Comparative antioxidant activity of edible Japanese brown seaweeds

Protective role of fucoxanthin in diethylnitrosamine-induced hepatocarcinogenesis in experimental adult rats

Hepatocellular carcinoma (HCC) accounts for majority of cancer related deaths. Two major risk factors in induction of HCC are chemical and virus, however, the possible mechanisms of their differences remain indefinable. The current study focused on protective role of Fucoxanthin (Fx) in liver affected by diethylnitrosamine (DEN)-induced HCC. In this study, levels of liver enzymes, oxidative stressors, antioxidant status, and lipoproteins were compared both in tissue and blood. Tissues were also analyzed extensively by histological studies using H and E staining and transmission electron microscopy (TEM). Rats were clustered into four groups of six experimental animals. Group I: Control rats were administered isotonic saline intraperitoneal Group II: Animals received 0.01% DEN through drinking water to induce hepatocellular carcinoma. Group III: Animals received 0.01% DEN simultaneously oral supplementation of Fx (50 mg/kg b.w). Group IV: Rats were given Fx alone (50 mg/kg b.w) orally and the treatment is for 15 weeks. Results showed the decrease in body weight, serum albumin, antioxidant enzymes, and increased all the liver enzymes, serum bilirubin, and stress markers in DEN induced rats, where as the simultaneous supplementation of Fx reverted them to normal levels. Administration of only Fx did not show any change. Therefore, Fx may serve as a chemotherapeutic agent against liver cancer.

Phycochemical Constituents and Biological Activities of Fucus spp

Seaweeds are known to be a good supply of key nutrients including carbohydrates, protein, minerals, polyunsaturated lipids, as well as several other health-promoting compounds capable of acting on a wide spectrum of disorders and/or diseases. While these marine macroalgae are deeply rooted in the East Asian culture and dietary habits, their major application in Western countries has been in the phycocolloid industry. This scenario has however been gradually changing, since seaweed consumption is becoming more common worldwide. Among the numerous edible seaweeds, members of the genus Fucus have a high nutritional value and are considered good sources of dietary fibers and minerals, especially iodine. Additionally, their wealth of bioactive compounds such as fucoidan, phlorotannins, fucoxanthin and others make them strong candidates for multiple therapeutic applications (e.g., antioxidant, anti-inflammatory, anti-tumor, anti-obesity, anti-coagulant, anti-diabetes and others). This review presents an overview of the nutritional and phytochemical composition of Fucus spp., and their claimed biological activities, as well as the beneficial effects associated to their consumption. Furthermore, the use of Fucus seaweeds and/or their components as functional ingredients for formulation of novel and enhanced foods is also discussed.

Enhancing colour and oxidative stabilities of reduced-nitrite turkey meat sausages during refrigerated storage using fucoxanthin purified from the Tunisian seaweed Cystoseira barbata

The present study investigated the angiotensin-I converting enzyme (ACE) inhibitory activity and the antioxidant properties, in vitro and in cured meat sausages containing reduced levels of sodium nitrite, of fucoxanthin extracted from the Tunisian brown seaweed Cystoseira barbata (CBFX). Results revealed that CBFX exhibited great scavenging activities against DPPH free radicals (EC50 = 136 μg/ml), peroxyl radicals in the linoleate-β-carotene system (EC50 = 43 μg/ml) and hydroxyl radicals generated by Fenton reaction (DNA nicking assay). A considerable ferric reducing potential was also recorded for CBFX (EC50 = 34 μg/ml). It is interesting to note that CBFX was found to modulate the ACE activity, which is the key enzyme involved in the blood pressure regulation, with an EC50 of 5 μg/ml. When fucoxanthin was supplemented, the concentration of sodium nitrite added to cured turkey meat sausages was reduced from 150 to 80 ppm, coupled with the enhancement of colour and oxidative stabilities. Thus, CBFX, with noticeable antioxidant and antihyertensive effects, could be used as a natural additive in functional foods to alleviate potential human health hazards caused by carcinogenic nitrosamines formation.

Characterization of dietary fucoxanthin from Himanthalia elongata brown seaweed

This study explored Himanthalia elongata brown seaweed as a potential source of dietary fucoxanthin which is a promising medicinal and nutritional ingredient. The seaweed was extracted with low polarity solvents (n-hexane, diethyl ether, and chloroform) and the crude extract was purified with preparative thin layer chromatography (P-TLC). Identification, quantification and structure elucidation of purified compounds was performed by LC-DAD-ESI-MS and NMR (1H and 13C). P-TLC led purification yielded 18.6mg/g fucoxanthin with 97% of purity based on the calibration curve, in single-step purification. LC-ESI-MS (parent ion at m/z 641 [M+H-H2O]+) and NMR spectra confirmed that the purified band contained all-trans-fucoxanthin as the major compound. Purified fucoxanthin exhibited statistically similar (p>0.05) DPPH scavenging capacity (EC50: 12.9μg/mL) while the FRAP value (15.2μg trolox equivalent) was recorded lower (p<0.05) than the commercial fucoxanthin. The promising results of fucoxanthin purity, recovery and activity suggested that H. elongata seaweed has potential to be exploited as an alternate source for commercial fucoxanthin production.

