N-acetylcysteine (NAC) is a medicine widely used to treat paracetamol overdose and as a mucolytic compound. It has a well-established safety profile, and its toxicity is uncommon and dependent on the route of administration and high dosages. Its remarkable antioxidant and anti-inflammatory capacity is the biochemical basis used to treat several diseases related to oxidative stress and inflammation. The primary role of NAC as an antioxidant stems from its ability to increase the intracellular concentration of glutathione (GSH), which is the most crucial biothiol responsible for cellular redox imbalance. As an anti-inflammatory compound, NAC can reduce levels of tumor necrosis factor-alpha (TNF-α) and interleukins (IL-6 and IL-1β) by suppressing the activity of nuclear factor kappa B (NF-κB). Despite NAC’s relevant therapeutic potential, in several experimental studies, its effectiveness in clinical trials, addressing different pathological conditions, is still limited. Thus, the purpose of this chapter is to provide an overview of the medicinal effects and applications of NAC to human health based on current therapeutic evidence.

Oxidative stress (OS) is considered as one of the etiologic factors involved in several signals and symptoms of inflammatory bowel diseases (IBD) that include diarrhea, toxic megacolon and abdominal pain. This systematic review discusses approaches, challenges and perspectives into the use of nontraditional antioxidant therapy on IBD, including natural and synthetic compounds in both human and animal models. One hundred and thirty four papers were identified, of which only four were evaluated in humans. Some of the challenges identified in this review can shed light on this fact: lack of standardization of OS biomarkers, absence of safety data and clinical trials for the chemicals and biological molecules, as well as the fact that most of the compounds were not repeatedly tested in several situations, including acute and chronic colitis. This review hopes to stimulate researchers to become more involved in this fruitful area, to warrant investigation of novel, alternative and efficacious antioxidant-based therapies.

Liver disease is highly prevalent in the world. Oxidative stress (OS) and inflammation are the most important pathogenetic events in liver diseases, regardless the different etiology and natural course. N-acetyl-l-cysteine (the active form) (NAC) is being studied in diseases characterized by increased OS or decreased glutathione (GSH) level. NAC acts mainly on the supply of cysteine for GSH synthesis. The objective of this review is to examine experimental and clinical studies that evaluate the antioxidant and anti-inflammatory roles of NAC in attenuating markers of inflammation and OS in hepatic damage. The results related to the supplementation of NAC in any form of administration and type of study are satisfactory in 85.5% (n = 59) of the cases evaluated (n = 69, 100%). Within this percentage, the dosage of NAC utilized in studies in vivo varied from 0.204 up to 2 g/kg/day. A standard experimental design of protection and treatment as well as the choice of the route of administration, with a broader evaluation of OS and inflammation markers in the serum or other biological matrixes, in animal models, are necessary. Clinical studies are urgently required, to have a clear view, so that, the professionals can be sure about the effectiveness and safety of NAC prescription.

Although the liver has a remarkable regenerative capacity, sepsis-associated liver injury (SLI) is a complication often seen in intensive care units. Due to its role in immune and inflammatory regulation, the liver is particularly vulnerable during severe infections. Understanding the global prevalence, causes, and management of SLI is essential to improve outcomes and reduce healthcare costs. This paper aims to explore these factors, with an emphasis on identifying effective strategies for clinical management. Zhang et al ’s bibliometric analysis of 787 publications (745 original articles and 42 reviews, mostly in animal models) from 2000 to 2023 highlights the growing interest in SLI, focusing on oxidative stress, gut microbiota, and inflammatory processes. Key components such as nuclear factor-kappa B and the NOD-like receptor thermal protein domain associated protein 3 inflammasome pathway, along with their links to gut microbiota imbalance and oxidative stress, are crucial for understanding SLI pathogenesis. The gut-liver axis, particularly the role of intestinal permeability and bacterial translocation in liver inflammation, is emphasized. In this context, bacterial translocation is especially relevant for critically ill patients, as it can exacerbate liver inflammation. The findings underscore the need for integrated care in intensive care units, prioritizing gut health and careful antibiotic use to prevent dysbiosis. Despite extensive research, there remains a lack of clinical trials to validate therapeutic approaches. The abundance of experimental studies highlights potential therapeutic targets, stressing the need for high-quality randomized clinical trials to translate these findings into clinical practice.

The development and course of inflammatory bowel disease (IBD) are significantly influenced by inflammation and oxidative stress. Antioxidant therapy is a promising therapeutic option to enhance the clinical results of these individuals in this particular scenario. The purpose of this study is to assess the impact of curcumin, with or without piperine, on cytokines, fecal calprotectin (CalF), and oxidative stress enzymatic and non-enzymatic indicators in patients with IBD. Methods: Patients with Crohn’s disease (CD) or ulcerative colitis (UC) who were at least 18 years old and had intact liver and kidney function participated in this randomized, double-blind trial (trial registration: ensaiosclinicos.gov.br as RBR-89q4ydz). For 12 weeks, participants were randomly assigned to one of three groups: placebo, curcumin (1000 mg/day), or curcumin plus piperine (1000 mg + 10 mg/day). In order to examine oxidative stress indicators, CalF, and pro-inflammatory cytokines, blood and fecal samples were obtained, both prior to and following the intervention time. Results: After adjusting for age, sex, and type of IBD, the curcumin plus piperine group had substantially higher serum levels of superoxide dismutase (SOD) than the placebo group (4346.9 ± 879.0 vs. 3614.5 ± 731.5; p = 0.041). There were no discernible variations between the groups in CalF, inflammatory markers, or other indicators of oxidative stress. Conclusions: In patients with inflammatory bowel disease (IBD), our study indicates that a 12-week curcumin plus piperine treatment effectively increases enzymatic antioxidant defense, especially SOD. These results demonstrate the potential therapeutic benefits of managing redox imbalance in individuals with IBD.