O estresse ambiental sobre algas marinhas pode ser causado por poluentes, ausência de nutrientes, variação da temperatura ou da intensidade luminosa. Embora vários grupos estudem os efeitos do estresse ambiental sobre a ecologia de animais marinhos, nos últimos anos, contudo, poucos pesquisadores têm investigado o seu efeito sobre a fisiologia das algas marinhas, sobretudo sobre a biossíntese e função de carotenóides e ácidos graxos. Deste modo, foram abordados experimentalmente a atividade antioxidante in vitro de alguns carotenóides encontrados em algas (determinação da constante de supressão (KQ) de oxigênio singlete (02 (1Δg)) e redução da lipoperoxidação em lipossomos incorporados com carotenóides) bem como a monitoração da biossíntese de pigmentos e os níveis de ácidos graxos em algumas espécies de algas cultivadas em situações de estresse ambiental, como exposição a metais pesados (Gracilaria tenuistipitata e Lingulodinium polyedrum), alta densidade populacional (Amphidinium cartareae, Nitzschia microcephala, Lingulodinium polyedrum, Minutocellus polymorphus e Tetraselmis gracilis), e intensidade luminosa (Lingulodinium polyedrum). Ainda, nas algas expostas a estas condições adversas, parâmetros de estresse oxidativo e indicadores enzimáticos do metabolismo oxidativo foram medidos, como a atividade de superoxido dismutase, catalase, ascorbato peroxidase, e o doseamento dos níveis de malonaldialdeído (MDA), tióis e carbonilas de proteínas. Por RMN de 1H, EM e HPLC com a co-injeção de padrões, foram identificados vários carotenos (β-caroteno e licopeno), xantofilas (peridinina, luteina, diadinoxantina, diatoxantina entre outras) e três tipos de clorofilas (a, b e c) das macro e micro algas estudadas. Paralelamente, seguindo as mesmas técnicas cromatográficas, estudamos a interconversão de tiamina com a identificação das três formas desta vitamina (livre, mono e difosfato). Nos ensaios in vitro, as KQs da peridinina, carotenóide isolado de Lingulodinium polyedrum, em dois sistemas de solventes (CDCl3: 0,95 x 109 M-1.s-1 e D20/CD3COCD3 1:1: 5,0 x 109 M-1.s-1) sugere que este pigmento apresenta uma melhor função protetora contra os efeitos deletérios do O2 (1ΔG) em ambiente hidrofílico. A presença de peridinina e astaxantina incorporadas em lipossomos preenchidos com Fe2+/EDTA foi determinante para diminuir os efeitos danosos de H202 e t-ButOOH, mostrando que a ação desses pigmentos depende da permeabilidade dos agentes oxidantes através da bicamada lipídica. Ambos carotenóides apresentaram atividade quando a peroxidação foi provocada pelo lado externo da bicamada. A concentração dos ácidos graxos em culturas de Lingulodinium polyedrum durante o ciclo claro:escuro sugee que o aumento de C18:3 e C22:6 durante a fase clara ocorreu para compensar a lipoperoxidação (os níveis de MDA foram altos durante a fase clara) e manter a integridade e homeostase celular. Em culturas de G. tenuistipitata expostas a Cd2+ e Cu2+, os níveis do ácido C20:4 (n-6) aumentaram cerca de 30% no tratamento com Cd2+, provavelmente para preservar a integridade de membrana em resposta ao desbalanço redox provocado por esse metal. Em contrapartida, os níveis de C20:4 (n-6) decaíram cerca de 15% no tratamento com Cu2+, evidenciando a especificidade desse metal em atingir as membranas tilacóides no cloroplasto. O ácido C18:3 (n-4) foi detectado apenas no tratamento com Cu2+. Os resultados encontrados para a monitoração da biossíntese de carotenóides abrem novas perspectivas para a compreensão dos mecanismos bioquímicos e fisiológicos adotados por algas marinhas cultivadas em ambientes adversos. Diferentes respostas foram encontradas para os níveis de pigmentos para as micro e macroalgas estudadas, mostrando que a biossíntese e a atividade das enzimas envolvidas no metabolismo oxidativo podem variar nas diferentes espécies e conforme o estímulo empregado. / Environmental stress on marine algae is provoked by pollutants, lack of nutrients, temperature oscillation or high light. Although some researchers have investigated environmental stress effects on marine animais ecology, lately, however, few groups have studied its effects on marine algae physiology, i.e. carotenoid function and biosynthesis and fatty acids contents. Thus, the in vitro activity, such as the quenching of 02 (1ΔG) (KQ) and the reduction of liposome peroxidation incorporated with carotenoids, of some pigments founded