Cytoprotective effect of seaweeds with high antioxidant activity from the Peniche coast (Portugal)

Current Research on the Bioprospection of Linear Diterpenes from Bifurcaria bifurcata: From Extraction Methodologies to Possible Applications

Marine resources are considered as a very promising source of bioactive molecules, and macroalgae in particular have gained special attention, due to their structurally diverse composition. Particular interest has been devoted to the brown macroalga Bifurcaria bifurcata, due to their abundance in bioactive linear diterpenes. In this appraisal, a thorough review concerning the methodologies used in the extraction, fractionation, and identification of diterpenes from B. bifurcata is provided and discussed in detail. An exhaustive compilation of the mass spectra and nuclear magnetic resonance (NMR) data are also provided. The in vitro and in chemico assays already performed to assess different biological activities attributed to B. bifurcata diterpenes are also reviewed, emphasizing the use of isolated components, enriched fractions, or crude extracts. The associated major strengths and challenges for the exploitation of B. bifurcata diterpenes for high-value applications are critically discussed.

Marine macroalgae as a dietary source of genoprotection in gilthead seabream (Sparus aurata) against endogenous and exogenous challenges

DNA integrity and stability are essential to organisms' health and survival. However, it has been neglected in what concerns to fish farming, disregarding the potential impact of endogenous/ exogenous factors. As marine macroalgae constitute a source of natural compounds with a large spectrum of biological activities, this study, situated in the interface of nutritional-genetic research and development of algae practical applications, aimed to evaluate the genoprotective properties of a macroalgae-enriched diet (total percentage of 5%, incorporating equal percentages of Ulva rigida, Gracilaria gracilis and Fucus vesiculosus) in gilthead seabream (Sparus aurata). Protection was assessed in relation to a basal genome integrity and against an exogenous genotoxic challenge (cyclophosphamide; CP). Fish were reared for 30 days with the supplemented diet, being then injected with CP and sampled at days 3 and 10 post-injection (p.i.). To evaluate whether the favorable effects remain after the end of supplementation, a fish subgroup previously fed with algae-enriched diet was submitted to a diet reversion at day 3 p.i., being thereafter fed with the standard diet. Genetic damage was evaluated through the erythrocytic nuclear abnormalities (ENA) and comet assays and complemented by the assessment of the antioxidant system. Results pointed out that algae-enriched feed exhibits anti-genotoxic properties, mostly expressed in relation to the exogenous pressure, manifest in relation to DNA strand breaks and chromosomal lesions, also reducing oxidative DNA damage. Nonetheless, blood antioxidants were only punctually altered by the supplemented diet (e.g. catalase and glutathione-S-transferase). Analyzing the effect persistence, it was perceived that 7 days without algae uptake was enough to partially reduce the protection efficacy. Overall, these findings are promising towards the benefits of macroalgae inclusion in fish diet, and thus, to invigorate mariculture activity and the commercial use of algae, also providing new insights on the DNA protection mechanisms.

Antioxidant and Neuroprotective Potential of the Brown Seaweed Bifurcaria bifurcata in an in vitro Parkinson's Disease Model

Bifurcaria bifurcata is a marine brown seaweed mainly found on the Atlantic coast. Herein, we report the antioxidant and neuroprotective activities of seven fractions (F1⁻F7) obtained by normal phase chromatography from the B. bifurcata dichloromethane extract, as well as of its two major isolated diterpenes. Total phenolic content of fractions was determined by the Folin⁻Ciocalteu method, while antioxidant activity was evaluated by the DPPH, ORAC, and FRAP assays. Neuroprotective effects were evaluated in a neurotoxic model induced by 6-hydroxydopamine (6-OHDA) in a human neuroblastoma cell line (SH-SY5Y), while the mechanisms associated to neuroprotection were investigated by the determination of mitochondrial membrane potential, H₂O₂ production, Caspase-3 activity, and by observation of DNA fragmentation. Fractions F4 and F5 exhibited the best neuroprotective and antioxidant activities, respectively. F4 fraction prevented changes in mitochondrial potential, and induced a reduction of H₂O₂ levels production and an increase in cell viability, suggesting that it may contain multi-target compounds acting on different pathways. Hence, this fraction was subjected to purification steps, affording the known diterpenes eleganolone and eleganonal. Both compounds exhibited antioxidant potential, being interesting candidates for further neuroprotective studies.