Efficacy of chlorophyll c2 for seasonal allergic rhinitis: single-center double-blind randomized control trial

Chlorophyll c2 extracted from Sargassum horneri improved allergic symptoms in an animal model of allergic rhinitis. In the present study, we explored the efficacy of chlorophyll c2 in patients with seasonal allergic rhinitis. This was a single-center, randomized, double-blind placebo-controlled trial. Sixty-six patients aged 20-43 years, each with a 2-year history of seasonal allergic rhinitis, were randomly assigned to receive either a single daily dose (0.7 mg) of chlorophyll c2 or placebo for 12 weeks. The use of medications including H1-antihistamines and topical nasal steroids was recorded by rescue medication scores (RMSs) noted after 4, 8, and 12 weeks of treatment. Disease-specific quality of life was measured using the Japan Rhinitis Quality of Life Questionnaire (JRQLQ) both before and after 4, 8, and 12 weeks of treatment. The RMS at 8 weeks was significantly better in the chlorophyll c2 than the placebo group (mean RMS difference = -3.09; 95 % confidence interval = -5.96 to -0.22); the mean RMS at 4 weeks was only slightly better in the chlorophyll c2 group. The JRQLQ scores did not differ significantly between the two groups. Chlorophyll c2 would have a potential to be an alternative treatment for allergic rhinitis.

Antioxidant capacities of fucoxanthin-producing algae as influenced by their carotenoid and phenolic contents

Natural antioxidants from sustainable sources are favoured to accommodate worldwide antioxidant demand. In addition to bioprospecting for natural and sustainable antioxidant sources, this study aimed to investigate the relationship between the bioactives (i.e. carotenoid and phenolic acids) and the antioxidant capacities in fucoxanthin-producing algae. Total carotenoid, phenolic acid, fucoxanthin contents and fatty acid profile of six species of algae (five microalgae and one macroalga) were quantified followed by bioactivity evaluation using four antioxidant assays. Chaetoceros calcitrans and Isochrysis galbana displayed the highest antioxidant activity, followed by Odontella sinensis and Skeletonema costatum which showed moderate bioactivities. Phaeodactylum tricornutum and Saccharina japonica exhibited the least antioxidant activities amongst the algae species examined. Pearson correlation and multiple linear regression showed that both carotenoids and phenolic acids were significantly correlated (p<0.05) with the antioxidant activities, indicating the influence of these bioactives on the algal antioxidant capacities.

Methanol extracts from Cystoseira tamariscifolia and Cystoseira nodicaulis are able to inhibit cholinesterases and protect a human dopaminergic cell line from hydrogen peroxide-induced cytotoxicity

Context Marine macroalgae contain several bioactive molecules that may be developed as functional foods, but information about their neuroprotective potential is scarce. Objective The objective of this study is to determine the in vitro antioxidant and neuroprotective features of marine algae from the southern coast of Portugal and to assess the total content of different types of bioactives. Materials and methods Methanol extracts from 21 macroalgal species from the southern Portugal were evaluated for in vitro antioxidant and acetylcholinesterase (AChE) inhibition. Active extracts were further evaluated for inhibitory activity against butyrylcholinesterase (BuChE) and tyrosinase (TYRO), and for their ability to attenuate hydrogen peroxide (H2O2)-induced toxicity in SH-SY5Y cells. The total contents of different phenolic groups were determined for the most active extracts. Results Cystoseira tamariscifolia (Hudson) Papenfuss (Sargassaceae) had the highest antiradical activity (92%, 1 mg/mL). Cystoseira nodicaulis (Withering) M. Roberts (Sargassaceae) (75%) and Cystoseira humilis Schousboe ex Kützing (Sargassaceae) (70%) had the highest iron-chelating activity at 10 mg/mL. Cystoseira baccata (S.G. Gmelin) P.C. Silva (Sargassaceae) was more active towards copper (66%, 10 mg/mL). Cystoseira tamariscifolia had the highest AChE inhibitory capacity (85%, 10 mg/mL). Cystoseira tamariscifolia and C. nodicaulis were also active against BuChE and TYRO, and were able to protect SH-SY5Y cells against oxidative stress induced by H2O2. Cystoseira tamariscifolia had the highest content of all the groups of phenolics, and was particularly enriched in hydroxycinnamic acids (106 mg CAE/g DW). Discussion and conclusion Results indicate that C. tamariscifolia and C. nodicaulis are important sources of nutraceutical compounds and may be considered functional foods that could improve cognitive functions.

