Ascophyllum nodosum is a large, brown alga belonging to the family Fucaceae. Found abundantly in the intertidal zones of the North Atlantic Ocean, this seaweed is renowned for its high nutritional content, environmental adaptability, and diverse applications in agriculture, cosmetics, and health supplements. Its knotted appearance, formed by air bladders along its fronds, gives it the common name "Knotted Wrack."

Botanical Classification

• Kingdom: Chromista
• Phylum: Ochrophyta
• Class: Phaeophyceae
• Order: Fucales
• Family: Fucaceae
• Genus: Ascophyllum
• Species: Ascophyllum nodosum

Physical Characteristics

• Size: Grows up to 2 meters in length.
• Fronds: Flattened, leathery, and olive-green to brown, with single, large air bladders spaced along the frond.
• Attachment: Anchored to rocks and substrates via a holdfast.
• Habitat: Thrives in sheltered intertidal zones, often forming dense mats in rocky coastal areas.

Chemical Composition

Ascophyllum nodosum is rich in bioactive compounds, making it highly valuable for various applications:

• Polysaccharides:
  • Alginate: A key component used in food, pharmaceuticals, and cosmetics.
  • Fucoidan: Known for its anti-inflammatory, antioxidant, and immune-modulating properties.
• Minerals: High in iodine, calcium, potassium, magnesium, and zinc.
• Vitamins: Contains vitamins A, B12, C, D, and E.
• Phenolic Compounds: Exhibits antioxidant activity.
• Proteins and Amino Acids: Contains essential amino acids.

Habitat and Ecology

• Geographical Distribution: Native to the cold waters of the North Atlantic Ocean, found along the coasts of Europe and North America.
• Ecological Role:
  • Provides habitat and food for marine life such as mollusks, crustaceans, and fish.
  • Acts as a natural carbon sink, contributing to marine ecosystem health.
  • Protects shorelines by reducing wave energy.

How to Harvest Ascophyllum nodosum

Harvesting Ascophyllum nodosum sustainably is essential to preserve its ecological role:

1. Timing: Harvested during low tide when the fronds are exposed.
2. Method: Hand-cut to allow regrowth and avoid damaging the holdfast.
3. Sustainability: Rotational harvesting practices ensure the population remains healthy.

Uses and Benefits

Ascophyllum nodosum has a wide range of applications:

• Agriculture:

  • Fertilizers: Used as an organic soil conditioner and fertilizer, enhancing soil health and plant growth due to its mineral and bioactive content.
  • Animal Feed: Added to livestock feed to improve health and productivity.

• Health and Nutrition:

  • Dietary Supplements: Rich in iodine, it supports thyroid health and metabolism.
  • Digestive Health: Fucoidan and alginates improve gut health and act as prebiotics.
  • Weight Management: Certain compounds may reduce fat absorption and appetite.

• Cosmetics:

  • Incorporated into skincare products for its hydrating, anti-aging, and antioxidant properties.
  • Used in shampoos and conditioners for its nourishing effects on hair.

• Industrial Applications:

  • Food Industry: Alginate is used as a thickener and stabilizer in products like ice cream, sauces, and dairy alternatives.
  • Pharmaceuticals: Fucoidan is being studied for its potential anticancer and immune-boosting properties.

Applications

• Medical:

  • Emerging research highlights its potential in managing inflammation, cardiovascular health, and metabolic disorders.
  • Its natural iodine content is essential for preventing iodine deficiency.

• Environmental:

  • Used in bioremediation projects to absorb heavy metals and pollutants from water.
  • Potential role in carbon sequestration to combat climate change.

• Culinary:

  • Occasionally used in traditional cuisines, especially in soups and as a flavoring.
  • Added to food products as a source of natural umami flavor.

Environmental and Safety Considerations

• Environmental Benefits:

  • Contributes to marine biodiversity by providing habitat and food for various organisms.
  • Acts as a natural buffer against coastal erosion.

• Sustainability:

  • Overharvesting can lead to habitat destruction. Adopting sustainable harvesting practices is critical.

• Safety:

  • Generally safe for consumption, but excessive intake of iodine-rich products may lead to thyroid imbalances.
  • Ensure that seaweed is harvested from non-polluted waters to avoid contamination with heavy metals or toxins.

Research and Future Potential

The unique biochemical properties of Ascophyllum nodosum continue to be a focus of research in fields such as nutrition, agriculture, and environmental science. Studies are exploring its applications in functional foods, pharmaceuticals, and sustainable farming practices. Its potential for carbon sequestration and bioremediation highlights its importance in combating climate change and preserving marine ecosystems.

