Seasonal influenza is an acute viral infection that spreads easily from person to person and is currently one of the major respiratory infections that pose a threat to human health. To date, the prevention and treatment of influenza has been mainly based on vaccination and the development of antiviral drugs. At present, the anti-influenza virus drugs used in clinical include matrix protein 2 inhibitors (such as amantadine), neuraminidase inhibitors (such as oseltamivir), endonuclease inhibitors(such as baloxavir), polymerase inhibitors(such as favipiravir), all of which have shown widespread resistance. The research and development of anti-influenza virus drugs with novel mechanisms and no cross-resistance to existing drugs is an effective means to solve the medical problem of seasonal influenza treatment, which has not yet been completely solved, and to deal with large-scale influenza outbreaks. The polymerase basic 2(PB2)of influenza virus RNA is not prone to drug resistance due to its high conserved nature among different influenza viruses, making it a very attractive drug target. At present, the research and development of PB2 inhibitors has become a hot spot for anti-influenza virus drugs, especially the research on the star molecule Pimodivir and its analogues has attracted great attention. Although Pimodivir was terminated in phase Ⅲ clinical trials due to its unsatisfactory efficacy, the binding pattern and structure-activity relationship between PB2 protein and small molecules revealed during its research process laid a solid foundation for the further development of this class of drugs. This article reviews the research progress of PB2 inhibitors in medicinal chemistry in the past 10 years, and puts forward the prospect of this drug research field.

In order to design a green, safe and generalizable gradient science popularization experiment, this study takes the natural pigment lac red pigment as the research object. Firstly, the lac red pigment was extracted from the Chinese medicinal material comfrey mushroom using the common reagents in the laboratory and substances in the family, which named laboratory method and home method, respectively. Secondly, the discoloration principle of lac red pigment extracted by two methods was verified. Finally, the science popularization was tried for the public of different ages. The laboratory method was to effectively extract lac red pigment from lac by salting out method, and preliminarily verified that the discoloration of lac red pigment was due to the acid-base ionization balance of lac red pigment. And the discoloration phenomenon of lac red pigment solution at different pH is obvious, and when the pH increases from low to high, the color of the solution changes to yellow, orange-yellow, orange, orange-red, light purple to purple. It can be used as an acid-base indicator with strong dyeing and coloring ability. Based on laboratory method, the home method used common substances with similar physical and chemical properties to replace the corresponding reagents, extracts lac red pigment from Chinese medicinal material comfrey, and verifies the discoloration reaction of lac red pigment. Therefore, the use of natural lac red pigment acid-base discoloration principle and dyeing agent can achieve gradient science popularization experiments for different levels of audiences.