Reactivity of γ-glutamyl-cysteine with intracellular and extracellular glutathione metabolic enzymes

Evaluating the potential impact of sodium-glucose cotransporter-2 inhibitor "canagliflozin" on the hepatic damage triggered by hypertension in rats

Hypertension (HTN) is a prevalent chronic disease. HTN and liver disease association is extensively noted. Thus, finding a medication that can alleviate HTN and its accompanying liver insult would be promising. This study investigated the potential impacts of canagliflozin "sodium-glucose cotransporter-2 inhibitor" on the liver of the Nω-nitro-L-arginine methyl ester (L-NAME)-induced HTN rat model. Twenty-four adult male rats were divided into four groups; negative control group, canagliflozin group, L-NAME group: 50 mg/kg of L-NAME was injected daily for 5 weeks and L-NAME + canagliflozin group: 1 week after L-NAME injection both L-NAME + canagliflozin (40 mg/kg) were given concomitantly daily for further 4 weeks. Liver functions, serum lipid profile, hepatic oxidative/nitrative stress biomarkers, gene expression of lipogenic enzymes, B-cell lymphoma 2 (Bcl2), and DNA fragmentation, were measured. Besides, hepatic histology and immunohistochemistry of nuclear factor kappa B (NF-κB) and endothelial nitric oxide synthase (eNOS) were assessed. Canagliflozin improved hepatic lipogenesis via the downregulation of fatty acid synthase (FAS) and transcriptional regulatory element binding protein 1c (SREBP1c) genes leading to an improved serum lipid profile. Further, canagliflozin modified the eNOS/inducible nitric oxide synthase (iNOS) pathway and decreased the NF-κB immunoreactivity besides restoring the oxidants-antioxidants balance; increased reduced glutathione concomitant with declined malondialdehyde. This improvement of the liver was mirrored by the significant restoration of liver architecture and confirmed by the preserved liver DNA content and upregulation of the antiapoptotic Bcl2 mRNA level and attenuation of the alanine transaminase, aspartate aminotransferase. In conclusion, canagliflozin is a promising anti-hypertensive and hepatic-supportive medication. RESEARCH HIGHLIGHTS: Canagliflozin's antioxidant, anti-inflammatory, anti-lipogenic, and antiapoptotic characteristics mitigate remote liver compromise caused by hypertension. Canagliflozin can be exploited as a hepatoprotective and antihypertensive medication.

Role of Glutathione in Parkinson's Disease Pathophysiology and Therapeutic Potential of Polyphenols

Oxidative stress is recognized to have a central role in the initiation and progression of Parkinson's disease (PD). Within the brain, neurons are particularly sensitive to oxidation due in part to their weak intrinsic antioxidant defense. Theoretically, neurons mostly depend on neighboring astrocytes to provide antioxidant protection by supplying cysteine-containing products for glutathione (GSH) synthesis. Astrocytes and neurons possess several amino acid transport systems for GSH and its precursors. Indeed, GSH is the most abundant intrinsic antioxidant in the central nervous system. The GSH depletion and/or alterations in its metabolism in the brain contribute to the pathogenesis of PD. Noteworthy, polyphenols possess potent antioxidant activity and can augment the GSH redox system. Numerous in vitro and in vivo studies have indicated that polyphenols exhibit potent neuroprotective effects in PD. Epidemiological studies have found an association between the consumption of dietary polyphenols and a lower PD risk. In this review, we summarize current knowledge on the biosynthesis and metabolism of GSH in the brain, with an emphasis on their contribution and therapeutic potential in PD. In particular, we focus on polyphenols that can increase brain GSH levels against PD. Furthermore, some current challenges and future perspectives for polyphenol-based therapies are also discussed.

GSH and Ferroptosis: Side-by-Side Partners in the Fight against Tumors

Glutathione (GSH), a prominent antioxidant in organisms, exhibits diverse biological functions and is crucial in safeguarding cells against oxidative harm and upholding a stable redox milieu. The metabolism of GSH is implicated in numerous diseases, particularly in the progression of malignant tumors. Consequently, therapeutic strategies targeting the regulation of GSH synthesis and metabolism to modulate GSH levels represent a promising avenue for future research. This study aimed to elucidate the intricate relationship between GSH metabolism and ferroptosis, highlighting how modulation of GSH metabolism can impact cellular susceptibility to ferroptosis and consequently influence the development of tumors and other diseases. The paper provides a comprehensive overview of the physiological functions of GSH, including its structural characteristics, physicochemical properties, sources, and metabolic pathways, as well as investigate the molecular mechanisms underlying GSH regulation of ferroptosis and potential therapeutic interventions. Unraveling the biological role of GSH holds promise for individuals afflicted with tumors.

Biosynthesis of the antioxidant γ-glutamyl-cysteine with engineered Yarrowia lipolytica

The dipeptide γ-glutamylcysteine (γ-GC), the first intermediate of glutathione (GSH) synthesis, is considered as a promising drug to reduce or prevent plethora of age-related disorders such as Alzheimer and Parkinson diseases. The unusual γ-linkage between the two constitutive amino acids, namely cysteine and glutamate, renders its chemical synthesis particularly challenging. Herein, we report on the metabolic engineering of the non-conventional yeast Yarrowia lipolytica for efficient γ-GC synthesis. The yeast was first converted into a γ-GC producer by disruption of gene GSH2 encoding GSH synthase and by constitutive expression of GSH1 encoding glutamylcysteine ligase. Subsequently genes involved in cysteine and glutamate anabolism, namely MET4, CYSE, CYSF, and GDH1 were overexpressed with the aim to increase their intracellular availability. With such a strategy, a γ-GC titer of 464 nmol mg-1 protein (93 mg gDCW-1 ) was obtained within 24 h of cell growth.

Iron homeostasis imbalance and ferroptosis in brain diseases

Brain iron homeostasis is maintained through the normal function of blood-brain barrier and iron regulation at the systemic and cellular levels, which is fundamental to normal brain function. Excess iron can catalyze the generation of free radicals through Fenton reactions due to its dual redox state, thus causing oxidative stress. Numerous evidence has indicated brain diseases, especially stroke and neurodegenerative diseases, are closely related to the mechanism of iron homeostasis imbalance in the brain. For one thing, brain diseases promote brain iron accumulation. For another, iron accumulation amplifies damage to the nervous system and exacerbates patients' outcomes. In addition, iron accumulation triggers ferroptosis, a newly discovered iron-dependent type of programmed cell death, which is closely related to neurodegeneration and has received wide attention in recent years. In this context, we outline the mechanism of a normal brain iron metabolism and focus on the current mechanism of the iron homeostasis imbalance in stroke, Alzheimer's disease, and Parkinson's disease. Meanwhile, we also discuss the mechanism of ferroptosis and simultaneously enumerate the newly discovered drugs for iron chelators and ferroptosis inhibitors.