Characterization of the photosynthetic conditions and pigment profiles of the colour strains of Hypnea musciformis from field-collected and in vitro cultured samples

Hypnea musciformis (Wulfen) JV Lamour. is a species of great economic interest as it produces Κ-carrageenan and has shown biological activities against HIV and HSV viruses. This species displays different colour strains in its natural habitat, which may have implications for the biotechnological potential of the species. The aim of this study was to characterize the photosynthetic apparatus and pigment profile of three colour strains of H. musciformis (green, brown and red) in their natural habitat and in culture. Chlorophyll a fluorescence of photosystem II was measured with a pulse-amplitude modulated fluorometer and pigments were quantified by spectrofluorimetry (chlorophyll a) and spectrophotometry (phycobiliproteins). In the natural habitat, we detected significant differences between the colour strains for the following photochemical parameters: the green strain had a higher effective quantum yield (ΦPSII) than the red strain and a higher maximum relative electron transport rate (rETRmax) than the brown and red strains. Saturation irradiances were 1000 µE.m-2.s-1 (green) and 500 µE.m-2.s-1 (brown and red). Concerning in vitro culture, the green strain presented the lowest ΦPSII, rETRmax, and α rETR, while the brown strain presented the highest values for these same parameters. The chlorophyll a content of the cultured green strain was the lowest. The phycoerythrin contents of the three colour strains were unchanged by either natural of in vitro conditions: lower in green, intermediate in brown and higher in the red strain, ensuring the chromatic identity of the strains. Our results suggest that the green strain has a better performance when exposed to high irradiance, but a lower efficiency under low irradiance compared to the brown and red strains.

Anti-HSV activity of Hypnea musciformis cultured with different phytohormones

Four extracts from the seaweed Hypnea musciformis (Wulfen in Jacq.) J.V. Lamour. (Rhodophyta), collected directly from its natural habitat or cultivated in the presence of phytohormones, were evaluated for their ability to inhibit the replication of acyclovir-resistant herpes simplex viruses types 1 (HSV-1) and 2 (HSV-2) strains. The main purpose was to determinate whether these growth conditions would affect the antiviral activity. Our results showed the possibility of improving the anti-HSV activity by using extracts from algae cultured in the presence of phytohormones.

Diterpenes from marine brown alga Dictyota guineensis (Dictyotaceae, Phaeophyceae)

The crude extract of the marine brown alga Dictyota guineensis was analyzed by high-resolution gas chromatography-mass spectrometry (HRGC-MS). Five diterpenes were identified: dictyol E (the most abundant diterpene), dictyotadiol, dictyoxide, isopachydictyol A and pachydictyol A, all diterpenes from the chemical group I, i.e., mainly prenylated derivatives of known sesquiterpene skeletons that result from a first cyclization of geranyl-geraniol between positions 1 and 10. These diterpenes are known for their activity against bacteria, fungi and other activities. The results characterize D. guineensis as a species that yields exclusively diterpenes from group I, with low oxidation and low structural complexity. On Brazilian coasts, only D. mertensii provides exclusively prenylated guaiane diterpenes. Although D. guineensis presents alternate branches and fixing by rhizoidal branches, it is easily distinguishable from D. mertensii by the much narrower stem, short stature and flabelliform habit of the former species. On the other hand, both species have been characterized as producers of diterpenes of group I, in particular, prenylated guaiane. However, D. guineensis has a majority dictyol E in the lipophilic extract, while D. mertensii produces more complex prenylated guaianes, like dictyol H.

Antiviral activity of extracts from Brazilian seaweeds against herpes simplex virus

Organic extracts of 36 species of marine algae (sixteen species of Rhodophyta, eight species of Ochrophyta and twelve species of Chlorophyta) from seven locations on the Brazilian coast were evaluated for their anti-HSV-1 and anti-HSV-2 activity resistant to Acyclovir (ACV). Activity tests in crude extracts, followed by the identification of the major compounds present, were performed for all species. The chemical profiles of all crude extracts were obtained by ¹H-NMR and 13C-NMR spectroscopy. The percentage of extracts with antiviral activity was higher for HSV-1 (86.1%) than for HSV-2 (55.5%). The green algae Ulva fasciata and Codium decorticatum both showed the highest activity (99.9%) against HSV-1, with triacylglycerols and fatty acids as the major components. The red alga Laurencia dendroidea showed good activity against HSV-1 (97.5%) and the halogenated sesquiterpenes obtusol and (-)-elatol were identified as the major components in the extract. Against HSV-2, the green alga Penicillus capitatus (Chlorophyta) and Stypopodium zonale (Ochrophyta) were the most active (96.0 and 95.8%). Atomaric acid, a meroditerpene, was identified as the major secondary metabolite in the S. zonale extract. These results reinforce the role of seaweeds as important sources of compounds with the potential to enter into the pipeline for development of new drugs against herpes simplex.

Sulfated fucan from marine alga inhibits HeLa cells infection by HTLV-1 free particles: semi-quantitative analysis

A sulfated fucan from Laminaria abyssalis marine alga prevented the interaction of HTLV-1 particles, purified from the MT-2 cell line, with HeLa cells. The infection obtained using a concentrated virus suspension was detected only by amplification of the newly synthesized HTLV-1 proviral cDNA by the nested-polymerase chain reaction (PCR). The sulfated polysaccharide was not toxic to the cells at a concentration of 100 µg/mL and prevented infection by the viral particles when added to the cell monolayers. The proviral cDNA was only detected when the sulfated polysaccharide was added to the cells three hours post-infection, indicating that the inhibitory activity occurred in the initial stages of virus-cell interaction. Our results demonstrate, for the first time, the ability of a sulfated fucan from marine algae to inhibit virus transmission through free virus particles.

