Variation in bioactive compounds in some seaweeds from Abo Qir bay, Alexandria, Egypt

Nutritional, bioactive compounds content, and antioxidant activity of brown seaweeds from the Red Sea

Introduction

Brown seaweeds are excellent sources of bioactive molecules with a wide range of pharmacological effects, whose content can vary depending on several factors, including the origin and the environment in which the algae grow.

Methods

This study aimed to estimate 19 compounds regarding primary and secondary metabolites of eight brown macroalgal species from a clean Egyptian Red Sea coast. A proximate analysis, pigment, phenolic compounds, and vitamin contents were determined. In addition, the energy content and antioxidant activity were estimated to explore the potential application of algae as functional foods to encourage the species' commercialization.

Results

Based on the chemical composition, Polycladia myrica was the most valuable species, with a comparatively high protein content of 22.54%, lipid content of 5.21%, fucoxanthin content of 3.12 μg/g, β-carotene content of 0.55 mg/100 g, and carbohydrate content of 45.2%. This species also acts as a great source of vitamin C, flavonoids, tannins, phenol content and total antioxidant capacity.

Discussion

The antioxidant activity of the selected algae indicated that its phenol, vitamin and pigment contents were powerful antioxidant compounds based on the structure-activity relationships. This result was verified by the strong correlation in statistical analysis at the 95% confidence level. From a worldwide perspective and based on the obtained results, these brown species may be reinforced as an essential line in future foods.

Variation in Anti-inflammatory, Anti-arthritic, and Antimicrobial Activities of Different Extracts of Common Egyptian Seaweeds with an Emphasis on Their Phytochemical and Heavy Metal Contents

The anti-inflammatory, anti-arthritic, and antimicrobial activities of some common Egyptian seaweeds in addition to their phytochemical and heavy metal contents were investigated. Phytochemical screening of the seaweed extracts showed the presence of different primary and secondary metabolites with different concentrations according to their species and the used solvent. The ethanolic extract of Colpmenia sinuosa (CSBE2) exhibited the maximum anti-inflammatory and anti-arthritic activity at 1000 μg/ml concentration compared to other seaweed extracts. The dichloromethane extract of Corallina officinalis (CORM) exerted the highest antimicrobial activity with an average inhibition zone diameter (AV) = 15.29 mm and activity index (AI) = 1.53 and with the highest antagonistic activity against Escherichia coli (28 mm). It is followed by Ulva linza ethanolic extract (ULGE2) which recorded (AV) of 14.71 mm and (AI) of 1.30 with the highest antifungal activity against Candida albicans (30 mm). The collected seaweeds would therefore be a very promising source for treating inflammatory, arthritic, and microbial diseases. Moreover, the investigated seaweeds showed variable concentrations of heavy metals among various species. The mean concentrations of the heavy metals took the following order: Fe > Zn > Mn > Ba > Cu > As > Cr > Ni > Pb > V > Cd > Se > Co > Mo. Based on the permissible limits set by the WHO and CEVA, Pb and Ni in the studied seaweeds were found to be within the permissible limits, whereas Cd and Zn contents were at the borderline. Significant correlations were observed between studied parameters. The estimated daily intakes for most heavy metals were lower than the recommended daily intakes.

The Lebanese Red Algae Jania rubens: Promising Biomolecules against Colon Cancer Cells

Colorectal cancer (CRC) is ranked the second most lethal type of tumor globally. Thus, developing novel anti-cancer therapeutics that are less aggressive and more potent is needed. Recently, natural bioactive molecules are gaining interest as complementary and supportive antineoplastic treatments due to their safety, effectiveness, and low cost. Jania rubens (J. rubens) is a red coral seaweed abundant in the Mediterranean and bears a significant pharmacological essence. Despite its therapeutic potential, the natural biomolecules extracted from this alga are poorly identified. In this study, the proximal analysis revealed high levels of total ash content (66%), 11.3% proteins, 14.5% carbohydrates, and only 4.5% lipids. The elemental identification showed magnesium and calcium were high among its macro minerals, (24 ± 0.5 mg/g) and (33 ± 0.5 mg/g), respectively. The Chlorophyll of J. rubens was dominated by other pigments with (0.82 ± 0.02 mg/g). A 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay identified effective antioxidant activity in various J. rubens extracts. More importantly, a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) tetrazolium reduction and wound healing assays indicate that organic extracts from J. rubens significantly counteract the proliferation of colon cancer cell lines (HCT-116 and HT-29) and inhibit their migratory and metastatic properties in a dose and time-dependent manner. Overall, this study provides insight into the physicochemical properties of red seaweed, J. rubens, and identifies its significant antioxidant, cytotoxic, and anti-migratory potential on two colorectal cell lines, HCT-116 and HT-29.

