Four Matrine-Based Alkaloids with Antiviral Activities against HBV from the Seeds of Sophora alopecuroides

Four
novel matrine-based alkaloids (1–4) were isolated from the seeds of Sophora
alopecuroides. Compounds 1 and 2 possess unprecedented 6/6/6/4 and 6/5/6/6 ring systems,
respectively, while 3 and 4 are a pair of
stereoisomeric matrine–acetophenone alkaloids with an unusual
skeleton. Their structures were elucidated by means of spectroscopic
methods and single-crystal X-ray diffraction. Hypothetical biogenetic
pathways for 1–4 are proposed, and
their antiviral activities are also discussed.