Marine algae have attracted a great deal of interest as excellent sources of nutrients. Polysaccharides are the main components in marine algae, hence a great deal of attention has been directed at isolation and characterization of marine algae polysaccharides because of their numerous health benefits. In this review, extraction and purification approaches and chemico-physical properties of marine algae polysaccharides (MAPs) are summarized. The biological activities, which include immunomodulatory, antitumor, antiviral, antioxidant, and hypolipidemic, are also discussed. Additionally, structure-function relationships are analyzed and summarized. MAPs' biological activities are closely correlated with their monosaccharide composition, molecular weights, linkage types, and chain conformation. In order to promote further exploitation and utilization of polysaccharides from marine algae for functional food and pharmaceutical areas, high efficiency, and low-cost polysaccharide extraction and purification methods, quality control, structure-function activity relationships, and specific mechanisms of MAPs activation need to be extensively investigated.

/pdf/recent-advances-in-marine-algae-polysaccharides-isolation-rb5dhsrfmd.pdf

Recent Advances in Marine Algae Polysaccharides: Isolation, Structure, and Activities.

Throughout human history, seaweeds have been used as food, folk remedies, dyes, and mineral-rich fertilisers. Seaweeds as nutraceuticals or functional foods with dietary benefits beyond their funda...

/pdf/seaweeds-as-nutraceuticals-for-health-and-nutrition-1ldd4o8vn4.pdf

Seaweeds as nutraceuticals for health and nutrition

Background Bioactive peptides have been studied in several sources due to their valuable potential in pharmaceutical, food and cosmetic industries. Algae, mussels and fish are examples of marine sources of bioactive peptides. Several biological properties have been identified in these peptides, such as antioxidant, antiatherosclerosis, anticancer, anticoagulant, anti-inflammatory, antihypertensive and antimicrobial activities. Furthermore, peptides derived from marine sources may also be of great interest due to their functional properties, such as solubility, emulsifying and foaming properties, which could be beneficial for industrial application. Scope and approach This paper aims to review information about bioactive peptides isolated from different marine sources, focusing on the different biological activities and functional properties already described, and the different industrial applications exploited. Key findings and conclusions Enzymatic hydrolysis appears as the most used method for peptide production. Bioactive peptides have not been widely used individually, although marine protein hydrolysates are already used with different industrial purposes. However, due to all the bioactivities showed, marine peptides may be of great interest to industrial applications, such as active ingredients for food or cosmetic products; preservatives for food or cosmetics; anti-inflammatory cosmeceuticals; pharmaceutical or nutraceutical products to treat or prevent diseases, with potentially fewer side effects when compared with synthetic drugs. To incorporate peptides in industrial matrices it is essential to guarantee that they will not suffer modifications or lose bioactivity inside new matrices. To empower peptides action in pharmaceuticals, food or cosmetics, they must be able to resist to adverse external factors. Encapsulation may be of one of the most interesting approaches to increase peptides protection.

Bioactive peptides derived from marine sources: Biological and functional properties

Anticancer activity of seaweeds.

In addition to cancer and diabetes, inflammatory and ROS-related diseases represent one of the major health problems worldwide. Currently, several synthetic drugs are used to reduce oxidative stress; nevertheless, these approaches often have side effects. Therefore, to overcome these issues, the search for alternative therapies has gained importance in recent times. Natural bioactive compounds have represented, and they still do, an important source of drugs with high therapeutic efficacy. In the ''synthetic'' era, terrestrial and aquatic photosynthetic organisms have been shown to be an essential source of natural compounds, some of which might play a leading role in pharmaceutical drug development. Marine organisms constitute nearly half of the worldwide biodiversity. In the marine environment, algae, seaweeds, and seagrasses are the first reported sources of marine natural products for discovering novel pharmacophores. The algal bioactive compounds are a potential source of novel antioxidant and anticancer (through modulation of the cell cycle, metastasis, and apoptosis) compounds. Secondary metabolites in marine Algae, such as phenolic acids, flavonoids, and tannins, could have great therapeutic implications against several diseases. In this context, this review focuses on the diversity of functional compounds extracted from algae and their potential beneficial effects in fighting cancer, diabetes, and inflammatory diseases.

Bioactive Metabolites from Marine Algae as Potent Pharmacophores against Oxidative Stress-Associated Human Diseases: A Comprehensive Review.

