Bioprospecting of Coralline Red Alga Amphiroa rigida J.V. Lamouroux: Volatiles, Fatty Acids and Pigments

Characterization of Rugulopteryx okamurae algae: A source of bioactive peptides, omega-3 fatty acids, and volatile compounds

This study provides a detailed characterization of the invasive algae Rugulopteryx okamurae, highlighting its nutritional composition, mineral content, and potential bioactive compounds. This biomass contains 14.18 % protein, 21.29 % lipids (with a high omega-3 content), fibre (31.32 %), and significant amounts of minerals like calcium, sodium, potassium, sulphur, and iron. Phenolic compounds (0.74 %) and volatile compounds, such as retinol, were also identified. Peptidome analysis revealed 626 unique peptides, with 21 low molecular weight peptides showing potential activity against angiotensin converting enzyme and dipeptidyl peptidase IV when assessed using in silico tools and using molecular docking. Additionally, the antioxidant capacity of the alga was demonstrated with a significant free radical inhibition (EC50: 2.09 mg/mL). Overall, this study provides initial evidence on the nutritional potential of R. okamurae, which may have potential for future applications in food and biotechnology fields.

Chemical Diversity of Mediterranean Seagrasses Volatilome

BACKGROUND/OBJECTIVES

Biogenic volatile organic compounds (BVOCs), extensively studied in terrestrial plants with global emissions around 1 PgC yr-1, are also produced by marine organisms. However, benthic species, especially seagrasses, are understudied despite their global distribution (177,000-600,000 km2). This study aims to examine BVOC emissions from key Mediterranean seagrass species (Cymodocea nodosa, Posidonia oceanica, Zostera noltei, and Zostera marina) in marine and coastal lagoon environments.

METHODS

BVOCs were collected using headspace solid-phase microextraction (HS-SPME) using divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fibers and analyzed by gas chromatography-mass spectrometry (GC-MS).

RESULTS

An important chemical diversity was found with a total of 92 volatile compounds (61 for Z. noltei, 59 for C. nodosa, 55 for P. oceanica, and 51 for Z. marina), from different biosynthetic pathways (e.g., terpenoids, benzenoids, and fatty acid derivatives) and with several types of chemical functions (e.g., alkanes, esters, aldehydes, and ketones) or heteroatoms (e.g., sulfur). No differences in chemical richness or diversity of compounds were observed between species. The four species shared 29 compounds enabling us to establish a specific chemical footprint for Mediterranean marine plants, including compounds like benzaldehyde, benzeneacetaldehyde, 8-heptadecene, heneicosane, heptadecane, nonadecane, octadecane, pentadecane, tetradecane, and tridecanal. PLS-DA and Heatmap show that the four species presented significantly different chemical profiles. The major compounds per species in relative abundance were isopropyl myristate for C. nodosa (25.6%), DMS for P. oceanica (39.3%), pentadecane for Z. marina (42.9%), and heptadecane for Z. noltei (46%).

CONCLUSIONS

These results highlight the potential of BVOCs' emission from seagrass ecosystems and reveal species-specific chemical markers.

Chemical diversity and antifouling activity of geniculate calcareous algae (Corallinales, Rhodophyta) from Brazil

