Tropical Brown Seaweed Research Articles

Methane gas production and phenolic compound of two species in tropical brown seaweeds

Abstract A study has indicated that the metabolites found in seaweed can lower methane emissions from ruminants, especially the phenolic compound. Indonesia is a tropical nation where seaweed variety is abundant, but it has not been widely reported to be used to reduce ruminant methane emissions. The research aims to measure the methane gas production and phenolic compound of two species in tropical brown seaweeds (Laminaria Sp. and Padina australis) from Tuban, East Java, in Kelapa Beach, Indonesia. The treatments were completely randomized with four replications and t test for the differences among treatment means. After a 24-hour incubation period, 10 mL samples used for the analysis of methane gas production were taken from the aliquot, preserved in a vacuum tube, and measured using gas chromatography (GC). The phenolic compound analysis included phenol, tannin, and flavonoid with a spectrophotometer according to Makkar (2003) and Arvouet-Grand et al. (1994) method. The result showed that Padina australis (2.47 mL and 13.00 mL/g DM) is lower in methane than Laminaria sp. (3.41 mL and 18.41 mL/g DM). Meanwhile, Padina australis is higher in flavonoid, phenol, and tannin (3.99, 0.88, 0.87 mg/g DM respectively) than Laminaria sp. (2.73, 0.63, 0.61 mg/g DM respectively). It was concluded that from two species of tropical brown seaweed, Padina australis had more potential to reduce methane emission than Laminaria sp. due to higher phenolic compounds (flavonoid, phenol, and tannin).

Docking Studies and Molecular Dynamics Simulations of Potential Inhibitors from the Brown Seaweed Sargassum polycystum (Phaeophyceae) against PLpro of SARS-CoV-2

The COVID-19 disease is a major problem affecting human health all over the world. Consequently, researchers have been trying to find solutions to treat this pandemic-scale disease. Even if there are vaccines and approved drugs that could decrease the spread of this pandemic, multidisciplinary approaches are still needed to identify new small molecules as alternatives to combat COVID-19, especially those from nature. In this study, we employed computational approaches by screening 17 natural compounds from the tropical brown seaweed Sargassum polycystum known to have anti-viral properties that benefit human health. This study assessed some seaweed natural products that are bound to the PLpro of SARS-CoV-2. By employing pharmacophore and molecular docking, these natural compounds from S. polycystum showed remarkable scores for protein targets with competitive scores compared to X-ray crystallography ligands and well-known antiviral compounds. This study provides insightful information for advanced study and further in vitro examination and clinical investigation for drug development prospects of abundant yet underexploited tropical seaweeds.

POTENTIAL USE OF BROWN ALGAE AS AN IMMUNOSTIMULANT MATERIAL IN THE AQUACULTURE FIELD TO INCREASE NON-SPECIFIC IMMUNITY AND FIGHT DISEASE

The aquaculture field continues to grow from year to year. This is because aquaculture fulfills the world's food needs. Aquaculture intensification continues. As a result of this intensification, the aquaculture environment experienced a decrease in water quality. This led to the rapid growth of bacteria, fungi, parasites, and viruses, resulting in a high incidence of disease outbreaks. An alternative solution that has been extensively researched recently is using immunostimulants to increase the non-specific immunity of fish and shrimp, which will help fish and insects prevent disease outbreaks. One of the natural ingredients that have the potential to become an immunostimulant is from the brown algae group. Immunostimulants from brown algae such as Hot-water Extract of Tropical Brown Seaweed, Sargassum cristaefolium, Sargassum glaucescens, Sargassum duplicatum, Sargassum wightii, Sargassum sp. Polysaccharides from seaweed, such as fucoidan extracts from brown algae, can enhance the non-specific immune system in shrimp Litopenaneus vannamei, Penaeus monodon, Fenneropenaeus indicus, and tilapia Oreochromis niloticus. These immunostimulants increase non-specific immunity, such as total hemocyte count, phagocytosis activity, phenoloxidase, phagocytic, respiratory burst, superoxide dismutase, and total plasma protein. Immunostimulants from brown algae can also fight bacterial disease attacks Vibrio parahaemolyticus, Streptococciasis, Streptococcus iniae, and White spot syndrome virus (WSSV) by increasing survival rate and can increase the growth and feed efficiency of cultivated commodities that are not given immunostimulants.

