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Over the past decades, the concern about lead pollution in marine environments has increased due to its remarkable toxicity, even at low concentrations. Lead is one of the significant contaminants arising from human activities in Antarctica. However, its effects on polar photosynthetic organisms are poorly known. This work aims to evaluate the effects of two different environmental concentrations of lead (10 μg/L and 50 μg/L) on pigment content, antioxidant enzyme activities (catalase, superoxide dismutase, ascorbate peroxidase and glutathione–S–transferase), metabolome, thalli morphology and cell ultrastructure of the red seaweed Iridaea cordata (Turner) Bory from Terra Nova Bay (Ross Sea, Antarctica). The results highlighted that lead exposure decreased phycocyanin and phycoerythrin content, starting from 10 μg/L, while induced carotenoid accumulation at 50 μg/L. Catalase, ascorbate peroxidase, and superoxide dismutase activities generally increased after lead exposure and distinct biochemical features were identified in the control and treatment groups. Further lead–related effects on cell ultrastructure comprised floridean starch accumulation and plastoglobuli formation. Overall, our results suggested that the enhanced formation of reactive oxygen species in response to lead altered the photosynthetic pigment pattern, antioxidant defenses, metabolome and ultrastructure of I. cordata. [Display omitted] • I. cordata increased antioxidant enzyme activities to cope with metal exposure; • Ultrastructure, metabolomes, and pigments were affected by lead; • Untargeted metabolomics could highlight possible biomarkers for metal exposure. [ABSTRACT FROM AUTHOR]

Leishmaniasis is considered a neglected disease and affects billions around the world, currently presenting few therapeutic options, which makes the development of new antileishmanial drugs urgent. Secondary metabolites from marine and terrestrial organisms are important sources of new chemical entities. Herein, the potential activity of crude extracts and fractions from the Antarctic macroalga Iridaea cordata (Turner) Bory de Saint-Vincent was studied against promastigote and intracellular amastigotes forms of Leishmania amazonensis. The cytotoxicity of the active fractions was evaluated on macrophages and 3T3 BALB/c fibroblasts. The chemical profile of volatile substances was analyzed using the GC-MS technique. The fractions IC-FE (IC50-AMA = 23.6 ± 3.4 μg mL−1; SI > 11) and IC-FF (IC50-AMA = 12.4 ± 1.2 μg mL−1; SI > 24) showed promising activity against amastigotes and higher selectivity to the parasite rather than to the mammalian host cells, when compared to the reference drug amphotericin B (IC50-AMA = 5.9 ± 0.3 μg mL−1; SI = 3.9). Their estimated LD50 in rodents are also higher than that in amphotericin B (LD50 IC-FE = 594.5 ± 25.87 mg kg−1; LD50 IC-FE = 580.1 ± 11.84 mg kg−1; LD50 amphoter = 172.20 ± 2.40 mg kg−1). The chemical profile of these fractions showed the presence of phthalates, esters, ketones, fatty acids, and carboxylic acids, which might be contributing alone or synergistically to the observed antileishmanial activity. Consequently, I. cordata might be used to identify new antileishmanial compounds. [ABSTRACT FROM AUTHOR]

Macroalgae are sources of bioactive compounds that are interesting from both a chemical and a medical point of view. Although their use in biomedicine has increased significantly in recent years, tests conducted to date have been mostly related to species from temperate latitudes, with the potential application of Antarctic biodiversity being minor. The wide variety of algae species present on Antarctic coastal areas can be a source of new antioxidants. Bearing this in mind, the brown macroalgae Desmarestia antarctica (DA) and the red Iridaea cordata (IC) were selected for the preparation of aqueous extracts with the aim of analyzing their antioxidant activity. This analysis was performed by determining reducing power, total phenolic content, and 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity. Furthermore, both extracts were employed to synthesize gold and silver nanoparticles. The nanomaterials were fully characterized by means of UV-Visible spectroscopy, transmission electron microscopy, Z potential measurements, and Fourier transform infrared spectroscopy, which confirmed the formation of stable, spherical nanoparticles with mean diameters of 13.7 ± 3.1 and 17.5 ± 3.7 nm for Ag@DA and Ag@IC and 12.6 ± 1.9 and 12.3 ± 1.6 nm for Au@DA and Au@IC. Antioxidant assays were performed after the synthesis of the nanomaterials to evaluate their possible synergistic effect with the extracts. The results suggest that polysaccharides and proteins may play a key role in the process of reduction and stabilization. Finally, for the sake of comparison, the results obtained for the Antarctic macroalgae Desmarestia menziesii and Palmaria decipiens have also been considered in the present work.