Structural Characteristics and Antioxidant Activities of Fucoidans from Five Brown Seaweeds

Five kinds of fucoidans from the brown seaweeds Cladosiphon okamuranus, Sargassum hornery, Kjellmaniella crassifolia (Saccharine sculpera), Nemacystus decipiens, and Fucus vesiculosus, were isolated according to a previously reported procedure with slight modification. The scavenging activities of DPPH radical, superoxide radical, and hydroxyl radical, as well as the ORAC value were measured for the isolated fucoidans. Fucoidans from S. hornery, F. vesiculosus, and K. crassifolia showed higher antioxidant activity than that from S. hornery and C. okamuranus, except for the hydroxyl radical scavenging activity. The relationship between the antioxidant activity and the structure was examined for each fucoidan. Fucoidans with high amount of sulfate groups did not necessarily result in increased antioxidant activity, although the sulfate group itself was essential for the antioxidant activity. Furthermore, the fucoidan linked to a side chain monosaccharide, such as GlcA, demonstrated similar antioxidant activity. The antioxidant activity of the fucoidans was possibly due to a combination of the factors involved, such as the amount of sulfate groups, the position of the sulfate groups, the kind of side chain sugar, the linkage of a side chain sugar, and the molecular weight.

Can macroalgae provide promising anti-tumoral compounds? A closer look at Cystoseira tamariscifolia as a source for antioxidant and anti-hepatocarcinoma compounds

Marine organisms are a prolific source of drug leads in a variety of therapeutic areas. In the last few years, biomedical, pharmaceutical and nutraceutical industries have shown growing interest in novel compounds from marine organisms, including macroalgae. Cystoseira is a genus of Phaeophyceae (Fucales) macroalgae known to contain bioactive compounds. Organic extracts (hexane, diethyl ether, ethyl acetate and methanol extracts) from three Cystoseira species (C. humilis, C. tamariscifolia and C. usneoides) were evaluated for their total phenolic content, radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radicals, and antiproliferative activity against a human hepatocarcinoma cell line (HepG2 cells). C. tamariscifolia had the highest TPC and RSA. The hexane extract of C. tamariscifolia (CTH) had the highest cytotoxic activity (IC50 = 2.31 µg/mL), and was further tested in four human tumor (cervical adenocarcinoma HeLa; gastric adenocarcinoma AGS; colorectal adenocarcinoma HCT-15; neuroblastoma SH-SY5Y), and two non-tumor (murine bone marrow stroma S17 and human umbilical vein endothelial HUVEC) cell lines in order to determine its selectivity. CTH strongly reduced viability of all tumor cell lines, especially of HepG2 cells. Cytotoxicity was particularly selective for the latter cells with a selectivity index = 12.6 as compared to non-tumor cells. Incubation with CTH led to a 2-fold decrease of HepG2 cell proliferation as shown by the bromodeoxyuridine (BrdU) incorporation assay. CTH-treated HepG2 cells presented also pro-apoptotic features, such as increased Annexin V/propidium iodide (PI) binding and dose-dependent morphological alterations in DAPI-stained cells. Moreover, it had a noticeable disaggregating effect on 3D multicellular tumor spheroids. Demethoxy cystoketal chromane, a derivative of the meroditerpenoid cystoketal, was identified as the active compound in CTH and was shown to display selective in vitro cytotoxicity towards HepG2 cells.

Fucoxanthin and lipid metabolism: A minireview

AIMS

Accumulating data suggest that food supplementation with seaweeds which traditionally are an important part of food culture in South-East Asian countries might lead to essential health benefits. In this short review, we summarize findings from experimental studies on the effects of fucoxanthin (a carotenoid derived from brown seaweeds) on lipid metabolism, adiposity, and related conditions and discuss the possible underlying mechanisms.

DATA SYNTHESIS

Supplementation of fucoxanthin or its derivatives consistently attenuated body and visceral fat weight gain, lipid accumulation in the liver, decreases insulin resistance, and improves the plasma lipid profile in rodents fed a high-fat diet. It should however be noted that in diabetic/obese KK-Ay mice with genetically compromised insulin signaling, fucoxanthin might increase the plasma levels of cholesterol and low-density lipoproteins. The anti-obesity effects of fucoxanthin are apparently mediated by the hormones leptin and adiponectin through their common target AMK-activated protein kinase, resulting in downregulation of lipogenic enzymes and upregulation of lipolytic enzymes. Fucoxanthin also suppresses adipocyte differentiation and induces the expression of uncoupling proteins in visceral adipose tissue.