The possible role of the seaweed Sargassum vulgare as a promising functional food ingredient minimizing aspartame-associated toxicity in rats

Thirty-two male Wistar albino rats were chosen to test the possible protective role of antioxidants of the edible seaweed Sargassum vulgare as a functional food additive to alleviate oxidative stress and toxicity associated with consumption of the artificial sweetener 'aspartame (ASP)'. Biochemical and spleen histopathological analyses of the orally ASP-administrated rats, at a dose of 500 mg/kg for one week daily, showed different apoptotic and inflammatory patterns. Rats treated with ASP and then supplemented orally with the S. vulgare-MeOH extract, at a dose of 150 mg/kg for three consecutive weeks daily, showed significant positive reactions in all investigated assays related to ASP consumption. The protective and immune-stimulant efficacy of S. vulgare-MeOH extract, inferred from combating oxidative stress-induced lipid peroxidation, modulating the low levels of the endogenous antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) and of the thyroid hormones T3 and T4, attenuating the elevated levels of apoptotic CASP-3 and inflammatory biomarkers TNF-α and IL-6, as well as heat shock proteins (Hsp70), can be most likely ascribed to the synergistic effect of its potent antioxidant phenolics (mainly gallic, ferulic, salicylic, and chlorogenic, and p-coumaric acids) and flavonoids (rutin, kaempferol, and hesperidin). Mechanism of action of these natural antioxidants was discussed.

Nanoencapsulated Extract of a Red Seaweed (Rhodophyta) Species as a Promising Source of Natural Antioxidants

Marine seaweed species represent an important source of bioactive compounds possessing antioxidant activity. This study aimed at evaluating the antioxidant capacity of the Jania rubens algal extract by means of two antioxidant assays, i.e., 2,2-diphenyl-1-picrylhydrazyl and ferric-reducing antioxidant power. The seaweeds' total phenolic and flavonoid contents were also assayed as markers of antioxidant activity. To identify active agents responsible for the antioxidant activity, gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry were used for comprehensive metabolites characterization. To enhance the Jania rubens efficacy, the extract was nanoencapsulated using an ionic gelation method by means of high-pressure homogenization. The optimum nanoformulation had a particle size of 161 nm, a ζ potential of 31.2 mV, a polydispersity index of 0.211, and entrapment efficiency of 99.7%. The in vitro phytochemicals' release profiles of Jania rubens chitosan nanoparticles in comparison to the concentration of the raw algal extract were studied by the dialysis bag diffusion method revealing that the extract was released in a controlled pattern. The results indicated the potential advantages of the encapsulated Jania rubens extract, with its potent antioxidant activity, for use in different applications where sustained release is useful.

Metabolite Profiling of Malaysian Gracilaria edulis Reveals Eplerenone as Novel Antibacterial Compound for Drug Repurposing Against MDR Bacteria

With a continuous threat of antimicrobial resistance on human health worldwide, efforts for new alternatives are ongoing for the management of bacterial infectious diseases. Natural products of land and sea, being conceived to be having fewer side effects, pose themselves as a welcome relief. In this respect, we have taken a scaffolded approach to unearthing the almost unexplored chemical constituents of Malaysian red seaweed, Gracilaria edulis. Essentially, a preliminary evaluation of the ethyl acetate and acetone solvent extracts, among a series of six such, revealed potential antibacterial activity against six MDR species namely, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella enterica, methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pyogenes, and Bacillus subtilis. Detailed analyses of the inlying chemical constituents, through LC-MS and GC-MS chromatographic separation, revealed a library of metabolic compounds. These were led for further virtual screening against selected key role playing proteins in the virulence of the aforesaid bacteria. To this end, detailed predictive pharmacological analyses added up to reinforce Eplerenone as a natural alternative from the plethora of plausible bioactives. Our work adds the ongoing effort to re-discover and repurpose biochemical compounds to combat the antimicrobial resistance offered by the Gram-positive and the -negative bacterial species.

Seaweed Proteins as a Source of Bioactive Peptides

Seaweeds have received great attention as a vegetarian and sustainable marine source of protein, which does not need irrigation, arable land, and fertilization. Besides, seaweeds are considered as an untapped resource for discovering bioactive compounds with health benefits where bioactive peptides have shown outstanding potential. This review provides a detailed overview of available scientific knowledge on production methods, bioactivity and application of peptides from seaweed proteins. The emphasis is on the effects from seaweed varieties and peptide production conditions on the bioactivity of the peptides and their potential health benefits. Bioactive properties of seaweed peptides, including antioxidant, antihypertensive, antidiabetic, anti-inflammatory, anticancer activities and other potential health benefits, have been discussed. It also covers current challenges and required future research and innovations for the successful application of seaweeds proteins as a sustainable source of bioactive peptides. Effects from seasonal variation of seaweed composition on the bioactivity of their peptides, difficulties in the extraction of proteins from seaweed complex structure, scalability and reproducibility of the developed methods for the production of bioactive peptides, the safety of the peptides are examples of highlighted challenges. Further studies on the bioavailability of the seaweed bioactive peptides and validation of the results in animal models and human trials are needed before their application as functional foods or pharmaceutical ingredients.

