Graphene‐based nanomaterials are gaining importance in biomedicine because of their large surface areas, solubility, and biocompatibility. Green synthesis is the most economical method for application, as it is rapid and sustainable. Biofunctionalized reduced graphene oxide (TrGO) nanosheets were synthesized using methanol extract of Turbinaria ornata , and bioreduction of graphene oxide was primarily confirmed and characterized using UV‐visible, Fourier transform infrared (FTIR), and X‐ray diffraction spectroscopy and further characterized by zeta potential and transmission electron microscopy. The FTIR spectra of TrGO showed a decrease in the band intensities of oxygen groups, thus confirming effective deoxygenation. The zeta potential value of −34.6 mV revealed that synthesized TrGO was highly stable. The cytotoxic effect of TrGO against MCF‐10A and MCF‐7 cells was ascertained using MTT assay, showed a greater cytotoxic effect on MCF‐7 cells. The IC ₅₀ of TrGO treatment against MCF‐7 was calculated to be 31.25 µg, which is onefold lower than the cytotoxic effect of methanolic extract of T. ornata (60.0 ± 1.14 µg/ml). In addition, there was a statistically significant difference in cell viability between MCF‐10A and MCF‐7 cells in the treatment of TrGO. Hence, this study results in an efficient green reductant for producing rGO nanosheets that possess cytotoxicity against breast cancer cells.

Haloarchaea from high saline habitats are known to contain industrially important value-added bioactive compounds such as bacteriorhodopsin, carotenoids, lipids, and proteins. The diversity of Haloarchaea from geographically less explored saline habitats has received less attention. In this study isolation and characterization of the biotechnological potential of novel haloarchaea strains from solar saltern, a hypersaline environment in Marakanam, Tamilnadu was carried out. The samples were collected during the pre-monsoon (July) and post-monsoon (January) season and ten different haloarchaea strains were isolated. UV-Vis spectroscopy analysis revealed the bacteriorhodopsin production by all the isolated strains. Further experiments were carried out to estimate the yield of bacteriorhodopsin and to assess their photocurrent activity and biosensor applications. The maximum yield of bacteriorhodopsin was 5.6 mg/L of cultured lysate. This study will contribute to a better understanding on effect of elicitors on bacteriorhodopsin producing different haloarchaea strains and growing knowledge on their biotechnological applications.

The present study was carried out to compare and correlate the phenolic and flavonoid contents of Turbinaria sp., Sargassum sp. and Gracilaria sp. extracted using different solvents including methanol, isopropyl alcohol, acetone, acetonitrile, ethyl acetate and hexane, and elucidated for their anti-oxidant activity. The total phenolic and flavonoid contents of the solvent extracts were determined using the Folin-Ciocalteau assay and aluminium chloride colorimetric assay with gallic acid and quercetin as standards, respectively. The anti-oxidant activity in phenolic and flavonoid content was also estimated by phosphomolybdenum method and was compared with gallic acid and quercetin standard. The quantitative analysis of flavonoid content reveals that methanolic extract of Sargassum sp. (9.56±0.38 mg QE/g during pre-monsoon and 9.44±0.48 mg QE/g during post-monsoon season); acetone extract of Gracilaria sp. (2.16±0.11 mg QE/g during pre-monsoon and 2.12±0.07 mg QE/g during post-monsoon season) and methanolic extract of Turbinaria sp. (4.11±0.12 mg QE/g during pre-monsoon and 4.22±0.15 mg QE/g during post-monsoon season) had higher concentration of flavonoid content. However, the quantitative analysis of phenolic content was found to be lower in all the seaweed extracts as compared to flavonoids. The anti-oxidant activity of a phenolic content and flavonoid content were also found to be correlated. The findings of the current study conclusively demonstrate the content of phenolic and flavonoid compounds significantly correlate with anti-oxidant activity.