Isoechinulin-type Alkaloids, Variecolorins A–L, from Halotolerant Aspergillus variecolor

Twelve new compounds, variecolorins A–L (1–12), together with eleven known analogues (13–23) were isolated from the broth of a halotolerant fungus, Aspergillus variecolor. The structures of compounds 1–12 were determined by chemical and spectroscopic methods. Compounds 1–11, 13–15, and 20–23 exhibited weak radical scavenging activity against DPPH, with IC50 values from 43 to 103 µM. The new compounds 1–12 all were essentially nontoxic against the P388, HL-60, BEL-7402, and A-549 cell lines with IC50 values from 70 to 260 µM.