Introduction INTRODUCTION

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1 I INTRODUCTION Algae are a large and diverse group of simple plant like organisms ranging from unicellular to multicellular forms. The largest and most complex marine algae are called seaweeds (Hardy and Guiry, 2006).Seaweeds are a group of macroscopic marine algae that form the biomass in the intertidal zone and the term seaweeds and sea vegetables are used interchangeably (Wong and Cheung, 2002). Seaweeds are multicellular and macrothallic. Seaweeds are salt water tolerant, land dependent plants growing almost exclusively at narrow interface where land and sea meet. They are photosynthetic and must be firmly attached to a stratum to stay in the photic zone where they can receive sufficient sunlight (Smith, 2004; Yang, 2002). Seaweeds are also called the benthic marine algae which just mean attached algae that live in the sea (Rindi, 2004). Seaweeds are macrophytic algae, a primitive type of plants lacking true roots, stems and leaves. Most seaweeds belong to one of the three divisions namely Chlorophyta (green algae), Phaeophyta (brown algae) and Rhodophyta (red algae). There are about 900 species of green seaweed, 4000 red species and 1500 brown species found in nature. A large variety of red and green seaweeds are found in subtropical and tropical waters, while brown seaweeds are more common in cooler and temperate waters. Seaweeds grow abundantly along the Tamil Nadu and Gujarat coasts and around Lakshadweep and Andaman and Nicobar islands. There are also rich seaweed beds around Mumbai, Ratnagiri, Goa, Karwar, Varkala, Vizhinjam and Pulicat in Tamil Nadu and Chilka in Orissa. Out of approximately 700 species of marine algae found in both inter-tidal and deep water regions of the Indian coast, nearly 60 species are commercially important. Agar yielding red seaweeds such as Gelidiella acerosa and Gracilaria species are collected throughout the year. 1

2 Amongst the many culture techniques, the Single Rope Floating Raft (SRFR) technique developed by Central Salt Marine and Chemical Research Institute (CSMCRI) is suitable for cultivating seaweeds in wide area and greater depth. Seaweed harvesters have joined to develop rope and net mariculture similar to noriculture and placed in regularly spaced places in twisted plastic ropes and suspended in seawater and allowed to grow in harvestable size (Rangasamy, 2004). Gracilaria edulis and Kappaphycus alvarezii are cultivated mainly by raft method and to some extent by rope mariculture in TamilNadu ( The total global seaweed production in the year 2004 was more than 15 million metric tonnes (FAO, 2006) of which 15 to 20 per cent was contributed by Indian Ocean region (Chandini et al., 2008). The seaweed industry in India is mainly a cottage industry and is based only on the natural stock of agar-yielding red seaweeds, such as Gelidiella acerosa and Gracilaria edulis and algin yielding brown seaweeds species such as Sargassum and Tubineria. India produces tons of dry agar annually utilizing about tons of dry agarophytes. Annual algin production is 360 to 540 tons from 3,600 to 5,400 tons dry alginophytes. Seaweeds are mainly used as human food sources. Seaweeds serve as food stuff in the Asian diet for centuries as it contains carotenoids, dietary fibers, proteins, essential fatty acids, vitamins and minerals. Today approximately one million metric tonnes of wet seaweeds are harvested and extracted to produce the three hydrocolloids like agar, carrageenan and alginate (Nussinovitch, 1997). Alginate is extracted from brown seaweeds. Agar and carrageenan are extracted from red seaweeds namely Gracilaria, Gelidium, Kappaphycus alvarezii and Euchema denticulatum. These are used as thickening agents and they improve the texture of foods. The Japanese have been consuming seaweeds for more than 10,000 years. The population in countries like New Zealand, Canada, Ireland, Norway, Iceland and Scotland have been consuming seaweeds since ancient times. Some Government and commercial organizations in France have been 2