Pro-Apoptotic Activity of French Polynesian Padina pavonica Extract on Human Osteosarcoma Cells

Recently, seaweeds and their extracts have attracted great interest in the pharmaceutical industry as a source of bioactive compounds. Studies have demonstrated the cytotoxic activity of macroalgae towards different types of cancer cell models, and their consumption has been suggested as a chemo-preventive agent against several cancers such as breast, cervix and colon cancers. Reports relevant to the chemical properties of brown algae Padina sp. are limited and those accompanied to a comprehensive evaluation of the biological activity on osteosarcoma (OS) are non existent. In this report, we explored the chemical composition of French Polynesian Padina pavonica extract (EPP) by spectrophotometric assays (total phenolic, flavonoid and tannin content, and antioxidant activity) and by gas chromatography-mass spectrometry (GC-MS) analysis, and provided EPP lipid and sterols profiles. Several compounds with relevant biological activity were also identified that suggest interesting pharmacological and health-protecting effects for EPP. Moreover, we demonstrated that EPP presents good anti-proliferative and pro-apoptotic activities against two OS cell lines, SaOS-2 and MNNG, with different cancer-related phenotypes. Finally, our data suggest that EPP might target different properties associated with cancer development and aggressiveness.

Environmentally-Friendly Extraction of Flavonoids from Cyclocarya paliurus (Batal.) Iljinskaja Leaves with Deep Eutectic Solvents and Evaluation of Their Antioxidant Activities

Deep eutectic solvents (DESs) are commonly employed as environmentally-friendly solvents in numerous chemical applications owing to their unique physicochemical properties. In this study, a novel and environmentally-friendly extraction method based on ultrasound assisted-deep eutectic solvent extraction (UAE-DES) was investigated for the extraction of flavonoids from Cyclocarya paliurus (Batal.) Iljinskaja (C. paliurus) leaves, and the antioxidant activities of these flavonoids were evaluated. Nine different DES systems based on either two or three components were tested, and the choline chloride/1,4–butanediol system (1:5 molar ratio) was selected as the optimal system for maximizing the flavonoid extraction yields. Other extraction conditions required to achieve the maximum flavonoid extraction yields from the leaves of C. paliurus were as follows: DES water content (v/v), 30%; extraction time, 30 min; temperature, 60 °C; and solid-liquid ratio, 20 mg/mL. Liquid chromatography-mass spectrometry allowed the detection of five flavonoids in the extract, namely kaempferol-7-O-α-l-rhamnoside, kaempferol, quercetin, quercetin-3-O-β-d-glucuronide, and kaempferol-3-O-β-d-glucuronide. In vitro antioxidant tests revealed that the flavonoid-containing extract exhibited strong DPPH and ABTS radical-scavenging abilities. Results indicate that UAE-DES is a suitable approach for the selective extraction of flavonoids from C. paliurus leaves, and DESs can be employed as sustainable extraction media for other bioactive compounds.

From Marine Origin to Therapeutics: The Antitumor Potential of Marine Algae-Derived Compounds

Marine environment has demonstrated to be an interesting source of compounds with uncommon and unique chemical features on which the molecular modeling and chemical synthesis of new drugs can be based with greater efficacy and specificity for the therapeutics. Cancer is a growing public health threat, and despite the advances in biomedical research and technology, there is an urgent need for the development of new anticancer drugs. In this field, it is estimated that more than 60% of commercially available anticancer drugs are natural biomimetic inspired. Among the marine organisms, algae have revealed to be one of the major sources of new compounds of marine origin, including those exhibiting antitumor and cytotoxic potential. These compounds demonstrated ability to mediate specific inhibitory activities on a number of key cellular processes, including apoptosis pathways, angiogenesis, migration and invasion, in both in vitro and in vivo models, revealing their potential to be used as anticancer drugs. This review will focus on the bioactive molecules from algae with antitumor potential, from their origin to their potential uses, with special emphasis to the alga Sphaerococcus coronopifolius as a producer of cytotoxic compounds.

