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Glutathione is the major protective agent against oxidative stress in Saccharomyces cerevisiae. Deletion of the GSH1 gene (strain Δgsh1) encoding the enzyme that catalyzes the first step of glutathione biosynthesis leads to growth arrest, which can be relieved by either glutathione or reducing agents such as dithiothreitol. Because defects in the biosynthesis of cellular iron-sulfur (Fe/S) proteins are associated with increases in glutathione levels, we examined the consequences of glutathione depletion on this essential process. No significant defects were detected in the amounts, activities, and maturation of mitochondrial Fe/S proteins in glutathione-depleted Δgsh1 cells. On the contrary, the maturation of extra-mitochondrial Fe/S proteins was decreased substantially. The defect was rectified neither by addition of dithiothreitol nor under anaerobic conditions excluding oxidative damage of Fe/S clusters. A double mutant in GSH1 andATM1 encoding a mitochondrial ATP binding cassette (ABC) transporter involved in cytosolic Fe/S protein maturation is nonviable even in the presence of dithiothreitol. Similar toatm1 and other mutants defective in cytosolic Fe/S protein maturation, mitochondria from glutathione-depleted Δgsh1 cells accumulated high amounts of iron. Together, our data demonstrate that glutathione, in addition to its protective role against oxidative damage, performs a novel and specific function in the maturation of cytosolic Fe/S proteins.

Previous studies have indicated that the essential protein Nfs1 performs a crucial role in cellular iron-sulfur (Fe/S) protein maturation. The protein is located predominantly in mitochondria, yet low amounts are present in cytosol and nucleus. Here we examined several aspects concerning the molecular function of yeast Nfs1p as a model protein. First, we demonstrated that purified Nfs1p facilitates the in vitro assembly of Fe/S proteins by using cysteine as its specific substrate. Thus, eukaryotic Nfs1 is a functional orthologue of the bacterial cysteine desulfurase IscS. Second, we showed that only the mitochondrial version but not the extramitochondrial version of Nfs1p is functional in generating cytosolic and nuclear Fe/S proteins. Mutation of the nuclear targeting signal of Nfs1p did not affect the maturation of cytosolic and nuclear Fe/S proteins, despite a severe growth defect under this condition. Nfs1p could not assemble an Fe/S cluster on the Isu scaffold proteins when they were located in the yeast cytosol. The lack of function of these central Fe/S cluster assembly components suggests that the maturation of extramitochondrial Fe/S protein does not involve functional copies of the mitochondrial Fe/S cluster assembly machinery in the yeast cytosol. Third, the extramitochondrial version of Nfs1p was shown to play a direct role in the thiomodification of tRNAs. Finally, we identified a highly conserved N-terminal β-sheet of Nfs1p as a functionally essential part of the protein. The implication of these findings for the structural stability of Nfs1p and for its targeting mechanism to mitochondria and cytosol/nucleus will be discussed.

Background: Pseudomonas aeruginosa is the most common Gram-negative bacterium associated with nosocomial respiratory infections. Lavender essential oil is mainly used in aromatherapy, but it has several pharmacological and therapeutic properties. Furthermore, it possesses antifungal and antibacterial activities. The anti-inflammatory activity of essential oils may depend on the composition and the ratio of the compounds. The constitution of the essential oils extracted from the different stages of flowering period varies, which makes it plausible that the collection time of the flowers influences the anti-inflammatory effects. Different types of essential oils reduce inflammation acting similarly by modulating the activity and action of the NFκB signalling pathway, which is the major regulator of the transcription of pro-inflammatory cytokines. Methods: Lavender essential oils were distilled from lavender plant cultivated in Hungary and the flowers were harvested at the beginning and at the end of flowering period. The experiments were carried out on THP-1 human monocyte/macrophage cell line as in vitro cell culture model for monitoring the effects of lavender essential oils and the main compound linalool on P. aeruginosa LPS stimulated inflammation. The mRNA and protein levels of four pro-inflammatory cytokines, IL-6, IL-1β, IL-8 and TNFα were determined by Real Time PCR and ELISA measurements. The effects of essential oils were compared to the response to two NFκB inhibitors, luteolin and ACHP. Results: Linalool and lavender essential oil extracted from plants at the beginning of flowering period were successful in decreasing pro-inflammatory cytokine production following LPS pretreatment. In case of IL-8 and IL-1β lavender oil showed stronger effect compared to linalool and both of them acted similarly to NFκB inhibitors. Pretreatments with linalool and lavender essential oil/beginning of flowering period prevented pro-inflammatory cytokine production compared to LPS treatment alone. Although lavender essential oil/end of flowering period decreased IL-6, IL-1β and IL-8 mRNA expression in case of LPS pretreatment, it was not capable to reduce cytokine secretion. Conclusion: Based on our results it has been proven that lavender essential oil extracted at the beginning of flowering period is a potent inhibitor of the synthesis of four pro-inflammatory cytokines IL-6, IL-8, IL-β and TNFα of THP-1 cells. This supports the relevance of the collection of the lavender flowers from early blooming period for essential oil production and for the utilization as an anti-inflammatory treatment.

