Ramasamy Rengasamy

A Perspective on the Biotechnological Potential of Microalgae

Microalgae are the untapped resource with more than 25,000 species of which only 15 are in use. In recent years, microalgal culture technology is a business oriented line owing to their different practical applications. Innovative processes and products have been introduced in microalgal biotechnology to produce vitamins, proteins, cosmetics, and health foods. For most of these applications, the market is still developing and the biotechnological use of microalgae will extend into new areas. With the development of sophisticated culture and screening techniques, microalgal biotechnology can meet the challenging demands of both the food and pharmaceutical industries. Genetic improvement should also play an important role in the future development of algal industries. Based on the preliminary research, several therapeutic benefits have been claimed for commercially produced microalgae including AIDS, cancer, and Cerebro vascular diseases. In near future, algal biomass will serve as a renewable energy source through commercial production of hydrocarbon by Botryococcus throughout the world.

Exploitation of Dunaliella for β-carotene production

Halotolerant microalga Dunaliella, which is exploited for the production of dried biomass or cell extract, is used as a medicinal food. With the advancement in this field in recent years, the production of bio-organic compounds such as β-carotene is established in many countries. Large-scale production of β-carotene is controlled by numerous stress factors like high light intensity, high salinity, temperature and availability of nutrients. The state-of-the-art strategies in industries in closed systems under new set of inductive factors will additionally promote the ease of commercial production of β-carotene. This review mainly focuses on the different methodologies employed recently for the optimum production of β-carotene from Dunaliella species.

Cardioprotective activity of Cladosiphon okamuranus fucoidan against isoproterenol induced myocardial infarction in rats

Fucoidans, sulfated polysaccharides of brown algae, have attracted steady attention in the last few years as readily accessible biopolymers possessing a wide spectrum of biological activities. In this study, cardioprotective activity of fucoidan extracted from Cladosiphon okamuranus was evaluated in isoproterenol induced myocardial infarction in rats. Male Wistar albino rats (180±25 g) were divided in to four groups of six animals each as follows: Group (1) control, Group (2) isoproterenol alone, Group (3) fucoidan alone and Group (4) fucoidan+isoproterenol. To evaluate the efficacy of fucoidan treatment against isoproterenol induced myocardial damage, biochemical parameters and histopathological studies were carried out. Isoproterenol administration produced severe myocardial damage and high lipid peroxidation level. On the contrary, fucoidan treatment reduced myocardial damage, which has been reflected by improvement in parameters such as creatinine phosphokinase (CPK), lactate dehydrogenase (LDH), alanine transaminase (ALT) and aspartate transaminase (AST). In addition, fucoidan improved the antioxidant defence system in treated animals and considerably reduced the oxidative stress exerted by isoproterenol. The reduction in oxidative stress in Group (4) was evident from the lipid peroxidation and antioxidant activities. Furthermore, the increase in the levels of total cholesterol, triglycerides and low density lipoprotein (LDL) and decrease in the levels of high density lipoprotein (HDL) was significantly reversed in Group (4), when compared with Group (2). The histopathological studies also showed that fucoidan treatment significantly minimized the damage induced by isoproterenol. Thus, fucoidan provide cardioprotection against isoproterenol induced myocardial infarction in rats.

Toxicological Evaluation of Fucoidan from Cladosiphon okamuranus

Fucoidans are sulfated polysaccharides extracted from brown seaweeds. They have a wide spectrum of activity in biological systems. Besides their well-known anticoagulant and anti-thrombotic activity, fucoidans modulate inflammation, possess antiproliferative and anti-adhesive effects on cells, protect cells from viral infection, and interfere with mammalian fertilization. Fucoidans are now used as raw material for development of drugs and are also widely used as a health-promoting food component. However, studies on the toxicity of fucoidans from different brown algae are limited. The present study examined the acute toxicity of varying levels of fucoidan extracted from Okinawa mozuku, a brown alga (Cladosiphon okamuranus), in Wistar rats after oral administration. No significant toxicological changes were induced by fucoidan at a dose of 600 mg/kg of body weight/day. However, with concentrations at and above 1,200 mg/kg of body weight/day, clotting time was significantly prolonged. No other signs of toxicity were observed.