Protocol for seaweed decontamination to isolate unialgal cultures

Decontamination protocols in seaweeds are essential tools for ecophysiological studies in laboratory cultures. These protocols consist of a set of procedures and physical and chemical treatments that must be adjusted for each species. Thus, the effects of explant size and of combinations of physical treatments (brushing and cutting) and chemical treatments (sodium hypochlorite, detergent, seawater, distilled water, germanium dioxide) on the process of obtaining unialgal culture of two pigmentar morphos of Hypnea musciformis were investigated. It was found that thallus segments 50 mm in length, when transported from the field to the laboratory, remained healthier and were less susceptible to epiphytes than those 7 mm in length. The collected material had surfaces contaminated by diatoms, which were weakly attached, as well as surface contamination caused by strongly attached Sahlingia subintegra. The most efficient combination of physical and chemical treatments was explant brushing, cutting and washing with detergent. This combination eliminated the contamination by S. subintegra, but not all of the diatom contamination. The population of the latter was reduced by using physical treatment and by washing with detergent and distilled water and then exterminated by using germanium dioxide (0.003 mg/L). Employing this protocol, unialgal cultures of H. musciformis could be established in approximately eight to ten weeks.

Micropropagation as a tool for sustainable utilization and conservation of populations of Rhodophyta

Micropropagation as a tool for sustainable utilization and conservation of populations of Rhodophyta. Micropropagation, or in vitro clonal propagation, allows the production of a large number of individuals within a short period. These micropropagated clones could be used as seedlings for seaweed cultivation, avoiding collection from natural beds. Consequently, there has been an increasing interest in micropropagation as a tool for preservation of populations of marine red algae on the Brazilian coast and for the sustainable production of raw material for commercial exploration. This paper reviews the literature on tissue culture and micropropagation of red algae published during the three last decades. Based on the literature, we can conclude that the regeneration process is complex and diversified in different species of Rhodophyta and that the success of micropropagation depends on this process. Species belonging to the orders Bangiales and Ceramiales showed low potential for regeneration, while Gigartinales species showed the highest potential for regeneration. Micropropagation of commercially important red algae is fundamental for the conservation of natural populations by providing seedlings for cultivation and for germplasm collections, both for the conservation of genetic diversity and for biotechnological applications.

Antiviral activity of the green marine alga Ulva fasciata on the replication of human metapneumovirus / Atividade antiviral da alga verde marinha Ulva fasciata na replicação do metapneumovírus humano

We evaluated the antiviral activity of the marine alga, Ulva fasciata, collected from Rasa beach and Forno beach, Búzios, Rio de Janeiro, Brazil on the replication of human metapneumovirus (HMPV). The algae extracts were prepared using three different methodologies to compare the activity of different groups of chemical composites obtained through these different methodologies. Four out of the six extracts inhibited nearly 100 percent of viral replication. The results demonstrated that the majority of the extracts (five out of six) possess virucidal activity and therefore have the ability to interact with the extracellular viral particles and prevent the infection. On the other hand, only two extracts (from Forno beach, obtained by maceration and maceration of the decoction) were able to interact with cell receptors, hindering the viral entry. Finally, only the extract of algae collected at Forno beach, obtained by maceration presented intracellular activity. To our knowledge, this is a pioneer study on antiviral activity of marine algae against HMPV. It is also the first on antiviral activity against HMPV ever done in Brazil. The study also shows the effect of different environment factors and different chemical procedures used to obtain the extract on its biological properties.

Neste artigo, foi avaliada a atividade antiviral da alga marinha Ulva fasciata, coletada nas Praias do Forno e Rasa, em Búzios, Rio de Janeiro, Brasil, sobre a replicação do metapneumovírus humano (HMPV). Os extratos desta alga foram preparados utilizando três diferentes metodologias, visando a comparação da atividade de diferentes grupos de compostos químicos que são obtidos dependendo da metodologia empregada. Quatro, do total de seis extratos foram capazes de inibir praticamente 100 por cento da replicação viral. Os resultados demonstram também que a maioria dos extratos (cinco, dos seis), possui atividade virucida e, portanto, possuem a habilidade de interagir com a partícula viral extracelularmente impedindo a infecção. Por outro lado, apenas dois extratos (coletado da Praia do Forno e, preparado através de maceração e maceração do decocto) foram capazes de se ligar a receptores celulares, impossibilitando assim a entrada das partículas virais nas células. Finalmente, apenas o extrato que foi preparado por maceração da alga coletada na Praia do Forno, demonstrou atividade intracelular. Até onde sabemos, este é um estudo pioneiro sobre a atividade antiviral de algas marinhas sobre o HMPV. É também o primeiro estudo sobre atividade antiviral sobre HMPV realizado no Brasil. O estudo também mostra o efeito de diferentes condições ambientais e procedimentos químicos utilizados na preparação do extrato sobre suas propriedades biológicas.