CONCLUSIONS

The results of experimental studies suggest that consumption of fucoxanthin and its derivatives as nutritional supplements is a promising option for prevention and treatment of obesity and a wide variety of related pathologies, including metabolic syndrome, type 2 diabetes, and heart disease. Yet, clinical trials are warranted to assess a therapeutic value of fucoxanthin.

Antioxidant and cytotoxic activities of three species of tropical seaweeds

BACKGROUND

Three species of seaweeds (Padina tetrastromatica, Caulerpa racemosa and Turbinaria ornata) are widely consumed by Asians as nutraceutical food due to their antioxidant properties. Studies have shown that these seaweeds exhibit bioactivities which include antimicrobial, antiviral, anti-hypertensive and anticoagulant activities. However, investigations into the mechanisms of action pertaining to the cytotoxic activity of the seaweeds are limited. The aim of this study was to determine the antioxidant and cytotoxic activities of whole extracts of P. tetrastromatica, C. racemosa and T. ornata, including the cellular events leading to the apoptotic cell death of the extract treated-MCF-7 cells. Bioassay guided fractionation was carried out and the compounds identified.

METHODS

Powdered samples were sequentially extracted for 24 h. Their antioxidant activities were assessed by the DPPH radical, superoxide, nitric oxide and hydroxyl radical scavenging assays. The cytotoxic activity of the extract-treated MCF-7cells was assessed using the MTT assay. The most potent fraction was subjected to bioassay guided fractionation with column chromatography. All the fractions were tested for cytotoxic activity, caspase activity and effect on DNA fragmentation.

RESULTS

All three seaweeds showed potent radical scavenging activities in the various assays. The activity of the cellular antioxidant enzymes, superoxide dismutase, catalase and glutathione reductase, in MCF-7 cells, decreased in a time-dependent manner. The partially purified fractions exhibited higher cytotoxic activity, as assessed by the MTT assay, than the whole extracts in the breast adenocarcinoma cell line, MCF-7. LC-MS analysis revealed the presence of bioactive alkaloids such as camptothecin, lycodine and pesudopelletierine.

CONCLUSION

Based on the results obtained, all three seaweeds are rich sources of enzymatic and non-enzymatic antioxidants which could contribute to their reported medicinal benefits.

Acetyl- and butyryl-cholinesterase inhibitory activities of the edible brown alga Eisenia bicyclis

As part of our ongoing isolation of cholinesterase (ChE) inhibitors from natural marine sources, the bioactivity of the ethanolic extracts from 12 Korean seaweeds were screened for their inhibitory activities against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and total reactive oxygen species (ROS) generation. Eisenia bicyclis exhibited promising inhibitory properties against AChE, BChE and total ROS with inhibition percentages (%) of 68.01 ± 1.37, 95.72 ± 3.80, and 73.20 ± 1.82 at concentrations of 25 µg/mL, respectively. Among the different solvent-soluble fractions obtained from the ethanolic extract, the ethyl acetate (EtOAc) fraction was found to cause the most potent scavenging, or inhibitory activities, against 2,2-diphenyl-1-picrylhydrazyl (DPPH), peroxynitrite (ONOO(-)) and total ROS with the respective IC50 values of 2.48 ± 0.01, 8.70 ± 0.06, and 0.81 ± 0.03 µg/mL. Likewise, the EtOAc fraction also exhibited potent inhibitory activities against AChE and BChE with IC50 values of 2.78 ± 0.07 and 3.48 ± 0.32 µg/mL, respectively. Silica gel column chromatography of the EtOAc fraction yielded a phlorotannin, 974-B, based on the comparison with reported (1)H- and (13)C-NMR spectroscopic data. 974-B showed strong scavenging/or inhibitory potential against DPPH, ONOO(-), total ROS, AChE, and BChE with the respective IC50 values of 0.86 ± 0.02, 1.80 ± 0.01, 6.45 ± 0.04, 1.95 ± 0.01, and 3.26 ± 0.08 µM, respectively. These results indicate that the potential of E. bicyclis and its phlorotannin for use in the development of therapeutic or preventive agents of Alzheimer's disease mainly through ChE inhibition and additional antioxidant capacities.