Two red algae, Rhodymenia antarctica and Iridaea cordata (Rhodophyta), were employed to investigate the pollution situation along Fildes Peninsula coastline, King George Island. Ten sites from east and west coastlines were investigated, and the concentrations of Cu, Pb, Zn, Cd, Cr, As and Hg were determined. The metal pollution index (MPI) was used to evaluate the overall pollution level represented by the investigated sites and for interregional comparisons. The two algae exhibited different preference to special trace metal. R. antarctica could accumulate more Cd (0.63 mg kg−1) and Hg (0.026 mg kg−1) than I. cordata (Cd 0.34 mg kg−1, Hg 0.019 mg kg−1). I. cordata could accumulate more As (15.53 mg kg−1) than R. antarctica (10.11 mg kg−1). There was no significant difference in accumulating Cu, Pb, Zn and Cr between the two algae. R. antarctica could be used to monitor Cd and Hg. I. cordata would be more appropriate for monitoring As. MPI monitored by the two algae were from 1.02 to 2.26 (R. antarctica), and 1.03 to 1.25 (I. cordata), respectively. Pollution situation of Fildes Peninsula was becoming serious, especially of the east coastline. The objective of this research was to gather the baseline information for trace metals investigation in Antarctic. [ABSTRACT FROM AUTHOR]

This study aimed to isolate and characterize sulfated polysaccharides (SPs) from Iridaea cordata and evaluate their anticancer activity. SPs of the Antarctic red seaweed were obtained by CaCl2 (SP1) and ethanol precipitations (SP2) following diluted acid extraction at room temperature. Yields of SP1 and SP2 were approximately 14% and 23%, respectively, of the dry weight of red seaweed. The average molecular mass of the SP1 and SP2 was estimated about 1.84 × 103 and 1.42 × 103 kDa, respectively, by size-fractionation High-Performance Liquid Chromatography (HPLC). From the High-Performance Anion- Exchange Chromatography-Pulsed Amperometric Detection (HPAEC-PAD) analysis, the main monosaccharide was galactose with glucose and fucose as minor components. The sulfate content of SP2 (40.4%) was slightly higher than that of SP1 (33.8%). The FT-IR spectra also showed characteristic band of carrageenan-like sulfated polysaccharides. Taken together the SPs are thought to be carrageenan-like sulfated galactan. The polysaccharides (SPs) from I. cordata exhibited weak antitumor activity against PC- 3 (prostate cancer), HeLa (cervical cancer), and HT-29 (human colon adenocarcinoma). To our knowledge, this is the first data on biological activity of the Antarctic red seaweed I. cordata. [ABSTRACT FROM AUTHOR]

Endophytic organisms are known to have varied effects on their host organism in terrestrial and marine environments. In previous studies on marine algae, these symbioses range from innocuous to pathogenic depending on the host and endophyte species. The present study further assessed a pathogenic relationship between filamentous algal endophytes and a red algal host from the western Antarctic Peninsula. We analyzed endophyte presence (appearance of filamentous thalli) in the three life history stages of Iridaea cordata and potential impacts on fertility in the fertilized female gametophytes (carposporophytes) and tetrasporophytes. We found that endophytes proliferate throughout significantly more thallus area in tetrasporophyte and unfertilized gametophyte hosts than in carposporophyte hosts, but there was no correlation between endophyte cover and fertility in these individuals. This study also provides a demographic analysis of I. cordata populations surrounding Palmer Station, Antarctica, showing that these populations are haploid dominated (∼78% of individuals). The differential presence of filamentous algal endophytes indicates that endophyte pathogenicity indirectly has greater effect on tetrasporophytes and unfertilized gametophytes than on the carposporophytes, which house the products of sexual recombination. [ABSTRACT FROM AUTHOR]

Abstract: The Western Antarctic Peninsula is strongly affected by stratospheric ozone depletion, leading to higher UVB radiation (UVBR) on the Earth surface. It is furthermore experiencing the fastest rates of global warming worldwide, resulting in an increased sediment run-off from glacial melting, altering the underwater light climate. Very little is known of how Antarctic organisms can cope with this rapidly changing environment. Seaweeds play an essential role within the Antarctic coastal ecosystems, building highly complex and productive underwater communities. The unicellular spores are the most sensitive stage in their life-cycle, forming the bottle-neck for successful recruitment. To supplement the very rare field experiments on seaweed propagules, three ecologically important Antarctic seaweeds (Adenocystis utricularis, Himantothallus grandifolius, Iridaea cordata) were investigated. The germination of spores after exposure in the field to different water depths to three light treatments (PAR; PAR+UVA; PAR+UVA+UVB) was recorded. In parallel, spores were exposed to the same treatments under artificial radiation in the laboratory for different periods. Germination of the intertidal species A. utricularis was not affected by the treatments. In spores of I. cordata and H. grandifolius depth was a major factor for successful germination. High PAR fluxes at 1 and 2m water depth inhibited germination significantly. UVR further lowered germination in H. grandifolius while in I. cordata UVBR had a negative impact only in the laboratory experiment. The results show that already the unicellular life stage expresses strong species-specific susceptibility to changes in the radiation climate. Not only UVR but also the high PAR fluxes in the field are important factors in determining the upper distribution limit of Antarctic seaweeds and laboratory experiments show stronger UVB effects as studies under natural radiation. [Copyright &y& Elsevier]