Angiotensin I-converting enzyme (ACE) inhibitory peptides derived from seaweed represent a potential source of new antihypertensive. The aim of this study was to isolate and purify ACE inhibitory peptides (ACEIPs) from the protein hydrolysate of the marine macroalga Ulva intestinalis. U. intestinalis protein was hydrolyzed by five different proteases (trypsin, pepsin, papain, α-chymotrypsin, alcalase) to prepare peptides; compared with other hydrolysates, the trypsin hydrolysates exhibited the highest ACE inhibitory activity. The hydrolysis conditions were further optimized by response surface methodology (RSM), and the optimum conditions were as follows: pH 8.4, temperature 28.5 °C, enzyme/protein ratio (E/S) 4.0%, substrate concentration 15 mg/mL, and enzymolysis time 5.0 h. After fractionation and purification by ultrafiltration, gel exclusion chromatography and reverse-phase high-performance liquid chromatography, two novel purified ACE inhibitors with IC50 values of 219.35 μM (0.183 mg/mL) and 236.85 μM (0.179 mg/mL) were obtained. The molecular mass and amino acid sequence of the ACE inhibitory peptides were identified as Phe-Gly-Met-Pro-Leu-Asp-Arg (FGMPLDR; MW 834.41 Da) and Met-Glu-Leu-Val-Leu-Arg (MELVLR; MW 759.43 Da) by ultra-performance liquid chromatography-tandem mass spectrometry. A molecular docking study revealed that the ACE inhibitory activities of the peptides were mainly attributable to the hydrogen bond and Zn(II) interactions between the peptides and ACE. The results of this study provide a theoretical basis for the high-valued application of U. intestinalis and the development of food-derived ACE inhibitory peptides.

https://www.mdpi.com/1660-3397/17/3/179/pdf

Preparation and Identification of ACE Inhibitory Peptides from the Marine Macroalga Ulva intestinalis.

Marine red alga Gracilariopsis lemaneiformis is the main cultured seaweed in China with potent economic and ecological value. In this paper, the algal protein was hydrolyzed using trypsin, flavourzyme, papain and alkaline protease. Among them, the trypsin hydrolysate exhibited the highest angiotensin-I-converting enzyme (ACE) inhibitory activity and was fractionated into three molecular weight of >10 kDa, 3–10 kDa and <3 kDa. The <3 kDa fraction showed the highest ACE inhibitory activity of 78.15 ± 1.56% (2.0 mg/mL) and was used for further purification. An ACE inhibitory peptide was isolated from the <3 kDa fraction by Sephadex G-25, G-15 gel chromatography and AKTA pure system. The molecular mass and amino acid sequence of the purified peptide were identified as Gln-Val-Glu-Tyr (QVEY; MW, 537.57 Da) by MALDI-TOF/TOF–MS and MALDI-TOF/TOF–MS/MS, respectively. The peptide showed an IC50 value of 474.36 μM (0.255 mg/mL). The present study indicated that the marine red alga G. lemaneiformis can provide good protein sources, and the hydrolyzed bioactive peptides could be a potential source of functional food ingredients against hypertension.

Purification and identification of a novel ACE inhibitory peptide from marine alga Gracilariopsis lemaneiformis protein hydrolysate

Seaweed is one of the important biomass producers and possesses active metabolites with potential therapeutic effects against tumors. The red alga Gracilariopsis lemaneiformis (Gp. lemaneiformis) possesses antitumor activity, and the polysaccharide of Gp. lemaneiformis (PGL) has been demonstrated to be an ingredient with marked anticancer activity. However, the anticancer mechanism of PGL remains to be elucidated. In this study, we analyzed the inhibitory effect of PGL on the cell growth of 3 human cancer cell lines and found that PGL inhibited cell proliferation, reduced cell viability, and altered cell morphology in a time- and concentration-dependent manner. Our transcriptome analysis indicates that PGL can regulate the expression of 758 genes, which are involved in apoptosis, the cell cycle, nuclear division, and cell death. Furthermore, we demonstrated that PGL induced apoptosis and cell cycle arrest and modulated the expression of related genes in the A549 cell line. Our work provides a framework to understand the effects of PGL on cancer cells, and can serve as a resource for delineating the antitumor mechanisms of Gp. lemaneiformis.