3 promoting seaweeds for restaurant and domestic use with some success. Fresh and dried seaweeds are utilized as human food (Erhart, 2001). Seaweeds are consumed as food in various forms as salad, soups, pickle, sauce, pasta and jellies. The alginates are used as thickening agents in sauces, syrups and toppings for ice creams. In pie fillings, it reduces moisture retention by the pastry and in cake mixes, it thickens the batter and aids in moisture retention and in canned meat and vegetables, it gives either temporary or delayed thickening. Alginates are the basis of many slimming diet foods, particularly biscuits, alginic acid which swells in the stomach and fills it so that the dieter no longer feels hungry. The body cannot assimilate the alginic acid, so no calories are absorbed (Bhaskar et al., 2006). Gracilaria species is one of the most widely cultivated genera, and is widely cultured extensively for subsistence farming and agar extraction, and is an important component of many traditional foods. Gracilaria species contribute to 70 per cent of the world s agar and is used in genetic engineering trials to take up nutritional properties of other seaweeds (Phang et al., 2007). Brown algae namely Padina gymnospora and Padina tetrastomatica., this is an abundant local species with the potential for integration with abalone culture as a feed source (Troell et al., 2006). However it is potentially hard to culture in tanks due to large morphology. Ulva and Enteromorpha species are cultured for the global food market, but are generally of a lower value than other red or brown seaweeds. However, as it is attractive and is purported to have good nutritional value, appropriate marketing may increase the value as appears to be the case of late as demand seems to have increased (Critchley, 2004). Current claims in the food market and elsewhere (Kirby, 2001) state that Ulva species. contain 15 per cent protein, 50 per cent sugar and starch, less than one per cent fat, high in iron, iodine and all elements. 3

4 The protein content of brown seaweeds are generally low when compared to red and green seaweeds. With respect to the high protein level and amino acid composition, the red seaweeds appear to be an interesting potential source of food protein. Certain species of green algae like Ulva species have high levels of arginine or glycine. The free amino acid fraction of seaweeds is composed of alanine, aminobutyric acid, taurine, ornithine, citrulline and hydroxyproline. Levels of these differ according to the species. All species of seaweeds contain histidine, which is necessary for children and taurine which has pharmacological activity (Hong et al., 2007). In general, seaweeds are rich in fatty acids. Among them, red algae contains 33 fatty acids and green algae contains 29 fatty acids (Hong et al., 2007). It is known that algae accumulate PUFA when there is decrease in the environment temperature (Khotimchenko, 1991). The ratio of n6 to n3 fatty acids is very important as a neutraceutical for human intake as both of these compete the same enzyme to synthesize prostaglandins derived from both n3 and n6 families. It has been reported that several seaweeds have balanced ratio of n3 and n6 fatty acid (Chandini et al., 2008). Most red seaweeds contain large amounts of vitamins B1 and B2. The annual production of carotenoids from seaweeds are estimated to be approximately 100 million tonnes of which fucoxanthin the main carotenoids from brown seaweeds contribute more than 10 per cent (Matsuno, 2001). These carotenoids have beneficial effects in cancer chemoprevention by acting either as an antioxidant or as a pro oxidant. Seaweeds are known to be high in mineral content. More than 30 per cent of the dry weight of marine algae is ash which contains various kinds of minerals as they are bathed in the rich seawater. Seaweeds contain diiodotyrosin (DIT) which is precursor to essential thyroid hormones thyroxine (T4) and triodothyronine (T3). Some species are also characterized by high levels of particular elements with catalytic functions, notably Ulva or Entermorpha species which possess high Mg content in the range of 2 to 5.2 per cent of dry weight. High intake of Ca and K are associated with lower risks 4

5 of hypertension. All seaweeds offer an extraordinary level of potassium that is very similar to our natural plasma level (Chandini et al., 2008). These seaweeds contain sulphated polysaccharides fucoidan, a polyuronic acid which is water soluble dietary fibre. Some green algae contain other kind of sulphated galactans (Nisizawa, 2002). Many of these viscous soluble polysaccharides have been correlated with hypercholesterolemia and hypoglycaemic effect, whereas water insoluble polysaccharides are mainly associated with decreases in digestive tract transit time. As seaweed polysaccharides cannot be entirely digested by humans, they are regarded as a new source of dietary fiber and food ingredient. Together with their low lipid content, seaweeds only provide a very low amount of energy. Consumption of seaweeds can increase the intake of dietary fiber and lower the occurrence of some chronic diseases. Several researchers have suggested that sulfated polysaccharides from marine algae serve as free-radical scavengers and antioxidants and thus can play an important role in preventing the free-radical-induced oxidative damage related to alcohol (Hui et al., 2008). Acanthophora spicifera, Ulva and Enteromorpha are highly sulfated at the C-2 position of β-d-galactose units, with some of the residues being 4,6-pyruvylated, are recognized to possess a number of biological activities including anticoagulant, antiviral, and immunoinflammatory activities that might find relevance in nutraceutical/functional food, cosmetic/cosmeceutical and pharmaceutical applications (Dhargalkar and Pereira, 2005). This traditional food source has been found to maintain good health by providing nutritional benefits and thus helping to treat disease. Traditionally in Chinese medicine, hot water extract of certain seaweeds are used in the treatment of cancer. Additionally, Japanese and Chinese have used seaweeds to treat goitre. The Romans used seaweeds in the treatment of wound, burns and rashes. In Scotland during 18 th century physicians used dried seaweeds stem to successfully drain abdominal wall abscesses (Wolter and Kluwer, 2007). 5

