Abstract Biosynthesis of titanium dioxide nanoparticles (TiO2NPs) by Sphingomonas paucimobilis B34 bacteria was successfully achieved and followed by UV-Vis spectroscopy. The nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and fourier transform infrared spectroscopy (FTIR) techniques. The biosynthesized TiO2NPs were spherical in shape with an average particle size of 15.6 nm. These TiO2NPs were used as nono-catalyst for removing of malachite green (MG) dye (at 103 mol/L) from wastewater solution. As indicated by the results, the biosynthesized TiO2NPs represented a capable approach for MG removal with up to 83 % efficiency. The removal process was found to follow a pseudo-first-order kinetics. Furthermore, the developed TiO2NPs-MG hybrid nanocomposite was efficiently removed from the medium by using Spirulina platensis cyanobacterial biomass after wastewater treatment. S. platensis biomass was able to remove up to 89.43 % of the hybrid nanocomposite by a biosorption process. The resultant water effluent, after TiO2NPs-MG removal, showed no toxicity towards Vigna radiate L. seedlings implying its safety for agriculture purposes. According to the obtained results, S. platensis living biomass could play a dual re-cycling role, as natural biosorbent for removing both nanoparticles and dye (TiO2NPs-MG hybrid nano-composite) from solution after wastewater treatment for healthier environmental management.

Abstract In this study crude extracts of Turbinaria decurrens, Padina pavonica, Sargassum muticum and Sargassum acinarium (Phaeophyta); Ulva lactuca (Chlorophyta) and Pterocladia capillacea (Rhodophyta) seaweeds were tested to evaluate their antioxidant properties and antidiabetic potential on α-amylase and α-glucosidase starch hydrolyzing enzymes. The results showed that all analyzed seaweeds exhibited antioxidant effects using DPPH (2,2-Diphenyl-1-picrylhydrazyl), reducing power and total antioxidant capacity assays in addition to antidiabetic activity that all depended on the species and the extract solvent. Among the tested extracts, acetone extract of Turbinaria decurrens showed the highest antioxidant activity and inhibitory effects for α-amylase (96.1%) and α-glucosidase (97.4%), respectively which was related with its total phenolic content and antioxidant activity. In vitro, the extract showed no toxicity against fibroblast normal cell lines at lower concentration of 250 µg/ml. Gas Chromatography-Mass Spectrum analysis (GC-MS) of this acetone extract showed the presence of different bioactive compounds mainly cyclotrisiloxane, hexamethyl which could be responsible for its antioxidant and antidiabetic activities. The study results suggest that brown seaweeds especially T. decurrens can be used as antioxidant ingredients and as potent reducing drug for postprandial hyperglycemia.

Abstract The present study investigated the biochemical composition of three seaweeds; Ulva fasciata (Chlorophyta), Sargassum linifolium (Phaeophyta) and Corallina officinalis (Rhodophyta). Total chlorophyll content was maximum in U. fasciata (34.06mg/g dry wt.) while carotenoid content was the highest in C. officinalis (3.8 mg/g dry wt.). The uppermost level of carbohydrates was (27.98% of dry wt.) in C. officinalis and proteins were maximum (14.89%) in S. linifolium. Aspartic, glutamic, alanine, leucine and proline were common amino acids in the three tested species. The polyunsaturated ω6 and ω3 essential fatty acids were recorded in S. linifolium (3.28%) and in U. fasciata (3.18%). The results showed that U. fasciata contained the highest amounts of lipids (2.96%), phenols (11.95mgGA/g dry wt.), flavonoid (7.04 mgCA/g dry wt.) and ascorbic acid (4.11mg/100g), respectively. β-Carotene was maximum (3940.12 IU/100 g) in C. officinalis. DPPH antioxidant activities were the highest in U. fasciata (81.3%) followed by S. linifolium (79.8%) then C. officinalis (72.6%). Among the 12 analyzed minerals, most of them were high in S. linifolium in which ion quotient ratio was the smallest (0.343). Since these algal species are common in the Egyptian coastal waters, their biochemical composition and antioxidant activities made them promising candidates for nutritional, pharmaceutical and medicinal applications.