Staminolactones A and B and norstaminol A: three highly oxygenated staminane-type diterpenes from Orthosiphon stamineus

[formula: see text] Staminolactones A (1) and B (2) and norstaminol A (3), three highly oxygenated staminane-type diterpenes having mild cytotoxic activities against highly liver-metastatic colon 26-L5 carcinoma cells, were isolated from the aerial part of the Vietnamese medicinal plant Orthosiphon stamineus (Lamiaceae). Their structures were elucidated on the basis of the extensive spectral analyses.     

Evaluation of a commercial immunoassay for the detection of chlorfenapyr in agricultural samples by comparison with gas chromatography and mass spectrometric detection

A commercially available enzyme-linked immunosorbent assay (ELISA) kit with a high affinity monoclonal antibody was applied to residual analysis of insecticide chlorfenapyr in agricultural samples, and drawn a parallel between the ELISA and gas chromatography (GC) with mass spectrometry (MS). For standards prepared in water containing 5% (v/v) methanol, the sensitivity (I50 value), the dynamic range, and the limit of detection of the ELISA kit were 2.3, 1 - 10, and 0.1 ng/g, respectively. The used monoclonal antibody in the ELISA kit had a high selectivity. The ELISA kit was applied to the determination of chlorfenapyr in two kinds of fruits (apple and peach). The examination of the influence of these matrices on the reliability of the assay performance indicated that the ELISA could determine it in these samples near the regulation values in Japan simply by diluting the methanolic extract or by concentrating it, without any clean-up procedures. Recovery and precision of the proposed ELISA method were assessed by fortifying fruit samples with chlorfenapyr ranging from 0.05 to 1.5 microg/g. Mean recoveries were 94.2 and 90.3% for apple and peach, and coefficients of variation were below 16% in most cases. The results obtained from the proposed ELISA method correlate well the reference GC/MS method for both fruit samples (r > 0.98). These considerations make the ELISA kit very useful analytical tool for monitoring and regulatory programs, without the need of complex and expensive instrumentation.     

Convergent synthesis of the F-K ring segment of brevetoxin B

A convergent synthesis of the F-K ring segment of brevetoxin B has been achieved via the intramolecular allylation of an α-chloroacetoxy ether and subsequent ring-closing metathesis.     

Epicalyxin F and calyxin I: two novel antiproliferative diarylheptanoids from the seeds of Alpinia blepharocalyx

[formula: see text] Epicalyxin F (1) and calyxin I (2), two novel diarylheptanoids, were isolated from a residual fraction of an EtOH extract of Alpinia blepharocalyx. Calyxin I (2) represented a new carbon skeleton, and epicalyxin F (1) possessed potent antiproliferative activity toward HT-1080 fibrosarcoma and colon 26-L5 carcinoma with ED50 values of 1.71 and 0.89 microM, respectively.     

Quadranosides VI-XI, six new triterpene glucosides from the seeds of Combretum quadrangulare

Six new triterpene glucosides, quadranosides VI-XI (1-6), belonging to three different [ursane- (1-4), oleanane- (5) and lupane-type (6)] triterpene classes, have been isolated from a MeOH extract of the seeds of Combretum quadrangulare KURZ (Combretaceae), together with nine known compounds, rosamutin (7), 28-O-beta-D-glucopyranosyl-6beta,23-dihydroxytormentic acid (8), arjunetin (9), arjunglucoside II (10), combreglucoside (11), chebuloside II (12), vitexin (13), (+)-catechin (14) and (-)-epigallocatechin (15). The structures of these compounds were elucidated by spectroscopic analysis.     

PHYTOCHROME-MEDIATED PHOTOTROPISM AND DIFFERENT DICHROIC ORIENTATION OF Pr AND Pfr IN PROTONEMATA OF THE FERN ADIANTUM CAPILLUS-VENERIS L.

Abstract— Single-celled protonemata of Adiantum capillus-veneris were cultured under continuous red light for 6 days and then in the dark for 15 h. Brief local exposure of a flank (5 times 20 /mi) of the subapical region of a protonema to a microbeam of red light effectively induced a phototropic response toward the irradiated side. The degree of the response was dependent upon the fluence of the red light. Red/far-red reversibility was typically observed in this photoreaction, showing that phytochrome was the photo-receptive pigment. When the flank was irradiated with a microbeam of linearly polarized red and far-red light, red light with an electrical vector parallel to the cell surface was most effective. However, the far-red light effect was most prominent when its electrical vector was normal to the cell surface. These polarized light effects indicate the different dichroic orientation of P_r (red-light-absorbing form of phytochrome) and P_r (far-red-light-absorbing form of phytochrome) at the cell flank.     

On Wainer's notation for a minimal subrecursive inaccessible ordinal

We show the following results on Wainer's notation for a minimal subrecursive inaccessible ordinal τ: First, we give a constructive proof of the collapsing theorem. Secondly, we prove that the slow-growing hierarchy and the fast-growing hierarchy up to τ have elementary properties on increase and domination, which completes Wainer's proof that τ is a minimal subrecursive inaccessible. Our results are obtained by showing a strong normalization theorem for the term structure of the notation. MSC: 03D20, 03F15.     

Perylene-tetrapalladium sandwich complexes

Bis-perylene-tetrapalladium sandwich complexes are synthesized and structurally characterized. These are the first examples of bis-arene sandwich complexes having metal-metal bond chains. X-ray crystallographic analyses showed that the tetrapalladium chain is bound to perylene ligands at the C8 edge position.