Activation of intrinsic apoptotic signaling pathway in cancer cells by Cymbopogon citratus polysaccharide fractions.

Essential oils of Cymbopogon citratus were already reported to have wide ranging medical and industrial applications. However, information on polysaccharides from the plant and their anticancer activities are limited. In the present study, polysaccharides from C. citratus were extracted and fractionated by anion exchange and gel filtration chromatography. Two different polysaccharide fractions such as F1 and F2 were obtained, and these fractions were found to have distinct acidic polysaccharides as characterized by their molecular weight and sugar content. NMR spectral analysis revealed the presence of (1→4) linked b-d-Xylofuranose moiety in these polysaccharides. Using these polysaccharide fractions F1 and F2, anti-inflammatory and anticancer activities were evaluated against cancer cells in vitro and the mechanism of action of the polysaccharides in inducing apoptosis in cancer cells via intrinsic pathway was also proposed. Two different reproductive cancer cells such as Siha and LNCap were employed for in vitro studies on cytotoxicity, induction of apoptosis and apoptotic DNA fragmentation, changes in mitochondrial membrane potential, and profiles of gene and protein expression in response to treatment of cells by the polysaccharide fractions. These polysaccharide fractions exhibited potential cytotoxic and apoptotic effects on carcinoma cells, and they induced apoptosis in these cells through the events of up-regulation of caspase 3, down-regulation of bcl-2 family genes followed by cytochrome c release.

Purification and characterization of a protease produced by Bacillus megaterium RRM2: application in detergent and dehairing industries

An alkaline serine protease produced by Bacillus megaterium RRM2 isolated from the red alga, Kappaphycus alvarezii (Doty) Doty ex Silva was studied for the first time and the same analyzed for the production of protease in the present study. Identification of the bacterium was done on the basis of both biochemical analysis and by 16S rDNA sequence analysis. The extracellular protease obtained from B. megaterium RRM2 was purified by a three‐step process involving ammonium sulphate precipitation, gel filtration (Sephadex G100) and Q‐Sepharose column chromatography. The purity was found to be 30.6‐fold with a specific activity of 3591.5 U/mg protein with a molecular weight of 27 kDa. The metal ions Ca2+, Mg2+, K+ and Na+ marginally enhanced the activity of the purified enzyme while Hg2+, Cu2+, Fe2+, CO2+ and Zn2+, had reduced the activity. The enzyme was found to be active in the pH range of 9.0–10.0 and remained active up to 60 °C. Phenyl Methyl Sulfonyl Fluoride (PMSF) inhibited the enzyme activity, thus, confirming that this enzyme is an alkaline serine protease. Likewise, DTT also inhibited the enzyme thus confirming the disulfide nature of the enzyme. The enzyme exhibited a high degree of tolerance to Sodium Dodecyl Sulphate (SDS). The partially purified protease when used as an additive in the commercial detergents was found to be a suitable source for washing clothes especially those stained with blood. Further, it showed good dehairing activity within a short duration in goat skin without affecting its collagen component. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Evaluation of Antibacterial Potential of Seaweeds Occurring along the Coast of Tamil Nadu, India against the Plant Pathogenic Bacterium Xanthomonas oryzae pv. oryzae (Ishiyama) Dye

