New natural cyclosporins were isolated from the mycelium of surface cu
ltivated fungus Tolypocladium terricola. The chemical structures of [L
eu(4)] CS and [MeLeu(1)] CS = cyclosporin-J, were deduced from the NMR
and mass spectral data. Biological activity of new cyclosporins is re
ported based on the proliferative mitogen stimulation test.