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- Evaluation of proximate composition, antioxidant properties, and phylogenetic analysis of two edible seaweedsPublication . Rathinam, Raja; Hemaiswarya, Shanmugam; Sridhar, Sekaran; Alagarsamy, Arun; Ganesan, Venkatesan; Elumalai, Sanniyasi; Carvalho, Isabel S.The present study was evaluated for the proximate composition (moisture, carbohydrate, protein, and lipid contents) of two seaweedsGracilaria corticata(Rhodophyceaen) andHalimeda opuntia(Chlorophycean). Phylogenetic analysis based on the SSU (small subunit) rRNA ascertained their molecular identification. The results showed that the carbohydrate (5.72 +/- 0.05 g/100 g), protein (42.38 +/- 0.08 g/100 g), and total lipids (10.09 +/- 0.06 g/100 g) are elevated inG. corticatawhen compared toH. opuntia. H. opuntiahad a protein content of 3.51 +/- 0.072 g/100 g and higher moisture content (95 +/- 0.45 g/100 g). The methanolic extracts ofG. corticataandH. opuntiawere used to examine the antioxidants (viz. TPC, TFC, DPPH, and FRAP) and antidiabetic (alpha-glucosidase) properties. The antioxidant results of the methanolic extract ofG.corticataexhibited a higher amount of phenolic compounds (13.37 +/- 0.01 mg GAE/g dry wt.) compared toH. opuntia. But in the case of flavonoids,H.opuntiacontained a slightly higher amount of quercetin equivalent 9.56 +/- 0.26 mg/g dry wt. In FRAP,H.opuntiashowed an elevated level (62.02 mg TE/g dry wt). DPPH scavenging activity in the seaweed extracts were recorded in the following order:H.opuntiaandG.corticata. The amino acid content ofH.opuntiawas 0.097 +/- 0.56 (mg/g) and 0.086 +/- 0.42 (mg/g) was recorded inG.corticata. [GRAPHICS.]
- Antioxidant and cytotoxic activities of sulfated polysaccharides from five different edible seaweedsPublication . Arunkumar, K.; Rathinam, Raja; Kumar, V. B. Sameer; Joseph, Ashna; Shilpa, T.; Carvalho, Isabel S.In recent times, there has been a growing interest in the exploration of antioxidants and global trend toward the usage of seaweeds in the food industries. The low molecular weight up to 14 kDa sulfated polysaccharides of seaweeds (Portieria hornemannii, Spyridia hypnoides, Asparagopsis taxiformis, Centroceras clavulatum and Padina pavonica) were evaluated for in vitro antioxidant activities and cytotoxic assay using HeLa cell line and also characterized by FTIR. The high yield (7.74% alga dry wt.) of sulfated polysaccharide was observed in P. hornemannii followed by S. hypnoides (0.69%), C. clavulaum (0.55%) and A. taxiformis (0.17%). In the brown seaweed P. pavonica, the sulfated polysaccharide yield was 2.07%. High amount of sulfate was recorded in the polysaccharide of A. taxiformis followed by C. clavulaum, P. pavonica, S. hypnoides and P. hornemannii as indicative for bioactivity. The FTIR spectroscopic analysis supports the sulfated polysaccharides of S. hypnoides, C. clavulatum and A. taxiformis are similar to agar polymer whereas the spectral characteristics of P. hornemannii have similarities to carrageenan. The higher DPPH activity and reducing power were recorded in the polysaccharide of brown seaweed P. pavonica than the red seaweeds as follows: DPPH activities: S. hypnoides > A. taxiformis > C. clavulatum > P. hornimanii; Reducing power: A. taxiformis > P. hornimanii > S. hypnoides > C. clavulatum. The polysaccharide fractions contain up to 14 kDa from red seaweeds P. hornemannii and S. hypnoides followed by brown seaweed P. pavonica exhibit cytotoxic activity in HeLa cancer cell line (and are similar to structural properties of carrageenan extracted from P. hornemannii). The low molecular weight agar like polymer of S. hypnoides and alginate like brown seaweed P. pavonica showing better in vitro antioxidant activities that are capable of exhibiting cytotoxicity against HeLa cell line can be taken up further in-depth investigation for nutraceutical study.
- Assessment of microbial diversity and enumeration of metal tolerant autochthonous bacteria from tailings of magnesite and bauxite minesPublication . Narayanan, Mathiyazhagan; Devarajan, Natarajan; He, Zhixia; Kandasamy, Sabariswaran; Ashokkumar, Veeramuthu; Rathinam, Raja; Carvalho, Isabel S.The magnesite and bauxite mines are a major source for some minerals and metals. The tailings of these magnesite and bauxite mines contains massive amount of Mn. (3221.2 +/- 6.51 & 7102.8.4 +/- 10.24), Cd (40.95 +/- 2.12 & 892.86 +/- 8.48), Zn (951.08 +/- 4.31 &724.12 +/- 3.18), and Pb (425.8 +/- 5.21 & 812.13 +/- 9.19 mg Kg(-1)) with alkaline and acid pH respectively. In the microbial diversity analysis, the results 8 (Thiobacillus thiooxidans, Leptospirillum ferrooxidans, Acetobacter methanolicus, T. intermedius, Bacillus cereus, Sulfobacillus acidophilus, Methylobacterium sp, and Thiobacillus ferooxidans) and 12 (Serratia marcescens, Metalogenium symbioticum 1, Metallogenium symbioticum 2, Bacillus alcalophilus, Aminobacter sp, Naumaniella neustonica, Staphylococcus aureus 1, Methylbacillus sp, Pandoraea sputorum, Acenetobacter sp, S. aureus 2, Pseudomonas aeruginosa) bacteria species were isolated from bauxite and magnesite mine tailings. The fungus such as Rhizopus arrhizus, Mucor sp, Aspergillus niger and Penicillium sp were obtained in both acid and alkaline environment. Among this microbial diversity, P. sputorum and B. cereus (identified through 16S rDNA sequencing) were shown better resistance to these four metals for up to 250 mg L-1. The bacterial diversity indexes, concludes that there was least diverse among the three sites. The evenness/equitability index also conform lower level of variation among these sites. (C) 2019 Elsevier Ltd. All rights reserved.