The Keap1/Nrf2/ARE system is a central defensive mechanism against oxidative stress which plays a key role in the pathogenesis and progression of many diseases. Nrf2 is a redox-sensitive transcription factor controlling a variety of downstream antioxidant and cytodefensive genes. Nrf2 has a powerful anti-inflammatory activity mediated via modulating NF-κB. Therefore, pharmacological activation of Nrf2 is a promising therapeutic strategy for the treatment/prevention of several diseases that are underlined by both oxidative stress and inflammation. Coumarins are natural products with promising pharmacological activities, including antioxidant, anticancer, antimicrobial, and anti-inflammatory efficacies. Coumarins are found in many plants, fungi, and bacteria and have been widely used as complementary and alternative medicines. Some coumarins have shown an ability to activate Nrf2 signaling in different cells and animal models. The present review compiles the research findings of seventeen coumarin derivatives of plant origin (imperatorin, visnagin, urolithin B, urolithin A, scopoletin, esculin, esculetin, umbelliferone, fraxetin, fraxin, daphnetin, anomalin, wedelolactone, glycycoumarin, osthole, hydrangenol, and isoimperatorin) as antioxidant and anti-inflammatory agents, emphasizing the role of Nrf2 activation in their pharmacological activities. Additionally, molecular docking simulations were utilized to investigate the potential binding mode of these coumarins with Keap1 as a strategy to disrupt Keap1/Nrf2 protein-protein interaction and activate Nrf2 signaling.

Berberine (BBR) is a natural compound of plant origin belonging to isoquinoline type of alkaloid. Methotrexate (MTX) is an anti-metabolite used widely for a variety of tumors and autoimmune conditions. Clinical uses of MTX were severely limited by its concomitant renal intoxication. The current study was designed to investigate the efficacy of BBR against MTX-induced nephrotoxicity and for exploring the underlying molecular mechanisms through examining the Keap1/Nrf2, NF-κB/P₃₈MAPK and Bax/Bcl2/caspase-3 pathways. Adults male rats were assigned to 4 groups: control, BBR, MTX and MTX + BBR. As compared to MTX-treated group, BBR effectively reduced the serum levels of creatinine, urea, uric acid and kidney/body weight ratio with a remarkable increase in serum level of albumin and the final body weight. Moreover, down-regulation of Keap1, P₃₈MAPK and NF-κB genes along with marked up-regulation of Nrf2 gene were observed. In addition, BBR negatively regulated both Bax and caspase-3 proteins expression along with increased expression of the Bcl2 protein. Also, BBR restored GSH content and SOD activity while it decreased both TBARS and NO₂^- contents. Biochemical findings confirmed and markedly supported by alleviation of histopathological changes in kidney tissues. Furthermore, MTX cytotoxic activity was markedly enhanced by BBR in vitro using some human cancer cell lines. In conclusion, the current findings indicated that co-administration of BBR with MTX may be a reasonable therapeutic strategy for attenuation of MTX -induced renal damage.

Mirtazapine (MTZ) is an antidepressant drug with an exceptional pharmacological profile. It also has an excellent safety and tolerability profile. The present review provides a pharmacological update on MTZ and summarizes the research findings of MTZ’s effects on different diseases. MTZ is hypothesized to have antidepressant effects because of the synergy between noradrenergic and serotonergic actions and is effective in treating major depressive disorder and depression associated with epilepsy, Alzheimer’s disease, stroke, cardiovascular disease, and respiratory disease. In cancer patients, MTZ significantly reduced sadness, nausea, sleep disruption, and pain and improved quality of life. Also, it has promising effects on Parkinson’s disease, schizophrenia, dysthymia, social anxiety disorder, alcohol dependency, posttraumatic stress disorder, panic disorder, pain syndromes, obsessive–compulsive disorder, and sleep disorders. Additionally, MTZ is potentially therapeutic in different situations associated with depression, such as liver, kidney, cardiovascular, respiratory, infertility, heavy metal-induced neurotoxicity, and pruritus. Potent antioxidative, anti-inflammatory, and anti-apoptotic bioactivities mediate these promising effects. These positive outcomes of the scientific investigations motivate more and more clinical trials for a golden exceptional antidepressant in different conditions.Graphical Abstract