Perumal Anantharaman

Biosynthesis of antibacterial gold nanoparticles using brown alga, Stoechospermum marginatum (kützing)

Biological synthesis of gold nanoparticles by brown alga, Stoechospermum marginatum biomasses through a green route was reported in this study. The formation of the gold nanoparticles was observed within 10 min. The properties of prepared nanoparticles were characterized by photoluminescence spectra, Fourier Transform Infrared Spectroscopy, scanning electron microscopy, Transmission Electron Microscopy, X-ray diffraction, particle size analysis and quantified by Wavelength Dispersive X-ray Fluorescence Spectrophotometer. The synthesized gold nanoparticles were found to be photoluminescent. The formation of gold nanoparticles was confirmed by the presence of an absorption peak at 550 nm using UV-visible spectrophotometer. TEM image revealed that most of the particles are spherical in shape and some are hexagonal and triangle with size ranged from 18.7 to 93.7 nm. The nanoparticles were crystalline in nature and it was confirmed by XRD pattern and the presence of elemental gold (45.92%) was confirmed by WD-XRF. From the FTIR measurements it is noticed that the reduction has been carried out by hydroxyl groups present in the diterpenoids of the brown seaweed. Furthermore the biologically synthesized gold nanoparticles were found to be effective against bacterial pathogens.

In vitro antioxidant activities of selected seaweeds from Southeast coast of India

OBJECTIVE In vitro antioxidant activities of three selected Indian seaweeds viz., Halimeda tuna (H. tuna), Turbinaria conoides (T. conoides) and Gracilaria foliifera (G. foliifera) were evaluated. METHODS Total antioxidant activity, total phenolic content, and reducing power of crude methanol and diethyl ether extracts were determined. RESULTS Total phenolic content and total antioxidant activity were higher (1.231±0.173 mg GAE/g, 1.675± 0.361 mg GAE/g) in T. conoides respectively. Reducing power of crude methanol extract increased with concentrations of the extract. The Fourier transform-infra red spectrum analysis revealed the presence of polyphenolic signals. The seaweed extracts displayed moderate antioxidant activity compared to gallic acid standard. CONCLUSIONS The seaweeds could be considered for curing diseases from oxidative deteriorations.

Antimicrobial potential of selected brown seaweeds from Vedalai coastal waters, Gulf of Mannar

OBJECTIVE To evaluate the antimicrobial activity of Turbinaria conoides (T. conoides), Padina gymnospora (P. gymnospora) and Sargassum tenerrimum against human bacterial and fungal pathogens. METHODS The antimicrobial activities of the extracts against various organisms were tested by using disc diffusion method. RESULTS The methanol extract showed the better result than the other extracts. Whereas, the strong antibacterial inhibition was noted in methanol extracts of P. gymnospora against Bacillus subtilus (26.33±1.86) and the mild inhibition of ethanol extracts from T. conoides against Klebsiella pneumoniae (2.33±0.51). Acetone extraction of P. gymnospora had strong antifungal inhibition against Cryptococcus neoformans (23.00±1.78), and acetone extract of T. conoides had mild inhibition against Aspergillus niger (3.00±0.89). CONCLUSIONS The seven different solvent extracts of seaweeds used in the present study have shown significant bacterial action. Further, a detailed study on the principle compound in the seaweeds which is responsible for antimicrobial activity is still needed and it can be achieved by using advanced separation techniques.