Abstract Eleven seaweeds were collected from seven different sites—one from the backwaters of Muttukadu, Chennai and six regions along the coast, Tamil Nadu, India and tested for antibacterial activity against the plant pathogenic bacterium, Xanthomonas oryzae pv. oryzae. Unsaponified fractions of red and green seaweeds exhibited maximum antibacterial activity followed by petroleum ether extracts, lipophilic fractions, diethyl ether extracts, saponified fractions, chloroform extracts and methanol extracts. However, methanol extracts of brown seaweeds showed the highest antibacterial activity followed by lipophilic fractions, unsaponified fractions, ethanol extracts, saponified fractions, chloroform:methanol (2:1 v/v) extracts and chloroform extracts. The antibacterial potential of the seaweeds was in the following order: Enteromorpha flexuosa > Sargassum wightii > Turbinaria conoides > Padina boergesenii > Gracilaria edulis > G. blodgettii > Hypnea valentiae ≥H. musciformis > Spyridia insignis > Chnoospora minima > Ulva lactuca. Seaweeds collected from the backwaters of Muttukadu possessed higher antibacterial potential than the same species collected from coastal waters. Significant seasonal differences in antibacterial activity of seaweeds were found in specimens collected at seven different localities.

Seasonal studies on the alginate and its biochemical composition I : Sargassum polycystum (Fucales), Phaeophyceae

Investigations were made on the brown seaweed Sargassum polycystum C. Agardh collected from Rameswaram Coast, Tamil Nadu. The alginates extracted from ‘leaf’, ‘stem’ and entire thallus of S. polycystum were investigated for their viscosity and chemical constituents, namely β‐D‐mannuronic acid (M‐block), α‐L‐guluronic acid (G‐block) and alternating sequences of β‐D‐mannuronic acid and α‐L‐guluronic acid (MG‐block) for six different seasons between August 1998 and November 1999. Significant seasonal variation (P< 0.05) was observed with high yield of alginate in February. The alginate extracted from the ‘leaf’ region showed a maximum yield whereas the ‘stem’ region exhibited maximum viscosity. The amount of G‐block was found to be more than M‐ and MG‐blocks in all the samples tested. The amount of G‐block was high in ‘stem’ followed by leaf and entire thallus. A positive correlation was recorded between viscosity and G‐block. Among the three alginates, the ratio of M/G was low in the ‘stem’ followed by ‘leaf’ and entire thallus.

Stabilization of mitochondrial and microsomal function of fucoidan from Sargassum plagiophyllum in diethylnitrosamine induced hepatocarcinogenesis

Crude fucoidan from Sargassum plagiophyllum extracted from blade and purified by Q-Sepharose fast flow anion-exchange chromatography and three fucoidan fractions were obtained. Maximum sulphate containing fucoidan fraction was considered as purified fucoidan and purity was checked with agarose gel electrophoresis. The monosaccharides of purified fucoidan analysed by HPLC revealed the presence of the sugars such as fucose as a major sugar were 70.8 mol%. The percentages of other sugars were galactose (13.5%), xylose (2.5%) and mannose (11.2%). GPC was used to analyse molecular weight of purified fucoidan and it was found to be 35 kDa. The levels of ICDH, SDH, MDH, a-KGDH, Phase-I biotransformation enzymes, and Phase-II biotransformation enzymes were decreased in cancer bearing animals which may be due to oxidative stress and mitochondrial damage and fucoidan restored these enzyme activities. The inhibition of carcinogen metabolic activation indicates the anticancer activity of fucoidan in DEN induced liver cancer.

Seasonal studies on alginate and its composition II: Turbinaria conoides (J.Ag.) Kütz. (Fucales, Phaeophyceae)

The alginates extracted from ‘leaf’, ‘stem’ and entire thallus of Turbinaria conoides (J.Ag.) Kütz. were investigated for their viscosity and biochemical constituents namely, β-D-mannuronic acid (M-block}), α-L-guluronic acid (G-Block) and alternating sequences of β–D-mannuronic acid and α-L-guluronic acid (MG-block). Substantial seasonal variation was recorded with high yield of alginate during premonsoon. The yield of alginate was maximum in ‘leaf’ region. In contrast to this, viscosity and G-block were maximum in the ‘stem’ region. A significant positive correlation was observed between viscosity and G-block}. The ratio of guluronic: mannuronic acid was also assessed. Low levels of M/G ratio were recorded in the ‘stem’ region followed by ‘leaf’ and entire thallus.