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Two new acid sorbicillin analogues, (E)-6-(2,4-dihydroxyl-5-methylphenyl)-6-oxo-2-hexenoic acid (1) and 6-(2,4-dihydroxyl-5-methylphenyl)-6-oxohexanoic acid (2), together with 12 known compounds, were isolated from a saline lands-derived fungus Trichoderma sp. The structures of the new compounds were established by interpretation of their spectroscopic data. Their cytotoxic effects on P388 and HL-60 cell lines were preliminarily evaluated by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) method. Furthermore, the new compounds exhibited weak radical scavenging activity against DPPH (1,1-diphenyl-2-picrylhydrazyl). The Journal of Antibiotics (2011) 64, 645-647; doi:10.1038/ja.2011; published online 20 July 2011Keywords: cytotoxicity; fungus; sorbicillinoids; Trichoderma sp. INTRODUCTIONFungi of the genus Trichoderma are ubiquitous in the environment. In recent years, more and more attention has been paid to them because of a wide range of prospective utility 1 as biological control agents to suppress different fungal plant pathogens and to promote plant growth and for producing commercial enzymes, such as cellulases, hemicellulases, proteases and b-1,3-glucanase. 2 At the same time, many structurally novel and biologically active secondary metabolites have been reported from the species. For example, peptibols, 3 which are linear peptides characterized by an acetylated N-terminus, showed cytotoxic, membraneperturbing and antibiotic activities. Trichocaranes 4 A-D, isolated from Trichoderma virens, significantly inhibited the growth of etiolated wheat coleoptiles. In addition, a series of sorbicillin-related compounds 5-7 from Trichoderma showed moderate radical scavenging activity.In our search for cytotoxic compounds from fungi, a Trichoderma sp. was isolated from the saline lands soil collected along the coast of Bohai Bay in Zhanhua, Shandong Province, China. Its extract showed moderate activity to brine shrimp. The isolation work led to the finding of two new compounds (E)-6-(2,4-dihydroxyl-5-methylphenyl)-6-oxo-2-hexenoic acid (1) and 6-(2,4-dihydroxyl-5-methylphenyl)-6-oxohexanoic acid (2), along with 12 known ones, which were trichodimerol, bisvertinolone, adenosine, ergosterol, ergosterol peroxide, cerevisterol, 3b,5a-dihydroxy-6b-methoxyergosta-7,22-diene, (22E,24R)-5a,6a-epoxyergosta-8,22-diene-3b,7a-respectively. The known compounds were identified by comparison with previously reported physical and spectral data. In this paper, we reported the new compounds' isolation, structure elucidation, cytotoxic activities to P388 and HL-60 cell lines and radical scavenging activity against DPPH (1,1-diphenyl-2-picrylhydrazyl) (Figure 1).

Three new diastereomers of polyketides (PKs), raistrickiones A−C (1–3), together with two new analogues, raistrickiones D and E (4 and 5), were isolated from a highly productive strain of Penicillium raistrickii, which was subjected to an experimental thermo-change strategy to tap its potential of producing new secondary metabolites. Metabolites 1 and 2 existed in a diastereomeric mixture in the crystal packing according to the X-ray data, and were laboriously separated by semi-preparative HPLC on a chiral column. The structures of 1–5 were determined on the basis of the detailed analyses of the spectroscopic data (UV, IR, HRESIMS, 1D, and 2D NMR), single-crystal X-ray diffractions, and comparison of the experimental and calculated electronic circular dichroism spectra. Compounds 1–5 represented the first case of 3,5-dihydroxy-4-methylbenzoyl derivatives of natural products. Compounds 1–5 exhibited moderate radical scavenging activities against 1,1-diphenyl-2-picrylhydrazyl radical 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl (DPPH).

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