Fucoxanthin and Its Metabolite Fucoxanthinol in Cancer Prevention and Treatment

Fucoxanthin is a carotenoid present in the chloroplasts of brown seaweeds. When ingested, it is metabolized mainly to fucoxanthinol by digestive enzymes of the gastrointestinal tract. These compounds have been shown to have many beneficial health effects, including anti-mutagenic, anti-diabetic, anti-obesity, anti-inflammatory and anti-neoplastic actions. In every cancer tested, modulatory actions of fucoxanthinol on viability, cell-cycle arrest, apoptosis and members of the NF-κB pathway were more pronounced than that of fucoxanthin. Anti-proliferative and cancer preventing influences of fucoxanthin and fucoxanthinol are mediated through different signalling pathways, including the caspases, Bcl-2 proteins, MAPK, PI3K/Akt, JAK/STAT, AP-1, GADD45, and several other molecules that are involved in cell cycle arrest, apoptosis, anti-angiogenesis or inhibition of metastasis. In this review, we address the mechanisms of action of fucoxanthin and fucoxanthinol according to different types of cancers. Current findings suggest that these compounds could be effective for treatment and/or prevention of cancer development and aggressiveness.

Biological Properties of Fucoxanthin in Oil Recovered from Two Brown Seaweeds Using Supercritical CO2 Extraction

The bioactive materials in brown seaweeds hold great interest for developing new drugs and healthy foods. The oil content in brown seaweeds (Saccharina japonica and Sargassum horneri) was extracted by using environmentally friendly supercritical CO2 (SC-CO2) with ethanol as a co-solvent in a semi-batch flow extraction process and compared the results with a conventional extraction process using hexane, ethanol, and acetone mixed with methanol (1:1, v/v). The SC-CO2 method was used at a temperature of 45 °C and pressure of 250 bar. The flow rate of CO2 (27 g/min) was constant for the entire extraction period of 2 h. The obtained oil from the brown seaweeds was analyzed to determine their valuable compounds such as fatty acids, phenolic compounds, fucoxanthin and biological properties including antioxidant, antimicrobial, and antihypertension effects. The amounts of fucoxanthin extracted from the SC-CO2 oils of S. japonica and S. horneri were 0.41 ± 0.05 and 0.77 ± 0.07 mg/g, respectively. High antihypertensive activity was detected when using mixed acetone and methanol, whereas the phenolic content and antioxidant property were higher in the oil extracted by SC-CO2. The acetone-methanol mix extracts exhibited better antimicrobial activities than those obtained by other means. Thus, the SC-CO2 extraction process appears to be a good method for obtaining valuable compounds from both brown seaweeds, and showed stronger biological activity than that obtained by the conventional extraction process.

Sargassum horneri methanol extract rescues C2C12 murine skeletal muscle cells from oxidative stress-induced cytotoxicity through Nrf2-mediated upregulation of heme oxygenase-1

BACKGROUND

Sargassum horneri, an edible marine brown alga, is typically distributed along the coastal seas of Korea and Japan. Although several studies have demonstrated the anti-oxidative activity of this alga, the regulatory mechanisms have not yet been defined. The aim of the present study was to examine the cytoprotective effects of S. horneri against oxidative stress-induced cell damage in C2C12 myoblasts.

METHODS

We demonstrated the anti-oxidative effects of a methanol extract of S. horneri (SHME) in a hydrogen peroxide (H2O2)-stimulated C2C12 myoblast model. Cytotoxicity was determined using the 3-(4,5-dimetylthiazol-2-yl)-2,5-diphenyl-tetrazolium assay and mode of cell death by cell cycle analysis. DNA damage was measured using a comet assay and expression of phospho-histone γH2A.X (p-γH2A.X). Levels of cellular oxidative stress as reactive oxygen species (ROS) accumulation were measured using 2',7'-dichlorofluorescein diacetate. The involvement of selected genes in the oxidative stress-mediated signaling pathway was explored using Western blot analysis.

RESULTS

SHME attenuated H2O2-induced growth inhibition and exhibited scavenging activity against intracellular ROS that were induced by H2O2. The SHME also inhibited comet tail formation, p-γH2A.X expression, and the number of sub-G1 hypodiploid cells, suggesting that it prevents H2O2-induced cellular DNA damage and apoptotic cell death. Furthermore, the SHME significantly enhanced the expression of heme oxygenase-1 (HO-1) associated with induction of nuclear factor-erythroid 2 related factor 2 (Nrf2) in a time- and concentration-dependent manner. Moreover, the protective effect of the SHME on H2O2-induced C2C12 cell damage was significantly abolished by zinc protoporphyrin IX, a HO-1 competitive inhibitor, in C2C12 cells.

CONCLUSIONS

These findings suggest that the SHME augments cellular antioxidant defense capacity through both intrinsic free radical scavenging activity and activation of the Nrf2/HO-1 pathway, protecting C2C12 cells from H2O2-induced oxidative cytotoxicity.

Eckols reduce dental pulp inflammation through the ERK1/2 pathway independent of COX-2 inhibition

OBJECTIVES

The aim of this study was to elucidate the role of 6-6 bieckol (EB1) and pholorofucofuroeckol-A (EB5) from brown seaweed marine algae (Eisenia bicyclis) on lipopolysaccharide (LPS)-induced inflammation in human dental pulp cells (HDPCs).