in algae were determined as well as the their biosynthesis when some species were growth under stressful condition, for example, heavy metal exposition (Gracilaria tenuistipitata and Lingulodinium polyedrum), cell density (Amphidinium cartareae, Nitzschia microcephala, Lingulodinium polyedrum, Minutocellus polymorphus and Tetraselmis gracilis) and high light (Lingulodinium polyedrum). In addition, some parameters of oxidative stress and enzymatic markers of oxidative metabolism such as superoxide dismutase, catalase and ascorbate peroxidase activities, malondialdehyde (MDA), protein carbonyls and thiols contents, were measured. Some carotenes (β-carotene and licopene), xanthophylls (peridinin, lutein, diadinoxanthin, diatoxanthin, etc) and three chlorophylls (a, b and c) were identified either by 1H NMR and MS or standards spiked in HPLC in the species studied. Also, using HPLC techniques, we studied the thiamine interconversion identifying three forms of this vitamin (free, mono- and diphosphate). The KQs obtained for peridinin, isolated from Lingulodinium polyedrum, using two solvent systems (CDCl3: 0,95 x 109 M-1.s-1 and D20/CD3COCD3 1:1: 5,0 x 109 M-1.s-1) suggest this pigment is more effective against the deleterious effects of O2 (1Δg) in hydrophilic environment. Peridinin and astaxanthin incorporated to liposomes filled with Fe2+/EDTA decreased the lipoperoxidation when H202 e t-ButOOH were added, showing that their function depending on the peroxidation promoters permeability through the membrane. Also, both carotenoids were able to protect the membrane when the lipoperoxidation was promoted outside. The fatty acid contents measured in cultures of L. polyedrum during the light:dark cycle suggest that the increase of C18:3 and C22:6 levels during the light phase occurred to compensate the lipoperoxidation, since the levels of MDA were high in the same phase, and to keep the membrane integrity and cell homeostasis. The levels of C20:4 (n-6) increased about 30% when cultures of G. tenuistipitata were exposed to Cd2+ may be to preserve the cell membranes in response to misbalance caused by this heavy metal. On the other hand, the levels of C20:4 (n-6) decreased almost 15% during the treatment with Cu2+, showing an evidence that this metal can affect the tilakoid membranes. The fatty acid C18:3 (n-4) was only detected in the assay with Cu2+. The carotenoid biosynthesis results bring new perspectives concerning the comprehension of the biochemistry and physiology mechanisms employed by marine algae against stressful environmental conditions. Different responses were founded for the carotenoid contents, showing that the biosynthesis and the activity of the enzymes involved in the oxidative metabolism can vary according to species or stimuli used.

Orientadora: Dulce Helena Siqueira Silva / Coorientador: Alan Cesar Pilon / Banca: Kelly Johana Dussan Medina / Banca: Lidiane Gaspareto Felippe / Banca: Ana Helena Januário / Banca: Paula Christine Jimenez / Resumo: A química de produtos naturais é uma estratégia de grande sucesso na descoberta de compostos bioativos para o desenvolvimento de novos fármacos. Neste contexto destacam-se os estudos com plantas, micro-organismos, e mais recentemente organismos marinhos. Avanços recentes nos estudos com algas marinhas e de seus fungos associados, com destaque para os fungos endofíticos, revelaram bioatividades relevantes, como anti-inflamatória, antioxidante antimicrobiana e antitumoral, além de estruturas químicas diversificadas, incluindo compostos halogenados. Este trabalho explorou o potencial químico e biológico dos endófitos associados às algas A. spicifera, D. marginata e S. vulgare, permitindo o isolamento de 40 linhagens fúngicas e a identificação de doze gêneros e espécies por taxonomia molecular e morfológica. Após isolados, preservados e cultivados no meio líquido extrato de Malte preparado com água do mar ou água ultra pura, foram obtidos os extratos brutos em acetato de etila, que foram avaliados quanto ao perfil químico por RMN de 1H, CLAEDAD, CG-EM e CL-EM, além de triagem biológica em ensaios antimicrobianos contra linhagens de bactérias super-resistentes e formadoras de biofilme, Doença de Chagas, Leishmaniose, bem como em ensaio anticolinesterásico, de inibição da atividade de protease de veneno de serpente e citotóxico frente as linhagens tumorais HCT-116 e MTT. A análise química permitiu a identificação de 78 compostos por CG-EM e 26 por CL-EM. A avaliação biológica dos e... