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Merulidial, a new antibiotic, was isolated from the culture fluid of the Basidiomycete Merulius tremellosus FR., strain No. WQ 568. Merulidial inhibits a variety of bacteria and fungi. In cells of the ascitic form of EHRLICH carcinoma, DNA synthesis is inhibited at lower concentration as compared to RNA and protein synthesis. Merulidial shows mutagenicity when incubated with the his--mutant TA 100 for Salmonella typhimurium (B.N. AMES). The molecular formula as determined by high resolution mass spectrometry is C15H20O3.

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 β-resorcylic and salicylic acid, carrying monounsaturated C17-alkyl side chains in 6-position. The merulinic acids are mixtures of the Δ8′-compounds with minor amounts of the corresponding Δ10′-, dehydro, and dihydro derivatives, separable only by means of HPLC. Δ8′-Merulinic acid A (1) 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 μg/ml of merulinic acid B and C or by 73 μg/ml of merulinic acid A.

A reinvestigation of the aerial parts of TEUCRIUM SCORDIUM afforded in addition to several known diterpenes five new clerodane derivatives, all closely related to teucrin. The structures and the stereochemistry were elucidated by high resolution (1)H-NMR spectroscopy.

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