METHODS

The cytotoxicity of EB1 and EB5 was examined by MTT assay on LPS-induced human dental pulp cells. Their role on expression of inflammatory, odontogenic, and osteogenic molecules was determined by Western blot analysis. The dentin mineralization was checked by alkaline phosphatase activity.

RESULTS

The five compounds from E. bicyclis have different structure with non-cytotoxic in HDPCs. EB1 and EB5 showed anti-inflammatory properties and inhibited phosphorylated-extracellular signal-regulated kinase (p-ERK1/2) and phosphorylated-c-jun N-terminal kinases (p-JNK) without any cytotoxicity. In particular, EB1 inhibited cyclooxygenase-2 (COX-2) and p-ERK1/2 signaling, and EB5 inhibited only p-ERK1/2 signaling but not COX-2. Both compounds inhibited nuclear factor kappa-B (NF-κB) translocation. Furthermore, EB1 and EB5 increased dentinogenic and osteogenic molecules, and dentin mineralized via alkaline phosphatase activity (ALP) in LPS-induced HDPCs.

CONCLUSIONS

This study elucidates that EB1 and EB5 have different types of anti-inflammatory property and help in dentin formation. Therefore, these compounds derived from marine algae of E. bicyclis may be used as selective therapeutic strategies for pulpitis and oral diseases.

The optimum conditions for the extraction of antioxidant compounds from the Persian gulf green algae (Chaetomorpha sp.) using response surface methodology

The potential of antioxidant activity of the green algae (Chaetomorpha sp.) was studied in this work. The optimum processing conditions for the extraction of antioxidant compounds from dried green algae were determined using response surface methodology (RSM). A central composite design (CCD) was applied to determine the effects of three process variables as follows: solvent concentration (percent), extraction time (min) and microwave power (w) on total phenolic contents, ferric reducing power, 2'2-dipheny-l-picrylhydrazyl (DPPH) radical scavenging activity and total antioxidant capacity assays. The independent variables were coded at five levels and CCD included 20 experimental runs with six replications at the center point. The statistical analysis of data was performed using design expert software and second-order polynomial models generated after analysis of variance (ANOVA) applied for predicting the responses. The results revealed that the highest total phenol content and reducing power were 1.09 and 0.12 mg of tannic acid equivalent/g dry weight, respectively. The maximum antioxidant activity was 0.19 mg ascorbic acid equivalent/g dry weight and DPPH was 99.8 % under MAE. The optimum conditions using RSM for the predicted responses were: microwave power 300 W, extraction time 8 min and solvent concentration 25 %, respectively. Furthermore the actual experimental values were adjacent to the corresponding predicted values which demonstrated fitness of the employed models and suitability of RSM in extraction parameters optimization.

Antioxidant potential and cytotoxic activity of two red seaweed species, Amansia multifida and Meristiella echinocarpa, from the coast of Northeastern Brazil

Natural antioxidants found in marine macroalgae are bioactive compounds known to play an important role in the prevention of diseases associated with aging cells protecting them against the oxidative damage. The purpose of this study was to evaluate the antioxidant and cytotoxic activity of ethanolic extracts of two species of red seaweeds, Amansia multifida and Meristiella echinocarpa. In vitro antioxidant activity was determined by DPPH radical scavenging assay, ferric-reducing antioxidant power (FRAP) assay, ferrous ion chelating (FIC) assay, β-carotene bleaching (BCB) assay and total phenolic content (TPC) quantification. Cytotoxicity was evaluated with the brine shrimp Artemia sp. lethality test. The TPC values observed in the present study indicated that both species A. multifida and M. echinocarpa are rich in phenolic compounds, reaching values of 45.40 and 28.46 mg gallic acid equivalent (GAE) g−1 of ethanolic extract, respectively. DPPH radical scavenging and ferrous ion chelating showed values of 60% and 17%, respectively. Both seaweed extracts inhibited β-carotene oxidation by approximately 40%. None of the algal extracts were potentially cytotoxic. The results have showed that extracts of both species of marine red algae exhibit antioxidant potential and low toxicity. They are sources of natural antioxidant compounds.

