Lipids and polar metabolites are emerging as promising indicators of the brain’s molecular phenotype in both clinical and fundamental research. However, the impact of postmortem delay on these compounds, unavoidable in human brain studies, remains insufficiently understood. In this study, we examined the postmortem stability of lipids and polar metabolites over a 48-h interval in the brains of three species: humans, rats, and mice. We show that the abundance levels of 23% of the 867 studied lipids and 75% of the 104 studied polar metabolites were affected significantly by postmortem delay in at least one species. The postmortem effects correlated positively and significantly among the species, while showing an approximately tenfold slower rate in humans compared to rodents. The only exception to the postmortem rates deceleration was a group of oxidized fatty acids, which accumulated at similar speed in both humans and rodents. These findings provide valuable insights for improving reproducibility and refining the interpretation of human and rodent brain lipidome and metabolome data in future studies.

Hypaphorines, tryptophan derivatives, have anti-inflammatory activity, but their mechanism of action was largely unknown. Marine alkaloid L-6-bromohypaphorine with EC₅₀ of 80 μM acts as an agonist of α7 nicotinic acetylcholine receptor (nAChR) involved in anti-inflammatory regulation. We designed the 6-substituted hypaphorine analogs with increased potency using virtual screening of their binding to the α7 nAChR molecular model. Fourteen designed analogs were synthesized and tested in vitro by calcium fluorescence assay on the α7 nAChR expressed in neuro 2a cells, methoxy ester of D-6-iodohypaphorine (6ID) showing the highest potency (EC₅₀ 610 nM), being almost inactive toward α9α10 nAChR. The macrophages cytometry revealed an anti-inflammatory activity, decreasing the expression of TLR4 and increasing CD86, similarly to the action of PNU282987, a selective α7 nAChR agonist. 6ID administration in doses 0.1 and 0.5 mg/kg decreased carrageenan-induced allodynia and hyperalgesia in rodents, in accord with its anti-inflammatory action. Methoxy ester of D-6-nitrohypaphorine demonstrated anti-oedemic and analgesic effects in arthritis rat model at i.p. doses 0.05–0.26 mg/kg. Tested compounds showed excellent tolerability with no acute in vivo toxicity in dosages up to 100 mg/kg i.p. Thus, combining molecular modelling and natural product-inspired drug design improved the desired activity of the chosen nAChR ligand.

Microscopic green algae are active producers of beneficial compounds, particularly those containing nitrogen. However, the metabolism of nitrogen-containing compounds is diverse and depends on the conditions of the nitrogen source. As a result, the approach to studying the metabolism of nitrogen-containing compounds becomes more complicated. This work demonstrates the metabolic changes in the high-productive green algae Neochlorella semenenkoi IPPAS C-1210 under conditions of nitrogen starvation and subsequent reintake, using high-performance liquid chromatography–mass spectrometry (HPLC–MS) with ¹⁵N isotopic labeling. The presented results include semi-quantitative chromatography–mass spectrometric analysis for 17 amino acids, a metabolomic profile of over 40 isotopically labeled compounds, an assessment of metabolic flux via isotopic incorporation, and an analysis of cellular lipid composition under varying growth conditions. The findings indicate that this strain can utilize ammonium acetate as a nitrogen source, consuming nitrogen in the ammonium form. The degree of isotopic labeling in compounds often diverged significantly from their quantitative changes (concentrations and chromatographic peak areas), suggesting that isotopic analysis may offer advantages over purely quantitative analysis for biological systems. Furthermore, in vivo biological isotopic labeling is shown to assist in identifying compounds absent from standard mass spectrometric databases.