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Antioxidant activities of both cells and extracellular substances were evaluated in 12 soil-isolated strains of microalgae according to FRAP and DPPH-HPLC assays. Their total phenolic contents were also determined by Folin-Ciocalteu method. Extractions were performed with hexane, ethyl acetate, and water. The results of FRAP assay showed that algal cells contained considerable amounts of antioxidants from 0.56 ± 0.06 to 31.06 ± 4.00 µmol Trolox g −1 for Microchaete tenera hexane extract and Chlorella vulgaris water extract, respectively. In water fractions of extracellular substances, the antioxidants were from 1.30±0.15 µmol Trolox g −1 for Fischerella musicola to 73.20±0.16 µmol Trolox g −1 for Fischerella ambigua. Also, DPPH-HPLC assay represented high antioxidant potential of water fractions. The measured radicalscavenging activities of the studied microalgae were at least 0.15±0.02 in Nostoc ellipsosporum cell mass to a maximum of 109.02±8.25 in C. vulgaris extracellular substance. The amount of total phenolic contents varied in different strains of microalgae and ranged from zero in hexane extract to 19.15±0.04 mg GAE g −1 in C. vulgaris extracellular water fraction. Significant correlation coefficients between two measured parameters indicated that phenolic compounds were a major contributor to the microalgal antioxidant capacities.

Laccase, a blue multicopper oxidase, has recently received considerable attention because of its usefulness in oxidizing phenolic and non‐phenolic compounds, as well as its suitability for organic synthesis, environmental pollutant treatment, and other biotechnological applications. This review covers recent studies on the structural properties, occurrence, reaction mechnisms, redox mediators of laccases and their application in organic synthesis procedures, such as dimerization, polymerization, oxidation, and amination. We also present a brief discussion on laccase activity in non‐aqueous media. Given that the development of green protocols for the synthesis of pure compounds is one of the main goals of sustainable chemistry, the exploitation of laccases is expected to remain one of the most popular directions in future biocatalysis research.magnified image

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Today, green synthesis of nanoparticles is attracting increasing attention. In the present study, the Bacillus sp. MSh-1 was isolated from the Caspian Sea (located in the northern part of Iran) and identified by various identification tests and 16S ribosomal DNA analysis. The reduction time course study of selenium ion (Se(4+)) reduction by using this test strain was performed in a liquid culture broth. Then, the intracellular NPs (nanoparticles) were released by the liquid nitrogen disruption method and thoroughly purified using an n-octyl alcohol water extraction system. Characterization of the separated NPs on features such as particle shape, size and purity was carried out with different devices. The energy dispersive X-ray and X-ray diffraction patterns showed that the purified NPs consisted of only selenium and are amorphous respectively. In addition, the transmission electron micrograph showed that the separated NPs were spherical and 80-220 nm in size. Furthermore, the cytotoxicity effect of these extracted biogenic selenium (Se) NPs on the fibrosarcoma cell line (HT-1080) proliferation and the inhibitory effect of the Se NPs on MMP-2 (matrix metalloproteinase-2) expression were studied using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide] assay and gelatin zymography. Biogenic Se NPs showed a moderately inhibitory effect on MMP-2 expression.

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