Molecules

4-hydroxy-TEMPO is a water-soluble nitroxide radical with potent antioxidant and redox-modulating properties. Its small molecular weight and membrane permeability enable it to act as a superoxide dismutase mimetic, efficiently scavenging reactive oxygen species and mitigating oxidative damage. In this study, we investigated the physiological and transcriptomic effects of 4-hydroxy-TEMPO in Saccharomyces cerevisiae, using wild-type and mutant strains deficient in key redox and DNA repair pathways (sod1Δ, sod2Δ, yap1Δ, rad52Δ). RNA-Seq analysis revealed widespread transcriptional reprogramming. Treatment with 4-hydroxy-TEMPO impaired cell growth, induced accumulation of cells with 1C (G1 phase) DNA content, and modulated chronological aging in a strain-dependent manner. Notably, low concentrations delayed aging in wild-type, yap1Δ, and rad52Δ strains, while accelerating it in sod1Δ mutants, consistent with a hormetic response. Unlike TEMPO, 4-hydroxy-TEMPO exhibited markedly reduced translational toxicity, preserved polysome structure at high doses, and triggered a non-canonical, redox-dependent transcriptional program characterized by induction of stress-response genes together with unexpected up-regulation of multiple ribosomal protein genes. This was accompanied by a biphasic, genotype-specific hormetic response and a measurable genoprotective effect. RT-qPCR confirmed key transcriptional changes, linking transcriptome remodeling to functional outcomes.

Effectively separating and utilizing macerals based on their properties is crucial for the efficient and high-value utilization of coal. This study enhances the traditional screening method by employing primary and stepwise crushing techniques to separate Yili coal (YLC) into inertinite-rich (YLI) and vitrinite-rich (YLV) concentrates. The structural characteristics and direct coal liquefaction (DCL) performance of YLC, YLV and YLI are subsequently studied. The results indicate that YLV exhibits the highest yield of oil, asphaltene and gas, a finding closely linked to its elevated content of highly active functional groups and its long aliphatic and bridge chains. Furthermore, the liquefaction oil from YLV contains the highest content of alkanes and phenols, which is attributed to its high content of aliphatic hydrocarbons and phenolic hydroxyl groups. In contrast, YLI exhibits the lowest product yield relative to YLC and YLV, with the highest contents of aromatics, esters, and ketones in its oil, due to its high contents of aromatic and carbonyl carbon. The separation, structural characteristics and DCL studies of macerals from Yili coal offer valuable insights for the efficient separation and utilization of macerals.

The idea of collecting novel contributions relating to the chemistry of natural compounds in this Special Issue stemmed from the success of the first edition of the collection entitled “Natural Products Chemistry: Advances in Synthetic, Analytical and Bioactivity Studies”, which was published in Molecules in 2023 [...]