Seasonal Variability of the Biochemical Composition and Antioxidant Properties of Fucus spiralis at Two Azorean Islands

This study evaluates, for the first time, the seasonal (winter and summer) and geographical (São Miguel⁻SMG and Santa Maria⁻SMA Islands) variability of Fucus spiralis (Fs) biochemical composition (dry weight basis) and antioxidant properties. Protein and carbohydrates presented higher values in Fs-SMGwinter, lipids, total dietary fiber, and energy value in Fs-SMAsummer, and ash and soluble dietary fiber/insoluble dietary fiber ratio in Fs-SMAwinter. The fatty acid (FA) profiles showed a lower SFA in Fs-SMGsummer, whereas MUFA and PUFA presented higher values in Fs-SMGsummer and Fs-SMGwinter, respectively. Excellent dietary ratios of n6/n3 PUFA and hypocholesterolemic/hypercholesterolemic FA were found, with lower values in Fs-SMAwinter and higher in Fs-SMGsummer, respectively. The highest total phenolics was found in Fs-SMAsummer acetone:water extract and total flavonoids showed the higher value in Fs-SMGwinter methanol extract. The best free radical-scavenging activity was observed in the Fs-SMAwinter methanol (EC50 = 0.045 mg/mL) and acetone:water (EC50 = 0.059 mg/mL) extracts. The ferric-reducing antioxidant power showed the best results in Fs-SMAwinter methanol extract (EC50 = 0.016 mg/mL) and Fs-SMAsummer acetone:water extract (EC50 = 0.017 mg/mL). The best ferrous ion-chelating activity was found in Fs-SMGwinter acetone:water extract. Overall, results revealed that F. spiralis nutritional and functional bioactivity values have geographical and seasonal variations and that its regular consumption may add benefits to human health.

Pressurized Liquid Extraction (PLE) as an Innovative Green Technology for the Effective Enrichment of Galician Algae Extracts with High Quality Fatty Acids and Antimicrobial and Antioxidant Properties

Marine organisms are potentially prolific sources of high qualify fatty acids that represent useful leads in the development of new nutraceutical agents. In this work, we investigated the lipid composition of six algae species from the Northwest of Spain (Ulva intestinalis, Ulva lactuca, Fucus vesiculosus,Dictyota dichotoma, Cystoseira baccata and Himanthalia elongata) and compared the antioxidant and antibacterial activity of ethanolic extracts obtained by pressurized liquid extraction (PLE). Furthermore, Fucus vesiculosus (F. vesiculosus) PLE using five solvents of different polarities (hexane, ethyl acetate, acetone, ethanol and ethanol:water 50:50) at three temperatures (80 °C, 120 °C and 160 °C) was investigated. F. vesiculosus ethanolic PLE extract presents considerably higher capacity of inhibiting 50% of DPPH (1,1-diphenyl-2-picryl hydrazyl) (IC50 = 7.17 μg/mL) in comparison with the rest of macroalgae studied. Moreover, the potential antimicrobial activity tested on E. coli and S. aureus shows that F. vesiculosus extract produced the best inhibition (IC50 was 2.24 mg/mL (E. coli) and 1.27 mg/mL (S. aureus)). Furthermore, regarding the different solvents and temperatures used to investigate F. vesiculosus PLE, results showed that this technique using ethyl acetate is a selective method to enrich long chain fatty acids (oleic acid, arachidonic acid and eicosapentaenoic acid) with ω-6/ω-3 ratios close to 2.7.

Influence of Codium tomentosum Extract in the Properties of Alginate and Chitosan Edible Films

The growing search for natural alternatives to synthetic food packaging materials and additives has increased, and seaweed extracts’ bioactivity has made them suitable candidates for incorporation in novel edible films. This study aims to investigate the effect of Codium tomentosum seaweed extract (SE) incorporation in alginate and chitosan edible films. Alginate- and chitosan-based films with and without the incorporation of 0.5% SE were characterized according to their physical, optical, mechanical, and thermal properties. Seaweed extract incorporation in chitosan films resulted in an increase of film solubility (50%), elasticity (18%), and decrease of puncture strength (27%) and energy at break (39%). In alginate films, the extract incorporation significantly decreased film solubility (6%), water vapour permeability (46%), and elasticity (24%), and had no effect on thermal properties. Depending on the type of application, the addition of SE in edible films can bring advantages for food conservation.

