Marine Drugs and Health Products
It has been shown that seaweeds contain many types of compounds with antitumor, antiviral, and other pharmacological activities (Murphy et al., 2014). Many reports have been published about isolated compounds from seaweeds with biological activities, demonstrating their ability to produce metabolites that can be used for marine drugs and health products. In this respect, daily consumption of seaweed has been proposed as a factor in explaining lower postmenopausal breast cancer incidence and mortality rates in Japan (Teas et al., 2013), where the average consumption of seaweeds is much higher than the rest of world. Natural products derived from seaweeds are both a fundamental source of a new chemical diversity and an integral component of today’s pharmaceutical collection. Nowadays, numerous marine compounds are isolated from marine animals, algae, fungi, and bacteria with antibacterial, anticoagulant, antifungal, antimalarial, antiprotozoal, antituberculosis, and antiviral activities. In the last three decades, the discovery of metabolites with biological activities from macroalgae has increased significantly. Substances that currently receive most attention from pharmaceutical companies for use in drug development, or from researchers in the field of medicine-related research include sulfated polysaccharides as antiviral substances, halogenated furanones from Delisea pulchra as antifouling compounds, and kahalalide F from a species of Bryopsis as a possible treatment of lung cancer, tumors, and AIDS. Other substances such as macroalgal lectins, fucoidans, kainoids, and aplysiatoxins are routinely used in biomedical research, and a multitude of other substances have known biological activities. There are huge potential for seaweed-based bioactive substances in pharmaceutical, medicinal, and research applications (Smit, 2004). The many medicinal benefits of bioactive seaweed substances include their antiherpes simplex virus type 1 activity, antibiotic activity (Fernandes et al., 2014), bioactivity against acne vulgaris (Kok et al., 2016), antiobesity property (Awang et al., 2014), inhibition of lipase activity (Chater et al., 2016), anticancer activity (Ermakova et al., 2016), enzyme inhibition (Olivares-Molina and Fernández, 2016), hepatoprotective effect (Chale-Dzul et al., 2015), antiinflammatory activity (McCauley et al., 2015), etc.
1.5.4 Marine Cosmetics In recent years, cosmeceuticals of natural origin are becoming more popular than synthetic cosmetics. Hence, the investigation of new seaweed-derived functional components has become a promising area of cosmeceutical studies. Chemical constituents isolated from diverse classes of seaweeds exert a wide range of nutritional, functional, and biological activities, which make these unique metabolites of seaweeds potential ingredients of high-class cosmetic products. For example, brown seaweeds produce a range of active components including unique secondary metabolites such as phlorotannins, many of which have specific biological activities. In cosmetic applications, brown seaweed– derived active compounds have shown various functional properties including antioxidant, antiwrinkling, whitening, antiinflammatory, and antiallergy, which are biological effects closely associated with cosmeceutical preparations (Wijesinghe and Jeon, 2011). 1.5.5 Marine Biomedical Materials Much attention has been paid to marine-derived biomaterials for various biological, biomedical, and environmental applications. Marine bioactive substances for health care are the most important and fastest growing sector among marine biomaterials. Seaweeds are the abundant source for polysaccharides such as alginate, agar, agarose, and carrageenan, of which, alginate is a biomaterial that has found numerous applications in biomedical science and engineering due to its favorable properties, including biocompatibility and ease of gelation. Alginate hydrogels have been particularly attractive in wound healing, drug delivery, and tissue engineering applications, as these gels retain structural similarity to the extracellular matrices in tissues and can be manipulated to play several critical roles. Alginic acid can combine with many types of metal ions to form fibrous materials containing a high concentration of metal ions, enabling the fibers to have flame retardant and magnetic wave shielding properties. Calcium alginate fibers also possess unique gel-forming capabilities when the calcium ions exchange with sodium ions in body fluid. Nonwoven fabrics made from alginate fibers can form a soft hydrogel when on contact with body fluid, a property highly valuable in wound dressings, face masks, absorbent pads, and other medical and hygiene textile materials (Qin, 2005, 2006, 2008). 1.5.6 Marine Fertilizers Seaweeds contain many growth promoting substances in addition to many organic and inorganic matters that can improve the physical and chemical nature of soil (Zhang et al., 2013; Rebours et al., 2014). In terms of soil structure, seaweed does not add a great deal of bulk, but its jelly-like alginate content helps to bind soil crumbs together, and it contains nitrogen, phosphorous, and potassium compounds in addition to various amino acids and other important soil nutrients. In the modern seaweed processing industry, seaweed fertilizers have become a fast growing sector where residues from the extraction processes can be utilized to serve as high-quality soil fertilizers. Fresh seaweeds can be processed for foliar feeding or root zone applications through drip lines with soluble extracts. Seaweeds, particularly bladderwrack, kelp, or laminaria, can be either applied to the soil as a mulch or can be added to the compost heap, where they can function as an excellent activator. 1.6 Summary Seaweeds represent a large and diversified group of marine organisms. Up to now, commercial exploration of seaweed bioresources are mainly concerned with the cultivation, harvesting, and processing of brown and red seaweeds, in particular for the extraction of alginate, agar, and carrageenan. With the increasing use of seaweeds as a source of bioactive substances for functional foods, new drugs, cosmetic ingredients, and biomedical materials, seaweed farming and its related downstream processing are increasingly becoming a sustainable green industry with many high-valued applications. 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