Omics analysis unveils changes in the metabolome and lipidome of Caenorhabditis elegans upon polydopamine exposure.

Polydopamine (PDA) is an insoluble biopolymer with a dark brown-black color that forms through the autoxidation of dopamine. Because of its outstanding biocompatibility and durability, PDA holds enormous promise for various applications, both in the biomedical and non-medical domains. To ensure human safety, protect health, and minimize environmental impacts, the assessment of PDA toxicity is important. In this study, metabolomics and lipidomics assessed the impact of acute PDA exposure on Caenorhabditis elegans (C. elegans). The findings revealed a pronounced perturbation in the metabolome and lipidome of C. elegans at the L4 stage following 24 hours of exposure to 100 µg/mL PDA. The changes in lipid composition varied based on lipid classes. Increased lipid classes included lysophosphatidylethanolamine, triacylglycerides, and fatty acids, while decreased species involved in several sub-classes of glycerophospholipids and sphingolipids. Besides, we detected 37 significantly affected metabolites in the positive and 8 in the negative ion modes due to exposure to PDA in C. elegans. The metabolites most impacted by PDA exposure were associated with purine metabolism, biosynthesis of valine, leucine, and isoleucine; aminoacyl-tRNA biosynthesis; and cysteine and methionine metabolism, along with pantothenate and CoA biosynthesis; the citrate cycle (TCA cycle); and beta-alanine metabolism. In conclusion, PDA exposure may intricately influence the metabolome and lipidome of C. elegans. The combined application of metabolomics and lipidomics offers additional insights into the metabolic perturbations involved in PDA-induced biological effects and presents potential biomarkers for the assessment of PDA safety.

Chiral separation and molecular modeling study of decursinol and its derivatives using polysaccharide-based chiral stationary phases.

Plant-based bioactive substances have long been used to treat inflammatory ailments, owing to their low toxicity and cost-effectiveness. To enhance plant treatment by eliminating undesirable isomers, optimizing the chiral separation techniques in pharmaceutical and clinical studies is important. This study reported a simple and effective method for chiral separation of decursinol and its derivatives, which are pyranocoumarin compounds with anti-cancer and anti-inflammatory properties. Baseline separation (Rs >1.5) was achieved using five different polysaccharide-based chiral stationary phases (CSPs) that differed in chiral origin, chiral selector chemistry, and preparation technique. To separate all six enantiomers simultaneously, n-hexane and three alcohol modifiers (ethanol, isopropanol, and n-butanol) were used as mobile phases in the normal-phase mode. The chiral separation ability of each column with various mobile phase compositions was compared and discussed. As a result, amylose-based CSPs with linear alcohol modifiers demonstrated superior resolution. Three cases of elution order reversal caused by modifications of CSPs and alcohol modifiers were observed and thoroughly analyzed. To elucidate the chiral recognition mechanism and enantiomeric elution order (EEO) reversal phenomenon, detailed molecular docking simulations were conducted. The R- and S-enantiomers of decursinol, epoxide, and CGK012 exhibited binding energies of -6.6, -6.3, -6.2, -6.3, -7.3, and -7.5 kcal/mol, respectively. The magnitude of the difference in binding energies was consistent with the elution order and enantioselectivity (α) of the analytes. The molecular simulation results demonstrated that hydrogen bonds, π-π interactions, and hydrophobic interactions have a significant impact on chiral recognition mechanisms. Overall, this study presented a novel and logical approach of optimizing chiral separation techniques in the pharmaceutical and clinical industries. Our findings could be further applied for screening and optimizing enantiomeric separation.

Lipid class-dependent alterations of Caenorhabditis elegans under harmane exposure.

Altered lipid patterns in Caenorhabditis elegans (C. elegans) resulting from exposure to harmane remain to be explored. In this study, untargeted lipidomics was carried out to elucidate the effects of acute exposure to harmane on the lipidome of C. elegans. Exposure to the compound was evaluated based on the reproduction ability of the worms at 0.1 and 1 µg/mL. No significant effects of harmane were observed at these concentrations. Furthermore, we found that the modulatory effects of harmane on the lipidome of C. elegans at 1 µg/mL were lipid class dependent. In particular, harmane-treated worms were enriched in triglycerides and fatty acids, regardless of the degree of saturation. Glycerophospholipids were generally down-regulated. Furthermore, functional analyses suggested that there was a reduction in lipid membrane bilayer-related terms, and in some related to the mitochondria, and endoplasmic reticulum of C. elegans when treated with harmane. Lipid droplets and storage appeared to be up-regulated. In conclusion, our findings suggest that harmane exposure affects the lipidome of C. elegans in a sophisticated manner. Further investigations are required to elucidate the molecular mechanisms underlying these lipid pattern changes.

Determination of enantiomeric impurity of tenofovir disoproxil fumarate on a cellulose tris(3,5-dichlorophenyl-carbamate) chiral stationary phase and the characterization of its related substances.

A simple and reliable high-performance liquid chromatography method was developed to determine the enantiomeric impurity of tenofovir disoproxil fumarate, an orally bioavailable prodrug of tenofovir, commonly used for the treatment of human immunodeficiency virus and hepatitis B. Tenofovir disoproxil and its enantiomer, were completely separated on a Chiralpak IC column (3 µm, 100 × 4.6 mm, i.d.). The chiral separation was achieved using a mobile phase containing n-hexane, ethanol, methanol, and triethylamine 65/25/10/0.1 (v/v/v/v) at a flow rate of 0.6 mL/min. Ideally, the reversal of enantiomer elution order was achieved on the Chiralpak IC column, to allow the elution of the minor enantiomeric impurity before the major component. Moreover, the proposed method was able to discriminate the active ingredient from the related substances available in the tenofovir disoproxil fumarate raw materials. These compounds were isolated and structurally elucidated by MS and nuclear magnetic resonance. Based on the spectral data, the structures of related substances were confirmed as tenofovir isoproxil monoester and fumaric acid. The high-performance liquid chromatography method was optimized by the design of experiment approach and successfully validated following the International Conference on Harmonization guideline. Proposed method was effectively applied for the quantification of enantiomeric impurity in tenofovir disoproxil fumarate raw materials.

A capillary electrophoresis method for the determination of the linagliptin enantiomeric impurity.

Linagliptin is a highly specific, long-acting inhibitor that is used as an orally administrable agent for type-2 diabetes treatment. Because only the R-enantiomer is of clinical use, we developed a capillary electrophoresis method for the determination of the enantiomeric impurity of this compound. Carboxymethyl-ß-cyclodextrin was selected as the chiral selector for the separation of linagliptin enantiomers. Design of experiments and desirability functions were used for the analytical optimization, which was focused on understanding and improving the electrophoretic process. The effects of significant parameters (background electrolyte concentration and pH, cyclodextrin concentration, temperature, and voltage) were thoroughly investigated. The complete separation of linagliptin and its enantiomeric impurity with baseline resolution was achieved within 10 min on an uncoated fused-silica capillary (50 µm inner diameter, 365 µm outer diameter, 64.5/56 cm in total/ effective length) maintained at 25°C, under an applied voltage of 28.0 kV. The background electrolyte contained 70 mM sodium acetate and 4.7 mM carboxymethyl-ß-cyclodextrin, and the pH was adjusted to 6.10. The method was validated, and a limit of quantitation of 0.05% for the impurity was estimated.