and SSU had 1.6%, 2.5%, and 5.4% genetic divergence, respectively, from the nearest neighbors. Both comparative genetic and distinct morphological data revealed that the collected Bay of Bengal specimens comprise a species new to science. In addition, the above-mentioned SDMs supported the genetic data and segregated our specimens as Melanothamnus coxsbazarensis sp. nov. as a distinct species.

Red algae are frequently dominant components of the non-native biotas in coastal areas. They often remain undetected because of morphological similarity between native and introduced species and cryptic diversity. Routine use of DNA barcodes can aid in setting baseline tabulations of native species and for detecting introduced species. We performed an extensive survey of the red algal family Rhodomelaceae in southern Australia, producing a dataset containing more than 1100 rbcL sequences. The objective of this study was to screen that dataset for introduced species of the tribes Polysiphoniaeae and Streblocladieae, and to provide morphological information of presumably introduced species that were not previously recorded in Australia. Molecular data and morphological observations confirmed the presence of five presumably introduced species: Leptosiphonia brodiei, Melanothamnus japonicus, M. strictissimus, Polysiphonia morrowii and P. delicata. Polysiphonia morrowii and M. strictissimus were detected for the first time in Australia, and M. japonicus and P. delicata were found to be more widely distributed than previously known. Somewhat unexpectedly, the distribution range of L. brodiei has apparently shrunk, with our survey suggesting it remains only in Tasmania. Four of these species have been reported as introduced species in other countries, but M. strictissimus is here recorded for the first time outside its native New Zealand. Although all five species can be considered introduced or cryptogenic, only P. morrowii, M. japonicus and M. strictissimus were locally abundant, and further work will be needed to assess their ability to spread and effect negative impacts on native biotas.

An R-phycoerythrin (R-PE) was isolated by gel filtrations on Sepharose CL-4B and Sephadex G-150 from the phycobiliprotein extract of the marine red macroalga Polysiphonia urceolata Grev and further purified by ion exchange chromatography on DEAE-Sepharose Fast Flow. The purified R-PE showed three absorption peaks at 498 nm, 538 nm, 566 nm and one fluorescent emission maximum at 577 nm. Although the R-PE showed a single band on the examination by native PAGE, it exhibited two very close bands at pH about 4.7 in native isoelectric focusing (IEF). Polypeptide analysis of the R-PE demonstrated that it contained four chromophore-carrying subunits, α18.2, β20.6, γ31.6 (γ'), γ34.6 (γ), and no colorless polypeptide; its subunit composition was 6α18.2:6β20.6:1 γ31.6:2γ34.6. The α and β subunits were distributed within a acidic pH range from 5.0 to 6.0 in denaturing IEF and the γ subunits were in a basic pH range from 7.6 to 8.1. These results reveal that the prepared R-PE may exist in two hexamers of γ (αβ)3 γ (αβ)3γ' and γ (αβ)3 γ'(αβ)3 γ and that the R-PE participate in the rod domain assembly of P. urceolata phycobilisomes by stacking each of its trimer (αβ)3 face-to-face with the aid of one γ subunit (γ or γ').

In this study, we investigated the anti-allergic effects of 3,4-dihydroxybenzaldehyde (DHB) isolated from the marine red alga, Polysiphonia morrowii, in mouse bone-marrow-derived cultured mast cells (BMCMCs) and passive cutaneous anaphylaxis (PCA) in anti-dinitrophenyl (DNP) immunoglobulin E (IgE)-sensitized mice. DHB inhibited IgE/bovine serum albumin (BSA)-induced BMCMCs degranulation by reducing the release of β-hexosaminidase without inducing cytotoxicity. Further, DHB dose-dependently decreased the IgE binding and high-affinity IgE receptor (FcεRI) expression and FcεRI-IgE binding on the surface of BMCMCs. Moreover, DHB suppressed the secretion and/or the expression of the allergic cytokines, interleukin (IL)-4, IL-5, IL-6, IL-13, and tumor necrosis factor (TNF)-α, and the chemokine, thymus activation-regulated chemokine (TARC), by regulating the phosphorylation of IκBα and the translocation of cytoplasmic NF-κB into the nucleus. Furthermore, DHB attenuated the passive cutaneous anaphylactic (PCA) reaction reducing the exuded Evans blue amount in the mouse ear stimulated by IgE/BSA. These results suggest that DHB is a potential therapeutic candidate for the prevention and treatment of type I allergic disorders.

