Accessing the biotechnological potential of a novel isolated microalga from a semi-arid region of Brazil.

The use of microalgae as a source of food and pharmaceutical ingredients has garnered growing interest in recent years. Despite the rapid growth of the nutraceutical market, knowledge about the potential of bioactive molecules from microalgae remains insufficient. The present study aimed to investigate the biotechnological potential of the green microalga Desmodesmus armatus isolated from a semi-arid region of Brazil. The algal biomass was characterized in terms of gross biochemical composition, exopolysaccharide content, enzymatic inhibition capacity, and antioxidant, antibacterial, and hemolytic activities from solvents of different polarities (water, ethanol, acetone, and hexane). D armatus biomass had 40% of crude protein content, 25.94% of lipids, and 25.03% of carbohydrates. The prebiotic potential of exopolysaccharides from D armatus was demonstrated, which stimulated the growth of Lacticaseibacillus rhamnosus and Lactiplantibacillus plantarum bacteria strains. Moreover, the enzyme inhibition capacity for the proteases chymotrypsin (34.78%-45.8%) and pepsin (16.64%-27.27%), in addition to α-amylase (24.79%) and lipase (31.05%) was confirmed. The antioxidant potential varied between the different extracts, with 2,2-diphenyl-1-picrylhydrazyl sequestration values varying between 17.51% and 63.12%, and those of the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) method between 6.82% and 22.89%. In the antibacterial activity test, only the ethanolic extract showed inhibition against Listeria sp. (at minimum inhibitory concentration [MIC] = 256 µg mL-1). This fraction also presented the highest significant levels of hemolysis (31.88%-52.45%). In summary, the data presented in the study suggest the presence of biocompounds with biotechnological and nutraceutical potential in the D armatus biomass. Future studies may evaluate the inclusion of this biomass in foods in order to increase their biological value.

Light induces peridinin and docosahexaenoic acid accumulation in the dinoflagellate Durusdinium glynnii.

Peridinin is a light-harvesting carotenoid present in phototrophic dinoflagellates and has great potential for new drug applications and cosmetics development. Herein, the effects of irradiance mediated by light-emitting diodes on growth performance, carotenoid and fatty acid profiles, and antioxidant activity of the endosymbiotic dinoflagellate Durusdinium glynnii were investigated. The results demonstrate that D. glynnii is particularly well adapted to low-light conditions; however, it can be high-light-tolerant. In contrast to other light-harvesting carotenoids, the peridinin accumulation in D. glynnii occurred during high-light exposure. The peridinin to chlorophyll-a ratio varied as a function of irradiance, while the peridinin to total carotenoids ratio remained stable. Under optimal irradiance for growth, there was a peak in docosahexaenoic acid (DHA) bioaccumulation. This study contributes to the understanding of the photoprotective role of peridinin in endosymbiont dinoflagellates and highlights the antioxidant activity of peridinin-rich extracts. KEY POINTS: • Peridinin has a protective role against chlorophyll photo-oxidation • High light conditions induce cellular peridinin accumulation • D. glynnii accumulates high amounts of DHA under optimal light supply.

Antimicrobial activity of bacteria isolated from tissue of the coral Palythoa caribaeorum (Zoantharia: Sphenopidae) from Paraíba, Brazil coastal reefs / Actividad antimicrobiana de bacterias aisladas del tejido del coral Palythoa caribaeorum (Zoantharia: Sphenopidae) de los arrecifes costeros de Paraíba, Brasil