References__________________________________________________________________________

Gisbert M, Franco D, Sineiro J, Moreira R. Antioxidant and Antidiabetic Properties of Phlorotannins from Ascophyllum nodosum Seaweed Extracts. Molecules. 2023 Jun 23;28(13):4937. doi: 10.3390/molecules28134937. 

Abstract. Seaweeds have gained considerable attention in recent years due to their potential health benefits and high contents of bioactive compounds. This review focuses on the exploration of seaweed's health-promoting properties, with particular emphasis on phlorotannins, a class of bioactive compounds known for their antioxidant and antidiabetic properties. Various novel and ecofriendly extraction methods, including solid-liquid extraction, ultrasound-assisted extraction, and microwave-assisted extraction are examined for their effectiveness in isolating phlorotannins. The chemical structure and isolation of phlorotannins are discussed, along with methods for their characterization, such as spectrophotometry, nuclear magnetic resonance, Fourier transform infrared spectroscopy, and chromatography. Special attention is given to the antioxidant activity of phlorotannins. The inhibitory capacities of polyphenols, specifically phlorotannins from Ascophyllum nodosum against digestive enzymes, such as α-amylase and α-glucosidase, are explored. The results suggest that polyphenols from Ascophyllum nodosum seaweed hold significant potential as enzyme inhibitors, although the inhibitory activity may vary depending on the extraction conditions and the specific enzyme involved. In conclusion, seaweed exhibits great potential as a functional food ingredient for promoting health and preventing chronic diseases. Overall, this review aims to condense a comprehensive collection of high-yield, low-cost, and ecofriendly extraction methods for obtaining phlorotannins with remarkable antioxidant and antidiabetic capacities.

Obluchinskaya ED, Pozharitskaya ON, Gorshenina EV, Daurtseva AV, Flisyuk EV, Generalova YE, Terninko II, Shikov AN. Ascophyllum nodosum (Linnaeus) Le Jolis from Arctic: Its Biochemical Composition, Antiradical Potential, and Human Health Risk. Mar Drugs. 2024 Jan 19;22(1):48. doi: 10.3390/md22010048.

Abstract.  Ascophyllum nodosum is a brown seaweed common in Arctic tidal waters. We have collected A. nodosum samples from the Barents Sea (BS), Irminger Sea (IS), and Norwegian Sea (NS) in different reproductive stages and have evaluated their biochemical composition, radical scavenging potential, and health risks. The total content of dominating carbohydrates (fucoidan, mannitol, alginate, and laminaran) ranged from 347 mg/g DW in NS to 528 mg/g DW in BS. The proportion of two main structural monosaccharides of fucoidan (fucose and xylose) differed significantly between the seas and reproductive phase, reaching a maximum at the fertile phase in the BS sample. Polyphenols and flavonoids totals were highest in NS A. nodosum samples and increased on average in the following order: BS < IS < NS. A positive correlation of free radical scavenging activity for seaweed extracts with polyphenols content was observed. The concentration of elements in A. nodosum from the Arctic seas region was in the following order: Ca > Mg > Sr > Fe > Al > Zn > As total > Rb > Mn > Ba > Cu > Co. Seaweeds from BS had the lowest metal pollution index (MPI) of 38.4. A. nodosum from IS had the highest MPI of 83. According to the calculated target hazard quotient (THQ) and hazard index (HI) values, Arctic A. nodosum samples pose no carcinogenic risk to adult and child health and are safe for regular consumption. Our results suggest that the Arctic A. nodosum has a remarkable potential for food and pharmaceutical industries as an underestimated source of polysaccharides, polyphenols, and flavonoids.

Usov AI, Bilan MI, Ustyuzhanina NE, Nifantiev NE. Fucoidans of Brown Algae: Comparison of Sulfated Polysaccharides from Fucus vesiculosus and Ascophyllum nodosum. Mar Drugs. 2022 Oct 13;20(10):638. doi: 10.3390/md20100638. 