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The chemistry of natural products is a highly successful strategy in the discovery of bioactive compounds for the development of new drugs. In this context studies with plants, microorganisms and more recently marine organisms stand out. Recent advances in marine algae studies, along with studies on their associated fungi, with emphasis on endophytic fungi, disclosed relevant bioactivities such as anti-inflammatory, antimicrobial,antitumor and antioxidant, as well as strong chemodiversity, including halogenated compounds. This work explored the chemical and biological potential of endophytes associated to marine algae A. spicifera, D. marginata and S. vulgare andled to the identification of twelve endophytic fungal strains by molecular and morphological taxonomy. After isolation, preservation and cultivation in Malte liquid medium prepared with sea water or ultra pure water, crude extracts were obtained in ethyl acetate, and were evaluated for their chemical profile by 1H NMR, HPLC-DAD, GC-MS and LC-MS, in addition to biological screening against multi-resistant bacterial strains and biofilm-forming bacteria, against Chagas disease, Leishmaniasis, as well as anti-cholinesterase assay, inhibition of snake venom protease activity and cytotoxic activity against human colon adenocarcinoma (HCT-116). Chemical analyses led to the identification of 78 compounds by GC-MS and 26 by LC-MS. Biological evaluation of crude extracts and fractions disclosed a high rate of bioactive samples,... (Complete abstract click electronic access below) / Doutor

Delisea pulchra is a red macroalga that produces furanones, a class of secondary metabolites that inhibit the growth and colonization of a range of micro- and macroorganisms. In bacteria, furanones specifically inhibit acyl homoserine lactone (AHL)- driven quorum sensing, which is known to regulate a variety of colonization and virulence traits. This thesis aims to unveil multiple aspects of the chemically mediated interactions between an alga and its bacterial flora. It was demonstrated that the quorum sensing genetic machinery of bacteria is laterally transferred, making traditional 16S rRNA gene based-diversity techniques poorly suited to identify quorum sensing species. Previous studies had shown that AHL-producing bacteria belonging to the roseobacter clade can be readily isolated from D. pulchra. Because of this, it was decided to use a roseobacter epiphytic isolate from this alga, Ruegeria strain R11, to conduct a series of colonization experiments on furanone free and furanone producing D. pulchra. Furanones were shown to inhibit Ruegeria strain R11's colonization and infection of D. pulchra. In addition, it was demonstrated that Ruegeria strain R11 has temperature-regulated virulence, similar to what is seen for the coral pathogen Vibrio shiloi. Rising ocean temperatures may explain bleached D. pulchra specimens recently observed at Bare Island, Australia. To assess whether quorum sensing is common within the roseobacter clade, cultured isolates from the Roseobacter, Ruegeria and Roseovarius genera were screened for AHL production. Half of the bacteria screened produced the quorum sensing signal molecules, AHLs. These AHLs were identified using an overlay of an AHL reporter strain in conjunction with thin layer chromatography (TLC). The prevalence of quorum sensing within the roseobacter clade, suggests that these species may occupy marine niches where cellular density is high (such as surface associated communities on substratum and marine eukaryotes). Diversity studies in marine microbial communities require appropriate molecular markers. The 16S rRNA gene is the most commonly used marker for molecular microbial ecology studies. However, it has several limitations and shortcomings, to which attention has been drawn here. The rpoB gene is an alternate ???housekeeping??? gene used in molecular microbial ecology. Therefore, the phylogenetic properties of these two genes were compared. At most taxonomic levels the 16S rRNA and rpoB genes offer similar phylogenetic resolution. However, the 16S rRNA gene is unable to resolve relationships between strains at the subspecies level. This lack of resolving power is shown here to be a consequence of intragenomic heterogeneity.