Macroalgae Extracts From Antarctica Have Antimicrobial and Anticancer Potential

Background: Macroalgae are sources of bioactive compounds due to the large number of secondary metabolites they synthesize. The Antarctica region is characterized by extreme weather conditions and abundant aggregations of macroalgae. However, current knowledge on their biodiversity and their potential for bio-prospecting is still fledging. This study evaluates the antimicrobial and cytotoxic activity of different extracts of four macroalgae (Cystosphaera jacquinotii, Iridaea cordata, Himantothallus grandifolius, and Pyropia endiviifolia) from the Antarctic region against cancer and non-cancer cell lines.

Methods: The antimicrobial activity of macroalgae was evaluated by the broth microdilution method. Extracts were assessed against Staphylococcus aureus ATCC 19095, Enterococcus faecalis ATCC 4083, Escherichia coli ATCC29214, Pseudomonas aeruginosa ATCC 9027, Candida albicans ATCC 62342, and the clinical isolates from the human oral cavity, namely, C. albicans (3), C. parapsilosis, C. glabrata, C. lipolytica, and C. famata. Cytotoxicity against human epidermoid carcinoma (A-431) and mouse embryonic fibroblast (NIH/3T3) cell lines was evaluated with MTT colorimetric assay.

Results: An ethyl acetate extract of H. grandifolius showed noticeable antifungal activity against all fungal strains tested, including fluconazole-resistant samples. Cytotoxicity investigation with a cancer cell line revealed that the ethyl acetate extract of I. cordata was highly cytotoxic against A-431 cancer cell line, increasing the inhibitory ratio to 91.1 and 95.6% after 24 and 48 h exposure, respectively, for a concentration of 500 μg mL⁻¹. Most of the algal extracts tested showed little or no cytotoxicity against fibroblasts.

Conclusion: Data suggest that macroalgae extracts from Antarctica may represent a source of therapeutic agents.

HIGHLIGHTS

Different macroalgae samples from Antarctica were collected and the lyophilized biomass of each macroalgae was extracted sequentially with different solvents

The antimicrobial and anticancer potential of macroalgae extracts were evaluated

Ethyl acetate extract of H. grandifolius showed noticeable antifungal activity against all the fungal strains tested, including fluconazole-resistant samples

Ethyl acetate extract of I. cordata was highly cytotoxic against the A-431 cancer cell line

Most of the algal extracts tested showed little or no cytotoxicity against normal cell lines

Neuroprotective effects of seaweeds against 6-hydroxidopamine-induced cell death on an in vitro human neuroblastoma model

BACKGROUND

Parkinson's disease (PD) is a progressive neurodegenerative disorder of the central nervous system. Although the causes of PD pathogenesis remain incomplete, some evidences has suggested that oxidative stress is an important mediator in its pathogenesis. The aim of this study was to evaluate the protective effects of seaweeds with high antioxidant activity on 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in the human neuroblastoma cell line SH-SY5Y, as well as the associated intracellular signaling pathways.

METHODS

Cell viability studies were assessed by 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium (MTT) bromide assay and the intracellular signaling pathways analyzed were: hydrogen peroxide (H2O2) production, changes in the mitochondrial membrane potential and Caspase-3 activity.

RESULTS

Exposure of SH-SY5Y cells to 6-OHDA (10-1000 μM) reduced cell's viability in a concentration and time-dependent manner. The data suggest that the cell death induced by 6-OHDA was mediated by an increase of H2O2 production, the depolarization of mitochondrial membrane potential and the increase of Caspase-3 activity. Extracts from S. polyshides, P. pavonica, S. muticum, C. tomentosum and U. compressa revealed to efficiently protect cell's viability in the presence of 6-OHDA (100 μM; 24 h). These effects appear to be associated with the reduction of H2O2 cell's production, the protection of mitochondrial membrane's potential and the reduction of Caspase-3 activity.

CONCLUSIONS

These results suggest that seaweeds can be a promising source of new compounds with neuroprotective potential.