Abstract Introduction: The coral-associated bacteria with antimicrobial activity may be important to promote the health of their host through various interactions, and may be explored as a source of new bioactive compounds. Objective: To analyze the antimicrobial activity of bacteria associated with the zoanthid Palythoa caribaeorum from the coral reefs of Carapibus, Paraiba state, Brazil. Methods: The phylogenetic analysis of the bacteria was conducted based on partial sequences of the 16S rRNA gene using molecular and bioinformatics tools. The antimicrobial activity of the 49 isolates was tested against four bacterial strains and one yeast strain: Bacillus cereus (CCT0198), Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa and Candida albicans (ATCC 10231). The antibiosis and antibiogram assays were conducted and the Minimal Inhibitory Concentration (MIC) was determined by the microdilution method. Results: The bacterial isolates belonged to Firmicutes phylum (84 % of the isolates) and the Proteobacteria phylum (16 % of the isolates). Among the 49 isolates five genera were found, with the Bacillus genus being the most abundant (82 % of the isolates), followed by Vibrio (10 %), Pseudomonas (4 %), Staphylococcus (2 %) and Alteromonas (2 %). Antibiosis test revealed that 16 isolates (33 %) showed antimicrobial activity against one or more of five tested reference strains. The highest number of antagonistic bacteria were found in the Bacillus genus (12 isolates), followed by Vibrio (three isolates) and Pseudomonas (one isolate) genera. The B. subtilis NC8 was the only isolate that inhibited all tested strains in the antibiosis assay. However, antibiogram test with post-culture cell-free supernatant of NC8 isolate showed the inhibition of only B. cereus, S. aureus and C. albicans, and the lyophilized and dialyzed material of this isolate inhibited only B. cereus. The lyophilized material showed bacteriostatic activity against B. cereus, with a MIC value of 125 μg/μl, and in the cytotoxicity assay, the hemolysis value was of 4.8 %, indicating its low cytotoxicity. Conclusions: The results show the antimicrobial potential of some bacterial isolates associated with the P. caribaeourum tissue, especially those belonged to Bacillus genus.

Resumen Introducción: La actividad antimicrobiana realizada por las bacterias asociadas con los corales, además de promover la salud de su huésped, representa una fuente para obtener nuevos compuestos bioactivos. Objetivo: Analizar la actividad antimicrobiana de las bacterias asociadas con el zoantario Palythoa caribaeorum de los arrecifes de Carapibus, Paraíba, Brasil. Metodología: El análisis filogenético de la bacterias se realizó con base en secuencias parciales del gen RNAr 16S utilizando herramientas moleculares y de bioinformática. La actividad antimicrobiana de las cepas se probó contra cuatro cepas bacterianas y una cepa de levadura: Bacillus cereus (CCT0198), Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa y Candida albicans (ATCC 10231), utilizando ensayos antibiosis y antibiograma, y la concentración inhibitoria mínima (CIM) que se determinó por el método de microdilución. Resultados: Las cepas bacterianas pertenecían a Firmicutes (84 %) y Gammaproteobacteria (16 %). Entre 49 cepas se encontraron cinco géneros de bacterias: Bacillus, Vibrio, Pseudomonas, Staphylococcus y Alteromonas. Un total de 19 cepas exhibieron actividad antimicrobiana, siendo el género Bacillus el responsable del mayor número de bacterias antagonistas, con 12 cepas positivas en el ensayo de antibiosis y cuatro en la prueba de antibiograma. El mayor número de bacterias antagonistas se encontró en Bacillus (12 aislamientos), seguido por Vibrio (tres aislamientos) y Pseudomonas (un aisladmiento). El NC8, clasificado como Bacillus subtilis, inhibió todas las cepas estándar en el ensayo de antibiosis y las cepas de B. cereus, S. aureus y C. albicans en la prueba de antibiograma. El material liofilizado del B. subtilis NC8 mostró acción bacteriostática contra B. cereus, con un valor de CIM de 125 μg/μl. En la prueba de citotoxicidad, el grado de hemólisis fue del 4.8 % para el material liofilizado a las concentraciones probadas, lo que indica su baja citotoxicidad. Conclusión: Los resultados muestran el potencial antimicrobiano de algunos aislamientos bacterianos asociados al P. caribaeourum, especialmente los pertenecientes al género Bacillus.

Impact on cholinesterase-inhibition and in silico investigations of sesquiterpenoids from Amazonian Siparuna guianensis Aubl.

