Thiagarajan Kalaivani

Free radical scavenging activity from leaves of Acacia nilotica (L.) Wild. ex Delile, an Indian medicinal tree.

The present study compares the two extraction methods and evaluates the free radical scavenging activity of Acacia nilotica. Results indicated that the sequential extraction method was effective in concentrating the active principles in the ethanol extract as compared to the maceration method in DPPH assay. Based on the results, free radical scavenging property of the extracts obtained from sequential extraction method was analyzed in different assays to find out the possible antioxidant mechanism. Our results indicate that ethanol extract rich in phenolic and flavonoid contents had potent antioxidant activity and were significant in comparison with all the positive controls used in this study. The possible antioxidant mechanism of the ethanol extract can be due to its hydrogen or electron donating and direct free radical scavenging properties. Hence, the ethanol extract represents a source of potential antioxidants that could be used in pharmaceutical and food preparations.

Free Radical Scavenging, Cytotoxic and Hemolytic Activities from Leaves of Acacia nilotica (L.) Wild. ex. Delile subsp. indica (Benth.) Brenan

Dietary intake of phytochemicals having antioxidant activity is associated with a lower risk of mortality from many diseases. Therefore, the aim of this study was to determine the free radical scavenging, cytotoxic and hemolytic activities of leaves of Acacia nilotica by using various methods. The results of the present study revealed that ethanol extract was the most effective and IC50 value was found to be 53.6 μg mL−1 for Vero cell lines and 28.9 μg mL−1 for Hela cell lines in cytotoxicity assays. The zone of color retention was 14.2 mm in β-carotene bleaching assay, which was as significant as positive control, butylated hydroxy toluene. None of the tested extracts possessed any hemolytic activity against rat and human erythrocytes revealing their cytotoxic mechanism and non-toxicity. Thus, only the ethanol extract could be considered as a potential source of anticancer and antioxidant compounds. Further phytochemical studies will be performed for specification of the biologically active principles.

Free Radical Scavenging, Cytotoxic, and Hemolytic Activities of an Active Antioxidant Compound Ethyl Gallate from Leaves of Acacia Nilotica (L.) Wild. Ex. Delile Subsp. Indica (Benth.) Brenan

UNLABELLED In the present study, free radical scavenging, cytotoxic, and hemolytic activities of the polyphenolic compound ethyl gallate isolated from ethanol extract of Acacia nilotica Wild. Ex. Del. leaves were determined. The free radical-scavenging activities of the ethyl gallate were demonstrated in several in vitro assays in order to evaluate the possible antioxidant mechanism. The results revealed ethyl gallate as hydrogen donor, metal chelator, and free radical scavenger. Ethyl gallate was effective in scavenging 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radicals and the IC₅₀ value was lower than all the positive controls used in this study. Deoxyribose degradation assay revealed that ethyl gallate had more iron-chelating ability than the direct hydroxyl radical-scavenging ability. The results of the cytotoxic study revealed that the compound was moderately active and IC₅₀ value was found to be >100 μg/mL for Vero cell lines and 72 μg/mL for Hela cell lines. The compound possessed no hemolytic activity against rat and human erythrocytes revealing its cytotoxic mechanism and nontoxicity. The results from this work will provide an important information for the food and pharmacological industries with respect to the use of the compound as an antioxidant and a health-related drug. PRACTICAL APPLICATION Antioxidant from plant sources is safe to use, as compared to synthetic products. It also can be used as a supplement to alleviate most of the diseases because of its free radical-scavenging activity.

Characterization of sorption sites and differential stress response of microalgae isolates against tannery effluents from ranipet industrial area—An application towards phycoremediation

ABSTRACT Phycoremediation ability of microalgae namely Oscillatoria acuminate and Phormidium irrigum were validated against the heavy metals from tannery effluent of Ranipet industrial area. The microalgae species were cultured in media containing tannery effluent in two different volumes and the parameters like specific growth rate, protein content and antioxidant enzyme activities were estimated. FTIR spectroscopy was carried out to know the sorption sites interaction. The antioxidant enzymes namely superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) contents were increased in microalgae species indicating the free radical scavenging mechanism under heavy metal stress. SOD activity was 0.502 and 0.378 units/gram fresh weight, CAT activity was 1.36 and 0.256 units/gram fresh weight, GSH activity was 1.286 and 1.232 units/gram fresh weight respectively in the effluent treated microalgae species. Bio sorption efficiency for Oscillatoria acuminate and Phormidium irrigum was 90% and 80% respectively. FTIR analysis revealed the interaction of microalgae species with chemical groups present in the tannery effluent. From the results, the microalgae Oscillatoria acuminate possess high antioxidant activity and bio sorption efficiency when compared to Phormidium irrigum and hence considered useful in treating heavy metals contaminated effluents.

Sorption sites of microalgae possess metal binding ability towards Cr(VI) from tannery effluents—a kinetic and characterization study

AbstractProminent microalgal species, namely Anabaena, Oscillatoria, Phormidium, and Spirogyra, were isolated from estuaries polluted with tannery effluents and studied to determine their Cr(VI) bio-sorption potential. The bio-sorption potential was determined by studying the effect of growth, biomass, reduction of Cr(VI) levels, and Cr(VI) absorption by the microalgal species. The respective values for Anabaena, Oscillatora, Phormidium, and Spirogyra compared with the control were as follows: growth in BG 11 medium containing tannery effluent was 53.99, 60.03, 55.76, and 55.85%; the biomass was 60.65, 77.61, 67.16, and 76.01%; the Cr(VI) reduction potential was 70.96, 80.64, 76.12, and 74.83%; and the bio-sorption potential was 75.48, 80.64, 79.35, and 77.41%. The removal of heavy metals by microalgal biomass involves bio-reduction and bio-sorption. Fourier-transform infrared spectroscopy and nuclear magnetic resonance results revealed the presence of microalgal sorption sites. All four species showed ma...