In vitro antioxidant activities of ethanol extract from Enhalus acoroides (L.F.) Royle

Objective: To search for new sources of safe and inexpensive antioxidants, the leaf, root and rhizome of Enhalus acoroides (E. acoroides) were screened for the first time for their antioxidant activities. Methods: Samples of leaf, root and rhizome from E. acoroides were tested for total phenolic content, proanthocyanidins and in vitro antioxidant activity in terms of total antioxidant assay, DPPH assay and FRAP assay. Results: The leaf sample was found to have high levels of phenolic (0.323±0.028 mg TAE/g) and proanthocyanidins (0.5700±0.0003 mg TAE/g) when compared to root and rhizome. The leaf samples exhibited higher total antioxidant activity (11.770±0.026 mg Ascorbic acid equivalent/g), higher percentage of DPPH radical scavenging activity (25.76±0.04) and higher reducing power (18.060±0.073) in terms of mg GAE/g. In addition, there was a significant correlation between total phenolic content and total antioxidant activity (R^2=0.923), DPPH assay (R^2=0.509), FRAP assay (R^2=0.994). Similarly, significant correlation was found between the proanthocyanidin and total antioxidant activity (R^2=0.977), DPPH assay (R^2=0.464) and the FRAP assay (R^2=0.998). Conclusions: These results suggested that E. acoroides have strong antioxidant potential. Further study is necessary for isolation and characterization of the active antioxidant agents, which can be used to treat various oxidative stress-related diseases.

Antibacterial potential of three seagrasses against human pathogens

Objective: To evaluate the antibacterial activity of Halophila stipulacea (H. stipulacea), Cymodocea serrulata (C. serrulata) and Halodule pinfolia (H. pinifolia) against seven human bacterial pathogens. Methods: The antibacterial activities of the extracts on the various test organisms using disc diffusion method and Minimum Inhibitory Concentraction (MIC). Results: Methanol and chloroform extracts of all the three seagrasses were active against all the tested pathogens, whereas the hexane extract of seagrasses was not active against Staphylococcus aureus (S. aureus). Antibacterial activity of three seagrass screened, was in the order of H. pinfolia ＞ H. stipulacea ＞ C. serrulata. Conclusions: This antibacterial studies can further investigated on seagrasses for purification of bioactive substance and its possible utility in disease control.

Antifouling and toxic properties of the bioactive metabolites from the seagrasses Syringodium isoetifolium and Cymodocea serrulata

The present study documents the antifouling and toxic properties of seagrasses Syringodium isoetifolium and Cymodocea serrulata. For that, the seagrasses S. isoetifolium and C. serrulata were extracted individually using organic solvents viz. dichloromethane, acetone and methanol. Amongst the extracts, the maximum antimicrofouling and antimacrofouling activities were exhibited by methanol extracts of both the seagrasses. The Minimal Inhibitory Concentration (MIC) of methanolic extracts of seagrasses was ranged from 1.0 to 10µg/ml against test biofilm bacteria and microalgal strains. Similarly, 100% fouling inhibition of limpet Patella vulgata was found at 6.0mg/ml of methanolic extracts of seagrasses. The mussel Perna indica showed 50% of byssal production and attachment inhibition at 21.51±2.03, 17.82±1.07µg/ml and the anticrustaecean activity for 50% mortality of Artemia salina was recorded at 732.14±9.21 and 394.16±5.16µg/ml respectively for methanolic extracts of S. isoetifolium and C. serrulata. The minimal inhibitory and higher lethal concentrations of active methanol extracts shows it׳s less toxic nature. Based on the prolific results, methanol extracts of S. isoetifolium and C. serrulata were subjected to purification using silica gel column and thin layer chromatography. Then the active compounds of the bioassay guided fractions were partially characterized using gas chromatography coupled with mass spectroscopy (GC-MS) and keyed out that fatty acids (C16 to C24) were the major components which responsible for the antifouling properties of the candidate seagrasses.

Chemical composition and antibacterial activity of Indian seagrasses against urinary tract pathogens.

Seagrasses have a long history of being used for a variety of remedial purposes, such as the fever, skin diseases, muscle pains, wounds and stomach problems. Hence it is essential to study their bioactive metabolites and medicinal properties when considering their food applications. The chemical composition of six seagrasses were determined and evaluated for their potential to urinary tract infection bacteria (UTI). The chemical composition determined by GC-MS yielded 24 compounds. For the first time 4H-Pyran-4-one-2,3-dihydro-3,5-dihydroxy-6-methyl- (6.68%), d-allose (3.67%) and 5-Caranol, trans,trans-(+)- (2.14%) were identified from Halodule pinifolia. d-Allose is a aldo-hexose (sugar) used as a potential inhibitor of glycosidases and low-calorie carbohydrate sweeteners. Among the six seagrasses tested, H. pinifolia and Cymodocea rotundata exhibited predominant growth inhibitory activity against all the UTI bacteria. This study shows the presence of various biological metabolites in tested seagrasses that can be used effectively in food and pharmacological industries.

