Alternative processes to produce chitin, chitosan, and their oligomers.

Sustainable recovery of chitin and its derivatives from shellfish waste will be achieved when the industrial production of these polymers is achieved with a high control of their molecular structure, low costs, and acceptable levels of pollution. Therefore, the conventional chemical method for obtaining these biopolymers needs to be replaced or optimized. The goal of the present review is to ascertain what alternative methods are viable for the industrial-scale production of chitin, chitosan, and their oligomers.

Cu(II)-disulfide complexes display simultaneous superoxide dismutase- and catalase-like activities.

Superoxide is a potentially toxic by-product of cellular metabolism. We have addressed here the in vitro ability of complexes formed between copper(II) ions and various biologically-occurring disulfides (RSSR: oxidized glutathione, cystine, homocystine and α-lipoic acid) to react with superoxide. The studied complexes were found to react with superoxide (generated by a xanthine/xanthine oxidase system) at rate constants (kCu(II)-RSSR) close to 10(6)M(-1)s(-1), which are three orders of magnitude lower than that reported for superoxide dismutase (SOD) but comparable to that of several other copper-containing complexes reported as SOD mimetics.