Abstract. Preparations of sulfated polysaccharides obtained from brown algae are known as fucoidans. These biopolymers have attracted considerable attention due to many biological activities which may find practical applications. Two Atlantic representatives of Phaeophyceae, namely, Fucus vesiculosus and Ascophyllum nodosum, belonging to the same order Fucales, are popular sources of commercial fucoidans, which often regarded as very similar in chemical composition and biological actions. Nevertheless, these two fucoidan preparations are polysaccharide mixtures which differ considerably in amount and chemical nature of components, and hence, this circumstance should be taken into account in the investigation of their biological properties and structure-activity relationships. In spite of these differences, fractions with carefully characterized structures prepared from both fucoidans may have valuable applications in drug development.

Ascophyllum nodosum (Ascophyllum nodosum (L.) Le Jolis)

Ascophyllum nodosum is a brown macroalga of the family Fucaceae, typical of cold to cool temperate rocky shores in the North Atlantic. It forms dense stands in the intertidal zone, where it often becomes a dominant canopy-forming species. The thallus consists of long, strap-like, tough and leathery fronds, olive to olive-brown in colour, lacking a distinct midrib and characterised by large nodular air bladders arranged in series along the main axis. Fronds generally reach 0.5–2 m in length under normal conditions and are attached to the substrate by a disc-shaped holdfast firmly anchored to rocks and boulders.

From an ecological standpoint, Ascophyllum nodosum typically colonises sheltered or moderately exposed rocky shores, including bays, fjords and estuarine environments with normal or slightly reduced salinity. It is a slow-growing, long-lived species capable of forming a continuous canopy that provides habitat, shelter and feeding grounds for numerous invertebrates and small fish. Distribution, frond length and morphology are influenced by wave exposure, tidal range, salinity, temperature and substrate characteristics. In particularly clear waters, stands may extend into the shallow subtidal zone. As a structural engineer species in intertidal communities, it contributes significantly to shoreline complexity and biodiversity.

From a compositional perspective, Ascophyllum nodosum biomass displays a very high water content, with the dry matter dominated by structural and storage carbohydrates. Major polysaccharides include alginates, fucoidans and laminarans, together with mannitol and other soluble sugars. The polyphenolic fraction is rich in phlorotannins, which contribute to antioxidant capacity and are involved in chemical defence against herbivores and environmental stress. The protein fraction is moderate, while the lipid content is relatively low but may include long-chain fatty acids of technological interest. The mineral profile is marked by high levels of iodine, potassium, calcium, magnesium and other trace elements, reflecting the ionic composition of seawater. Overall composition and concentration of constituents depend strongly on geographical origin, season of harvest, depth, and the trophic and physicochemical conditions of the site.

In terms of applications, Ascophyllum nodosum is one of the most important brown seaweeds industrially. The biomass is widely used for the production of alginates and for liquid or powdered extracts applied as agricultural biostimulants, used on arable crops, fruit trees and horticultural species as seaweed-based amendments and fertilising products. It is also processed as meal or extract for inclusion in animal feeds and feed additives, where the combination of polysaccharides, minerals and bioactive compounds is of interest. In the food and nutraceutical sectors, standardised extracts are investigated and used as functional ingredients in certain foods, supplements and health-oriented products, within the framework of regulatory and safety constraints. The polysaccharide and polyphenolic fractions are further studied for applications in cosmetics, gelling and thickening systems, and biorefinery processes aimed at producing bioethanol, biogas and other bioproducts.

Quality assessment of Ascophyllum nodosum biomass intended for processing typically considers residual moisture, ash content, quantity and quality of polysaccharides (especially alginates and fucoidans), polyphenol levels, microbial load, and the presence of metals or environmental contaminants. Batch purity is also critical, with attention to the absence or minimal presence of other macroalgae, excessive sediment, and unwanted macro-epiphytes. Reliable traceability of the harvesting area, adoption of sustainable harvesting practices (cutting height, rotation of harvesting zones, regeneration time), and controlled drying, storage and transport conditions are essential to preserve the chemical–physical properties, functionality and technological performance of the raw material.

Physical characteristics
Size: It can grow up to 2 meters in length.
Fronds: Flattened, leathery, olive-green or brown, with large air vesicles distributed along the stipe.
Attachment: Firmly anchors to rocks or substrates through a thallus (holdfast).
Habitat: Lives in sheltered intertidal zones, often forming dense mats along rocky shores.

Chemical composition
Ascophyllum nodosum is rich in bioactive compounds that make it a valuable resource:

Polysaccharides:

• Alginate: Used in the food, pharmaceutical, and cosmetic industries.

• Fucoidan: Known for its anti-inflammatory, antioxidant, and immunomodulating properties.