The plant popularly known as "negramina" (Siparuna guianensis Aubl.), member of the family Siparunaceae produces an essential oil that presents several biological activities reported in literature. Here, the essential oil was obtained by hydrodistillation from fresh leaves collected in the state of Roraima, far north of the Amazon. Chemical composition of the essential oil was characterized by gas chromatography coupled to mass spectrometry (GC-MS) and flame ionization detector (GC-FID). The sesquiterpenoid shyobunone and its derivatives were identified as major compounds in the oil (>40%). The effect of S. guianensis essential oil on the acetylcholinesterase (AChE) activity from Crassostrea rhizophorae, Litopenaeus vannamei and Electrophorus electricus was tested by spectrophotometric assays. The essential oil has been identified as an AChE inhibitor. The mechanism of inhibition was investigated as well as spectrofluorimetric interactions between the essential oil and the enzyme. 1H NMR titration and molecular docking were also investigated. The spectrophotometric results revealed that shyobunone and its derivatives strongly interact with AChE with a kind of non-competitive inhibition. Interaction studies support the results of enzyme inhibition. Molecular coupling predicted that iso-shyobunone is the strongest ligand, corroborated by fluorescence suppression and 1H NMR titration results. In conclusion, Siparuna guianensis essential oil can be a new source of shyobunone and derivatives capable to reversibly inhibit AChE showing potential neuroprotective properties to be applied in the treatment of Alzheimer's disease.

Production of cupcake-like dessert containing microbial biosurfactant as an emulsifier.

This work describes the application of the biosurfactant from Candida bombicola URM 3718 as a meal additive like cupcake. The biosurfactant was produced in a culture medium containing 5% sugar cane molasses, 5% residual soybean oil and 3% corn steep liquor. The surface and interfacial tension of the biosurfactant were 30.790 ± 0.04 mN/m and 0.730 ± 0.05 mN/m, respectively. The yield in isolated biosurfactant was 25 ± 1.02 g/L and the CMC was 0.5 g/L. The emulsions of the isolated biosurfactant with vegetable oils showed satisfactory results. The microphotographs of the emulsions showed that increasing the concentration of biosurfactant decreased the oil droplets, increasing the stability of the emulsions. The biosurfactant was incorporated into the cupcake dessert formulation, replacing 50%, 75% and 100% of the vegetable fat in the standard formulation. Thermal analysis showed that the biosurfactant is stable for cooking cupcakes (180 °C). The biosurfactant proved to be promising for application in foods low in antioxidants and did not show cytotoxic potential in the tested cell lines. Cupcakes with biosurfactant incorporated in their dough did not show significant differences in physical and physical-chemical properties after baking when compared to the standard formulation. In this way, the biosurfactant has potential for application in the food industry as an emulsifier for flour dessert.

Antioxidant and Antiulcerogenic Activity of the Dry Extract of Pods of Libidibia ferrea Mart. ex Tul. (Fabaceae).

Ethnomedicinal studies in the Amazon community and in the Northeast region of Brazil highlight the use of Libidibia ferrea fruits for the treatment of gastric problems. However, there are no data in the literature of this pharmacological activity. Thus, the aim of this paper is to provide a scientific basis for the use of the dry extract of L. ferrea pods (DELfp) for the treatment of peptic ulcers. Phytochemical characterization was performed by HPLC/MS. In vitro antioxidant activity was assessed using DPPH, ABTS, phosphomolybdenum, and superoxide radical scavenging activity. The gastroprotective activity, the ability to stimulate mucus production, the antisecretory activity, and the influence of -SH and NO compounds on the antiulcerogenic activity of DELfp were evaluated. The healing activity was determined by the acetic acid-induced chronic ulcer model. Anti-Helicobacter pylori activity was investigated. HPLC/MS results identified the presence of phenolic compounds, gallic acid and ellagic acid, in DELfp. The extract showed antioxidant activity in vitro. In ulcers induced by absolute ethanol and acidified ethanol, the ED50 values of DELfp were 113 and 185.7 mg/kg, respectively. DELfp (100, 200, and 400 mg/kg) inhibited indomethacin-induced lesions by 66.7, 69.6, and 65.8%, respectively. DELfp (200 mg/kg) reduced gastric secretion and H+ concentration in the gastric contents and showed to be independent of nitric oxide (NO) and dependent on sulfhydryl (-SH) compounds in the protection of the gastric mucosa. In the chronic ulcer model, DELfp reduced the area of the gastric lesion. DELfp also showed anti-H. pylori activity. In conclusion, DELfp showed antioxidant, gastroprotective, healing, and antiulcerogenic activities. The mechanism of these actions seems to be mediated by different pathways and involves the reduction of gastric secretion and H+ concentration, dependence on sulfhydryl compounds, and anti-H. pylori activity. All these actions support the medicinal use of this species in the management of peptic ulcers.