[Antibiotics from basidiomycetes, VI. Merulinic acids A, B, and C, new antibiotics from Merulius tremellosus and Phlebia radiata (author's transl)].

Three new antibiotics, merulinic acids A, B, and C, have been isolated from fruiting bodies of Merulis tremellosus and Phlebia radiata. They are closely related derivatives of beta-resorcylic and salicylic acid, carrying monounsaturated C17-alkyl side chains in 6-position. The merulinic acids are mixtures of the delta8'-compounds with minor amounts of the corresponding delta10'-, dehydro, and dihydro derivatives, separable only by means of HPLC. delta8'-Merulinic acid A (I) was synthesized via a biomimetic cyclization of a linear precursor. The merulinic acids inhibit a variety of bacteria and are not active against fungi. RNA, DNA, and protein synthesis in Bacillus brevis and Ehrlich carcinoma ascites cells are inhibited shortly after the addition of the antibiotics. Almost complete hemolysis of human erythrocytes is caused by 25 microgram/ml of merulinic acid B and C or by 73 microgram/ml of merulinic acid A.