Minerals: High levels of iodine, calcium, potassium, magnesium, and zinc.
Vitamins: Contains vitamins A, B12, C, D, and E.
Phenolic compounds: Powerful antioxidants.
Proteins and amino acids: Provides essential amino acids.

Habitat and ecology
Geographical distribution: Native to the cold waters of the North Atlantic Ocean, found along the coasts of Europe and North America.

Ecological role:

• Provides habitat and food for marine fauna, including mollusks, crustaceans, and fish.

• Acts as a natural carbon sink, contributing to the health of marine ecosystems.

• Protects coastlines by reducing wave energy.

How to harvest Ascophyllum nodosum
The sustainable harvesting of Ascophyllum nodosum is essential to preserve its ecological role:

• Timing: Harvested during low tide, when the fronds are exposed.

• Method: Manual cutting to allow regrowth, avoiding damage to the thallus.

• Sustainability: Rotational harvesting ensures a healthy and stable population.

Uses and benefits
Ascophyllum nodosum offers numerous applications:

Agriculture:

• Fertilizers: Used as an organic soil conditioner and fertilizer; it improves soil health and plant growth thanks to its mineral content and bioactive compounds.

• Animal feed: Added to feed to improve the health and productivity of livestock.

Health and nutrition:

• Dietary supplements: Rich in iodine, it supports thyroid health and metabolism.

• Gut health: Fucoidan and alginates improve digestive tract health and act as prebiotics.

• Weight management: Some compounds may reduce fat absorption and appetite.

Cosmetic and Personal Care Applications

Moisturizing: The polysaccharides in Ascophyllum Nodosum Extract help to maintain skin hydration, keeping it soft and supple.

Skin Soothing: The extract has skin-soothing properties, making it ideal for calming irritated or sensitive skin.

Anti-Aging: By promoting collagen production and improving skin elasticity, the extract helps to reduce the signs of aging such as fine lines and wrinkles.

Antioxidant Protection: The antioxidants in the extract help to protect the skin from free radical damage and environmental stressors.

Skin conditioning agent. It is the mainstay of topical skin treatment as it has the function of restoring, increasing or improving skin tolerance to external factors, including melanocyte tolerance. The most important function of the conditioning agent is to prevent skin dehydration, but the subject is rather complex and involves emollients and humectants that can be added in the formulation.

Hair Care: In haircare products, the extract helps to nourish and strengthen the hair, improving its texture, manageability, and shine.

Ascophyllum Nodosum Extract is generally considered safe for use in cosmetic and personal care products. It is non-irritating and suitable for most skin types. As a naturally derived ingredient, it poses minimal risk to the environment when sourced and disposed of responsibly. Utilizing Ascophyllum Nodosum Extract supports sustainable practices by promoting the use of renewable marine resources.

Industry:

• Food industry: Alginate is used as a thickener and stabilizer in products such as ice cream, sauces, and dairy alternatives.

• Pharmaceuticals: Fucoidan is being studied for its potential anticancer and immune-stimulating effects.

Applications

Medicine:

• Emerging research highlights its potential in the management of inflammation, cardiovascular health, and metabolic disorders.

• Its natural iodine content is essential for preventing deficiencies.

Environment:

• Used in bioremediation projects to absorb heavy metals and pollutants from water.

• Shows potential for carbon sequestration, contributing to the fight against climate change.

Culinary use:

• Occasionally used in traditional cuisines, especially in soups and as a flavoring agent.

• Added to food products as a natural source of umami flavor.

Environmental and safety considerations

Environmental benefits:

• Contributes to marine biodiversity by providing shelter and food for many species.

• Acts as a natural barrier against coastal erosion.

Sustainability:

• Overharvesting can lead to habitat destruction. It is essential to adopt sustainable harvesting practices.

Safety:

• Generally safe for consumption, but excessive intake of iodine-rich products can cause thyroid imbalances.

• It is important to ensure that the seaweed is harvested from uncontaminated waters to avoid heavy metals or toxins.

Research and future potential
The biochemical properties of Ascophyllum nodosum continue to be an active field of research in nutrition, agriculture, and environmental science. Ongoing studies are exploring its applications in functional foods, pharmaceuticals, and sustainable agricultural practices. Its ability to sequester carbon and contribute to bioremediation underscores its importance in combating climate change and conserving marine ecosystems.

References__________________________________________________________________________

Gisbert M, Franco D, Sineiro J, Moreira R. Antioxidant and Antidiabetic Properties of Phlorotannins from Ascophyllum nodosum Seaweed Extracts. Molecules. 2023 Jun 23;28(13):4937. doi: 10.3390/molecules28134937. 

