ABSTRACT
Synthesis of assumed natural (12R,13S)-enantiomers of pyriculariol (1) and dihydropyriculariol (2), phytotoxins isolated from rice blast disease fungus, Pyricularia oryzae, was achieved using Wittig reaction or microwave-assisted Stille coupling reaction as the key step. The synthesis revealed that the natural 1 and 2 are racemates. Foliar application test on a rice leaf indicated that both the salicylaldehyde core and side chain were necessary for phytotoxic activity. The fungus is found to produce optically active phytotoxins when incubated with rotary shaker, but racemic ones when cultured using an aerated jar fermenter.
Subject(s)
Ascomycota/metabolism , Mycotoxins/biosynthesis , Mycotoxins/chemistry , Oryza/microbiology , Ascomycota/physiology , Mycotoxins/toxicity , Oryza/drug effects , Oryza/growth & development , StereoisomerismABSTRACT
A new rifamycin antibiotic, salinisporamycin (1), has been isolated from a culture of a marine actinomycete. The producing organism was identified as Salinispora arenicola [corrected] on the basis of the 16S rRNA sequence. High-resolution FAB-MS established the molecular formula of 1 as C(33)H(43)NO(9). The planar structure of 1 was elucidated by NMR spectral analysis including COSY, heteronuclear single quantum coherence and heteronuclear multiple bond correlation. The relative stereochemistry of 1 was determined on the basis of rotating frame nuclear Overhauser effect spectroscopy. In addition, the solvatochromic behavior of 1 was investigated by measuring the UV spectra. This compound inhibited the growth of A549 cells, the human lung adenocarcinoma cell line, with an IC(50) value of 3 microg ml(-1), and also showed antimicrobial activity.
Subject(s)
Anti-Infective Agents/chemistry , Antineoplastic Agents/chemistry , Micromonosporaceae/metabolism , Rifamycins/chemistry , Anti-Infective Agents/metabolism , Anti-Infective Agents/pharmacology , Antineoplastic Agents/metabolism , Antineoplastic Agents/pharmacology , Cell Line, Tumor , Cell Proliferation/drug effects , Geologic Sediments/microbiology , Humans , Rifamycins/metabolism , Rifamycins/pharmacology , Water MicrobiologyABSTRACT
New nematicides named fumiquinones A (1) and B (2), together with spinulosin (3), LL-S490beta (4), and pseurotin A (5), were isolated from Aspergillus fumigatus and their structures were established by spectroscopic methods including 2D-NMR. Compound 1 showed effective nematicidal activities against Bursaphelenchus xylophilus and Pratylenchus penetrans without inhibiting plant growth except for lettuce seedlings. Compound 2 showed effective nematicidal activity against B. xylophilus, but had no inhibitory activity against P. penetrans. Compounds 3-5 showed effective nematicidal activities against B. xylophilus without any plant growth inhibition. Compounds 1-5 had no nematicidal activity against Caenorhabditis elegans. This is the first report of the nematicidal activities of compounds 3-5.
Subject(s)
Antinematodal Agents/metabolism , Aspergillus fumigatus/physiology , Quinones/metabolism , Animals , Antinematodal Agents/pharmacology , Caenorhabditis elegans/drug effects , Lactuca/drug effects , Pinus/drug effects , Quinones/pharmacology , Seedlings/drug effects , Tylenchoidea/drug effectsABSTRACT
A new ergothioneine derivative named beta-hydroxyergothioneine was isolated from the mushroom Lyophyllum connatum. Ergothioneine,N-hydroxy-N',N'-dimethylurea, and connatin (N-hydroxy-N',N'-dimethylcitrulline) were also isolated. All the compounds displayed the ability to scavenge free radicals, based on a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. Structural determination, including the absolute stereochemistry of beta-hydroxyergothioneine, was achieved by spectroscopic analysis and X-ray crystallography. The radical scavenging activity of beta-hydroxyergothioneine was almost the same as that of ergothioneine. beta-Hydroxyergothioneine showed the greatest protective activity against carbon tetrachloride-induced injury in primary culture hepatocytes.
Subject(s)
Agaricales/chemistry , Ergothioneine/analogs & derivatives , Ergothioneine/isolation & purification , Free Radical Scavengers/isolation & purification , Hepatocytes/drug effects , Animals , Biphenyl Compounds , Carbon Tetrachloride/antagonists & inhibitors , Cells, Cultured , Ergothioneine/pharmacology , Free Radical Scavengers/pharmacology , Hydrazines , Molecular Structure , Picrates , Rats , Rats, WistarABSTRACT
Our search for new 3-hydroxyfusicoccins structurally related to cotylenin A from a culture of Phomopsis amygdali Niigata 2-A resulted in the isolation of novel 3-hydroxy fusicoccins, called fusicoccins R and S, and the fusicoccin S aglycon, called phomopsiol, together with known 3alpha-hydroxyfusicoccin J. The structure of phomopsiol was identified as that of O-demethyl-3-epicotylenol based on spectroscopic evidence. The structures of fusicoccins R and S were also determined to be those of 3'-deacetyl-3alpha-hydroxyfusicoccin A and 3beta-hydroxy-3-epifusicoccin H. The lettuce seed germination-stimulating activity of fusicoccins R and S, phomopsiol and 3alpha-hydroxyfusicoccin J was examined in the presence of ABA; fusicoccin R and 3alpha-hydroxyfusicoccin J were highly active, while fusicoccin S and phomopsiol were inactive. The possible biosynthetic relationships among these novel fusicoccins having a 3alpha- or 3beta-hydroxy group in their diterpene moiety are briefly discussed.