Halogen content relative to the chemical and biochemical composition of fifteen marine macro and micro algae: nutritional value, energy supply, antioxidant potency, and health risk assessment

Marine algae have made a strong contribution to global food security in the future. This study is the first report describing the concentration, pathways, and interactions of halogens in 15 species of marine algae collected from the Eastern Harbor in Alexandria, Egypt, relative to 22 key variables. The relationship between halogen content and chemical and biochemical parameters was studied through multivariate analysis. Among all the tested algae, the iodine content was the lowest (2.53-3.00 μg/g). The range of fluoride and chloride in macroalgae (1.12-1.70 and 0.10-0.46 mg/g) was smaller than that of microalgae (0.10-0.46 and 1.48-3.17 mg/g). The bromide content in macroalgae (0.36-5.45 mg/g) was higher than that in microalgae (0.40-0.76 mg/g). The halogen content in macroalgae was arranged in the order of Br > F > Cl > I. In addition, the biochemical parameters such as carbohydrates, proteins, lipids, and certain heavy metals (Fe, Zn, Cu, Mn, Pb, Ni, Co, Cd, and Cr) were determined. Calories, energy, total antioxidant activity (TAC), K/Na, and ion quotient amounts were estimated. The results showed that the green seaweed species had the highest TAC content. In most of the studied algal species, the calculated ion quotient referred to their likelihood of overcoming high blood pressure. The estimated daily intake (EDI) of algae showed no adverse effects on human health. Most of the research variables are below the acceptable WHO/FAO level. Generally, the calorie content of the selected algae is less than 2 kcal, which makes the algae considered an alternative source of healthy food to reduce obesity.Graphical abstract.

Technofunctional quality assessment of soymilk fermented with Lactobacillus acidophilus and Lactobacillus casei

The current research work was carried out to evaluate the effect of three different varieties (NARC-II, Williams 82, Ajmeri) of soybean along with single and coculture impact of Lactobacillus acidophilus and Lactobacillus casei on fermented soymilk. The periodically microbial and antioxidative activities of fermented soymilk were analyzed during the storage of 24 days. Moreover, the effect of fermentation on rheological and structural changes was examined along with isoflavone contents in fermented soymilk. Viability of cells and antioxidative activities were found to be significantly (P < 0.05) higher in fermented soymilk using mixed cultures. The rheological attributes demonstrated higher viscosity in coculture fermented soymilk. Scanning electron microscopic examination indicated that the growth characteristic of L. casei has a relatively more uniform texture and smaller pore size in comparison to L. acidophilus. Nevertheless, the combination of cultures exhibited precise pore formation with stronger cross-links of soybean protein throughout the structure. Assessment of isoflavones exhibited higher values, for daidzein (20.87 ppm) in comparison to genistein (6.57 ppm), in Ajmeri-based coculture soymilk. Conclusively, L. casei and L. acidophilous exhibited considerable antioxidant potential in the development of viscous, less porous, and rich in bioactive metabolites fermented soymilk, when used in combination and among varieties Ajmeri results it was the top of all. This suggests that the process evidence in this study could be recommended for high-quality soymilk production.

Therapeutic Uses of Red Macroalgae

Red Seaweed “Rhodophyta” are an important group of macroalgae that include approximately 7000 species. They are a rich source of structurally diverse bioactive constituents, including protein, sulfated polysaccharides, pigments, polyunsaturated fatty acids, vitamins, minerals, and phenolic compounds with nutritional, medical, and industrial importance. Polysaccharides are the main components in the cell wall of red algae and represent about 40–50% of the dry weight, which are extensively utilized in industry and pharmaceutical compounds, due to their thickening and gelling properties. The hydrocolloids galactans carrageenans and agars are the main red seaweed cell wall polysaccharides, which had broad-spectrum therapeutic characters. Generally, the chemical contents of seaweed are different according to the algal species, growth stage, environment, and external conditions, e.g., the temperature of the water, light intensity, nutrient concentrations in the ecosystem. Economically, they can be recommended as a substitute source for natural ingredients that contribute to a broad range of bioactivities like cancer therapy, anti-inflammatory agents, and acetylcholinesterase inhibitory. This review touches on the main points of the pharmaceutical applications of red seaweed, as well as the exploitation of their specific compounds and secondary metabolites with vital roles.