Antioxidant, Scavenging, Reducing, and Anti-Proliferative Activities of Selected Tropical Brown Seaweeds Confirm the Nutraceutical Potential of Spatoglossum asperum.

Brown seaweeds have shown high potential of bioactivity and provide health benefits as an important functional food ingredient. Therefore, four abundantly growing tropical brown seaweeds—Iyengaria stellata, Spatoglossum asperum, Sargassum linearifolium, and Stoechospermum polypodioides—were collected from the Saurashtra Coast of the Arabian Sea. They were analyzed for metabolite profiling, biochemical activities (including total antioxidant, reducing, scavenging, and anti-proliferative characteristics), and total phenolic and flavonoid contents. A concentration-dependent antioxidant, reducing, and scavenging activities were observed for all four brown seaweeds. The S. asperum and I. stellata extracts showed maximum total antioxidant activity. S. asperum also showed high scavenging and reducing activities compared to other studied brown seaweeds. Further, S. asperum contained high total phenolic and flavonoid content compared to other brown seaweeds collected from the same coast. A multivariate correlation study confirmed a positive correlation between total phenolic and flavonoid contents, and biochemical activities (total antioxidant, scavenging and reducing) for all brown seaweeds. About 35% anti-proliferative activity was observed with S. asperum extract on Huh7 cells; in contrast S. polypodioide showed about 44% proliferation inhibition of Huh7 cells. Similarly, 26% proliferation inhibition of HeLa cells was observed with S. asperum extract. Overall, S. asperum possesses high total flavonoid and phenolic amounts, and showed potential antioxidant, scavenging and reducing characteristics. The study confirmed the nutraceutical potential of S. asperum and that it could be a promising functional food ingredient.

Chemical composition diversity of fucoidans isolated from three tropical brown seaweeds (Phaeophyceae) species

Abstract. Lutfia FN, Isnansetyo A, Susudarti RA, Nursid M. 2020. Chemical composition diversity of fucoidans isolated from three tropical brown seaweeds (Phaeophyceae) species. Biodiversitas 21: 3170-3177. Fucoidan is a polysaccharide with high sulfate content, found in the cell walls matrix of brown seaweed. Its bioactivities vary depending on the algae species and the chemical structure. The aims of this research were to extract, purify, and characterize fucoidan from three Indonesian brown seaweed, Sargassum sp., Turbinaria sp., and Padina sp. The extraction was carried out using acid method followed by precipitation with ethanol and CaCl2, while its purification using DEAE-cellulose ion-exchange chromatography. Characterization was performed by FTIR and 1H-NMR spectroscopic analyses. Chemical components of fucoidan determined were total carbohydrates, sulfate residue, uronic acid residue, and monosaccharide components. The results revealed that the Turbinaria sp. produced highest yield of fucoidan (4.8% dry matter), followed by Sargassum sp. (2.7% dry matter) and Padina sp. (2.6% dry matter). The carbohydrate contents of Sargassum sp., Turbinaria sp. and Padina sp. fucoidan were 64.55±0.12%, 67.42 ± 0.03% and 62.90 ± 0.04% with sulfate residues of 0.013% ± 4.71; 19.47±0.002% and 0.016%±8.81; and uronic acid residues of 25.19±0.03%; 12.69±0.03% and 12.91±0.01%, respectively. Sargassum sp., Turbinaria sp., and Padina sp. fucoidans consist of fucose and some other minor monosaccharides.

Culture of the tropical brown seaweed Sargassum aquifolium: From hatchery to field out-planting

As part of the preparation for the mass cultivation of the brown seaweed, Sargassum aquifolium, the following were investigated in a replicated experiment: patterns on the early post-settlement stage of the germlings on three types of artificial substrates (i.e., clay, limestone, and nylon string), and growth and development of the hatchery-derived S. aquifolium juveniles out-planted in the sea. Our investigation during the early post-settlement stage demonstrated: 1) recruit density to be highest on nylon string followed by clay, then limestone throughout a one-week observation period, 2) survival rate of germlings to be highest on limestone, followed by clay, then nylon string at day 9, and 3) higher daily growth rate (DGR) of germlings on clay at day 14, 21, 35, and 49. Recruits on clay substrates were the first to reach young juvenile stage and were used in out-planting. Young juveniles demonstrated continuous increase in length until 42 days post out-planting with some fluctuations thereafter. Lateral branches started to decrease 7 days post out-planting and throughout the sampling days. Overall, clay substrate was found to be suitable for the attachment and cultivation of S. aquifolium. However, an optimal density and optimal site selection seemed to be required during hatchery cultivation and out-planting, respectively. This would also prevent infestation of epiphytic organisms and grazers, and accumulation of sediment which could hamper the growth and development of S. aquifolium.

