Biosurfactants: The green generation of speciality chemicals and potential production using Solid-State fermentation (SSF) technology.

Surfactants are multipurpose products found in most sectors of contemporary industry. Their large-scale manufacturing has been mainly carried out using traditional chemical processes. Some of the chemical species involved in their production are considered hazardous and some industrial processes employing them categorised as "having potential negative impact on the environment". Biological surfactants have therefore been generally accepted worldwide as suitable sustainable greener alternatives. Biosurfactants exhibit the same functionalities of synthetic analogues while having the ability to synergize with other molecules improving performances; this strengthens the possibility of reaching different markets via innovative formulations. Recently, their use was suggested to help combat Covid-19. In this review, an analysis of recent bibliography is presented with descriptions, statistics, classifications, applications, advantages, and challenges; evincing the reasons why biosurfactants can be considered as the chemical specialities of the future. Finally, the uses of the solid-state fermentation as a production technology for biosurfactants is presented.

Enzymatic oxidation of ansa-ferrocifen leads to strong and selective thioredoxin reductase inhibition in vitro.

This paper reports the inhibitory effect on the cytosolic thioredoxin reductase (TrxR1) in vitro by the ansa-ferrocifen derivative (ansa-FcdiOH, 1). We found that 1 decreased only slightly enzyme activity (IC50=8µM), while 1*, the species generated by enzymatic oxidation by the HRP (horseradish peroxidase)/H2O2 mixture, strongly inhibited TrxR1 (IC50=0.15µM). At the same concentrations, neither 1 nor 1* had effect on glutathione reductase (GR). The most potent TrxR1 inhibitor did not appear to be the corresponding quinone methide as it was the case for ferrocifens of the acyclic series, or the stabilized carbocation as in the osmocifen series, but rather the quinone methide radical. This hypothesis was confirmed by ab-initio calculations of the species generated by oxidation of 1 and by EPR spectroscopy. BIAM (biotin-conjugated iodoacetamide) assay showed that 1* targeted both cysteine and selenocysteine of the C-terminal redox center of TrxR1.