Abstract. Seaweeds have gained considerable attention in recent years due to their potential health benefits and high contents of bioactive compounds. This review focuses on the exploration of seaweed's health-promoting properties, with particular emphasis on phlorotannins, a class of bioactive compounds known for their antioxidant and antidiabetic properties. Various novel and ecofriendly extraction methods, including solid-liquid extraction, ultrasound-assisted extraction, and microwave-assisted extraction are examined for their effectiveness in isolating phlorotannins. The chemical structure and isolation of phlorotannins are discussed, along with methods for their characterization, such as spectrophotometry, nuclear magnetic resonance, Fourier transform infrared spectroscopy, and chromatography. Special attention is given to the antioxidant activity of phlorotannins. The inhibitory capacities of polyphenols, specifically phlorotannins from Ascophyllum nodosum against digestive enzymes, such as α-amylase and α-glucosidase, are explored. The results suggest that polyphenols from Ascophyllum nodosum seaweed hold significant potential as enzyme inhibitors, although the inhibitory activity may vary depending on the extraction conditions and the specific enzyme involved. In conclusion, seaweed exhibits great potential as a functional food ingredient for promoting health and preventing chronic diseases. Overall, this review aims to condense a comprehensive collection of high-yield, low-cost, and ecofriendly extraction methods for obtaining phlorotannins with remarkable antioxidant and antidiabetic capacities.

Obluchinskaya ED, Pozharitskaya ON, Gorshenina EV, Daurtseva AV, Flisyuk EV, Generalova YE, Terninko II, Shikov AN. Ascophyllum nodosum (Linnaeus) Le Jolis from Arctic: Its Biochemical Composition, Antiradical Potential, and Human Health Risk. Mar Drugs. 2024 Jan 19;22(1):48. doi: 10.3390/md22010048.

Abstract.  Ascophyllum nodosum is a brown seaweed common in Arctic tidal waters. We have collected A. nodosum samples from the Barents Sea (BS), Irminger Sea (IS), and Norwegian Sea (NS) in different reproductive stages and have evaluated their biochemical composition, radical scavenging potential, and health risks. The total content of dominating carbohydrates (fucoidan, mannitol, alginate, and laminaran) ranged from 347 mg/g DW in NS to 528 mg/g DW in BS. The proportion of two main structural monosaccharides of fucoidan (fucose and xylose) differed significantly between the seas and reproductive phase, reaching a maximum at the fertile phase in the BS sample. Polyphenols and flavonoids totals were highest in NS A. nodosum samples and increased on average in the following order: BS < IS < NS. A positive correlation of free radical scavenging activity for seaweed extracts with polyphenols content was observed. The concentration of elements in A. nodosum from the Arctic seas region was in the following order: Ca > Mg > Sr > Fe > Al > Zn > As total > Rb > Mn > Ba > Cu > Co. Seaweeds from BS had the lowest metal pollution index (MPI) of 38.4. A. nodosum from IS had the highest MPI of 83. According to the calculated target hazard quotient (THQ) and hazard index (HI) values, Arctic A. nodosum samples pose no carcinogenic risk to adult and child health and are safe for regular consumption. Our results suggest that the Arctic A. nodosum has a remarkable potential for food and pharmaceutical industries as an underestimated source of polysaccharides, polyphenols, and flavonoids.

Usov AI, Bilan MI, Ustyuzhanina NE, Nifantiev NE. Fucoidans of Brown Algae: Comparison of Sulfated Polysaccharides from Fucus vesiculosus and Ascophyllum nodosum. Mar Drugs. 2022 Oct 13;20(10):638. doi: 10.3390/md20100638. 

Abstract. Preparations of sulfated polysaccharides obtained from brown algae are known as fucoidans. These biopolymers have attracted considerable attention due to many biological activities which may find practical applications. Two Atlantic representatives of Phaeophyceae, namely, Fucus vesiculosus and Ascophyllum nodosum, belonging to the same order Fucales, are popular sources of commercial fucoidans, which often regarded as very similar in chemical composition and biological actions. Nevertheless, these two fucoidan preparations are polysaccharide mixtures which differ considerably in amount and chemical nature of components, and hence, this circumstance should be taken into account in the investigation of their biological properties and structure-activity relationships. In spite of these differences, fractions with carefully characterized structures prepared from both fucoidans may have valuable applications in drug development.