Latitudinal variation in phlorotannin contents from Southwestern Atlantic brown seaweeds.

Phlorotannins are primary and/or secondary metabolites found exclusively in brown seaweeds, but their geographic distribution and abundance dynamic are not very well understood. In this study we evaluated the phlorotannin concentrations among and within-species of brown seaweeds in a broad latitudinal context (range of 21°) along the Brazilian coast (Southwestern Atlantic), using the Folin-Ciocalteau colorimetric method. In almost all species (16 out of 17) very low phlorotannin concentrations were found (<2.0%, dry weight for the species), confirming reports of the typical amounts of these chemicals in tropical brown seaweeds, but with significantly distinct values among seven different and probably highly structured populations. In all 17 seaweed species (but a total of 25 populations) analyzed there were significant differences on the amount of phlorotannins in different individuals (t-test, p < 0.01), with coefficients of variation (CV) ranging from 5.2% to 65.3%. The CV, but not the total amount of phlorotannins, was significantly correlated with latitude, and higher values of both these variables were found in brown seaweeds collected at higher latitudes. These results suggest that brown seaweeds from higher latitudes can produce phlorotannins in a wider range of amounts and probably as response to environmental variables or stimuli, compared to low latitude algae.

Oral Administration of Hot‐water Extract of Tropical Brown Seaweed, Sargassum cristaefolium, to Enhance Immune Response, Stress Tolerance, and Resistance of White Shrimp, Litopenaeus vannamei, to Vibrio parahaemolyticus

AbstractThe efficacy of hot‐water extract of tropical brown seaweed, Sargassum cristaefolium (SCE), supplemented in diets on immune response, stress tolerance, and disease resistance of Litopenaeus vannamei to Vibrio parahaemolyticus was evaluated. Shrimp were fed diets containing graded levels of SCE (0, 250, 500, 750, and 1000 mg/kg). The results showed that shrimp fed all diets containing SCE had significantly higher (P &lt; 0.05) immune response in total hemocyte count (THC), differential hemocyte count (granular and hyaline cells), and phagocytic activity than those of shrimp fed the control diet. Similarly, in low dissolved oxygen stress tolerance test and the challenge test with V. parahaemolyticus, survival rates of shrimp fed all diets containing SCE were significantly higher (P &lt; 0.05) (83–93% in stress test and 27–47% in challenge test) than those of shrimp fed the control diet (77 and 3.3%, respectively). These results suggest that oral administration of SCE at 500 and 750 mg/kg can be effectively used to enhance immune response, stress tolerance, and resistance of white shrimp, L. vannamei, against V. parahaemolyticus infection. These findings also confirm that using dietary SCE as immunostimulant is effective at increasing the nonspecific immune system in penaeid shrimp, L. vannamei.

Protective effect of fucoidans from tropical seaweeds against oxidative stress in HepG2 cells

Fucoidans are sulfated polysaccharides with proven pharmacological effects localized in the cell wall of marine brown algae. The majority of studies have been performed with temperate brown algal species, but in recent years, the evaluation of species from tropical areas has been growing. The aim of this study was to determine the protective effect of fucoidans extracted from the tropical brown seaweeds Dictyota ciliolata, Padina sanctae-crucis, and Sargassum fluitans, against oxidative stress (OS). The D. ciliolata fucoidan (FDc) exhibited the highest reactive oxygen species (ROS) scavenging activity (26%), followed by P. sanctae-crucis fucoidan (FPs) (22%) and S. fluitans fucoidan (FSf) (14%). No cytotoxic effect was detected for any of the extracted fucoidans at a concentration of 2 mg mL−1. Not only did the fucoidans tested show protective effect against OS by reducing ROS generation, but they also increased the glutathione (GSH) level and restored catalase (CAT) activity. Fucoidans obtained from tropical seaweeds could be used as a potential natural ingredient for functional foods.

