Search Results (9)

Background: Brown algae from the order Dictyotales are known to produce specialized metabolites with a wide array of biological activities. Studying these compounds is important for understanding their ecological roles, exploring biomedical potential and developing biotechnological applications. Methods: To evaluate the metabolic diversity of brown algae from the shallow habitats of the northern region of San Andrés Island (Colombia, SW Caribbean), a metabolic profiling approach was employed, based on ¹H-NMR spectra taken from organic extracts. Four sampling expeditions were conducted to collect the most abundant species, taking into account the taxonomic identity, growth substrate and collection date. Results: Five species were found and identified as Canistrocarpus crispatus, Stypopodium zonale, Dictyopteris delicatula, Padina gymnospora and Dictyota spp. Multivariate analyses applied to these spectra revealed that S. zonale and C. crispatus differentiated from the other samples mainly due to the signals for meroditerpenes and diterpenes, respectively. S. zonale had differential metabolic production observed when comparing algae collected in rocky bottoms with thalli growing on dead coral. This difference was attributed to changes in concentrations of the meroditerpene atomaric acid (1). Meanwhile, the major metabolite found in C. crispatus samples was dictyol B acetate (2). Conclusions: NMR metabolomics of San Andrés brown algae differentiated species based on lipid content and metabolic complexity. Notably, prenylated-guaiane diterpenes characterized C. crispatus, and meroditerpenoid concentrations varied in S. zonale. Temporal lipid variations were observed in P. gymnospora, while juvenile Dictyota spp. presented a less complex metabolic signature. Full article

A study was conducted on growing sheep to investigate the effect of two selected levels of biowaste of Padina gymnospora on feed intake, digestibility, daily enteric methane (CH₄) emission, growth performance, and rumen metagenome. We randomly divided the 18 growing male sheep into three groups of six animals each. The animals were fed on a basal diet comprising finger millet straw (Eleusine coracana) and a concentrate mixture in a 35:65 ratio. The sheep in the control group (C) were offered a concentrate mixture without waste, whereas the wheat bran in the concentrate mixture in test group I (A₂) and test group II (A₅) was replaced (w/w) with the biowaste of Padina gymnospora at a level of 3.07 and 7.69%, respectively. The biowaste of Padina gymnospora at the above levels in concentrate constituted 2 and 5% of the diet. A significant decrease of 28.4% in daily enteric CH₄ emission (g/d) was reported in the A₅ group, whereas the difference in daily enteric CH₄ emission between the C and A₂ & A₂ and A₅ groups did not prove significant. The inclusion of Padina gymnospora biowaste did not affect the nutrient intake and digestibility among the groups. The inclusion of Padina gymnospora biowaste in the A₅ group resulted in a significant reduction (p = 0.0012) in daily CH₄ emissions compared with group C; however, no significant differences were observed in daily CH₄ emissions between groups C–A₂ (p = 0.0793) and A₂–A₅ (p = 0.3269). Likewise, the adjustment of data to CH₄ emissions per 100 g of organic matter intake indicated a substantial decrease in the A₅ group relative to C. The energy loss in CH₄ as a percentage of GE relative to group C decreased significantly (−23.4%) in the A₅ group; however, this reduction was not associated with an increase in productivity, as almost similar average daily gain (p = 0.827) was observed in the groups. The replacement of wheat bran with the biowaste of Padina gymnospora significantly decreased the numbers of total protozoa and holotrichs in the A₅ group. Irrespective of the group, the Bacteroidota was the single largest phylum in the rumen metagenome, representing >60% of the microbiota. However, the abundance of Bacteroidota was similar among the groups. The methanogenic phyla Euryarchaeota was the 5th most abundant; however, it constituted only 3.14% of the metagenome. The abundance of Desulfovibrio was significantly higher in the A₅ group as compared with the control. In conclusion, the significant increase in the abundance of sulfate-reducing bacteria and reduction in protozoal numbers led to a significant reduction in CH₄ emissions with the incorporation of biowaste of Padina gymnospora at a 5% level of the diet. Full article