Contaminants may affect marine organisms through various pathways with impacts evident across a variety of spatial and temporal scales. Organisms may encounter short pulsed exposures which contaminate surface waters for hours to days, or more persistent but patchy contamination of benthic habitats throughout their entire life-cycle. This thesis examines the responses of epifauna associated with macroalgae to a pulsed exposure of contaminants (storm-water input) and to chronic contamination via metal accumulation within temperate algal beds. The effects of storm water were monitored during a two-year survey of Sydney Harbour which sampled epifauna before and after heavy rainfall. Epifaunal assemblages declined throughout the harbour following storm events but for the most part these declines were not attributable to storm-water runoff. However, transient (&lt 4 d) and localized impacts of storm water upon physico-chemical characteristics of recipient water and some epifaunal groups were identified around storm drains. A novel field dosing technique tested the relative importance of freshwater and associated metals as causative agents of behavioural avoidance and direct mortality responses. Strong avoidance of storm-water plumes was found which could be entirely explained by freshwater inundation, with no additional effects of metals. No direct mortality was observed following brief exposures. Contaminants introduced by storm water may accumulate within the tissues of macroalgae and potentially pose persistent threats to epifauna. Colonisation of epifauna was reduced on algae with enhanced copper levels, and the nesting behaviour, feeding and survival of an abundant amphipod were all negatively affected by copper load. Subsequent field surveys identified sufficient copper, lead and zinc contamination in Sydney Harbour algal beds to pose direct toxic threats to epifauna. The abundance of herbivorous amphipods correlated negatively with the copper content of a common algal species. However, differences in metal accumulation between algal species resulted in spatially variable levels of contamination. Small-scale patchiness of contaminants within these landscapes may allow populations of mobile species to persist if contaminated hosts are avoided. In summary, epifaunal assemblages appeared resilient to storm-water pulses. Recovery of affected groups was rapid and large fluctuations in abundance appear to be part of the natural flux of epifaunal communities. In contrast, assemblages responded strongly to algal-bound contaminants and this has emerged as an important pathway of contaminant exposure and impact within algal habitats.

Phytoplankton growth is iron limited in at least 20% of the world’s oceans. Iron is an important nutrient required to synthesise enzymes necessary for photosynthesis, respiration, and nitrogen assimilation. Due to its low solubility in seawater, iron limitation of phytoplankton production has been the focus of much recent research. These organisms secrete ligands in order to solubilise the available iron, but not all of the iron dissolved in seawater is biologically available. In this study a molecular based approach was employed to investigate the acclimation of the marine haptophyte Coccolithus pelagicus to iron limitation. Using two dimensional electrophoresis, subtractive cDNA hybridisation, and RT real time PCR, changes in the proteome and in gene expression were examined. Iron limited cells were characterised by slower specific growth rates, lower chlorophyll a concentrations per unit biomass and less extensive calcification relative to iron replete cells. Addition of iron to iron limited cultures resulted in increased specific growth rates and increased chlorophyll a concentration per unit biomass. A subtracted cDNA library revealed seventeen identifiable sequences of which photosystem I protein E (PsaE), a fucoxanthin binding protein transcript, two chlorophyll binding proteins and a predicted membrane protein were shown to be up-regulated in iron-limited cells to varying extents. Two dimensional SDS PAGE revealed 11 differentially expressed proteins in iron limited cells and 1 highly expressed protein exclusive to iron replete cells. The potential utility of each of these as biomarkers of iron-limitation/iron sufficiency for natural populations of coccolithophorids like Coccolithus pelagicus is discussed.

Delisea pulchra is a red macroalga that produces furanones, a class of secondary metabolites that inhibit the growth and colonization of a range of micro- and macroorganisms. In bacteria, furanones specifically inhibit acyl homoserine lactone (AHL)- driven quorum sensing, which is known to regulate a variety of colonization and virulence traits. This thesis aims to unveil multiple aspects of the chemically mediated interactions between an alga and its bacterial flora. It was demonstrated that the quorum sensing genetic machinery of bacteria is laterally transferred, making traditional 16S rRNA gene based-diversity techniques poorly suited to identify quorum sensing species. Previous studies had shown that AHL-producing bacteria belonging to the roseobacter clade can be readily isolated from D. pulchra. Because of this, it was decided to use a roseobacter epiphytic isolate from this alga, Ruegeria strain R11, to conduct a series of colonization experiments on furanone free and furanone producing D. pulchra. Furanones were shown to inhibit Ruegeria strain R11's colonization and infection of D. pulchra. In addition, it was demonstrated that Ruegeria strain R11 has temperature-regulated virulence, similar to what is seen for the coral pathogen Vibrio shiloi. Rising ocean temperatures may explain bleached D. pulchra specimens recently observed at Bare Island, Australia. To assess whether quorum sensing is common within the roseobacter clade, cultured isolates from the Roseobacter, Ruegeria and Roseovarius genera were screened for AHL production. Half of the bacteria screened produced the quorum sensing signal molecules, AHLs. These AHLs were identified using an overlay of an AHL reporter strain in conjunction with thin layer chromatography (TLC). The prevalence of quorum sensing within the roseobacter clade, suggests that these species may occupy marine niches where cellular density is high (such as surface associated communities on substratum and marine eukaryotes). Diversity studies in marine microbial communities require appropriate molecular markers. The 16S rRNA gene is the most commonly used marker for molecular microbial ecology studies. However, it has several limitations and shortcomings, to which attention has been drawn here. The rpoB gene is an alternate ???housekeeping??? gene used in molecular microbial ecology. Therefore, the phylogenetic properties of these two genes were compared. At most taxonomic levels the 16S rRNA and rpoB genes offer similar phylogenetic resolution. However, the 16S rRNA gene is unable to resolve relationships between strains at the subspecies level. This lack of resolving power is shown here to be a consequence of intragenomic heterogeneity.

