Sophalines E–I, Five Quinolizidine-Based Alkaloids with Antiviral Activities against the Hepatitis B Virus from the Seeds of Sophora alopecuroides

Five novel quinolizidine-based alkaloids (1–5) were obtained from the seeds of Sophora alopecuroides L. Compounds 1 and 2 are the first examples of sparteine-indolizine and matrine-indolizine alkaloids, respectively, whereas 3 and 4 are epimeric normatrine-julolidine alkaloids with unusual skeletons. The structures of these compounds were determined by spectroscopic methods, single-crystal X-ray diffraction, and electronic circular dichroism analyses. Hypothetical biosynthetic pathways of 1–5 were proposed. Compound 2 exhibited significant antiviral activity against the hepatitis B virus.