Algae in food: a general review

Algae are common all over the Earth. Due to their rich chemical composition and content of bioactive substances they have been used in many fields of industry. Their gelling, thickening and stabilizing properties have led to the development of such products as agar, alginate and carrageenan. Moreover, algae are used in the food industry as food supplements and an addition to functional food. Algae are also added to meat products, such as pasty, steaks, frankfurters and sausages, as well as to fish, fish products, and oils, to improve their quality. Cereal-based products, such as pasta, flour and bread, are another group of products enriched with algae. Due to their properties algae may also be used for construction of fermented functional food. Fermented products containing algae are, most of all, dairy products, such as cheese, cream, milk deserts, yoghurt, cottage cheese, and processed cheese. Combination of fermented products offering a high content of lactic acid bacteria with algae possessing biologically active metabolites of natural origin allows not only to compose products with a high content of nutrients, but also to create a brand new segment of fermented food.

Protective effect of polysaccharides from Celluclast-assisted extract of Hizikia fusiforme against hydrogen peroxide-induced oxidative stress in vitro in Vero cells and in vivo in zebrafish

Polysaccharides were extracted by Celluclast-assisted hydrolysis and ethanol precipitation from Hizikia fusiforme (HFPS), and their in vitro antioxidant effects were evaluated in Vero cells. HFPS contains 63.56±0.32% sulfate polysaccharides, which comprise fucose (53.53%), galactose (23.15%), glucose (5.95%), and xylose (17.37%). HFPS scavenged DPPH, alkyl, and hydroxyl radicals at IC50 values of 0.81±0.02, 0.25±0.02, and 0.21±0.03mg/mL, respectively. HFPS significantly reduced H2O2-induced cytotoxicity in Vero cells. Furthermore, HFPS reduced intracellular ROS levels, and H2O2-induced apoptosis. HFPS has a strong protective effect against H2O2-stimulated oxidative stress in vivo in zebrafish, and showed improved survival rate, decreased heart rate, and reduced ROS generation and cell death. These results suggest that HFPS may be useful as an antioxidant in medical and cosmetic industries.

Improving oxidative stability of olive oil: Incorporation of Spirulina and evaluation of its synergism with citric acid

The effects of different Spirulina concentrations used alone and in combination with citric acid on the oxidative stability of olive oil were assessed. The amounts of primary and secondary oxidation products produced in Spirulina samples were lower than that of the control. The improved oxidative stability indices of Spirulina samples with and without citric acid were in the range of 85.20–94.47% and 258.10–260.21%, respectively. In comparison with the control, Spirulina samples manifested significantly higher carotenoid and chlorophyll contents at the beginning and end of the storage period. The presence of these bioactive compounds results from the presence of Spirulina in the medium and can thus retard the oxidation of olive oil. A higher oxidative stability was reached using BHT in comparison with Spirulina samples. Furthermore, no synergistic action was observed in possible connections between citric acid and Spirulina. In conclusion, Spirulina can enhance oxidative stability and improve the shelf life of olive oil.

Antioxidant Potential of Ecklonia cavaon Reactive Oxygen Species Scavenging, Metal Chelating, Reducing Power and Lipid Peroxidation Inhibition

The antioxidative potential of different fractions (respective organic and aqueous fractions of n-hexane, chloroform and ethyl acetate) of 70% methanol extract of Ecklonia cava(a brown seaweed) was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion, hydrogen peroxide, hydroxyl radical, nitric oxide, ferrous ion chelating, reducing power and lipid peroxidation inhibition (conjugated diene hydroperoxide and thiobarbituric acid-reactive substances production) assays. The 70% methanol extract showed significant (p< 0.05) activities in all antioxidant assays and contained a high level of total phenolic content. It was observed that the level of hydrophilic phenolic content was higher than that of hydrophobics. Among those organic solvent fractions, ethyl acetate fraction exhibited significant activities due to the highest level of total phenolic content and their IC50 values were 0.013mg/mL, 0.009mg/mL and 0.33mg/mL in DPPH, hydrogen peroxide and nitric oxide radical inhibition, respectively. These activities were superior to those of a commercial synthetic and natural antioxidants tested. The aqueous chloroform and ethyl acetate fractions also exhibited significant (p< 0.05) activities in reactive oxygen species (ROS) scavenging and metal chelating, attributed to the high amount of hydrophilic phenolics. Moreover, E. cava extracts showed strong reducing power and a notable capacity to suppress lipid peroxidation.

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.

Aqueous extracts of the edible Gracilaria tenuistipitata are protective against H₂O₂-induced DNA damage, growth inhibition, and cell cycle arrest

Potential antioxidant properties of an aqueous extract of the edible red seaweed Gracilaria tenuistipitata (AEGT) against oxidative DNA damage were evaluated. The AEGT revealed several antioxidant molecules, including phenolics, flavonoids and ascorbic acid. In a cell-free assay, the extract exhibited 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity that significantly reduced H₂O₂-induced plasmid DNA breaks in a dose-response manner (P < 0.001). The AEGT also suppressed H₂O₂-induced oxidative DNA damage in H1299 cells by reducing the percentage of damaged DNA in a dose-response manner (P < 0.001) as measured by a modified alkaline comet-nuclear extract (comet-NE) assay. The MTT assay results showed that AEGT confers significant protection against H₂O₂-induced cytotoxicity and that AEGT itself is not cytotoxic (P < 0.001). Moreover, H₂O₂-induced cell cycle G2/M arrest was significantly released when cells were co-treated with different concentrations of AEGT (P < 0.001). Taken together, these findings suggest that edible red algae Gracilaria water extract can prevent H₂O₂-induced oxidative DNA damage and its related cellular responses.