Alopecines A–E, five chloro-containing matrine-type alkaloids with immunosuppressive activities from the seeds of Sophora alopecuroides

Alopecines A–E (1–5), five unusual matrine-type alkaloids featuring with an additional dichlorocyclopropane (1–3) or a di/tri-chloromethyl (4/5) attached on the D ring, were isolated from the seeds of Sophora alopecuroides. Their structures and absolute configurations were elucidated by extensive spectroscopic techniques, and X-ray diffraction analyses or time-dependent density functional theory-based electronic circular dichroism (TDDFT-ECD) calculations. Alkaloid 4 exhibited potent inhibitory effects on the proliferation of ConA-induced T lymphocytes or LPS-induced B cells with IC50 value of 3.98 or 3.74 μM, respectively.