Three new cyclic peptides, tunicyclins B-D, and a known cyclic peptide, psammosilenin B, were isolated from the root of Psammosilene tunicoides. The structures of new cyclic peptides were elucidated by extensive NMR and MS analysis. Tunicyclin B contains an unusual alpha,beta-dehydrotryptophan (Delta(Z)-Trp) residue, previously reported from marine sponges and bacteria. Tunicyclin D showed a broad spectrum of antifungal activity against Candida albicans (SC5314), Candida albicans (Y0109), Candida tropicalis, Candida parapsilosis, and Cryptococcus neoformans (BLS 108) with MIC80 values of 4.0, 16.0, 0.25, 1.0, and 1.0 mu g mL(-1), respectively.