Seaweed Phenolics: From Extraction to Applications

Seaweeds have attracted high interest in recent years due to their chemical and bioactive properties to find new molecules with valuable applications for humankind. Phenolic compounds are the group of metabolites with the most structural variation and the highest content in seaweeds. The most researched seaweed polyphenol class is the phlorotannins, which are specifically synthesized by brown seaweeds, but there are other polyphenolic compounds, such as bromophenols, flavonoids, phenolic terpenoids, and mycosporine-like amino acids. The compounds already discovered and characterized demonstrate a full range of bioactivities and potential future applications in various industrial sectors. This review focuses on the extraction, purification, and future applications of seaweed phenolic compounds based on the bioactive properties described in the literature. It also intends to provide a comprehensive insight into the phenolic compounds in seaweed.

Enhancement of Biochemical and Nutritional Contents of Some Cultivated Seaweeds Under Laboratory Conditions

Six species of macroalgae belonging to the Chlorophyta, Phaeophyta, and Rhodophyta divisions were cultivated in a closed system with Guillard's f/2, Walne's, Provasoli Enriched Seawater (PES) medium, and seawater (control) for 6 weeks. The growth rate and parameters of the tested seaweeds showed that all used media enhanced the growth rate and chemical content as compared with other seaweeds cultivated in seawater without addition of any nutrients. There are significant differences in the effect of the used media on the seaweed composition at p = .01; PES is more effective than the f/2 and Walne's media. The results indicate that the cultivation technique of some macroalgae was an efficient tool for increasing the seaweeds' biomass and increasing their chemical compounds, calories, and energy under laboratory conditions.

Variation in biochemical constituents and master elements in common seaweeds from Alexandria Coast, Egypt, with special reference to their antioxidant activity and potential food uses: prospective equations

Biochemical constituents and master elements (Pb, Cr, Cd, Fe, Cu, Zn, Hg, B, Al, SO42-, Na, K, Li, Ca, Mg, and F) were investigated in six different seaweed species from Abu Qir Bay in the Egyptian Mediterranean Sea coast. The moisture level ranged from 30.26% in Corallina mediterranea to 77.57% in Padina boryana. On dry weight basis, the ash contents varied from 25.53% in Jania rubens to 88.84% in Sargassum wightii. The protein contents fluctuated from 8.26% in S. wightii to 28.01% in J. rubens. Enteromorpha linza showed the highest lipids (4.66%) and carbohydrate contents (78.95%), whereas C. mediterranea had the lowest lipid (0.5%), and carbohydrate contents (38.12%). Chlorophylls and carotenoid contents varied among the species. Total antioxidant capacity of the tested green seaweeds had the highest activities followed by brown and red seaweeds which had a similar trend of phenol and tannins contents. High reducing power was observed in all tested seaweeds extract except Ulva lactuca. Brown species had the highest amount of elements followed by red and green seaweeds. Notably, SO42- recorded the highest level in the tested green species (108.05 mg/g dry weight (DW)). The Ca/Mg and K/Na ratios reflected highly significant difference between seaweed species. This study keeps an eye on 29 parameters and by applying stepwise multiple regression analysis, prospective equations have been set to describe the interactions between these parameters inside seaweeds. Accordingly, the tested seaweeds can be recommended as a source of healthy food with suitable ion quotient and estimated daily intake values.

Variation in oxidative stress indices of two green seaweeds growing under different heavy metal stresses

Concentrations of nine heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) were determined in the green seaweed species Cladophora glomerata and Ulva compressa collected from El-Mex and Sidi Kirayr locations. The heavy metal concentrations in algal tissues were in direct correlation with their soluble concentrations in seawater with the descending order: Fe<Mn<Zn<Cu<Cr<Pb<Ni<Cd<Co. The bioaccumulation factor of iron and copper was higher in both tested species collected from El-Mex, while it was maximum for cadmium in Sidi Kirayr location. This metal contamination led to apparent alternation in algal thalli morphology. The results showed that C. glomerata had a superior adaptation to metal stress than U. compressa, due to its ability to produce non-enzymatic and enzymatic compounds for scavenging of the produced reactive oxygen species. The recorded contents of the oxidative stress indices (phenols, antioxidant activity, lipid peroxidation, hydrogen peroxide, and ascorbic acid) and the antioxidant enzymes (catalase, peroxidase, and superoxide dismutase) were higher in both tested seaweeds from El-Mex bay. Additionally, the estimated metal pollution index and pollution load index for the tested algae and seawaters ensured their ability as metal pollution bioindicators for monitoring marine environment quality and as biomarkers for oxidative damage assessment.