Degradation studies of dimethachlor in soils and water by UHPLC-HRMS: putative elucidation of unknown metabolites

Degradation of limonene and trans-cinnamaldehyde in soil, and detection of their metabolites by UHPLC and GC-HRMS

Two commercial biopesticides were studied to determine their persistence in two soil types, such as sandy clay loam and clay loam soils. For this purpose, an orange oil-based biopesticide was used, being limonene its main ingredient. The other biopesticide was based on cinnamon extract and trans-cinnamaldehyde as its main component. Degradation of these compounds was monitored, and transformation products or metabolites were detected. Limonene and its metabolites were analyzed by gas chromatography (GC) and trans-cinnamaldehyde by ultra-high-performance liquid chromatography (UHPLC). Both techniques were coupled to a high-resolution mass (HRMS) analyzer, such as quadrupole (Q)-Orbitrap. Limonene and trans-cinnamaldehyde were rapidly degraded as result of first-order kinetics. Possible metabolites such as thymol, cymene, isoterpinolene and cymenene for limonene, and hydroxycinnamic acid for trans-cinnamaldehyde were tentatively identified. Moreover, four other metabolites of trans-cinnamaldehyde, some of them not previously described, were also detected.

MassChemSite for In-Depth Forced Degradation Analysis of PARP Inhibitors Olaparib, Rucaparib, and Niraparib

Drugs must satisfy several protocols and tests before being approved for the market. Among them, forced degradation studies aim to evaluate drug stability under stressful conditions in order to predict the formation of harmful degradation products (DPs). Recent advances in LC-MS instrumentation have facilitated the structure elucidation of degradants, although a comprehensive data analysis still represents a bottle-neck due to the massive amount of data that can be easily generated. MassChemSite has been recently described as a promising informatics solution for LC-MS/MS and UV data analysis of forced degradation experiments and for the automated structural identification of DPs. Here, we applied MassChemSite to investigate the forced degradation of three poly(ADP-ribose) polymerase inhibitors (olaparib, rucaparib, and niraparib) under basic, acidic, neutral, and oxidative stress conditions. Samples were analyzed by UHPLC with online DAD coupled to high-resolution mass spectrometry. The kinetic evolution of the reactions and the influence of solvent on the degradation process were also assessed. Our investigation confirmed the formation of three DPs of olaparib and the wide degradation of the drug under the basic condition. Intriguingly, base-catalyzed hydrolysis of olaparib was greater when the content of aprotic-dipolar solvent in the mixture decreased. For the other two compounds, whose stability has been much less studied previously, six new degradants of rucaparib were identified under oxidative degradation, while niraparib emerged as stable under all stress conditions tested.

Changes in soil microbial community and activity caused by application of dimethachlor and linuron

Soil microorganisms and their activities are essential for maintaining soil health and fertility. Microorganisms can be negatively affected by application of herbicides. Although effects of herbicides on microorganisms are widely studied, there is a lack of information for chloroacetamide herbicide dimethachlor. Thus, dimethachlor and well known linuron were applied to silty-loam luvisol and their effects on microorganisms were evaluated during112 days long laboratory assay. Dimethachlor and linuron were applied in doses 1.0 kg ha-1 and 0.8 kg ha-1 corresponding to 3.33 mg kg-1 and 2.66 mg kg-1 respectively. Also 100-fold doses were used for magnification of impacts. Linuron in 100-fold dose caused minor increase of respiration, temporal increase of soil microbial biomass, decrease of soil dehydrogenase activity, and altered microbial community. Dimethachlor in 100-fold dose significantly increased respiration; microbial biomass and decreased soil enzymatic activities. Microbial composition changed significantly, Proteobacteria abundance, particularly Pseudomonas and Achromobacter genera increased from 7 to 28th day. In-silico prediction of microbial gene expression by PICRUSt2 software revealed increased expression of genes related to xenobiotic degradation pathways. Evaluated characteristics of microbial community and activity were not affected by herbicides in recommended doses and the responsible use of both herbicides will not harm soil microbial community.

Automatic Identification of Lansoprazole Degradants under Stress Conditions by LC-HRMS with MassChemSite and WebChembase

Stress testing is one of the most important parts of the drug development process, helping to foresee stability problems and to identify degradation products. One of the processes involving stress testing is represented by forced degradation studies, which can predict the impact of certain conditions of pH, moisture, heat, or other negative effects due to transportation or packaging issues on drug potency and purity, ensuring patient safety. Regulatory agencies have been working on a standardization of laboratory procedures since the past two decades. One of the results of those years of intensive research is the International Conference on Harmonization (ICH) guidelines, which clearly define which forced degradation studies should be performed on new drugs, which become a routine work in pharmaceutical laboratories. Since used techniques based on high-performance liquid chromatography coupled with high-resolution mass spectrometry have been developed years ago and are now mastered by pharmaceutical scientists, automation of data analysis, and thus data processing, is becoming a hot topic nowadays. In this work, we present MassChemSite and WebChembase as a tandem to automatize the routine analysis studies without missing information quality, using as a case study the degradation of lansoprazole under acidic, oxidative, basic, and neutral stress conditions.