Dihydrochalcones from the leaves of Lithocarpus litseifolius.

Three new phlorizin derivatives, 6"-O-vanilloylphlorizin (1), 6"-O-(4-hydroxybenzoyl)phlorizin (2), 6"-O-feruloylphlorizin (3), along with four known dihydrochalcones, phlorizin (4), 3-hydroxyphlorizin, trilobatin, and 6"-O-acetylphlorizin were isolated from the leaves of Lithocarpus litseifolius. Their structures were established by analysis of extensive spectroscopic data. The new compounds were shown to be non-cytotoxic when tested against A549, HeLa, HepG2, and MCF-7 cell lines.

Xylarodons A and B, new hexaketides from the endophytic fungus Xylaria sp. SC1440.

Two new hexaketides, xylarodons B (1) and C (2), were isolated from solid cultures of the endophytic fungus Xylaria sp. SC1440. The structures of these compounds were elucidated on the basis of detailed 1D, 2D NMR, and HRESIMS analysis. Their absolute configurations were established by experimental and TDDFT calculated ECD spectra. The isolated compounds were evaluated for cytotoxic and tyrosinase inhibitory activity.

Absolute configurations of four resorcylic acid lactones, paecilomycins J-M, by CD/TDDFT calculations.

The absolute configurations of four resorcylic acid lactones (RALs), paecilomycins J-M (1-3 and 5), were assigned by Time-Dependent Density-Functional Theory (TDDFT) calculations of their electronic circular dichroism (CD) spectra. The previously reported structure 4 for paecilomycin M was found to be incorrect and should be changed to structure 5. Analysis of structure-spectrum relationship for this group of RALs suggested that V'-shape conformations give type I CD spectra (two negative Cotton effects around 300 and 260 nm, a positive Cotton effect around 220 nm) while V-shape conformations yield type II spectra (signs of three Cotton effects were opposite to those in type I).

Micropyrones A and B, two new α-pyrones from the actinomycete Microbacterium sp. GJ312 isolated from Glycyrrhiza uralensis Fisch.

Two new α-pyrones, micropyrones A (1) and B (2), along with four known γ-pyrones, nocapyrone D (3), nocapyrone A (4), marinactinone A (5), and nocapyrone H (6), were isolated from the culture extract of actinomycete Microbacterium sp. GJ312, which was isolated from Glycyrrhiza uralensis. The structures of these compounds were identified by analysis of spectral data. They are the first α- and γ-pyrones reported from the genus Microbacterium. The antibacterial activity of all compounds against Staphylococcus aureus and methicillin resistant S. aureus was evaluated. However, none of them showed significant activity. This study represents the first phytochemical example of a Glycyrrhiza-derived actinomycete.

Bioactive Diarylheptanoids from Alpinia coriandriodora.

Eight new diarylheptanoids, coriandralpinins A-H (1-8), were isolated from the rhizomes of Alpinia coriandriodora, an edible plant of the ginger family. Their structures, including the absolute configurations, were established by extensive spectroscopic analysis and ECD calculations. Compounds 1-8 have a 1,5-O-bridged diarylheptanoid structure featuring polyoxygenated aryl units. When evaluated for intracellular antioxidant activity using t-BHP stressed RAW264.7 macrophages, all these compounds scavenged reactive oxygen species (ROS) in a concentration-dependent manner. Compounds 3 and 5 also showed inhibitory activity against NO release in LPS-induced RAW 264.7 cells. Six known flavonols, 7,4'-di-O-methylkaempferol, 7-O-methylquercetin, 7,4'-di-O-methylquercetin, 7,3',4'-tri-O- methylquercetin, kaempferol 3-O-ß-D-(6-O-α-L-rhamnopyranosyl)glucopyranoside, and 3-O-ß-D-glucopyranuronosylquercetin were also isolated and characterized from the rhizomes.

Response of soil fauna to simulated nitrogen deposition: a nursery experiment in subtropical China.

We studied the responses of soil fauna to a simulated nitrogen deposition in nursery experimental plots in Subtropical China. Dissolved NH4NO3 was applied to the soil by spraying twice per month for 16 months, starting in January 2003 with treatments of 0, 5, 10, 15 and 30 gN/(m2 x a). Soil fauna was sampled after 6, 9, 13 and 16 months of treatment in three soil depths (0-5 cm, 5-10 cm, 10-15 cm). Soil available N increased in correspondence with the increasing N treatment, whereas soil pH decreased. Bacterial and fungal densities were elevated by the N treatment. Soil fauna increased in the lower nitrogen treatments but decreased in the higher N treatments, which might indicate that there was a threshold around 10 gN/(m2 x a) for the stimulating effects of N addition. The N effects were dependent on the soil depth and sampling time. The data also suggested that the effects of the different N treatments were related to the level of N saturation, especially the concentration of NO3- in the soil.