Potential anti-H1N1 schitriterpenoids from Kadsura japonica L. vines

Lethal contagious pathogens wreak havoc on human life and the global economy, especially influenza and other respiratory pathogens, as exemplified by the enduring impact of COVID-19. This study reports that triterpenoids isolated from the stems of medicinal plants Kadsura japonica L. (Schisandraceae), which exhibit potent anti-viral activity against collected influenza viruses. Collectively, four undescribed schitriterpenoids named kadsujanonols J-M (1-4) along with five previously reported, schincarin D (5), ananosin E (6), changnanic acid (7), longipedlactone A (8), and schiglansin S (9), were isolated and identified. Their chemical structures were determined using ¹H-, ¹³C-, and 2D-NMR spectra in conjunction with spectroscopic analyses, such as UV, IR, ECD, and HRESIMS. These schitriterpenoids were then subjected to antiviral examination against the collected H1N1 influenza viruses, in which several, changnanic acid (7) in particular, unveiled excellent anti-H1N1 activity compared to Tamiflu.