Abstract: Lead (Pb) isotope ratios were measured in the marine macroalga Iridaea cordata collected from four locations in the Windmill Islands, East Antarctica. Based on the masses of thalli collected, samples analysed in this study were likely to be a mixture of one and two year old thalli. For a sample of thalli of various ages (<12 months to 2 years old) from the same site there was no apparent variation in Pb concentration or Pb isotope ratio with thallus mass/age, indicating that contaminant sources had been constant over the lifetime of the thalli sampled. I. cordata samples close to the Thala Valley waste disposal site (Brown Bay Inner) near the Australian Station, Casey, displayed isotopic signatures (208Pb/204Pb 35.99; 206Pb/207Pb 1.066; n =3; average values shown) trending towards that possessed by major Australian Pb sources (Broken Hill and Mt Isa, 208Pb/204Pb 35.60; 206Pb/207Pb 1.041) suggesting that these samples had been exposed to anthropogenic Pb originating from the Thala Valley waste disposal site. Material collected hundreds of metres from the tip location at Brown Bay Outer had isotopic values (208Pb/204Pb 36.32; 206Pb/207Pb 1.088; n =10) intermediate between Brown Bay Inner and sites further from the contaminant source at Sparkes Bay and Wilkes (208Pb/204Pb 36.46; 206Pb/207Pb 1.094; n =4) showing that contaminant transport was predominantly restricted to Brown Bay Inner. This study demonstrates that the isotope ratios of Pb in marine macroalgae can provide valuable information as to the origin and extent of heavy metal flux in a marine environment. [Copyright &y& Elsevier]

Iridaea cordata, including varieties cordata (Turner) Bory and splendens (Setchell and Gardner) Abbott, has a geo­graphic distribution that rims the north Pacific basin from Honshu, Japan to northern Mexico with its major populations from central California to southern Oregon (Abbott, 1972). Morphological and cytological descriptions of the life history stages have been reported (Setchell and Gardner, 1903; Kylin, 1928; Smith, 1938; Norris and Kim, 1972; Fralick and Cole, 1973; Kim, 1976) and the taxonomy of the genus has been reviewed (Abbott, 1971; Kim, 1976). The life history described (Kylin, 1928), involves the alternation of morphologically similar haploid and diploid generations. I. cordata is a source of the polysaccharide carrageenan and sporadic commercial harvesting of natural populations of this plant has occurred in northern California (Tseng, 1947) and Washington (Silverthorne and Sorensen, 1971). Some quantitative work on the population biology of Iridaea spp. (Hasegawa and Fukuhara, 1952; 1955; Fralick, 1971; Austin and Adams, 1974;Waaland, 1973; 1976; Hansen, in press) and other closely related genera, Gigartina spp. (Marshall et al., 1949; Burns and Mathieson, 1972) and Chondrus (Marshall et al., 1949;Taylor, 1970; Prince and Kingsbury, 1973; Mathieson and Prince, 1973; Mathieson and Burns, 1975) has been done.This is the first detailed study designed to explore the relationships between the population biology and physiological ecology of a red alga: Iridaea cordata.

The polysaccharide systems from cystocarpic and tetrasporic phases of the Sub-Antarctic algae Iridaea cordata were studied. Cystocarpic plant polysaccharides are mainly composed by carrageenans of the κ–family. However, agaran structures were also detected in the fraction soluble in 2.00 M KCl, after fractionation with increasing potassium chloride solutions. The presence of β- d -galactose-α- l -galactose 3-sulfate, β- d -galactose-α- l -galactose 6-sufate, β- d -galactose 6-sulfate-α- l -galactose 6-sufate, and of β- d -galactose 4-sulfate-α- l -galactose 2,3-disulfate diads was confirmed by means of methylation and NMR spectroscopy analyses; the latter diad has been scarcely reported. The first extracts from tetrasporic plants rendered a pure λ-carrageenan with considerable yield, which confers this species promising commercial applications. In some cystocarpic and tetrasporic extracts α-glucose was also found and assigned to floridean starch by 1H-13C HSQC NMR spectroscopy. [Display omitted] • Cistocarpic plants are mainly composed by κ–carrageenans, but agarans were also found. • G-L3S, G-L6S, G6S-L6S, and G4S-L2S,3S diads were identified in cistocarpic plants. • Tetrasporic plants biosynthesize λ-carrageenan in high yield. • High purity λ-carrageenan was obtained from the first two extracts. [ABSTRACT FROM AUTHOR]

