Synthesis of cationic plastoquinone derivatives (SkQs) containing positively charged phosphonium or rhodamine moieties connected to plastoquinone by decane or pentane linkers is described. It is...

A moderately salt-tolerant and obligately alkaliphilic, chemolithoautotrophic sulfur-oxidizing bacterium, strain HL-EbGr7^T, was isolated from a full-scale bioreactor removing H₂S from biogas under oxygen-limited conditions. Another strain, ALJ17, closely related to HL-EbGr7^T, was isolated from a Kenyan soda lake. Cells of the isolates were relatively long, slender rods, motile by a polar flagellum. Although both strains were obligately aerobic, micro-oxic conditions were preferred, especially at the beginning of growth. Chemolithoautotrophic growth was observed with sulfide and thiosulfate in a pH range of 8.0–10.5 (optimum at pH 10.0) and a salinity range of 0.2–1.5 M total Na⁺ (optimum at 0.4 M). The genome sequence of strain HL-EbGr7^T demonstrated the presence of genes encoding the reverse Dsr pathway and a truncated Sox pathway for sulfur oxidation and enzymes of the Calvin–Benson cycle of autotrophic CO₂ assimilation with ribulose-bisphosphate carboxylase/oxygenase (RuBisCO) type I. The dominant cellular fatty acids were C_18 : 1ω7, C_16 : 0 and C_19 : 0 cyclo. Based on 16S rRNA gene sequencing, the two strains belonged to a single phylotype within the genus Thioalkalivibrio in the Gammaproteobacteria . Despite being related most closely to Thioalkalivibrio denitrificans , the isolates were unable to grow by denitrification. On the basis of phenotypic and phylogenetic analysis, the novel isolates are proposed to represent a novel species, Thioalkalivibrio sulfidiphilus sp. nov., with the type strain HL-EbGr7^T ( = NCCB 100376^T = UNIQEM U246^T).

Some organic cations are known to be electrophoretically imported into bacterial cells and actively extruded from these cells by multidrug resistance (MDR) pumps. We have studied penetration of plant antimicrobial agents berberine and palmatine and synthetic antiseptic benzalkonium chloride through black planar phospholipid membrane (BLM) and membrane of Staphylococcus aureus cells. Gradients of these cations across BLM generated an electric potential difference. Penetrating anion tetraphenyl borate and phloretin (a plant substance decreasing membrane dipole potential) stimulated this effect. Under optimal conditions, the magnitude of the electric potential was close to theoretical, that is, 60 mV/10‐fold cation gradient. Berberine accumulated in S. aureus cells as shown by direct measurement of berberine with a berberinesensitive electrode. The berberine accumulation was prevented by protonophore CCCP and was stimulated by mutation in the MDR pump NorA. It is concluded that the plant alkaloids and benzalkonium are penetrating cations and substrates of an MDR pump.

Background: Multiple sclerosis (MS) is one of the most widespread chronic neurological diseases that manifests itself by progressive demyelination in the central nervous system. The study of MS pathogenesis begins with the onset of the relapsing–remitting phase of the disease, which becomes apparent due to microglia activation, neuroinflammation and demyelination/ remyelination in the white matter. The following progressive phase is accompanied by severe neurological symptoms when demyelination and neurodegeneration are spread to both gray and white matter. In this review, we discuss a possible role of mitochondrial reactive oxygen species (mtROS) in MS pathogenesis, mechanisms of mtROS generation and effects of some mitochondria-targeted antioxidants as potential components of MS therapy. Results: In the early phase of MS, mtROS stimulate NLRP3 inflammasomes, which is critical for the formation of local inflammatory lesions. Later, mtROS contribute to blood-brain barrier disruption induced by mediators of inflammation, followed by infiltration of leukocytes. ROS generated by leukocytes and activated microglia promote mitochondrial dysfunction and oligodendrocyte cell death. In the progressive phase, neurodegeneration also depends on excessive mtROS generation. Currently, only a few immunomodulatory drugs are approved for treatment of MS. These drugs mainly reduce the number of relapses but do not stop MS progression. Certain dietary and synthetic antioxidants have demonstrated encouraging results in animal models of MS but were ineffective in the completed clinical trials. Conclusion: Novel mitochondria-targeted antioxidants could be promising components of combined programs for MS therapy considering that they can be applied at extremely low doses and concurrently demonstrate anti-inflammatory and neuroprotective activities.