Biochemical alterations in duckweed and algae induced by carrier solvents: Selection of an appropriate solvent in toxicity testing

Carrier solvents are often used in aquatic toxicity testing for test chemicals with hydrophobic properties. However, the knowledge of solvent effects on test organisms remains limited. This study aimed to understand biochemical effects of the four common solvents ((methanol, ethanol, acetone and dimethylsulfoxide (DMSO)) on two test species Lemna minor and Raphidocelis subcapitata by applying Fourier transform infrared spectroscopy (FTIR) coupled with multivariate analysis in order to select appropriate solvents in the toxicity testing. The results showed biochemical variations associated with solvent treatments at different doses on test species. From the obtained infrared spectra, the structures of lipid membrane and protein phosphorylation in the test species were found sensitive to the solvents. Methanol and ethanol mainly affected the protein secondary structure, while acetone and DMSO primarily induced the alterations of carbohydrate and proteins in the test species. The FTIR results demonstrated that methanol and ethanol showed higher biochemical alterations in the test species than acetone and DMSO, especially at the high doses (0.1% and 1% v/v). Based on the growth inhibition and FTIR spectroscopy, acetone and DMSO can be used as carrier solvent in the toxicity testing when their doses are lower than 0.1% v/v. This article is protected by copyright. All rights reserve

Epoxy–amine oligomers from terpenes with applications in synergistic antifungal treatments

A bis-epoxide monomer was synthesised in two steps from (R)-carvone, a terpenoid renewable feedstock derived from spearmint oil, and used to prepare β-aminoalcohol oligomers in polyaddition reactions with bis-amines without requiring solvent or catalyst. A sub-set of the resultant materials were readily water soluble and were investigated for antifungal activity in combination with the fungicide iodopropynyl-butylcarbamate (IPBC) or the antifungal drug amphotericin B. The oligo-(β-aminoalcohol)s alone were inactive against Trichoderma virens and Candida albicans but in combination with IPBC and amphotericin B demonstrated synergistic growth-inhibition of both fungi. Quantitative analysis showed that the presence of the terpene-based oligomers decreased the minimum inhibitory concentration (MIC) of IPBC by up to 64-fold and of amphotericin B by 8-fold. The efficacy of the combined formulation was further demonstrated with agar disk diffusion assays, which revealed that IPBC and amphotericin B reduced the growth of the fungi, as shown by zones of inhibition, to a greater extent when in the presence of the oligo-(β-aminoalcohol)s. These data suggest potential future use of these renewable feedstock derived oligomers in antifungal material and related biomedical applications