Contaminants may affect marine organisms through various pathways with impacts evident across a variety of spatial and temporal scales. Organisms may encounter short pulsed exposures which contaminate surface waters for hours to days, or more persistent but patchy contamination of benthic habitats throughout their entire life-cycle. This thesis examines the responses of epifauna associated with macroalgae to a pulsed exposure of contaminants (storm-water input) and to chronic contamination via metal accumulation within temperate algal beds. The effects of storm water were monitored during a two-year survey of Sydney Harbour which sampled epifauna before and after heavy rainfall. Epifaunal assemblages declined throughout the harbour following storm events but for the most part these declines were not attributable to storm-water runoff. However, transient (&lt 4 d) and localized impacts of storm water upon physico-chemical characteristics of recipient water and some epifaunal groups were identified around storm drains. A novel field dosing technique tested the relative importance of freshwater and associated metals as causative agents of behavioural avoidance and direct mortality responses. Strong avoidance of storm-water plumes was found which could be entirely explained by freshwater inundation, with no additional effects of metals. No direct mortality was observed following brief exposures. Contaminants introduced by storm water may accumulate within the tissues of macroalgae and potentially pose persistent threats to epifauna. Colonisation of epifauna was reduced on algae with enhanced copper levels, and the nesting behaviour, feeding and survival of an abundant amphipod were all negatively affected by copper load. Subsequent field surveys identified sufficient copper, lead and zinc contamination in Sydney Harbour algal beds to pose direct toxic threats to epifauna. The abundance of herbivorous amphipods correlated negatively with the copper content of a common algal species. However, differences in metal accumulation between algal species resulted in spatially variable levels of contamination. Small-scale patchiness of contaminants within these landscapes may allow populations of mobile species to persist if contaminated hosts are avoided. In summary, epifaunal assemblages appeared resilient to storm-water pulses. Recovery of affected groups was rapid and large fluctuations in abundance appear to be part of the natural flux of epifaunal communities. In contrast, assemblages responded strongly to algal-bound contaminants and this has emerged as an important pathway of contaminant exposure and impact within algal habitats.