Marine biofouling is a natural process by which many organisms colonize and grow in submerged structures, causing serious economic consequences for the maritime industry. Geniculate calcareous algae (GCA; Corallinales, Rhodophyta) produce bioactive secondary metabolites and are a promise for new antifouling compounds. Here, we investigated the antifouling activity of four GCA species-Amphiroa beauvoisii, Jania sagittata (formerly Cheilosporum sagittatum), Jania crassa, and Jania prolifera (formerly Amphiroa flabellata)-from the Brazilian coast against macro- and microorganisms. Simultaneously, metabolomic tools were applied to assess the chemical profiles of these seaweeds using gas chromatography coupled to mass spectrometry (GC-MS). Data analysis by principal component and molecular networking analyses used the global natural products social molecular networking platform (GNPS). Our results showed that all extracts were active against different strains of marine bacteria and that the J. sagittata (JsSI) extract showed the highest percentage of bacterial inhibition. The J. sagittata (JsSI) extract was the most active against the mussel Perna perna, showing 100% byssus inhibition. Regarding toxicity, only the J. crassa (JcP) extract showed a 20% mortality rate. The chemical profiles of the evaluated GCA extracts differed qualitatively and quantitatively. Yet, the steroid (3β)-cholest-5-en-3-ol was the major compound commonly identified in all extracts, with the exception of J. sagittata (JsSI). Moreover, we observed intra- and interspecific chemical variabilities among GCA extracts for the different populations, which could explain their antifouling activity variability. This study contributed new information about the chemical compounds produced by this group of seaweeds and showed its antifouling potential. These GCA species may be the subject of future studies to obtain new bioactive compounds with biotechnological potential in maritime areas.

Bioprospecting of Five Ocimum sp. Cultivars from Croatia: New Potential for Dietary and Dermatological Application with Embryotoxicity Tests

Ocimum basilicum L. is the most common Ocimum species, and it is used as an ornamental plant and in food condiments. This unique study examined the chemical composition and biological activities of six extracts from five basil cultivars, including their antimicrobial, antidiabetic, antilipidemic, neuroprotective, and anticollagenase activity. Moreover, their toxicological effects were studied using the zebrafish Danio rerio. Volatile components were determined using HS-SPME and GC-MS, while total polyphenols were detected using HPLC and the spectrophotometric Folin-Ciocalteu method. Spectrophotometric assays (DPPH, ABTS, ORAC, FRAP) were performed to determine antioxidant activity, collagenase inhibition, acetylcholinesterase inhibition, and pancreatic lipase inhibition. Antimicrobial activity was determined using the broth microdilution test. The study found that the biological activities of different basil cultivars varied depending on the proportion of active compounds, as determined by chemical analyses. All six basil extracts significantly inhibited α-amylase, while Purple basil extract most significantly inhibited the activity of collagenase, acetylcholinesterase, and pancreatic lipase. Purple basil and Dark Opal basil I extracts exhibited the highest antimicrobial activity, while the Dark Opal basil II extract had the most significant antioxidant potential. The findings in this study suggest that ethanolic basil extracts have the potential to be used as dietary drugs and implemented in antiaging products. This study is unique in its aims to compare the chemical composition and biological activities of basil cultivars from Croatia and to evaluate potential toxicological effects through embryotoxicity tests on zebrafish Danio rerio embryos, and it reports the first evidence of anticollagenase, antidiabetic, and antilipidemic activities for these cultivars.

Intra-Species Variations of Bioactive Compounds of Two Dictyota Species from the Adriatic Sea: Antioxidant, Antimicrobial, Dermatological, Dietary, and Neuroprotective Potential

The marine environment has a significant impact on life on Earth. Organisms residing in it are vital for the ecosystem but also serve as an inexhaustible source of biologically active compounds. Herein, the biodiversity of two brown seaweeds, Dictyota dichotoma and Dictyota fasciola from the Adriatic Sea, was evaluated. The aim of the study was the determination of differences in compound composition while comparing their activities, including antioxidant, antimicrobial, and enzyme inhibition, in connection to human digestion, dermatology, and neurological disorders. Chemical analysis revealed several terpenoids and steroids as dominant molecules, while fucoxanthin was the main identified pigment in both algae. D. dichotoma had higher protein, carbohydrate, and pigment content. Omega-6 and omega-3 fatty acids were identified, with the highest amount of dihomo-γ-linolenic acid and α-linolenic acid in D. dichotoma. Antimicrobial testing revealed a dose-dependent inhibitory activity of methanolic fraction against Escherichia coli and Staphylococcus aureus. Moderate antioxidant activity was observed for both algae fractions, while the dietary potential was high, especially for the D. fasciola dichloromethane fraction, with inhibition percentages of around 92% for α-amylase and 57% for pancreatic lipase at 0.25 mg/mL. These results suggest that Dictyota species might be a potent source of naturally derived agents for obesity and diabetes.