Lipids, Fatty Acids, and Fucoxanthin Content from Temperate and Tropical Brown Seaweeds

Brown seaweeds lipid fraction contains several bioactive components such as Fx, polyphenol and n-3 PUFA. In this research, total lipids, Fx and FA compositions of brown seaweeds harvested from cold waters and warm waters were evaluated. The seven brown seaweeds studied were collected in different months from two different geographical areas, viz. cold waters (Japan) and warm waters (Indonesia). The result show that total lipid and Fucoxanthin in temperate brown seaweeds were higher than tropical brown seaweeds. The major PUFA from warm water seaweeds were 16:0, 18:1n-9, 20:4n-6, and cold water continued dominantly 16:0, 20:4n-6, 20:5n-3. Temperate brown seaweeds [S. horneri (Turner) J. Agardh] was rich in fucoxanthin and n-3 PUFA especially EPA.

Oral Administration of Alginate From A Tropical Brown Seaweed, Sargassum sp. To Enhance Non-Spesific Defense In Walking Catfish (Clarias sp.)

Alginate that is usually extracted from brown seaweeds, is a bioactive substance with immunomodulator activity. The purpose of this research was to evaluate the effect of oral administration of alginate on the non-specific immune system of walking catfish ( Clarias sp.). An experiment was conducted in a Completely Randomized Design with five treatments in triplicates. Alginate was supplemented in feed at doses of 0 (control treatment), 2, 4, 6 and 8 g/kg of feed. The walking catfish was fed twice daily at feeding rate of 5%. Non-specific defense parameters evaluated were Nitroblue Tetrazolium (NBT) activity, phagocytic activity (PA), phagocytic index (PI), leukocyte differentiation, hematocrit and leucocrit. The parameters were observed prior to be treated, 5 th , 10 th and 15 th days after treatments. Oral administration of alginate at 4 g/kg of feed increased NBT and PA activities significantly ( P <0.05) in 5 days, while alginate at a dose of 6 g/kg increased NBT activity and monocyte percentage significantly ( P <0.05) in 5 days. These results suggested that oral administration of alginate at 4 g/kg effectively increased non-specific immune system of walking catfish.

Seasonal and within-plant variation in fatty acid content and composition in the brown seaweed Spatoglossum macrodontum (Dictyotales, Phaeophyceae)

We investigated seasonal and within-plant variation in total fatty acids (TFAs) and biomass increase in the tropical brown seaweed Spatoglossum macrodontum which was sampled from Magnetic Island (Queensland, Australia) at monthly intervals over 1 year. In this habitat, S. macrodontum is an annual species with a growth period from June to September where mean biomass changed from 8- to 136-g fresh weight. Although TFA content and fatty acid (FA) composition were not directly correlated to individual plant size, there was clear seasonal variation in TFA content with a peak in July (82.7 mg g−1 dry weight (dw)) followed by a 30 % decline in August and little subsequent variation from September to November (65.9–55.5 mg g−1 dw). The FA profile was rich in polyunsaturated FAs (PUFAs) (39 %); however, there was a change to a higher percentage of saturated FAs (SFAs) (42 %) and reduced PUFA (31 %) as plants reached the end of the growth period. Averaged across sampling periods, TFA content ranged from 77 mg g−1 dw in the tips to 30 mg g−1 dw in the base section. While PUFA content (37–38 %) was similar across sections, the base had less SFAs and a higher content of monounsaturated FAs (MUFAs) (29 %). These results are the first data on the seasonal biomass increase and the temporal and internal variations in FAs for this species with important implications when targeting large brown seaweeds as a source of FAs for nutraceuticals (PUFA(n-3), 21.8 % of TFA) or chemicals (C18:1 (n-9), 17.6 % of TFA).

Volatile halocarbon emissions by three tropical brown seaweeds under different irradiances

The emission rates of eight volatile halogenated compounds by three tropical brown seaweed species collected from Cape Rachado, west coast Peninsular Malaysia, under different irradiances have been determined. A purge-and-trap sample preparation system with a gas chromatograph and mass-selective detector was used to measure a suite of halocarbons released by Sargassum binderi Sonder ex J. Agardh, Padina australis Hauck, and Turbinaria conoides (J. Agardh) Kutzing. All species are widely distributed in Peninsular Malaysia, with S. binderi a dominant seaweed species at our survey site. Release of few halocarbons was found to be influenced by irradiance. Correlations were also observed between emission of certain halocarbons with photosynthetic activity, especially bromo-and iodinated compounds (0.6 < r <0.9; p < 0.01) suggesting that environmental factors such as light can affect the release of these volatile halogenated compounds by the seaweeds into the atmosphere. Compared with temperate and polar brown seaweeds, tropical species, such as T. conoides, may emit higher levels of bromoform, CHBr3, and other halocarbons. It is therefore important to investigate the contribution of tropical seaweeds towards the local atmospheric composition of halocarbons.