Seaweed Bioactive Compounds against Pathogens and Microalgae: Potential Uses on Pharmacology and Harmful Algae Bloom Control

Cyanobacteria are found globally due to their adaptation to various environments. The occurrence of cyanobacterial blooms is not a new phenomenon. The bloom-forming and toxin-producing species have been a persistent nuisance all over the world over the last decades. Evidence suggests that this trend might be attributed to a complex interplay of direct and indirect anthropogenic influences. To control cyanobacterial blooms, various strategies, including physical, chemical, and biological methods have been proposed. Nevertheless, the use of those strategies is usually not effective. The isolation of natural compounds from many aquatic and terrestrial plants and seaweeds has become an alternative approach for controlling harmful algae in aquatic systems. Seaweeds have received attention from scientists because of their bioactive compounds with antibacterial, antifungal, anti-microalgae, and antioxidant properties. The undesirable effects of cyanobacteria proliferations and potential control methods are here reviewed, focusing on the use of potent bioactive compounds, isolated from seaweeds, against microalgae and cyanobacteria growth.

Optimization and validation of reverse phase HPLC method for qualitative and quantitative assessment of polyphenols in seaweed

A simple reverse phase-high performance liquid chromatography (RP-HPLC) coupled to a diode array detector (DAD) and negative ion electrospray mass spectrometer (ESI-MS) method was developed for simultaneous identification and quantification of phenolic antioxidants in seaweed. The proposed method was validated in terms of linearity, limits of detection (LOD), limits of quantification (LOQ), recovery and intermediate precision. The calibration curves were linear with correlation coefficient ranging from 0.9909 to 0.9997 while the values of LOD (0.26-0.82mg/L), LOQ (0.77-2.50mg/L), recovery (≥97.2%) and precision in terms of retention time (%RSD ≤2.27) and peak area (% RSD ≤5.11) were satisfactory. Brown seaweed Himanthalia elongata used in this study was extracted with 60% methanol and the crude extract was cleaned with SPE (Solid Phase Extraction) cartridge. HPLC-DAD-MS/MS analysis of the SPE fraction allowed the identification of 7 phenolic compounds comprising phlorotannins, hydroxybenzoic acid, hydroxycinnamic acid and flavonols subclasses of polyphenols. Quantitative analysis of these compounds revealed the presence of phloroglucinol (394.1±4.33μg/g), gallic acid (96.3±3.12μg/g), chlorogenic acid (38.8±1.94μg/g), caffeic acid (44.4±2.72μg/g), ferulic acid (17.6±0.85μg/g), myricetin (8.6±0.85μg/g) and quercetin (4.2±0.15μg/g), in the extract. The SPE fraction were tested for antioxidant capacity which were significantly (P <0.05) higher (EC50; 14.5±0.57mg/g) than the ascorbic acid (EC50; 35.8±0.59mg/g) and the crude extract (EC50; 46.3±0.48mg/g). The occurrence of all these phenolic antioxidant compounds in H. elongata extract suggested that the developed method is sensitive enough and reproducible and could be used for qualitative and quantitative assessment of polyphenols in seaweed.

In vitro amoebicidal and antioxidant activities of some Tunisian seaweeds

Free-living amoebae of genus Acanthamoeba are opportunistic pathogens widely distributed in the environment, and are the causative agents of several humans' infections, such as Acanthamoeba keratitis, Granulomatous Amoebic Encephalitis and also disseminated infections. The existence of the cyst stage complicates Acanthamoeba therapy as it is highly resistant to antibiotics and physical agents. All these facts reinforced the necessity to find and develop an effective therapy against Acanthamoeba infections. In the present study, we are interested to several seaweeds species collected from the Tunisian coasts and belonging to the 3 phyla (brown, green and red algae). The aim was to quantify the Total Phenolic Compounds in different organic extract, to evaluate antioxidant capacity (DPPH and ABTS) and to study the antiprotozoal activity against A. castellanii Neff. The parasites have been inhibited by all extracts with an IC50 ranged from 52,3±1.8 μg/mL for ethyl acetate extract, to 134,6±0.7 μg/mL for the hexanic one for the various species studied.

