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Three new 4-hydroxy-2-pyridone alkaloids, arthpyrones A-C (1-3), were isolated from the sponge-derived fungus Arthrinium arundinis ZSDS1-F3. Their structures were elucidated on the basis of spectroscopic analysis, CD spectra, quantum chemical calculation, and X-ray single-crystal diffraction analysis. Compounds 1 and 2 possessed a 2-pyridone core featured with a decalin moiety linked via a carboxide bridge bearing a novel oxabicyclo[3.3.1]nonane ring system rarely discovered in nature. A possible biosynthetic pathway for them was proposed.

Background: Species of Cephalotaxus (the plum yews) produce nematotoxic compounds of unknown identity. Consequently, bioassay-guided fractionation was employed to identify the compound(s) in Cephalotaxus fortunei twigs and leaves with activity against plant-parasitic nematodes., Results: A crude alkaloid extract, particularly drupacine, was responsible for much of the nematotoxicity. The ED50 of drupacine for Bursaphelenchus xylophilus was 27.1 µg mL⁻¹, and for Meloidogyne incognita it was 76.3 µg mL⁻¹. Immersion of M. incognita eggs in 1.0 mg mL⁻¹ crude alkaloid extract (the highest tested concentration) reduced hatch by 36%; immersion of second-stage juveniles (J2) resulted in 72-98% immobility. Crude alkaloid extract and drupacine suppressed protease activity in extracts of the microbivorous nematode Panagrellus redivivus by 50% and 80%, respectively. Application of 0.02-0.5 mg mL⁻¹ crude alkaloid extract to soil with M. incognita inoculum did not significantly reduce pepper plant shoot length or weight, compared with nematode-inoculated, water-treated controls, but the number of eggs and J2 per root system respectively decreased by 69% and 73% at 0.5 mg mL⁻¹., Conclusion: Drupacine and a crude alkaloid extract suppress nematode hatch, activity of mixed life stages, and population numbers on plant roots. This is the first demonstration of nematotoxicity of crude Cephalotaxus alkaloids and drupacine., (© 2013 Society of Chemical Industry.)

A new carbazole alkaloid, streptoverticillin, and a new 2-azetidinone, streptoverticillinone, along with three known cyclodipeptides were isolated from the mycelial solid culture of Streptoverticillium morookaense. Their structures were elucidated by analysis of 1D and 2D NMR, mass spectra and optical rotation data. Two new compounds exhibited antifungal activity against Peronophythora litchii.

Two new quinazoline alkaloids, 2-(2-carboxyethyl)-8-hydroxyquinazolin-4(3H)-one ( 1) and 2-(2-carboxyethyl)6-hydroxyquinazolin-4(3H)-one ( 2), along with the previously synthesized 2-(4-hydroxyphenyl)quinazolin4(3H)-one ( 3), were isolated from the solid cultures of Streptomyces michiganensis strain SC0642. Their structures were elucidated by spectroscopic methods. [ABSTRACT FROM AUTHOR]

A novel Cephalotaxus alkaloid with an N -alkyl-3-benzazepine skeleton, cephalofortunone ( 1 ), and known congeners, cephalotaxine, drupacine, and demethylcephalotaxinone, were isolated from the stems of Cephalotaxus fortune Hook. f. Their structures were elucidated on the basis of spectroscopic data. The absolute configuration of 1 was assigned by the comparison of its experimental solution CD spectrum with the TDDFT-calculated one on DFT-optimized geometries. This is the first cephalotaxine derivative with an N -alkyl chain rather than 1-azaspiro[4.4]nonane moiety from Cephalotaxus spp. [ABSTRACT FROM AUTHOR]

Seven new dimeric tryptophol-related alkaloids (1–4, 5a, 5b , and 6) were isolated from solid cultures of the endophytic fungus Colletotrichum sp. SC1355. The structures and absolute configurations of these compounds were determined by NMR spectroscopic analyses in combination with quantum chemical calculations of NMR (GIAO) shifts and ECD spectra. This is the first report of fungus-derived tryptophol dimers. In addition, the isolated compounds were evaluated for acetylcholinesterase (AchE) inhibitory activity. Unlabelled Image [ABSTRACT FROM AUTHOR]

isolation and structure elucidation [ABSTRACT FROM AUTHOR]

isolation, structure determination and biological activity of nine new oxindole alkaloids, cyclopiamides B-J (I)-(V) [ABSTRACT FROM AUTHOR]