Antioxidant effects of fucoxanthin rich powder in rats fed with high fat diet

The purpose of this study was to determine the antioxidant effect of fucoxanthin. After rats were fed a normal fat diet (NF), high fat diet (HF), and high fat with 0.2% fucoxanthin diet (HF + Fxn) for 4 weeks, the markers of oxidative stress and antioxidant capacity like lipid peroxidation, plasma total antioxidant capacity (TAC), and activities of antioxidant enzymes (catalase, superoxide dismutase (SOD), and gluthathione peroxidase (GSH-Px)) were determined. mRNA expression of transcription factor, nuclear erythroid factor like 2 (Nrf2), and its target genes such as NAD(P)H quinone oxidoreductase1 (NQO1) and heme oxygenase-1 (HO-1) were also determined. Mean weight gain in the HF + Fxn group was lower, without statistical significance, and the total food intake in the HF + Fxn group was lower than that in the HF group (P < 0.05). The activity of GSH-Px (P < 0.05) in plasma was significantly higher in the HF + Fxn group than those in the HF group (P < 0.05). In the liver, the activities of catalase (P < 0.05) and GSH-Px (P < 0.05) in the HF + Fxn group were significantly higher than those in the HF group. Plasma TAC level was significantly higher in the HF + Fxn group than that in the HF group (P < 0.05). Lipid peroxidation in plasma tended to be lower without statistical significance. Fucoxanthin supplements were shown to have higher mRNA expression of Nrf2 and NQO1 than those in the high fat diet only group (P < 0.05). In conclusion, supplementation of fucoxanthin improved the antioxidant capacity, depleted by high fat diet, by activating the Nrf2 pathway and its downstream target gene NQO1. Therefore, supplementation of fucoxanthin, especially for those who consume high fat in their diet, may benefit from reduced risk of oxidative stress.

Chemical and in vitro assessment of Alaskan coastal vegetation antioxidant capacity

Alaska Native (AN) communities have utilized tidal plants and marine seaweeds as food and medicine for generations, yet the bioactive potential of these resources has not been widely examined. This study screened six species of Alaskan seaweed ( Fucus distichus , Saccharina latissima , Saccharina groenlandica , Alaria marginata , Pyropia fallax , and Ulva lactuca ) and one tidal plant ( Plantago maritima ) for antioxidant activity. Total polyphenolic content (TPC) was determined, and chemical antioxidant capacity was assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, ferrous ion chelating, and nitric oxide (NO) inhibition assays. In vitro inhibition of radical oxygen species (ROS) generation and NO synthesis was evaluated in a RAW 264.7 macrophage culture. Greatest TPC (557.2 μg phloroglucinol equivalents (PGE)/mg extract) was discovered in the ethyl acetate fraction of F. distichus, and highest DDPH scavenging activity was exhibited by F. distichus and S. groenlandica fractions (IC50 = 4.29-5.12 μg/mL). These results support the potential of Alaskan coastal vegetation, especially the brown algae, as natural sources of antioxidants for preventing oxidative degeneration and maintaining human health.

Production, characterization, and antioxidant activity of fucoxanthin from the marine diatom Odontella aurita

The production, characterization, and antioxidant capacity of the carotenoid fucoxanthin from the marine diatom Odontella aurita were investigated. The results showed that low light and nitrogen-replete culture medium enhanced the biosynthesis of fucoxanthin. The maximum biomass concentration of 6.36 g L⁻¹ and maximum fucoxanthin concentration of 18.47 mg g⁻¹ were obtained in cultures grown in a bubble column photobioreactor (Ø 3.0 cm inner diameter), resulting in a fucoxanthin volumetric productivity of 7.96 mg L⁻¹ day⁻¹. A slight reduction in biomass production was observed in the scaling up of O. aurita culture in a flat plate photobioreactor, yet yielded a comparable fucoxanthin volumetric productivity. A rapid method was developed for extraction and purification of fucoxanthin. The purified fucoxanthin was identified as all-trans-fucoxanthin, which exhibited strong antioxidant properties, with the effective concentration for 50% scavenging (EC₅₀) of 1,1-dihpenyl-2-picrylhydrazyl (DPPH) radical and 2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) radical being 0.14 and 0.03 mg mL⁻¹, respectively. Our results suggested that O. aurita can be a natural source of fucoxanthin for human health and nutrition.

Antioxidant marine products in cancer chemoprevention

SIGNIFICANCE

Oxidative stress resulting from excessive reactive oxygen/nitrogen/electrophilic species (ROS/RNS/RES) can lead to diseases such as cancer. The health benefits of dietary fruits and vegetables with antioxidant potential have received a great deal of attention. On the other hand, marine botanicals have been less well characterized and still remain as terra incognita.

RECENT ADVANCES

In some parts of the world, appreciable quantities of seaweeds are consumed on a daily basis. Along with current globalization, cuisines using seaweeds are now being used throughout the world, sometimes considered as healthy delicacies. Thus, it is relevant to explore the medicinal and pharmacological properties of seaweeds, as well as the health ramifications of this dietary practice.

CRITICAL ISSUES

We currently review the antioxidant potential of seaweed components such as sulfated polysaccharides, phenolic compounds (phlorotannins and bromophenols), and fucoxanthins. In addition to seaweeds, the chemistry and antioxidant activities of some marine fungi and bacteria are described. Since antioxidants are considered promising cancer chemopreventive agents, the in vitro, in vivo, and clinical aspects of antioxidant marine products are presented, and potential implications are discussed.