An Insight into Sargassum muticum Cytoprotective Mechanisms against Oxidative Stress on a Human Cell In Vitro Model

Sargassum muticum is a brown seaweed with strong potential to be used as a functional food ingredient, mainly due to its antioxidant properties. It is widely used in traditional oriental medicine for the treatment of numerous diseases. Nevertheless, few studies have been conducted to add scientific evidence on its effects as well as on the mechanisms of action involved. In this work, the human cell line MCF-7 was used as an in vitro cellular model to evaluate the capability of Sargassum muticum enriched fractions to protect cells on an oxidative stress condition. The concentration of the bioactive compounds was obtained by vacuum liquid chromatography applied on methanol (M) and 1:1 methanol:dichloromethane (MD) crude extracts, resulting in seven enriched fractions from the M extraction (MF2-MF8), and eight fractions from the MD extraction (MDF1-MDF8). All fractions were tested for cytotoxic properties on MCF-7 cells and the nontoxic ones were tested for their capacity to blunt the damaging effects of hydrogen peroxide-induced oxidative stress. The nontoxic effects were also confirmed in 3T3 fibroblast cells as a nontumor cell line. The antioxidant potential of each fraction, as well as changes in the cell's real-time hydrogen peroxide production, in the mitochondrial membrane potential, and in Caspase-9 activity were evaluated. The results suggest that the protective effects evidenced by S. muticum can be related with the inhibition of hydrogen peroxide production and the inhibition of Caspase-9 activity.

Angiotensin I-Converting Enzyme (ACE) Inhibitory Activity, Antioxidant Properties, Phenolic Content and Amino Acid Profiles of Fucus spiralis L. Protein Hydrolysate Fractions

Food protein-derived hydrolysates with multi-bioactivities such as antihypertensive and antioxidant properties have recently received special attention since both activities can play significant roles in preventing cardiovascular diseases. This study reports, for the first time, the angiotensin I-converting enzyme (ACE)-inhibition and antioxidant properties of ultrafiltrate fractions (UF) with different molecular weight ranges (<1, 1-3 and ≥3 kDa) obtained from Fucus spiralis protein hydrolysate (FSPH) digested with cellulase-bromelain. The amino acids profile, recovery yield, protein, peptide and total phenolic contents of these FSPH-UF, and the in vitro digestibility of F. spiralis crude protein were also investigated. FSPH-UF ≥3 kDa presented remarkably higher ACE-inhibition, yield, peptide and polyphenolic (phlorotannins) contents. Antioxidant analysis showed that FSPH-UF <1 kDa and ≥3 kDa exhibited significantly higher scavenging of 2,2-diphenyl-1-picrylhydrazyl radical and ferrous ion-chelating (FIC) activity. FSPH-UF ≥3 kDa had also notably higher ferric reducing antioxidant power (FRAP). Strong correlations were observed between ACE-inhibition and antioxidant activities (FIC and FRAP). The results suggest that ACE-inhibition and antioxidant properties of FSPH-UF may be due to the bioactive peptides and polyphenols released during the enzymatic hydrolysis. In conclusion, this study shows the potential use of defined size FSPH-UF for the prevention/treatment of hypertension and/or oxidative stress-related diseases.

Antioxidant and Cytoprotective Activities of Fucus spiralis Seaweed on a Human Cell in Vitro Model

Antioxidants play an important role as Reactive Oxygen Species (ROS) chelating agents and, therefore, the screening for potent antioxidants from natural sources as potential protective agents is of great relevance. The main aim of this study was to obtain antioxidant-enriched fractions from the common seaweed Fucus spiralis and evaluate their activity and efficiency in protecting human cells (MCF-7 cells) on an oxidative stress condition induced by H₂O₂. Five fractions, F1-F5, were obtained by reversed-phase vacuum liquid chromatography. F3, F4 and F5 revealed the highest phlorotannin content, also showing the strongest antioxidant effects. The cell death induced by H₂O₂ was reduced by all fractions following the potency order F4 > F2 > F3 > F5 > F1. Only fraction F4 completely inhibited the H₂O₂ effect. To understand the possible mechanisms of action of these fractions, the cellular production of H₂O₂, the mitochondrial membrane potential and the caspase 9 activity were studied. Fractions F3 and F4 presented the highest reduction on H₂O₂ cell production. All fractions decreased both caspase-9 activity and cell membrane depolarization (except F1). Taken all together, the edible F. spiralis reveal that they provide protection against oxidative stress induced by H₂O₂ on the human MCF-7 cellular model, probably acting as upstream blockers of apoptosis.