Less Polar Compounds and Targeted Antioxidant Potential (In Vitro and In Vivo) of Codium adhaerens C. Agardh 1822

Codium adhaerens from the Adriatic Sea (Croatia) was comprehensively investigated regarding less polar compounds for the first time. Although there are several phytochemical studies on C. adhaerens from other regions, this is the first report on volatile organic compounds (VOCs) from fresh (FrCa) and air-dried (DrCa) samples. The novelty is also related to its targeted antioxidant potential in vitro and in vivo. The main aims were to: (a) identify and compare VOCs of FrCa and DrCa obtained by headspace solid-phase microextraction (HS-SPME) and hydrodistillation (HD); (b) determine fatty acid (FA) composition of freeze-dried sample (FdCa); (c) determine the composition of less polar fractions of FdCa by high-performance liquid chromatography-high-resolution mass spectrometry with electrospray ionisation (UHPLC-ESI-HRMS); and (d) comprehensively evaluate the antioxidant activity of the fractions by four in vitro assays and in vivo zebrafish model (including embryotoxicity). Significant changes of VOCs were found after air drying. ω6 FAs were present in higher content than ω3 FAs indicating C. adhaerens as a good source of dietary polyunsaturated FAs. The results obtained in vivo correlate well with in vitro methods and both fractions exerted similar antioxidative responses which is in agreement with the high abundance of present biomolecules with known antioxidant properties (e.g., fucoxanthin, pheophytin a, and pheophorbide a). These results suggest that C. adhaerens might be a potent source of natural antioxidants that could be further used in the research of oxidative stress-related diseases.

Bioprospecting of Less-Polar Constituents from Endemic Brown Macroalga Fucus virsoides J. Agardh from the Adriatic Sea and Targeted Antioxidant Effects In Vitro and In Vivo (Zebrafish Model)

The endemic brown macroalga Fucus virsoides J. Agardh from the Adriatic Sea was in the focus of the present research. The volatiles of fresh (FrFv) and air-dried (DrFv) samples of F. virsoides obtained by headspace solid-phase microextraction (HS-SPME) and hydrodistillation (HD) were analyzed by gas chromatography equipped with flame ionization detector and mass spectrometry (GC-FID/MS). The major HS-FrFv compound was pentadecane (61.90-71.55%) followed by pentadec-1-ene (11.00-7.98%). In HS-DrFv, pentadec-1-ene was not present, and few lower aliphatic compounds appeared, as well as benzaldehyde and benzyl alcohol. In HD-FrFv, particularly abundant were alkenes (such as pentadec-1-ene (19.32%), or (E)-pentadec-7-ene (8.35%)). In HD-DrFv, more oxidation products were present (e.g., carbonyl compounds such as tridecanal (18.51%)). The fatty acids profile of freeze-dried sample (FdFv) after conversion to methyl esters was determined by GC-FID, and oleic acid was dominant (42.28%), followed by arachidonic acid (15.00%). High-performance liquid chromatography-high-resolution mass spectrometry with electrospray ionization (HPLC-ESI-HRMS) was used for the screening of less polar fractions (F3 and F4) of F. virsoides. Mono- and diglycerides of stearic, palmitic, oleic, and arachidonic acids were found. Terpenoids and steroids comprised the compounds C20H30(32)O2 and C29H48O(2). Among carotenoids, fucoxanthin was identified. Chlorophyll derivatives were also found (C55H74(72)N4O(5-7)), dominated by pheophytin a. The antioxidant activity of the fractions was investigated by in vitro assays (oxygen radical absorbance capacity (ORAC), reduction of radical cation (ABTS•+), 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) assay, and ferric reducing antioxidant power (FRAP)) and by in vivo zebrafish model (along with fish embryotoxicity). In vitro experiments proved good radical scavenging abilities of F3 and F4 fractions, which were additionally supported by the protective effect against hydrogen peroxide-induced oxidative stress in zebrafish embryos.