FUTURE DIRECTIONS

Although some data suggest that health benefits are derived from the consumption of marine natural products, further epidemiological or clinical studies are needed to strengthen these observations. In addition, many studies have demonstrated the antioxidant effects of seaweeds with in vitro models, but further characterization of bioavailability is necessary to suggest the significance of these responses. It is also important to define the safety of some seaweeds containing inorganic arsenics.

In vitro antioxidant properties of crude extracts and compounds from brown algae

Research on the bioactives from seaweeds has increased in recent years. Antioxidant activity is one of the most studied, due to the interest of these compounds both as preservatives and protectors against oxidation in food and cosmetics and also due to their health implications, mainly in relation to their potential as functional ingredients. Brown algae present higher antioxidant potential in comparison with red and green families and contain compounds not found in terrestrial sources. In vitro antioxidant chemical methods, used as a first approach to evaluate potential agents to protect from lipid oxidation in foods, confirmed that the brown algae crude extracts, fractions and pure components are comparatively similar or superior to synthetic antioxidants. Particular emphasis on the fucoidan and phlorotannin polymeric fractions is given, considering variations associated with the species, collection area, season, and extraction and purification technologies.

Antioxidant activity of various solvent fractions from edible brown alga, Eisenia bicyclis and its active compounds

In this study, we aimed to elucidate the antioxidant capacity of Eisenia bicyclis and evaluated its antioxidant activity using various assay systems such as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, 2,2-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging, reducing power ability, and content of total polyphenol. Among all the performed experiments, the ethyl acetate fraction of E. bicyclis exhibited higher antioxidant activities. From this finding, isolation and purification were performed on the ethyl acetate fraction and identified dieckol and phlorofucofureoeckol-A by spectroscopic analyses including FAB-mass in the negative mode, (1) H NMR, (13) C NMR, (1) H-(1) H COSY, HMQC, and HMBC spectra. Interestingly, ABTS radical scavenging activities of dieckol and phlorofucofuroeckol showed strong effects of 65.36% and 70.38% at a concentration of 50 μg/mL, respectively. DPPH radical scavenging and reducing power abilities were increased in a dose-dependent manner at various concentrations. These results suggest that dieckol and phlorofucofuroeckol-A of E. bicyclis may play an important role in protection from oxidative stress involving reactive oxygen species and may contribute to the development of new bio products, for example, a useful preservative to improve food quality and a drug for various oxidative damage-associated diseases. Practical Application: The results suggest that dieckol and phlorofucofuroeckol-A can be utilized as a natural source for potential application of antioxidant in food industry and drug for oxidative damage-associated diseases.

Fucoxanthin content and antioxidant properties of Undaria pinnatifida

This study investigated the fucoxanthin content of New Zealand (NZ) Undaria pinnatifida harvested from two locations in the Marlborough Sounds, New Zealand across its growing season. Fucoxanthin content and antioxidant properties of processed New Zealand U. pinnatifida and commercial wakame from Japan and Korea were further compared. Results showed that U. pinnatifida harvested from Port Underwood had higher fucoxanthin content in the blade compared to Pelorus Sound. The sporophyll also contained a significant amount of fucoxanthin throughout the harvest season, although lower than in the blade. Two antioxidant measurement methods, DPPH and CUPRAC, were utilised to measure antioxidant activities. Processed NZ U. pinnatifida had a lower fucoxanthin content and antioxidant activity than freeze-dried Undaria. Fucoxanthin content and antioxidant activities of NZ processed U. pinnatifida were not significantly different from other commercial samples from Japan and Korea. In conclusion, U. pinnatifida in New Zealand has a great potential to be a food and nutraceutical resource.

Fucoxanthin, a marine carotenoid present in brown seaweeds and diatoms: metabolism and bioactivities relevant to human health

The marine carotenoid fucoxanthin can be found in marine brown seaweeds, the macroalgae, and diatoms, the microalgae, and has remarkable biological properties. Numerous studies have shown that fucoxanthin has considerable potential and promising applications in human health. In this article, we review the current available scientific literature regarding the metabolism, safety, and bioactivities of fucoxanthin, including its antioxidant, anti-inflammatory, anticancer, anti-obese, antidiabetic, antiangiogenic and antimalarial activities, and its protective effects on the liver, blood vessels of the brain, bones, skin, and eyes. Although some studies have shown the bioavailability of fucoxanthin in brown seaweeds to be low in humans, many studies have suggested that a dietary combination of fucoxanthin and edible oil or lipid could increase the absorption rate of fucoxanthin, and thus it might be a promising marine drug.