R-phycoerythrin prepared from red algae ( Bangia fusco - purpurea ) was hydrolyzed by pepsin followed by trypsin to produce angiotensin I-converting enzyme (ACE) inhibitory peptides. The IC 50 of the hydrolysate of R-phycoerythrin (HRPE) was 191.1 ± 4.1 μg/mL, and the molecular weight of most products (89.9 %) was below 2 kDa. After sequential gel permeation and reversed-phase chromatography steps to purify the hydrolysate, two peptides with the sequences of ALLAGDPSVLEDR and VVGGTGPVDEWGIAGAR were obtained and their IC 50 values were 57.2 ± 5.0 and 66.2 ± 4.2 μg/mL, respectively. The ALLAGDPSVLEDR and VVGGTGPVDEWGIAGAR peptides were derived from the β- and α-subunit of R-phycoerythrin from Polysiphonia urceolata , with a 92.3 % (12/13) and 94.1 % (16/17) match, respectively. Both peptides were resistant to digestion by proteinases common in the gastrointestinal tract. Therefore, the identified novel peptides derived from R-phycoerythrin may be used as potential nutraceuticals for development of functional foods.

An R-phycoerythrin (R-PE) was isolated by gel filtrations on Sepharose CL-4B and Sephadex G-150 from the phycobiliprotein extract of the marine red macroalga Polysiphonia urceolata Grev and further purified by ion exchange chromatography on DEAE-Sepharose Fast Flow. The purified R-PE showed three absorption peaks at 498 nm, 538 nm, 566 nm and one fluorescent emission maximum at 577 nm. Although the R-PE showed a single band on the examination by native PAGE, it exhibited two very close bands at pH about 4.7 in native isoelectric focusing (IEF). Polypeptide analysis of the R-PE demonstrated that it contained four chromophore-carrying subunits, alpha 18.2, beta 20.6, gamma 31.6 ( gamma '), gamma 34.6 ( gamma ), and no colorless polypeptide; its subunit composition was 6 alpha 18.2:6 beta 20.6:1 gamma 31.6:2 gamma 34.6. The alpha and beta subunits were distributed within a acidic pH range from 5.0 to 6.0 in denaturing IEF and the gamma subunits were in a basic pH range from 7.6 to 8.1. These results reveal that the prepared R-PE may exist in two hexamers of gamma ( alpha beta )3 gamma ( alpha beta )3 gamma ' and gamma ( alpha beta )3 gamma '( alpha beta )3 gamma and that the R-PE participate in the rod domain assembly of P. urceolata phycobilisomes by stacking each of its trimer ( alpha beta )3 face-to-face with the aid of one gamma subunit ( gamma or gamma ').

A group of five Gram-negative aerobic halophilic bacteria was isolated from the red alga Polysiphonia sp. specimen collected from the Sea of Japan seashore and subjected to a taxonomic study. On the basis of 16S rRNA gene sequence analysis, the novel isolates were affiliated to the genus Labrenzia sharing the highest gene sequence similarities of 98.1–98.4% with the type strain of Labrenzia suaedae KACC 13772T. The DNA–DNA hybridization values of 83–91% obtained between five novel strains, and 26 and 36% between two of the five novel strains and the closest neighbor Labrenzia suaedae KACC 13772T confirmed their assignment to the same separate species. Novel isolates were characterized by Q-10 as the major ubiquinone, by the predominance of C18:1ω7c followed by 11-methyl C18:1ω7c and C14:0 3-ОН in their fatty acid profiles. Polar lipids consisted of phosphatidylcholine, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol, an unknown aminophospholipid, and an unknown phospholipid. Some of novel strains were found to inhibit growth of Gram-negative and Gram-positive test microorganisms. On the basis of phylogenetic analysis, DNA–DNA hybridization and phenotypic traits, a novel species with the name Labrenzia polysiphoniae sp. nov. (type strain KMM 9699T = rh46T = KACC 19711T), is proposed.