An Iridaea cordata (Turner) Bory population made up of 83% gametophytes and 17% tetrasporophutes demonstrated little variation in these proportions over three years. These data contrast with an expectation that alternations of generations, as demonstrated by cultured studies. Analyses of reproductions and demographic attributes of alternation of generations in this populations. Growth and mortality rates in the summer could not account for the success of gametophytes, however, size class frequencies demonstrated that tetrasporophytes were smaller individuals. Sporelings recruited into this intertidal region and made up 20% of the spring population numbers. Even with this level of recruitment, gametophyte-to-tetrasporophyte ratios did not change. Perenating holdfasts regenerated 80% of the spring number and 90% of the total blade area. Consequently, perennation and differential survival of gametophyte spores or sporelings are proposed as mechanisms maintaining gametophyte dominance in this San Juan Island, Washinton population.] [ABSTRACT FROM AUTHOR]

Macroalgae are sources of bioactive compounds that are interesting from both a chemical and a medical point of view. Although their use in biomedicine has increased significantly in recent years, tests conducted to date have been mostly related to species from temperate latitudes, with the potential application of Antarctic biodiversity being minor. The wide variety of algae species present on Antarctic coastal areas can be a source of new antioxidants. Bearing this in mind, the brown macroalgae Desmarestia antarctica (DA) and the red Iridaea cordata (IC) were selected for the preparation of aqueous extracts with the aim of analyzing their antioxidant activity. This analysis was performed by determining reducing power, total phenolic content, and 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity. Furthermore, both extracts were employed to synthesize gold and silver nanoparticles. The nanomaterials were fully characterized by means of UV-Visible spectroscopy, transmission electron microscopy, Z potential measurements, and Fourier transform infrared spectroscopy, which confirmed the formation of stable, spherical nanoparticles with mean diameters of 13.7 ± 3.1 and 17.5 ± 3.7 nm for Ag@DA and Ag@IC and 12.6 ± 1.9 and 12.3 ± 1.6 nm for Au@DA and Au@IC. Antioxidant assays were performed after the synthesis of the nanomaterials to evaluate their possible synergistic effect with the extracts. The results suggest that polysaccharides and proteins may play a key role in the process of reduction and stabilization. Finally, for the sake of comparison, the results obtained for the Antarctic macroalgae Desmarestia menziesii and Palmaria decipiens have also been considered in the present work. [ABSTRACT FROM AUTHOR]

Botanical and marine extracts have been used in cosmetic products as natural antioxidants or UV-absorbers to reduce the use of organic UV filters. However, despite the high UV exposure of Antarctic macroalgae that induces the production of photoprotective compounds, the use of marine macroalgae extracts for photoprotection has been little explored. Thus our objective was to assess the photoprotective potential and the toxicity of extracts from two red macroalgae Curdiea racovitzae and Iridaea cordata. Chemical characterization was based on the qualitative and quantitative analyses of mycosporine-like amino acids (MAAs) by high performance liquid chromatography coupled to mass spectrometry. Photoprotective properties were assessed by UV spectrophotometry and photostability assay. Antioxidant capacity was studied by DPPH and superoxide radical scavenging assays. UVB and UVA photoprotection was assessed in keratinocytes by cell viability analysis after UVB irradiation and quantification of intracellular reactive oxygen species (ROS) induced by UVA, respectively. Toxicity was estimated by cytotoxicity, phototoxicity and HET-CAM (Hen's egg test-chorioallantoic membrane) assays. Red algae extracts had high concentrations of MAAs, mainly consisted of palythine. The extracts absorbed in the UVB and UVA-II and were photostable. The C. racovitzae extract showed antioxidant activity against superoxide radicals. In addition, the C. racovitzae (1.0 and 0.5 mg/mL) and I. cordata (1.0 mg/mL) extracts had an UVB photoprotection similar to benzophenone-3, which was dependent on the total MAAs concentration. Besides, the C. racovitzae extract decreased ROS generation by 31 and 24% at 100 and 50 μg/mL, respectively. Furthermore, it was more effective in reducing ROS generation than quercetin and Helioguard 365®. Finally, both extracts were considered to be non-cytotoxic, non-phototoxic and non-irritant. Therefore, the C. racovitzae extract is a good candidate to be added to anti-aging and sunscreen formulations in order to protect against oxidative stress and to improve the absorption spectra of UV filters. Unlabelled Image • Red macroalgae extracts had high concentrations of mycosporine-like amino acids. • Both extracts absorbed in UVB and UVA-II and were photostable after UVA irradiation. • C. racovitzae extract had UVB photoprotection similar to benzophenone-3, UV filter. • Reactive oxygen species were more reduced with C. racovitzae extract than quercetin. • The studied extracts were non-cytotoxic, non-phototoxic and non-irritant. [ABSTRACT FROM AUTHOR]