Generalist herbivores profoundly influence the biomass and species composition of macroalgae assemblages. In subtidal ecosystems of temperate latitudes, large invertebrates are usually the most influential herbivores. I tested the prediction that exclusion of invertebrate herbivores would lead to changes in the biomass and species composition of the macroalgae assemblages that are a prominent feature of the reefs in south-western Australia. The most abundant invertebrate herbivores were sea urchins (Heliocidaris erythrogramma, Phyllacanthus irregularis and Centrostephanus tenuispinus), and these occupied different trophic positions. Heliocidaris was present at virtually all reefs surveyed, and was particularly abundant in the Fremantle region. Analyses of stable isotopes and direct observations of gut contents revealed that it was almost exclusively herbivorous, and that it mainly ate foliose brown algae. In contrast, Phyllacanthus and Centrostephanus were omnivorous; while they consumed large proportions of algae, a substantial proportion of the diet of both species was animal tissue. Because Heliocidaris is a generalist herbivore that occurs at high densities, it could exert a large influence on the macroalgae assemblage. This prediction was tested by a series of press experiments. Contrary to the prediction, Heliocidaris exerted a very minor influence on the biomass, and no detectable influence on the species composition, of attached macroalgae. However, it exerted a major influence on the retention of drift macroalgae and seagrass by trapping and feeding on drift. It exerted a particularly strong influence on retention of the kelp Ecklonia radiata. This kelp was not abundant in the attached algae assemblage (when all plots were pooled it ranked 35th in biomass), but was abundant as drift (ranking 1st). Most of the drift Ecklonia was retained by sea urchins, rather than freely drifting.Herbivorous fish may also influence macroalgae assemblages. To compare the effects of sea urchins versus fish on recruiting and adult macroalgae a 13-month exclusion experiment was conducted. There were no detectable effects of sea urchins (mainly Heliocidaris) on either recruiting or adult macroalgae. There were some patterns in the biomass of recruiting algae consistent with an influence by herbivorous fish; however, these patterns were also consistent with the presence of artefacts (shading and reduced water flow) by fish exclusion devices. I began with the prediction that large invertebrate herbivores were a major influence on the macroalgae assemblages of subtidal reefs in south-western Australia. Overall, there was little evidence to support this prediction: within spatial extents of tens of square metres and over periods of 1-2 years, only minor effects were detected. However, it remains plausible that herbivores exert an influence over long time periods across large spatial extents in south-western Australia. I propose that trophic subsidies support the comparatively high densities of Heliocidaris that exist at some reefs. I further propose that these subsidies mediate the effects of sea urchins on the attached macroalgae assemblage, and that they might play an important role in energy and nutrient cycling in these nearshore ecosystems.

Submitted by Iatã do Carmo Mendonça null (iata.mendonca@hotmail.com) on 2018-11-13T19:26:17Z No. of bitstreams: 1 Dissertação Iatã Final.pdf: 6444130 bytes, checksum: 11f109faa73fa111dd02175f3cf51eaf (MD5) / Approved for entry into archive by Ana Carolina Gonçalves Bet null (abet@iq.unesp.br) on 2018-11-21T12:18:13Z (GMT) No. of bitstreams: 1 mendonca_ic_me_araiq_int.pdf: 6335142 bytes, checksum: 3275b085559a59aa0ff58a993812c371 (MD5) / Made available in DSpace on 2018-11-21T12:18:13Z (GMT). No. of bitstreams: 1 mendonca_ic_me_araiq_int.pdf: 6335142 bytes, checksum: 3275b085559a59aa0ff58a993812c371 (MD5) Previous issue date: 2018-10-05 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Considerando a variedade de compostos encontrados em produtos de origem natural, o estudo da biodiversidade de um país é de interesse tanto científico quanto econômico. Sendo possível destacar os ecossistemas marinhos que apresentam biodiversidade comparável às florestas tropicais. Devido ao ambiente diferenciado, muitas vezes inóspito, os habitantes do ambiente marinho exibem características bioquímicas diferenciadas, mostrando grande potencial para bioprospecção. A importância do estudo de organismos marinhos na busca por metabólitos secundários bioativos levou à proposta de aprofundar a prospecção química do fungo endofítico Humicola fuscoatra, isolado da alga vermelha Asparagopsis taxiformis. A partir de seu extrato foi possível purificar por técnicas cromatográficas, e identificar 7 substâncias com base nos dados de ressonância magnética nuclear uni e bidimensional (RMN de 1H, RMN de 13C, TOCSY-1D, COSY, HSQC, HMBC) e espectrometria de massas (EM). Dentre estes foram identificados um composto da classe das dicetopiperazinas (P01), duas isocumarinas (P02 e P05), além de 4 substâncias não relatadas na literatura, incluindo três valerolactamas (P03, P06 e P07) e uma cicloexadienona (P04). Além dos compostos purificados por CLAE, foi possível identificar duas substâncias por cromatografia a gás acoplada a espectrometria de massas (CG-EM) sendo elas uma dicetopiperazina e um ftalato. A variedade estrutural dos