Biotransformation of Dimethenamid-P by the basidiomycete Irpex consors

Fungal biodegradation of chlorinated herbicides: an overview with an emphasis on 2,4-D in Argentina

Chlorinated herbicides are one of the main types of pesticide used in agriculture. In Argentina, 2,4-dichlorophenoxyacetic acid (2,4-D) is the most applied herbicide for the control of broadleaf weeds, but the risks it poses for the environment and human health are cause for great concern. A promising technology to remove this kind of pollutants, or neutralize them in such a way that they become less or non-toxic, is the use of degrading or detoxifying microorganisms from contaminated sites. Filamentous fungi can bioremediate xenobiotics thanks to their efficient enzymatic machinery. However, most studies on the degradation of 2,4-D have been carried out with bacteria, and little is known about whether it can be efficiently biodegraded by fungi. In the environment, fungal strains and native microbiota may detoxify contaminants through mechanisms like biosorption, bioabsortion, biotransformation, and/or degradation. Whether these processes occur separately or simultaneously depends on the metabolic ability of the strains that conform the microbial community. Another important concern when attempting to introduce detoxifying microorganisms into a contaminated environment is the GRAS ("Generally Recognized As Safe") assessment or status. These are studies that help predict a biodegrading microorganism's pathogenicity, toxicity, and infectivity before in situ application. This application, moreover, is regulated by different legal frameworks. The present review aims to outline the main aspects of 2,4-D degradation by fungi, and to summarize the current state of research on the topic in Argentina.

Monooxygenase- and Dioxygenase-Catalyzed Oxidative Dearomatization of Thiophenes by Sulfoxidation, cis-Dihydroxylation and Epoxidation

Enzymatic oxidations of thiophenes, including thiophene-containing drugs, are important for biodesulfurization of crude oil and drug metabolism of mono- and poly-cyclic thiophenes. Thiophene oxidative dearomatization pathways involve reactive metabolites, whose detection is important in the pharmaceutical industry, and are catalyzed by monooxygenase (sulfoxidation, epoxidation) and dioxygenase (sulfoxidation, dihydroxylation) enzymes. Sulfoxide and epoxide metabolites of thiophene substrates are often unstable, and, while cis-dihydrodiol metabolites are more stable, significant challenges are presented by both types of metabolite. Prediction of the structure, relative and absolute configuration, and enantiopurity of chiral metabolites obtained from thiophene enzymatic oxidation depends on the substrate, type of oxygenase selected, and molecular docking results. The racemization and dimerization of sulfoxides, cis/trans epimerization of dihydrodiol metabolites, and aromatization of epoxides are all factors associated with the mono- and di-oxygenase-catalyzed metabolism of thiophenes and thiophene-containing drugs and their applications in chemoenzymatic synthesis and medicine.