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Continuous cropping often leads to plant diseases caused by root-knot nematodes (RKN). Owing to the difficulty in laboratory culture of RKN, microbial biocontrol agents are mainly screened for through contact killing assay, which requires a substantial effort to acquire RKN. This study was undertaken to verify the feasibility of using Caenorhabditis elegans – a model nematode that can be easily grown in the laboratory – to screen for microbial antagonists against RKN. Tomato (Solanum lycopersicum L. cv. Houpi Maofen 802) plants were grown in pots containing RKN-infested soil with and without inoculation of an antagonistic actinobacterial strain, designated Streptomyces albidoflavus T4. Exposure to T4 culture filtrate that contained catecholate siderophore and indole acetic acid resulted in a mortality rate of 95.4% for C. elegans and increased seed vigor by 113% for tomato. While root rotting rate and RKN incidence decreased following T4 inoculation, plant survival rate and stem diameter increased correspondingly. The root-associated microbiota of inoculated plants were optimized, as indicated by increased proportions of potentially beneficial bacteria (e.g. Bacillus amyloliquefaciens) and decreased proportions of pathogenic fungi (e.g. Fusarium oxysporum). The results demonstrate the outstanding performance of S. albidoflavus T4 to control root-knot disease and benefit tomato plant growth through multifaceted mechanisms. [ABSTRACT FROM AUTHOR]

Actinomycin Z6 (1), a new member of the actinomycin family, along with three congeners of the Z-type (Z1, Z3, Z5) actinomycins, are produced from Streptomyces sp. KIB-H714. Their structures were authenticated by comprehensive spectroscopic data interpretation. Different from all the reported Z-type actinomycins, the β-ring of the new compound actinomycin Z6 includes an additional ring linked between the actinoyl chromophore and β-peptidolactone. In Z3 and Z5, the L-threonine in β-depsipeptide is replaced by the unusual 4-chlorothreonine, an amino acid rarely found in actinomycin family. All isolates were evaluated for cytotoxicity against five human tumor cell lines and for inhibitory activity against Candida albicans and Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

Rubrolones are tropolonoid natural products with a unique carbon skeleton. Extensive secondary metabolite analysis of the endophytic Streptomyces sp. KIB-H033 revealed a new class of rubrolone analogue possessing a rare benzoic acid-pyridine inner salt moiety. Precursor feeding with [(13)C]-acetate revealed a labeling pattern consistent with tropolone moiety construction via type-II PKS chemistry followed by complex oxidative rearrangements. This bacterial biosynthetic route represents a surprising departure from fungal tropolone assembly during stipitatic acid biosynthesis.

Duclauxamide A1 (1), a new polyketide-derived heptacyclic oligophenalenone dimer with a N-2-hydroxyethyl moiety, was isolated from Penicillium manginii YIM PH30375. Spectroscopic analysis, X-ray single crystal diffraction, and (13)C NMR DFT calculations confirmed that compound 1 and other duclauxin analogues possess the unified S configuration at C-9', which corrects a long-standing misrepresentation of duclauxins as C-9'R epimers. A plausible biosynthetic pathway for duclauxins is proposed on the basis of previous acetate labeling results for duclauxin and sclerodin.

The title compound, C(10)H(13)ClN(2)O, was obtained as a by-product in the reaction of 2-chloro-methyl-1H-benzimidazole, dimethyl sulfate and toluene to synthesise 2-chloro-methyl-1-methyl-benzimidazole. The dihedral angle between the benzene ring and the acetamide group is 89.72  (6)° while that between the aromatic ring and the chloracetyl group is 84.40 (4)°. In the crystal, adjacent mol-ecules are linked by pairs of N-H⋯O hydrogen bonds into inversion dimers.

The title compound, C(15)H(14)O(3), has been obtained from the reaction of 2,4-dihy-droxy-acetophenone, potassium carbonate and benzyl bromide. The remaining hy-droxy group is involved in an intra-molecular O-H⋯O hydrogen bond. In the crystal, inter-molecular C-H⋯O contacts occur.

The title compound, C(16)H(14)Cl(2)O(4)S, was obtained by the reaction of eugenol (4-allyl-2-meth-oxy-phenol) and 3,4-dichloro-benzene-sulfonyl chloride. The dihedral angle between the benzene rings in the mol-ecule is 40.53 (4)°. No significantly short inter-molecular contacts are observed in the crystal structure.

The title compound, C(13)H(11)Cl(2)N(3)O(2), was obtained by the reaction of eugenol and cyanuric chloride. The dihedral angle between the benzene and triazine rings is 87.56 (4)°. Two C atoms of the allyl group are disordered over two sites in a 0.72 (2):0.28 (2) ratio.

The title compound, C(15)H(12)F(2)O(3), has been obtained by the reaction of 2,4-dihy-droxy-lacetonephenone, potassium carbonate and 3,5-difluoro-benzyl bromide. The hy-droxy group is involved in an intra-molecular O-H⋯O hydrogen bond in each of the two independent mol-ecules in the asymmetric unit. The dihedral angle between the aromatic rings is 0.5 (2)° in one molecule and 1.9 (2)° in the other. In the crystal, weak C-H⋯O inter-actions link the mol-ecules into tetra-meric units aligned perpendicular to b.

In the title compound, C(15)H(12)F(2)O(2), the dihedral angle between the aromatic rings is 70.43 (4)°. The crystal packing exhibits no significantly short inter-molecular contacts.

Two new polyketide-derived pigments, named rufoolivacins B (), and D (), with a 4',10-coupled aryl linkage between polysubstituted 1-naphthol and 1,4- or 1,2-anthraquinone, together with nine known metabolites including rufoolivacins A () and C (), have been isolated from the fruiting bodies of the Chinese toadstool Cortinarius rufo-olivaceus (basidiomycetes). Their structures were characterized on the basis of spectroscopic methods, including 2D-NMR experiments (COSY, NOESY, HSQC, and HMBC). The axial chirality of and was assigned through analysis of their CD spectra and ZINDO and TDDFT calculations. Compounds and were found to be unusual natural products incorporating an ortho-anthraquinone chromophore. All the metabolites were shown to be toxic toward the brine shrimp.

The title compound, C(11)H(13)ClO(3), has been obtained in the reaction of 2, 4-dihydroxy-lacetonephenone, potassium carbonate and 1-bromo-3-chloro-hexane. The hydr-oxy group is involved in an intra-molecular O-H⋯O hydrogen bond. The crystal packing exhibits no significantly short inter-molecular contacts.

From the medicinal plant Ginkgo biloba the fungal endophyte Alternaria no.28 was isolated. Extract of the fungus grown in liquid culture media exhibited marked cytotoxic activity when tested in vitro against brine shrimp (Artemia salina). Eight compounds were isolated from the extract of cultures of this endophytic fungus and were elucidated as alterperylenol (1), altertoxin I (2), alternariol (3), alternariol monomethyl ether (4), tenuazonic acid (5) and its derivative (6), together with ergosterol and ergosta-4, 6, 8, 22-tetraen-3-one by means of spectroscopic analysis. Among them, both 5 and 6 showed significant cytotoxic effects in the brine shrimp bioassy, with mortality rates of 73.6% and 68.9%, respectively, at a concentration of 10 microg x mL(-1), and they were first isolated from endophytic fungi.