Ulvan dialdehyde-gelatin hydrogels for removal of heavy metals and methylene blue from aqueous solution.

Hydrogels based on the polysaccharide ulvan from the green macroalgae Ulva fenestrata were synthesized and evaluated as an adsorbent for heavy metals ions and methylene blue. Ulvan was extracted from Ulva fenestrata using diluted hydrochloric acid and recovered by precipitation with EtOH. The extracted ulvan was converted into ulvan dialdehyde via periodate-oxidation and subsequently combined with gelatin yielding hydrogels. The hydrogels showed good water-uptake capacity with a maximum swelling degree of 2400 % in water and 900 % in PBS buffer. Adsorption tests of methylene blue showed a maximum adsorption capacity of 465 mg/g. The adsorption data of methylene blue followed the pseudo-second order kinetics and agreed with the Langmuir adsorption isotherm. The maximum adsorption capacity of heavy metal ions was 14 mg/g for Cu2+, 7 mg/g for Co2+and 6 mg/g for Ni2+and Zn2+ indicating that the hydrogels have a stronger affinity for Cu2+ than for Co2+, Ni2+, and Zn2+.

Composition and structure of cell wall ulvans recovered from Ulva spp. along the Swedish west coast.

The cell wall polysaccharide ulvan was isolated from two species of the seaweed Ulva collected along the Swedish west coast. Acidic extraction was benchmarked against hot water extraction with enzymatic purification and against commercial ulvan. Extracted ulvan contained 11-18 % g/g of ash, some protein (up to 1.3 % g N/g) but minimal colored impurities. The ulvans had high molecular weights (660,000-760,000 g/mol) and were composed of 77-79 % g/g carbohydrates, mainly rhamnose, xylose, glucose, glucuronic acid, and iduronic acid. The extraction protocol and the ulvan source strongly impact the molecular weight and the chemical composition. Acidic extraction caused almost complete desulfation of the isolated ulvan while the other method preserved a significant degree of SO3 substituents. Elemental analysis of ash remaining after thermal degradation showed presence of common mineral elements such as Na, Ca, Mg, Al, and K, but none of the heavy metals Pb, Hg, or As.

Chemistry and Properties of Indolocarbazoles.

The indolocarbazoles are an important class of nitrogen heterocycles which has evolved significantly in recent years, with numerous studies focusing on their diverse biological effects, or targeting new materials with potential applications in organic electronics. This review aims at providing a broad survey of the chemistry and properties of indolocarbazoles from an interdisciplinary point of view, with particular emphasis on practical synthetic aspects, as well as certain topics which have not been previously accounted for in detail, such as the occurrence, formation, biological activities, and metabolism of indolo[3,2- b]carbazoles. The literature of the past decade forms the basis of the text, which is further supplemented with older key references.

Synthetic applications of cyanoacetylated bisindoles: synthesis of novel cycloheptadiindoles, indolocarbazoles, and related aza analogues.

Cyclization reactions involving cyanoacetylated bisindoles have been studied, providing access to various novel cyclohepta[2,1-b:3,4-b']diindole derivatives as well as some related fused pentacyclic systems. Treatment of 3-cyanoacetyl-2,3'-diindolylmethane with methanesulfonic acid gave 6-(cyanomethyl)indolo[3,2-b]carbazole in a good yield.

Characterization of in vitro metabolites of the aryl hydrocarbon receptor ligand 6-formylindolo[3,2-b]carbazole by liquid chromatography-mass spectrometry and NMR.

The tryptophan photoproduct 6-formylindolo[3,2-b]carbazole (FICZ) exhibits the highest aryl hydrocarbon receptor (AhR) binding affinity reported so far. In different cells, in vitro, both extracts of UV-irradiated tryptophan and the synthesized pure compound FICZ induce a rapid and transient expression of AhR-regulated genes. The transient induction suggests that the biotransformation gene battery induced by AhR activation takes part in a metabolic degradation of the ligand, whereby a low steady-state level is regained. The down-regulation of AhR-regulated gene expression was previously shown to be dependent on cytochrome P450 1A1 (CYP1A1). Metabolism of FICZ generates five major metabolites, which appeared as three peaks (M1-M3) in the high performance liquid chromatography. The aim of the present study was to use rat liver S9 from Aroclor-pretreated rats to produce large enough quantities of FICZ metabolites for structure characterization and to determine their product precursor relationship. NMR analysis of large combined fractions of the metabolites indicated that M3 and M2 contained 2 isomers, respectively. By means of liquid chromatography-mass spectrometry (negative ion electrospray mode) and NMR spectroscopy (by (1)H-NMR, correlation spectroscopy, and nuclear Overhauser effect spectroscopy techniques) five metabolites of FICZ were identified, and their structures were elucidated. The molecular weights of the two M3 isomers were 300 and both M2 and M1 compounds demonstrated molecular weights of 316, corresponding to addition of one (M3) and of two oxygen (M2 and M1), respectively. The structures were assigned as 2- and 8-hydroxy (M3), 2,10- and 4,8-dihydroxy (M2) and 2,8-dihydroxy derivatives of indolo[3,2-b]carbazole-6-carboxaldehyde (6-formylindolo[3,2-b]carbazole).