Polysaccharides composition from tropical brown seaweeds

SummaryPolysaccharides composition of the tropical brown seaweeds Turbinaria turbinata, Sargassum filipendula, Dictyota caribaea and Padina perindusiata collected at Yucatan Peninsula (Mexico) was determined in this study. Crude fucoidan extracted with HCl and alginate extracted with a hot alkali solution were characterized in terms of their molecular weight, sulfate content, uronic acid, total carbohydrate and neutral sugar components. Low molecular weight sulfated‐fucoidan was the major component in all species studied. Fucoidan from T. turbinata and from D. caribaea were characterized as a homofucan, with fucose as the neutral sugar. Fucoidan from S. filipendula was composed of a galactofucan, and fucoidan from P. perindusiata was characterized as a heterofucan consisting of fucose, glucose and galactose. The Fourier transform infrared (FT‐IR) spectra of fucoidan extracted from species studied indicated that the majority of sulfate groups are located at C‐4 and to a lesser extent at C‐2 and/or C‐3 of the fucopyranose residues. This could be advantageous since several therapeutic effects have been reported for fucoidans with similar characteristics. FT‐IR spectra from D. caribaea and P. perindusiata revealed the presence of O‐acetyl groups in crude fucoidan, which could be potentially utilized as an immune stimulant. Molecular weight of alginate varied between 595 and 1301 kDa with similar uronic acid content in all species. Alginate M : G ratio inferred from FT‐IR spectra suggests a high content of G‐block in all species. Potential applications of these polysaccharides are discussed.

Chemical defenses of the tropical marine seaweed Canistrocarpus cervicornis against herbivory by sea urchin

This paper reports on the defensive chemical properties of the marine tropical brown seaweed Canistrocarpus cervicornis against herbivory. A natural concentration of dichloromethane crude extract (DCE) obtained from this seaweed significantly inhibited feeding by the sea urchin Lytechinus variegatus. The major metabolite isolated from this active DCE extract was identified as the (4R,7R,14S)-4α,7α-diacetoxy-14-hydroxydolast-1(15),8-diene that strongly inhibited feeding by the same sea urchin. This result suggests that the dolastane diterpenes class may constitute the defensive system of C. cervicornis against herbivory, and probably also of that of other brown seaweeds endowed with a biosynthetic pathway capable of producing compounds of the dolastane-type, a typical skeleton found in Dyctioteae species worldwide. This is the first report showing this compound-type (dolastane diterpenes) as a chemical defense against herbivory in marine seaweeds. This study constitutes an additional report broadening the known spectrum of action and roles of secondary metabolites of the C. cervicornis and Dyctioteae species.

ANALYSES OF EXPRESSED SEQUENCE TAGS FROM SARGASSUM BINDERI (PHAEOPHYTA)1

Sargassum is a source for many metabolites, including alginic acid, alginates, sulfated fucoidans, pigments, oils, sterols, and mannitols. The present study is the first attempt to examine Sargassum binderi (Sonder) J. Agardh, a tropical brown seaweed, using an expressed sequence tag (EST) approach. Single‐pass 5′ sequencing of 2304 cDNA clones generated 1876 ESTs of good quality, from which 1270 tentative unique genes (TUGs) consisting of 991 singletons and 279 contigs were obtained. Approximately 39.5% of the TUGs from S. binderi showed significant matches to the existing data bases and were further divided into nine subcategories: metabolism (24.9%); transcription and translation (22.5%); cellular processes (7.2%); protein folding, sorting, and degradation (5.6%); signaling (2.8%); membrane and transport (3%); receptor (1.1%); other functions (4.2%); and unknown proteins (28.7%). The sequences were compared with ESTs from Laminaria digitata (Hudson) J. V. Lamour.