6 Seaweeds have recently received significant attention for their potential as natural antioxidants. Antioxidant activity of marine algae may arise from carotenoids, tocopherols and polyphenols (Kumar et al., 2009). These compounds directly or indirectly contribute to inhibition or suppression of free radical generation (Hung and Wang, 2004). Investigation on dimethyl sulphoniopropionate (DMSP) has recently revealed that their compound from marine algae could serve as an effective antioxidant (Athukorala et al., 2005). It provides blood thinning, anti-inflammatory and antioxidant polysaccharides, which keeps the blood thin and easier for the heart to push through the blood vessels, prevents clots from forming, prevents free radical damage to the blood vessels and keeps plaques from clogging the blood vessels that feed the body. Edible seaweeds contain appreciable amounts of polyphenols (Rodriguez et al., 2011), which are effective antioxidants and may have particular biological activities. Polyphenols from edible seaweeds have also been suggested to influence responses relevant to diabetes through modulation of glucose-induced oxidative stress, as well as through inhibition of starch-digestive enzymes (Kim et al., 2010) thus which possess antidiabetic activity. Polyphenol-rich extracts and isolated phlorotannin components have been shown to inhibit proliferation of cancer cells and to influence antiinflammatory responses. Seaweeds have traditionally been used as food and folk medicine for curing helminthes infections, gout and eczema, particularly by coastal people in several countries (Duarte et al., 2004). Compounds with cytostatic, antiviral, antihelmintic, antifungal, and antibacterial activities have been detected in green, brown and red algae. There are numerous reports concerning the inhibiting activities from macroalgae against human pathogens, fungi and yeasts Over 15,000 novel bioactives have been chemically isolated from a diverse range of algae and the prospect of commercial application is enormous (Cardozo et al., 2007). Seaweeds have caused an emerging interest in the biomedical area due to the presence of potent 6

7 pharmacologically bioactive substances with wide arrays of potential health benefits (Smit, 2004). Of the substances, the bioactives most used by pharmaceutical companies for developing new drugs are the sulphated polysaccharides (anti-tumours and antivirals), the halogenated furanones (antifouling compounds) and the kahalalide F (anticancer and anti-aids compounds) (Smit, 2004). Wide arrays of bioactive compounds found in seaweeds await a major breakthrough for a variety of food/medical applications as natural antioxidants in different food/pharmaceutical products (Cardozo et al., 2007). Thus seaweeds not only possess nutrient potentials but also nutraceutical potentials like antioxidant, antimutagenic, anticoagulant, anticancerous and antibacterial activity. Hence, seaweeds can be considered as futuristically promising plants forming one of the important marine living resources of high nutritional value and nutraceutical potentials. Being plants of unique structure and biochemical compostion, Acanthophora spicifera, Gracilaria edulis, Padina gymnospora, Ulva fasciata and Enteromorpha flexuosa could be exploited for their multifunctional properties in the form of food, energy, medicine and as biotechnological tools. The coastal region of Tamilnadu, South India supports a rich vegetation of marine algae. It has been shown that a great diversity exists in the macroalgal community of the marine algal vegetation of the region. Among the macro algae of the region, the red algae Acanthophora spicifera, and Gracilaria edulis, brown algae Padina gymnospora, the green algae namely Ulva fasciata and Enteromorpha flexuosa are grown in abundance as dominant communities in the shores of Kanyakumari and Ramanthapuram districts of Tamilnadu State, India. Seaweeds are consumed by coastal people in many regions of the world. However, systematic studies on the nutrient content, nutraceutical potentials and sub chronic toxicity of these seaweeds are not available in India. Moreover, seaweeds tend to accumulate metal ions and hence data on metal toxicity are also scarce. Hence the need for the present study. 7

8 The Specific Objectives of the present study are: To Evaluate the nutrient content and nutraceutical potentials of the underexploited seaweeds Evaluate the sub-chronic toxicity of the underexploited seaweeds in albino rats Develop and study the acceptability of recipes incorporated with seaweeds Evaluate the nutraceutical potentials of the selected seaweed Ulva fasciata and Develop, characterize nanoparticles and study the anticancer activity of Ulva fasciata 8