compostos isolados e a grande quimiodiversidade do extrato de Humicola fuscoatra reforçam a necessidade de se realizar estudos químicos de fungos endofíticos de origem marinha, visto que estes são uma fonte de metabólitos com grande potencial para contribuir na busca por protótipos para novos agentes terapêuticos, além de enfatizar a importância da preservação dos biomas aquáticos, sob constante ameaça por impactos ambientais e mudanças climáticas. / Seeing the variety of compounds obtained from natural products, study a country biodiversity have a scientific interest as well as economic. It is possible to highlight marine ecosystems that present biodiversity comparable to rainforests. Due to the unique environment, often inhospitable, the organisms of the marine environments display uncommon biochemical characteristics, showing great potential for bioprospecting. The importance of the study of marine organisms in the search for bioactive compounds led to the proposal to deepen the prospection of the endophytic fungus Humicola fuscoatra, isolated from the red alga Asparagopsis taxiformis. Its extract led to the purification by chromatographic methods, and identification of 7 compounds based on their NMR spectral data obtained by uni and bidimensional experiments (1H NMR, 13C NMR, TOCSY-1D, COSY, HSQC, HMBC) and mass spectrometry (MS). One diketopiperazine (P01), two isocoumarins (P02 and P05) in addition to four novel compounds, including three valerolactams (P03, P06 and P07) and one cyclehexadienone (P04) were isolated. Moreover another diketopiperazine and one phthalate derivative were identified by gas chromatography coupled to mass spectrometry (GC-MS). The structural variety of the identified compounds associated to the rich chemodiversity observed for the Humicola fuscoatra extract reinforces the need to develop additional chemical studies of endophytic fungal strains of marine origin, since they have been providing metabolites with great potential to the development of novel therapeutic agents, in addition to emphasize the importance of aquatic biomes preservation, as they have been continuously threatened by environmental and climate change impacts.

Orientadora: Dulce Helena Siqueira Silva / Banca: Alberto José Cavalheiro / Banca: Taicia Pacheco Fill / Resumo: Considerando a variedade de compostos encontrados em produtos de origem natural, o estudo da biodiversidade de um país é de interesse tanto científico quanto econômico. Sendo possível destacar os ecossistemas marinhos que apresentam biodiversidade comparável às florestas tropicais. Devido ao ambiente diferenciado, muitas vezes inóspito, os habitantes do ambiente marinho exibem características bioquímicas diferenciadas, mostrando grande potencial para bioprospecção. A importância do estudo de organismos marinhos na busca por metabólitos secundários bioativos levou à proposta de aprofundar a prospecção química do fungo endofítico Humicola fuscoatra, isolado da alga vermelha Asparagopsis taxiformis. A partir de seu extrato foi possível purificar por técnicas cromatográficas, e identificar 7 substâncias com base nos dados de ressonância magnética nuclear uni e bidimensional (RMN de 1H, RMN de 13C, TOCSY-1D, COSY, HSQC, HMBC) e espectrometria de massas (EM). Dentre estes foram identificados um composto da classe das dicetopiperazinas (P01), duas isocumarinas (P02 e P05), além de 4 substâncias não relatadas na literatura, incluindo três valerolactamas (P03, P06 e P07) e uma cicloexadienona (P04). Além dos compostos purificados por CLAE, foi possível identificar duas substâncias por cromatografia a gás acoplada a espectrometria de massas (CG-EM) sendo elas uma dicetopiperazina e um ftalato. A variedade estrutural dos compostos isolados e a grande quimiodiversidade do extrato de Humi... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Seeing the variety of compounds obtained from natural products, study a country biodiversity have a scientific interest as well as economic. It is possible to highlight marine ecosystems that present biodiversity comparable to rainforests. Due to the unique environment, often inhospitable, the organisms of the marine environments display uncommon biochemical characteristics, showing great potential for bioprospecting. The importance of the study of marine organisms in the search for bioactive compounds led to the proposal to deepen the prospection of the endophytic fungus Humicola fuscoatra, isolated from the red alga Asparagopsis taxiformis. Its extract led to the purification by chromatographic methods, and identification of 7 compounds based on their NMR spectral data obtained by uni and bidimensional experiments (1H NMR, 13C NMR, TOCSY-1D, COSY, HSQC, HMBC) and mass spectrometry (MS). One diketopiperazine (P01), two isocoumarins (P02 and P05) in addition to four novel compounds, including three valerolactams (P03, P06 and P07) and one cyclehexadienone (P04) were isolated. Moreover another diketopiperazine and one phthalate derivative were identified by gas chromatography coupled to mass spectrometry (GC-MS). The structural variety of the identified compounds associated to the rich chemodiversity observed for the Humicola fuscoatra extract reinforces the need to develop additional chemical studies of endophytic fungal strains of marine origin, since they have been providin... (Complete abstract click electronic access below) / Mestre