Main observation and conclusion Sophaloseedlines A-G (1-7), seven new matrine-based alkaloids along with two known analogues, were isolated from the seeds of Sophora alopecuroides. The new structures were determined based on extensive spectroscopic data, electronic circular dichroism calculations, and X-ray crystallography. Notably, sophaloseedline A (1) represents a novel rearranged 6(5 -> 17)-abeo-matrine alkaloid featuring unprecedented highly constructed 7/6/5/6 tetracyclic fused ring skeleton. The hypothetical biosynthetic pathways for sophaloseedlines A-F were proposed based on co-existing precursors. Additionally, all the isolated alkaloids were screened for their antiviral activities against hepatitis B virus, and new alkaloids 1 and 2 displayed more potent activities than those of matrine (a parent alkaloid of title plant) and positive control (lamivudine).