/pdf/transcriptome-profiling-reveals-the-antitumor-mechanism-of-485cjn7lai.pdf

Transcriptome Profiling Reveals the Antitumor Mechanism of Polysaccharide from Marine Algae Gracilariopsis lemaneiformis.

http://www.jbc.org/article/S0021925822004409/pdf

Oxidized high-density lipoprotein promotes CD36 palmitoylation and increases lipid uptake in macrophages

China is considered as the main producer of kiwifruit (Actinidia spp.) in the world. During 2020-2021, root rot (~8000 plants, ~5% disease incidence) of 3-year-old kiwifruit (cv. Xuxiang) was observed in Lujiang County (117°24'E, 31°15'N), Anhui, China. This disease usually occurred in fields with poor drainage in hot and humid summers. Symptoms started on leaves showing dehydration and curling, the last root of diseased plant turned black and died. Dig out the skin on rotten root was cracking and flaking and white mycelium covered on surface. Twenty rotten tissues from ten plants were cut and surface disinfected with 1% NaOCl for 5 min, rinsed in sterile water, and cultured on potato dextrose agar (PDA) at 25 ± 2°C in the dark. Fifteen fungal isolates were obtained. The first type (KWRR1, 3-10) was cotton-like, reverse with white outer margin, and light brown inner region on PDA. The second type (KWRR2, 11-15) was cotton-like on PDA but appeared pale yellow in reverse. On oatmeal agar, the KWRR1 colony was flat with little aerial hyphae and was red, while KWRR2 was hyaline. On carnation leaf agar (CLA), microconidia of the KWRR1 and KWRR2 isolates were reniform, fusiform or oblong, 0-1 septate, and measuring 1.9-4.3×8.4-15.7 µm and 3.0-3.8×8.2-16.7 µm, respectively (n=50). The macroconidia of KWRR1 were straight or moderately curved, 3-5 septa (2.7-4.6×21.5-52.6 µm in size, n=50). For KWRR2, the macroconidia were straight or slightly curved and with 3-4 septate, 4.1-4.8×26.1-30.8 µm (n=50). Chlamydospores of the KWRR1 and KWRR2 isolates were 1-2 celled, irregular globose, measuring 4.5-8.5 µm and 7.6-9.0 µm diam, respectively (n=50). To identify the isolates, four DNA fragments (RPB1, RPB2, ITS and TEF-1α) were amplified and sequenced from all isolates (O'Donnell, et al. 2012; White et al. 1990; O'Donnell et al. 2022). BLAST analysis of the RPB1, RPB2, ITS and TEF-1α sequences of the KWRR1 isolates (OL474057, OL474055, OL468550, OP382187) showed highest identity with F. solani (NRRL66304; MW218134, KT313623, KT313633, KT313611) at 98.2%-99.8%, while KWRR2 (OL505579, OL474056, OL468551, OP382188) showed that their homology with F. breve (NRRL28009; HM347149, EF470136, DQ094351, DQ246869) at 98.2%-99.4%. F. solani and F. breve belong to clade 3 of the F. solani species complex (FSSC) (Geiser et al. 2021). Phylogenetic analysis based on RPB2, ITS and TEF-1α sequences with MEGA7 software (Šišić et al. 2018), placed the KWRR1 sequences with F. solani (FSSC5), while there of KWRR2 nested with F. breve (FSSC15). One-year-old seedlings (n=6) of 'Xu Xiang', growing in a greenhouse (at 28℃, relative humidity 80%), were inoculated by drenching the soil with a conidial suspension with one of the two isolates (30 ml, 106 conidia/ml). Control plants (n=6) were inoculated with sterilized water and the pathogenicity assay was repeated three times. One month post-inoculation, the leaves of inoculated plants became chlorotic, wilted and died, whereas the controls were disease-free. F. solani and F. breve were successfully reisolated from diseased samples (n=6) and verified based on morphology and sequencing as described above, fulfilling Koch's postulates. Members of the FSSC cause root rot on many hosts (Coleman. 2016; Schroers et al. 2016), but this is the first report of F. solani and F. breve causing root rot disease on kiwifruit in China. The result will serve as the foundation for management of root rot of kiwifruit.

First Report of root rot Caused by Fusarium solani and F. breve on kiwifruit in China.

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