Sargassum is an important primary producer of rocky bottom communities in coastal ecosystems. Like other parts of the planet, benthic populations of S. natans from Ilha Grande Bay (IGB), southeastern Brazil, have been suffering from different forms of natural and anthropogenic disturbances, in particular increasing seawater temperatures. The aim of this study was to understand the effects of temperature on the photosynthetic performance of S. natans using the pulse amplitude modulated (PAM) fluorometry. In the field experiments, the occurrence of photoprotection resulted in a difference between the effective and maximum quantum yields [(ΔF (F’_m − F_s)/F’_m and F_v/F_m, respectively) that was maximized at noon. The stress induced by incubation at 32–35 °C caused a decrease in F_v/F_m by 33% on the first day and approximately 20% on subsequent days. In the laboratory, using two co-occurred species of S. natans and Padina gymnospora, we verified that the photosynthetic apparatus of S. natans collapses at 34 °C. The fate of the energy absorbed by photosystem II (PSII) antenna showed that, in S. natans, photochemical activity and non-photochemical quenching of chlorophyll fluorescence (NPQ) drastically decrease, and only the passive dissipation in the form of heat and fluorescence remains. Our results indicate the disappearance of the NPQ photoprotection at 34 °C before the decline of F_v/F_m as the reason for the collapse of photochemistry of Sargassum. Full article

A series of in vitro studies were conducted to explore the anti-methanogenic potential of five seaweeds collected from the Indian sea and to optimize the level(s) of incorporation of the most promising seaweed(s) into a straw and concentrate diet to achieve a significant reduction in methane (CH₄) production without disturbing rumen fermentation characteristics. A chemical composition analysis revealed a notable ash content varying between 55 and 70% in seaweeds. The crude protein content was highly variable and ranged between 3.25 and 15.3% of dry matter. Seaweeds contained appreciable concentrations of tannins and saponins. Among the seaweeds, Spyridia filamentosa exhibited significantly higher CH₄ production, whereas the percentage of CH₄ in total gas was significantly lower in the cases of Kappaphycus alvarezii and Sargassum wightii. The ranking of seaweeds in terms of CH₄ production (mL/g OM) is as follows: Sargassum wightii < Kappaphycus alvarezii < Acanthophora specifera < Padina gymnospora < Spyridia filamentosa. A remarkable decrease of 31–42% in CH₄ production was recorded with the incremental inclusion of Kappaphycus alvarezii at levels of 3–5% of the dry matter in the diet. The addition of Sargassum wightii led to a significant decrease of 36–48% in CH₄ emissions when incorporated at levels of 4–5% of dry matter, respectively. The findings of this study revealed a significant decrease in the numbers of total protozoa and Entodinomorphs, coupled with increasing abundances of sulfate-reducing microbes and minor methanogens. Metagenome data revealed that irrespective of the seaweed and treatment, the predominant microbial phyla included Bacteroidota, Bacillota, Pseudomonadota, Actinomycetota, Fibrobacterota, and Euryarchaeota. The prevalence of Methanobrevibacter was similar across treatments, constituting the majority (~79%) of the archaeal community. The results also demonstrated that the supplementation of Kappaphycus alvarezii and Sargassum wightii did not alter the feed fermentation pattern, and therefore, the reduction in CH₄ production in the present study could not be attributed to it. Animal studies are warranted to validate the extent of reduction in CH₄ production and the key processes involved by supplementation with Kappaphycus alvarezii and Sargassum wightii at the recommended levels. Full article

Up to the present study, only 8.5% of the 522 macroalgal species reported at the Azores have sequences deposited in GenBank and BOLD public repositories. The sequences of four genetic markers (cox1, rbcL, UPA, tufA) were obtained for recently collected samples from two Azorean islands. DNA barcode-assisted identification was conducted on newly generated and unpublished sequences from public repositories. A literature review of recently published studies, including the molecular identifications of Azorean macroalgae, was also performed. The results confirm the occurrence of 51 species (including subspecific ranks) and provide four new records, namely, three cryptogenic species (Olokunia boudouresquei, Padina gymnospora, and Ulva lacinulata) and one introduced species (Ulva australis). This study contributes 23 DNA barcodes generated for the first time to the Azores, which now has 10.5% of its marine flora represented in public repositories. Additionally, UPA sequences were generated for the first time for the five taxa. Full article

Brown seaweed is a promising source of polysaccharides and phenolics with industrial utility. This work reports the development of a green enzyme-assisted extraction method for simultaneously extracting polysaccharides and phenolics from the brown seaweed Padina gymnospora. Different enzymes (Cellulast, Pectinex, and Alcalase), individually and in combination, were investigated, with Alcalase alone showing the highest efficiency for the simultaneous extraction of polysaccharides and phenolics. Yields from Alcalase-assisted aqueous extraction were higher than those obtained using either water alone or conventional ethanol extraction. Alcalase-assisted extraction was subsequently optimized using a response surface methodology to maximize compound recovery. Maximal polysaccharide and phenolic recovery was obtained under the following extraction conditions: a water-to-sample ratio of 61.31 mL/g, enzyme loading of 0.32%, temperature of 60.5 °C, and extraction time of 1.95 h. The extract was then fractionated to obtain alginate-, fucoidan-, and phenolic-rich fractions. Fractions exhibited potent 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity with IC₅₀ values of 140.55 µg/mL, 126.21 µg/mL, and 48.17 µg/mL, respectively, which were higher than those obtained from conventional extraction methods. The current work shows that bioactive polysaccharides and phenolics can be obtained together in high yield through a single aqueous-only green and efficient Alcalase-assisted extraction. Full article

