Algal extracts are gaining increasing interest due to their unique composition and possibilities of wide industrial applications. Various extraction techniques are used for conversion of algal biomass into extracts. Recently, attention of scientists has been paid to novel methods, such as enzyme-assisted extraction, microwave-assisted extraction, pressurized liquid extraction, supercritical fluid extraction, and ultrasound-assisted extraction, which enable the extraction of biologically active compounds without their degradation. In this review, the properties of biologically active compounds extracted from the biomass of algae reported in the literature are presented in a structured way. Algal extracts contain compounds such as carbohydrates, proteins, minerals, oil, fats, polyunsaturated fatty acids as well as bioactive compounds such as antioxidants (polyphenols, tocopherols [vitamin E], vitamin C, mycosporine-like amino acids), and pigments, such as carotenoids (carotene xanthophyll), chlorophylls, and phycobilins (phycocyanin, phycoerythrin), which possess antibacterial, antiviral, antifungal, antioxidative, anti-inflammatory, and antitumor properties. Finally, we assemble a list of applications of algal extracts in different developing branches of agriculture (biostimulants, bioregulators, feed additives) and in pharmaceutical industry.

Algae as production systems of bioactive compounds

Chemical composition of red, brown and green macroalgae from Buarcos bay in Central West Coast of Portugal

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.

https://www.mdpi.com/1660-3397/18/8/384/pdf

Seaweed Phenolics: From Extraction to Applications.

Natural anti-obesity agents

Medicinal plants are the most popular forms of traditional plants used to maintain health, as well as prevent or treat physical and mental disorders. Chemical compounds of plants are classified into primary metabolites and secondary metabolites. Plants produce a great variety of secondary metabolites related to the mechanisms of adaptation and important in mediating interactions between plants and the biotic environment. Among secondary metabolites, essential oils (EOs) are very important natural products, which have different therapeutic and biological activities. EOs (volatile oils) are complex mixtures of odorous principles stored in special plant cells and glands in different parts of plants, which are obtained by living organisms and isolated by pressing and hydro or steam distillation in some plant families. The constituents of plant EOs fall mainly into two distinct chemical classes: terpenes and phenylpropanoids. Furthermore, terpene compounds can be divided into two main categories: (1) hydrocarbons, mainly the mono-, sesqui-, and diterpenes; and (2) their oxygenated compounds, for instance, alcohols, oxides, aldehydes, ketones, phenols, acids, esters, and lactones. Several factors can influence the composition of EOs, including growth conditions, climate, altitude, soil type, agricultural methods and practices, developmental stage, plant part extracted, and harvesting time. The aim of this chapter is to investigate the chemical composition of various EO-bearing plants and the factors that are most influential in affecting the ratios of essential oil molecules made by the plant.

Chemistry of Essential Oils and Factors Influencing Their Constituents

The paper covers the latest developments in research on the utilitarian properties of algal extracts. Their appli- cation as the components of pharmaceuticals, feeds for animals and fertilizers was discussed. The classes of various bio- logically active compounds were characterized in terms of their role and the mechanism of action in an organism of hu- man, animal and plant. Recently, many papers have been published which discuss the methods of manufacture and the composition of algal ex- tracts. The general conclusion is that the composition of extracts strongly depends on the raw material (geographical loca- tion of harvested algae and algal species) as well as on the extraction method. The biologically active compounds which are transferred from the biomass of algae to the liquid phase include polysaccharides, proteins, polyunsaturated fatty ac- ids, pigments, polyphenols, minerals, plant growth hormones and other. They have well documented beneficial effect on humans, animals and plants, mainly by protection of an organism from biotic and abiotic stress (antibacterial activity, scavenging of free radicals, host defense activity etc.) and can be valuable components of pharmaceuticals, feed additives and fertilizers.

Lukasz Tuhy

Papers

Biologically Active Compounds in Seaweed Extracts - the Prospects for the Application