Thyme (Thymus vulgaris L.) essential oil (TEO) is widely used as an alternative therapy especially for infections of the upper respiratory tract. TEO possesses antiviral, antibacterial, and antifungal properties. The emerging antibiotic resistance of bacterial strains, including Pseudomonas aeruginosa, has prompted the urge to find alternative treatments. In the present study, we examined the anti-inflammatory and antioxidant effects of thymol, the main compound of TEO, and two TEOs prepared at the beginning and at the end of the flowering period that may make these oils promising candidates as complementary or alternative therapies against P. aeruginosa infections. The activity measurements of the antioxidant enzymes peroxidase (PX), catalase (CAT), and superoxide dismutase (SOD) as well as the determination of total antioxidant capacity of P. aeruginosa-activated THP-1 cells revealed that thymol and both TEOs increased CAT and SOD activity as well as the antioxidant capacity of the THP-1 cells. The measurements of the proinflammatory cytokine mRNA expression and secreted protein level of LPS-activated THP-1 cells showed that from the two TEOs, only TEO prepared at the beginning of the flowering period acted as a potent inhibitor of the synthesis of IL-6, IL-8, IL-β, and TNF-α. Our results suggest that not only thymol, but also the synergism or the antagonistic effects of the additional compounds of the essential oils are responsible for the anti-inflammatory activity of TEOs.

Lutein is a tetraterpene carotenoid, which has been reported as an important antioxidant and it is widely used as a supplement. Oxidative stress participates in many human diseases, including different types of neurodegenerative disorders. Microglia, the primary immune effector cells in the central nervous system, are implicated in these disorders by producing harmful substances such as reactive oxygen species (ROS). The protective mechanisms which scavenge ROS include enzymes and antioxidant substances. The protective effects of different carotenoids against oxidative stress have been described previously. Our study focuses on the effects of lutein on antioxidant enzymes, cytokines and iron metabolism under stress conditions in BV-2 microglia. We performed cell culture experiments: BV-2 cells were treated with lutein and/or with H₂O₂; the latter was used for inducing oxidative stress in microglial cells. Real-time PCR was performed for gene expression analyses of antioxidant enzymes, and ELISA was used for the detection of pro- and anti-inflammatory cytokines. Our results show that the application of lutein suppressed the H₂O₂-induced ROS (10′: 7.5 ng + 10 µM H₂O₂, p = 0.0002; 10 ng/µL + 10 µM H₂O₂, p = 0.0007), influenced iron utilization and changed the anti-inflammatory and pro-inflammatory cytokine secretions in BV-2 cells. Lutein increased the IL-10 secretions compared to control (24 h: 7.5 ng/µL p = 0.0274; 10 ng/µL p = 0.0008) and to 10 µM H₂O₂-treated cells (24 h: 7.5 ng/µL + H₂O₂, p = 0.0003; 10 ng/µL + H₂O₂, p = 0.0003), while it decreased the TNFα secretions compared to H₂O₂ treated cells (24 h: 7.5 ng/µL + H₂O₂, p < 0.0001; 10 ng/µL + H₂O₂, p < 0.0001). These results contribute to understanding the effects of lutein, which may help in preventing or suppressing ROS-mediated microglia activation, which is related to neuronal degeneration in oxidative stress scenario.