In vitro antibacterial, cytotoxicity and haemolytic activities and phytochemical analysis of seagrasses from the Gulf of Mannar, South India.

It is essential to study the phytochemical constituents and toxicological properties of seagrasses when considering their food applications. Aqueous methanolic extracts of six seagrasses were evaluated for their antibacterial, cytotoxic (brine shrimp leathality assay) and haemolytic activity. Thin layer chromatography (TLC) and phytochemical analysis were used to compare the phytochemical profiles of six seagrasses. Among the six seagrasses examined, Halodule pinifolia and Cymodocea rotundata showed predominant growth inhibitory activity against all the tested human pathogens. Cytotoxicity of seagrass extracts against nauplii of Artemia salina revealed that Syringodium isoetifolium exhibited lesser toxicity with LC(50) value of 699.096 μg/ml. Of all the seagrasses tested, H. pinifolia recorded the minimum haemolytic activity of 2.07±0.63% at 1000 μg/ml concentration. Phytochemical analysis showed the presence of common plant chemical constituents which varied with respect to species. The present findings suggest the possible pharmacological applications of selected seagrasses that can be used as food ingredients.

Hepatoprotective activity of brown alga Padina boergesenii against CCl4 induced oxidative damage in Wistar rats

Abstract Objective To investigate the protective effects of brown alga Padina boergesenii ( P. boergeseii ) against carbon tetrachloride (CCl 4) induced oxidative damage and liver fibrosis in rats. Methods To assess the hepatic damage liver weight, the activities of TBARS level, glutathione, SOD, CAT and GP x in circulation and liver. Results The group of rats induced with CCl 4 alone (2 mL/kg body weight), showed noticeable increase in the liver weight and TBARS level. Followed by, the level of antioxidant enzymes glutathione peroxidase, Superoxide dismutase and catalase was also significantly (P P. boergesenii (150 mg/kg body weight) modulated the CCl 4 induced liver fibrosis. The level of antioxidant enzymes and lipid peroxidation products was found to be significantly (P P. boergesenii. Conclusions The protective role of brown alga P. boergesenii extract has confirmed its potential activity through its antioxidant sparing actions against CCl 4 i nduced free radical damage. However, the possible mechanism of hepatoprotection is rather speculative at this stage and investigations are underway to isolate and characterize the bioactive compounds from P. boergesenii .

Phytofabrication of gold nanoparticles assisted by leaves of Suaeda monoica and its free radical scavenging property.

Development of biologically inspired experimental processes for the synthesis of nanoparticles is evolving into an important branch of nanotechnology. An eco-friendly synthesis of inorganic nanoparticle is a fast growing research in the limb of nanotechnology. In the present study, it is reported that Suaeda monoica leaf mediated synthesis of gold nanoparticles by the reduction of gold ions. The formation of gold nanoparticle was confirmed by color changes from turbid brown to deep purple violet color and a characteristic peak at 535 nm. The morphology and structure of synthesized gold nanoparticles were characterized on Scanning Electron Microscopy (SEM) equipped with a Thermo EDAX attachment, Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), (FT-IR), Dynamic Light Scattering (DLS) which reveals that the Au nanoparticles are spherical and the average particle size is 12.96 nm. Crystalline nature of the nanoparticles is confirmed from the XRD pattern. FTIR spectrum indicates that the biomolecules of carboxyl, amine and hydroxyl functional groups involved in the reduction of gold nanoparticles. The biosynthesized gold nanoparticles displayed considerable antioxidant capacity.