Influenza viruses are RNA viruses of the Orthomyxoviridae family. Seasonal epidemics are associated with 3–5 million cases of severe illness each year and from 290- to 650-thousand deaths worldwide (https://www.who.int/news-room/fact-sheets/detail/influenza-(seasonal); accessed on 3 August 2021). Although safe and effective vaccines are available, their specificity is limited because of the diversity of the circulating influenza strains and the ability of the virus to acquire mutations. The treatment options for influenza infections are limited to inhibitors of neuraminidase and blockers of the M2 proton channel. In patients infected with IV, marked increases of oxidation byproducts are found, including 8-hydroxydeoxyguanosine, malondialdehyde, F2-isoprostane, 7-ketocholesterol, and 7β-hydroxycholesterol (reviewed in reference [3]). Additionally, elevated levels of sterol oxidation products are observed up to three months after IV clearance (reviewed in reference [3]). Finally, increased levels of ROS, as well as of nitric oxide synthase 2 (iNOS) and nitrotyrosine, are found in the lung tissues of patients that died from an IV infection (reviewed in reference [3]). Several reports have shown that NAC, ascorbic acid, and vitamin E have positive effects on IV infections by inhibiting viral replication and inflammation both in the cells and in the mice (reviewed in reference [3]). In an in vitro study, LA inhibited IV replication in MDCK cells and reduced the nuclear translocation of NF-κB. Additionally, the caspase-3 activity was remarkably inhibited and type I interferons (IFNs) were upregulated upon LA treatment [80]. Overall, the available data indicated that LA might be a potential anti-influenza agent, deserving further investigation.

Chronic viral hepatitis is the leading cause of liver fibrosis and cirrhosis. Replication of the virus in liver cells results in decreased levels of glutathione in hepatocytes. The viral load in hepatitis C is directly related to the glutathione levels [83]. Eventually, the oxidative stress leads to necrotic inflammation and the necrosis of liver cells. Increased lipid peroxidation leads to hepatic cytotoxicity, causing immune-mediated inflammation and fibrosis [84,85,86]. Supportive therapeutic effects of LA have been demonstrated in the clinical setting in patients with a Hepatitis C infection [87,88]. The LA antioxidant properties have been recognized as potential therapeutic effects based on its ability to exert anti-inflammatory, antifibrotic, and anti-TNF-α effects that produce restoration of the damaged areas of the liver, as well as its function, as demonstrated in HCV patients [87,88]. According to a clinical study with a small number of patients conducted by Berkson in 1999, therapy with the antioxidant LA, the hepatoprotector silymarin, and the element selenium, completely restores the liver function of patients, and the proposed combination allows avoiding liver transplantation [87]. The beneficial effect of the application of various antioxidants, including LA, was later confirmed in a clinical trial enrolling 50 patients with chronic hepatitis C infection [88]. Among them, 48% responded with improvement in at least one of the observed liver parameters, and a decrease in the viral load was observed in 25% of the patients.