SARS-CoV-2 is a betacoronavirus causing severe inflammatory pneumonia, so that excessive inflammation is considered a risk factor for the disease. According to reports, cytokine storm is strongly responsible for death in such patients. Some of the consequences of severe inflammation and cytokine storms include acute respiratory distress syndrome, acute lung injury, and multiple organ dysfunction syndromes. Phylogenetic findings show more similarity of the SARS-CoV-2 virus with bat coronaviruses, and less with SARS-CoV. Quercetin is a carbohydrate-free flavonoid that is the most abundant flavonoid in vegetables and fruits and has been the most studied to determine the biological effects of flavonoids. Inflammasomes are cytosolic multi-protein complexes assembling in response to cytosolic PAMP and DAMPs, whose function is to generate active forms of cytokines IL-1β and IL-18. Activation or inhibition of the NLRP3 inflammasome is affected by regulators such as TXNIP, SIRT1 and NRF2. Quercetin suppresses the NLRP3 inflammasome by affecting these regulators. Quercetin, as an anti-inflammatory, antioxidant, analgesic and inflammatory compound, is probably a potential treatment for severe inflammation and one of the main life-threatening conditions in patients with COVID-19.

, the SARS-CoV-2 virus has infected more than 27 million people and left more than 800 000 victims. According to statistics, a high percentage of patients with COVID-19 recover and only a small percentage of them succumb to death. Studies have documented the important role of the immune system in determining the fate of COVID-19 patients. Observations have so far shown that destructive and severe inflammation is the leading cause of death in patients with COVID-19. 1 Significant increases in the levels of inflammatory cytokines (TNF, IL-1β, IL-6, IL-8), colony-stimulating factors (G-CSF and GM-CSF) and inflammatory chemokines (MCP1, IP10 and MIP1α) and the destructive role of inflammatory monocytes and macrophages indicate the role of inflammation in COVID-19 pathogenesis. 2,3 Acute respiratory distress syndrome (ARDS) and cytokine storm are the two main causes of severe COVID-19. 1

Antioxidant compounds are thought to prevent and treat diseases, especially cancer, under any circumstances. For this purpose, nature-based antioxidants nowadays are being commonly used to prevent and treat diseases. Indeed, phenolic compounds found in medicinal plants have opened a new horizon to prevent and treat diseases because of having antioxidant properties. However, some recent studies have reported that antioxidants are not absolute anticancer compounds and certain drugs have been reported to reduce levels of reactive oxygen species (ROS) in the cancer cells, i.e., their main action mechanism. It has been argued that increasing levels of ROS cause an increase in apoptosis rate and therefore can be considered an approach to treat fatal and hard-to-treat cancers. This chapter seeks to partly explain the role of ROS in progression or inhibition of cancer growth in addition to the role of antioxidants in preventing and treating this disease.

Introduction: Tinnitus is one of the common diseases of the ear that is associated with numerous physical and mental disorders. One of the known mechanisms in the tinnitus area with unknown reason is oxidative events. Based on the prevalence and economic costs and physical-psychological side effects caused by tinnitus and the importance of finding a suitable solution for its prevention and treatment, the need for further studies becomes more obvious in this context. This review article aimed to review studies on the effectiveness of Ginkgo biloba as a medicinal plant on patients with tinnitus. Evidence Acquisitions: Google Scholar, Directory of Open Access Journals (DOAJ), PubMed, LISTA (EBSCO) and Web of Science have been searched. Results: There are many studies on the therapeutic effect of Ginkgo biloba on patients with tinnitus. Most findings are in contrast with each other so that some of studies reported that Ginkgo biloba is effective in the treatment of tinnitus and other studies referred to it as ineffective herbal medicine. Generally, according to the previous studies and the present study, it can mention that the Ginkgo biloba may somewhat improve tinnitus. Conclusion: Since tinnitus is multifactorial, it is recommended to evaluate patients individually based on the cause of tinnitus, treatment formulas, and different doses of Ginkgo biloba at the more extensive level in future studies.

Tumor cells have deviated pathway that lead to increased constant state levels of free radicals and consequently lead to DNA damage, and then activates signaling pathways that causes unlimited growth, the inability to differentiation, and the malignant phenotype. Some studies have demonstrated that antioxidants can inhibit free radicals generation and repress oxidative damage and can prevent the creation of most diseases like cancer. There are some studies that investigated the mechanism and regulative effects of herbal extract antioxidant carcinogenesis prevention; they have documented that antioxidant effects and the inhibition of cancer development depends on a number of basic cellular mechanisms by phenolic compounds including a spectrum of cellular basic machinery. This systematic review aimed at providing an overview on the relevant data available in antioxidant activity of herbal products for cancer prevention and treatment. In this regards, Web of Science and PubMed databases were searched by the application of Endnote software for the publications about the role of herbal antioxidants on cancer; published from 2000 to February 2016. This study can/might provide a new horizon on the design of anticancer herbal medicines.