Two New Curine-Type Bisbenzylisoquinoline Alkaloids from the Roots of Cyclea wattii with Cytotoxic Activities

Two new curine-type bisbenzylisoquinoline alkaloids, wattisines A (1) and B (2) along with three known alkaloids were isolated from the roots of Cyclea wattii. Their structures were established by interpretation of NMR and high-resolution electrospray ionization (ESI)-MS data. Absolute configuration of wattisines A and B were determined by single-crystal X-ray diffraction and circular dichroism (CD) spectra, respectively. In vitro, wattisine A (1) showed significant cytotoxic activities with IC50 value of 1.74 mu M against HCT-8, and 7.29 mu M against Bel-7402.