In recent years, marine organisms including seaweeds have been highlighted as potential sources of useful metabolites and bioactive compounds, with vast biological and physiological activities. Seaweeds have long been used as a food source, for medicinal purposes, and as dietary supplements in various Asian countries, and their potential benefits have recently attracted the attention of many Western and European countries. Their commercial value depends on their applications in the food, nutraceutical, and pharmaceutical industries. Seaweeds are considered a potential source of nutraceuticals or functional foods, and analysis of taste‐oriented motives has revealed that seaweeds are preferentially selected over other types of marine foods by seafood consumers and people with high levels of health, education, and living status. It is a general perception that health conscious people prefer environmentally friendly food sources, and present an opportunity to focus on seaweed‐based foods, which have significant nutritional benefits to humans. Among the various bioactive constituents, seaweed polysaccharides have been proven to possess various beneficial properties including anticoagulant, anti‐inflammatory, antioxidant, anticarcinogenic, and antiviral activities. The diversity and composition of seaweed polysaccharides play vital roles in these biological activities. Seaweeds are a rich source of sulfated polysaccharides, which are responsible for much of the bioactivity, as they can interact with various textures and cellular proteins. A number of toxicological assays and clinical trials suggest that the ingestion of seaweeds as functional foods should be considered worldwide to improve immune responses. In this review, different polysaccharides from seaweeds and their compositions and potential nutraceutical applications are discussed.

Halophytes have demonstrated their capability to thrive under extremely saline conditions and thus considered as one of the best germplasm for saline agriculture. Salinity is a worldwide problem, and the salt-affected areas are increasing day-by-day because of scanty rainfall, poor irrigation system, salt ingression, water contamination and other environmental factors. The salinity stress tolerance mechanism is a very complex phenomenon, and some pathways are coordinately linked for imparting salinity tolerance. Though a number of salt responsive genes have been reported from the halophytes, there is always a quest for promising stress-responsive genes that can modulate plant physiology according to the salt stress. Halophytes such as Aeluropus, Mesembryanthemum, Suaeda, Atriplex, Thellungiella, Cakile and Salicornia serve as a potential candidate for the salt-responsive genes and promoters. Several known genes like antiporters (NHX, SOS, HKT, VTPase), ion channels (Cl-, Ca2+, aquaporins), antioxidant encoding genes (APX, CAT, GST, BADH, SOD) and some novel genes such as USP, SDR1, SRP etc. were isolated from halophytes and explored for developing stress tolerance in the crop plants (glycophytes). It is evidenced that stress triggers salt sensors that lead to the activation of stress tolerance mechanisms which involve multiple signaling proteins, up- or down- regulation of several genes, and finally the distinctive or collective effects of stress-responsive genes. In this review, halophytes are discussed as an excellent platform for salt responsive genes which can be utilized for developing salinity tolerance in crop plants through genetic engineering.

Functional foods are nutritional compounds which also provide health and medicinal benefits. Daily food intake has much impact on the quality of life, and therefore inclusion of functional foods is now essential to our diet. Nutraceuticals are neither food nor drug but are added to food to provide extra nutritional and physiological properties. Though nutraceutical compounds provide minimal actions, their regular involvement in the diet can provide major and long‐term health benefits. Global demand for additional and sustainable biomass for the production of important metabolites with nutraceutical potential has resulted in renewed interest in seaweeds. Seaweeds have been consumed from ancient times in Asian areas, and in recent times they have been demonstrated to possess many medicinal effects. Seaweeds are considered a rich source of various nutritional ingredients and metabolites that have pharmaceutical properties. It has been observed that total protein, from terrestrial plants such as soybean and wheat, produces an allergic response on consumption. Therefore, seaweed proteins can be considered a promising source for food industries. Overall, seaweeds are a rich source of PUFAs, metabolites, proteins, sulfated polysaccharides, vitamins, and minerals, which are all responsible for different bioactivities; they are therefore considered a promising functional food (nutraceutical). In this review we discuss the nutraceutical potential of seaweeds regarding different metabolites (primary and secondary), variation in composition, probable biological applications, limitations, research gaps, and future prospects.