Brown marine macroalga Padina gymnospora (Phaeophyceae, Ochrophyta) produces both secondary metabolites (phlorotannins) and precipitate calcium carbonate (CaCO₃—aragonite) on its surface as potential defensive strategies against herbivory. Here, we have evaluated the effect of natural concentrations of organic extracts (dichloromethane—DI; ethyl acetate—EA and methanol—ME, and three isolated fractions) and mineralized tissues of P. gymnospora as chemical and physical resistance, respectively, against the sea urchin Lytechinus variegatus through experimental laboratory feeding bioassays. Fatty acids (FA), glycolipids (GLY), phlorotannins (PH) and hydrocarbons (HC) were also characterized and/or quantified in extracts and fractions from P. gymnospora using nuclear magnetic resonance (NMR) and gas chromatography (GC) coupled to mass spectrometry (CG/MS) or GC coupled to flame ionization detector (FID) and chemical analysis. Our results showed that chemicals from the EA extract of P. gymnospora were significantly important in reducing consumption by L. variegatus, but the CaCO₃ did not act as a physical protection against consumption by this sea urchin. An enriched fraction containing 76% of the new hydrocarbon 5Z,8Z,11Z,14Z-heneicosatetraene exhibited a significant defensive property, while other chemicals found in minor amounts, such as GLY, PH, saturated and monounsaturated FAs and CaCO₃ did not interfere with the susceptibility of P. gymnospora to L. variegatus consumption. We suggest that the unsaturation of the 5Z,8Z,11Z,14Z-heneicosatetraene from P. gymnospora is probably an important structural characteristic responsible for the defensive property verified against the sea urchin. Full article

Seaweed has a variety or biological activities, including antibacterial, antioxidant, antidiabetic, and anti-inflammatory ones. Mexico has great macroalgae diversity, with nearly 1700 species; therefore, in this research two seaweeds from Mexico, Sargassum buxifolium and Padina gymnospora, were investigated for their antibacterial, antidiabetic, and toxic potential; and to understand their phytochemical components both were subjected to various extractions. Only the hexanic fraction was active, and the presence of fatty acids was detected. The two algal extracts showed interesting antimicrobial properties, which mostly inhibited the growth of Gram-positive bacteria (E. faecalis, S. aureus, and S. epidermidis). The α-glucosidase activity was estimated for checking the antidiabetic capacity; S. buxifolium had best α-glucosidase inhibition compared with P. gymnospora. For toxicity, the hexanic extracts administered orally as nontoxic in the treated mice. These results suggest that the two algae have potential as resources for the development of antimicrobial agents. Full article

Biostimulants constitute an emerging group of crop management products used to enhance productivity under abiotic stress conditions. The ability of some biostimulant products, such as seaweed extracts (SE), to enhance crop tolerance to salinity stress has been documented. SE contain a series of bioactive compounds and signaling molecules, as well as mineral and organic nutrients, that greatly benefit plants. A greenhouse experiment was conducted in order to evaluate SE-mediated tolerance mechanisms in tomato plants under salinity stress. The experiment was divided into two developmental phases (vegetative and reproductive) and included four treatments: control (plants with neither treatment), SE (plants treated with seaweed extract), NaCl (plants irrigated with 300 mM NaCl), and SE + NaCl (plants treated with seaweed extract and irrigated with 300 mM NaCl). Tomato plants treated with the SE from Padina gymnospora showed an increase in root and shoot length (18 cm and 13 cm), root and shoot area (33 cm² and 98 cm²), and shoot and root fresh weight (1.0 and 3.8 g) under the control and salinity stress conditions. The decrease in productivity (number of fruits) associated with salinity stress was reduced from 28.7% to only 3.4% in SE-treated plants. The positive effects of SE application also included early flowering and enhanced fruit weight and quality. Our findings suggest that optimized photosynthetic performance and antioxidant defense systems (proline, total phenols, and flavonoids) appear to be major factors modulating SE responses to salinity tolerance in tomato plants with promising agricultural applications. Full article