Many of the medicinally active molecules in the flavonoid class of phytochemicals are being researched for their potential antiviral activity against various DNA and RNA viruses. Quercetin is a flavonoid that can be found in a variety of foods, including fruits and vegetables. It has been reported to be effective against a variety of viruses. This review, therefore, deciphered the mechanistic of how Quercetin works against some of the deadliest viruses, such as influenza A, Hepatitis C, Dengue type 2 and Ebola virus, which cause frequent outbreaks worldwide and result in significant morbidity and mortality in humans through epidemics or pandemics. All those have an alarming impact on both human health and the global and national economies. The review extended computing the Quercetin-contained natural recourse and its modes of action in different experimental approaches leading to antiviral actions. The gap in effective treatment emphasizes the necessity of a search for new effective antiviral compounds. Quercetin shows potential antiviral activity and inhibits it by targeting viral infections at multiple stages. The suppression of viral neuraminidase, proteases and DNA/RNA polymerases and the alteration of many viral proteins as well as their immunomodulation are the main molecular mechanisms of Quercetin’s antiviral activities. Nonetheless, the huge potential of Quercetin and its extensive use is inadequately approached as a therapeutic for emerging and re-emerging viral infections. Therefore, this review enumerated the food-functioned Quercetin source, the modes of action of Quercetin for antiviral effects and made insights on the mechanism-based antiviral action of Quercetin.

Plant-based nanoformulation is one of the novel approaches for therapeutic benefits. This research synthesized a silver nanoparticle from the polyherbal combination of four plants/seeds (Momordica charantia, Trigonella foenum-graecum, Nigella sativa, and Ocimum sanctum) and investigated its antidiabetic effects in streptozotocin-induced Wistar albino rat model. The polyherbal extract (PH) was extracted by the Soxhlet-solvent extraction method and the resulting crude extract was undergone for silver nanoparticle synthesis. The PH extract was subjected to a four-week intervention in fructose-fed streptozotocin-induced Wistar Albino rats’ models and in vitro antioxidative tests. Experimental animals (age: 6–7 weeks, male, body weight: 200–220 g), were divided into five groups including normal control (NC), reference control (RC), diabetic control (DC), and treatment groups PH200, PH100, and PHAgNP20. After three weeks of intervention, body weight, weekly blood glucose level, oral glucose tolerance test, AST, ALT, alkaline phosphatase, total cholesterol, triglycerides, uric acid, urea, and creatinine level of PH200 were found to be significantly (P < 0.05) improved compared to the diabetic control. The same dose demonstrated better regeneration of damaged pancreatic and kidney tissues. In vitro antioxidant assay manifested promising IC50 values of 86.17 μg/mL for DPPH, 711.04 μg/mL for superoxide free radical, and 0.48 mg/mL for Iron chelating activity of the polyherbal extract. GC-MS analysis impacted the major volatile compounds of the PH. The data demonstrate that the PH and its nanoparticles could be a novel source of antidiabetic therapeutics through an advanced dose-response study in the type 2 diabetic model.