C19 and C20 Diterpene Alkaloids from Aconitum toxicum Rchb.

Acotoxinine ( 1 ), a new norditerpene alkaloid, was isolated from the roots of Aconitum toxicum Rchb ., together with the structurally related C₁₉ diterpene alkaloids neoline ( 2 ) and aconitine ( 3 ) and C₂₀ diterpene alkaloids songorine ( 4 ) and songoramine ( 5 ). The structures were elucidated by HR‐MS and advanced NMR methods, including ¹H‐NMR, JMOD, ¹H,¹H‐COSY, HSQC, and HMBC experiments. This is the first report of C₂₀ diterpenoid alkaloids in Aconitum toxicum.     

Die Herzglykoside des Pfeilgiftes von Lophopetalum toxicum LOHER. 13. Mitteilung über Celastraceen-Inhaltsstoffe

The Heart Glycosides of the Arrow Poison of Lophopetalum toxicum LOHER From the cytotoxic and positive inotropic acting bark extract of the Philippinan Lophopetalum toxicum eight heart glycosides have been isolated and their structures have been elucidated mainly by field-desorption-MS- and ¹- and ¹³C-NMR spectroscopy. Besides the known k-Strophanthidin ( 1 ), Antiarigenin ( 6 ) and β-Antiarin (Antiarigenin-3-β-O-α-L -rhamnoside, 10 ) the following mono- and diglycosides could be identified: strophanthidin-3-β-O-α-6-desoxy-D -allopyranoside (strophalloside, 2 ), strophanthidin-3-β-O-β-6-desoxy-D -glucopyranoside (= Strophanthidin chinovoside, 3 ), strophanthidin-3-β-O[-4Oβ-D -allopyranosyl-β-6-desoxy-D -allopyranoside] ( 4 ), strophanthidin-3-β-O-[3-O-β-D -glucopyranosyl-β-6-desoxy-D -talopyranoside] ( 5 ), antiarigenin-3-β-O-[3-O-β-D -gulopyranosyl-β-6-desoxy-D -talopyranoside] ( 7 ), antiarigenin-3-β-O-[4O-β-D -allopyranosyl-β-6-desoxy-D -allopyranoside] ( 8 ), and antiarigenin-3-β-O-β-6-desoxy-D -allopyranoside (antiallosid) ( 9 ). The structure of strophanthidinchinovoside ( 3 ) could be confirmed by synthesis.     

Synthesis of Verrucarin A and 3α-Hydroxyverrucarin A from Verrucarol and Diacetoxyscripenol (Anguidine). 39th Communication on Verrucarins and Roridins

The title compounds have been synthesized starting from verrucarol and diacetoxyscripenol (anguidine), (E, Z)-muconic half ester and a derivative of verrucarinic acid. The latter has been prepared in optically active form from dimethyl 3-methylglutarate.     

The Absolute Configuration of the Fungal Metabolite Verrucarin B. Biosynthetic Consequences. Verrucarins and roridins, 36th communication

The absolute configuration of verrucarin B (2) has been determined by a single crystal X-ray diffraction analysis. This result permits the stereochemistry of the biogenetic transformation of mevalonic acid (12) to verrucarinic acid (7) to be deduced.     

Isolation of 2'-dehydroverrucarin A as metabolite of Myrothecium roridum Tode ex Fr.,species type by Fries. Verrucarin and roridin, 13

From cultures of Myrothecium roridum TODE ex FRIES 2′-dehydroverrucarin ( 1 ) was isolated. 1 is a genuin metabolite of the micro-organism.     

Revidierte Struktur von Verrucarin E. Eine Synthese des Antibioticums und verwandter β-Acetyl-Pyrrol-Derivate. Verrucarine und Roridine, 18. Mitteilung [1]

The structure of Verrucarin E, an antibiotic isolated from Myrothecium verrucaria, has been corrected (cf. [4]) and shown to be that of 3-acetyl-4-hydroxymethyl-pyrrole ( 2 ) by comparison with a variety of β-acetylpyrrole-derivatives, whose NMR. chemical shifts and coupling constants are reported. Verrucarin E ( 2 ) has been synthesized in low yield from 3-acetylpyrrole ( 12 ). The following previously unknown β-acetylpyrrole-derivatives are described: 3-acetyl-5-methyl-pyrrole-2-carbonic-acid ( 11 ), 4-acetyl-2-methyl-pyrrole ( 13 ), 3-acetyl-4-formyl-pyrrole ( 7 ), 3-acetyl-1-hydroxymethyl-pyrrole ( 14 ), 3-(3-hydroxypropionyl)-pyrrole ( 15 ), 3-(3-hydroxy-2-hydroxymethyl-propionyl)-pyrrole ( 16 ), and 3-(3-acetyl-pyrr-1-yl)-1-(pyrr-3-yl)-propan-1-one ( 17 ).     

Benzopentalenonaphthalenones from the intramolecular capture of a merocyanine derived from a naphthopyran

Novel, highly coloured benzopentalenonaphthalenones result from a cascade process initiated by the thermally-induced ring-opening of diarylmethanol substituted 2H-naphtho[1,2-b]pyrans in the presence of acid.     

Characterization of a lactate oxidase from a strain of gram negative bacterium from soil

A lactate oxidase was purified about 36-fold from a newly screened strain KY6 of gram negative bacterium from soil to yield a homogeneous protein. The native enzyme had a molecular mass of 204 kDa measured by Sephadex G-200 and that of subunit on the SDS-PAGE was found to be 45 kDa. The enzyme was optimally active at pH 7.7 and showed stability at pH range of 5.7 to 9.5 for 24 h at 4?C. The optimum temperature was 70?C and the enzyme activity was stable for 10 min up to 45?C. The half-life of the enzyme activity was about 10 min at 55?C. The best substrate of the enzyme was D-lactate and Km value for D-lactate was 0.14 mM. The Km value for DL-lactate was 0.20 mM. Substrate inhibition of the enzyme was observed at higher concentrations than 20 mM of DL-lactate and 10 mM of D-lactate.     

Radiation from metastable highly-charged ions extracted from a gas target

Few-electron ions of argon have been produced by heavy ion impact in a gas target. The recoil ions have been extracted into a region with high vacuum, and the K radiation of long-lived states has been observed by means of a position sensitive proportional counter oriented along the flight path of the ions. Fast ion beams are frequently used to determine the lifetimes τ of excited levels by time-of-flight techniques [1]. Typical ion velocities are v=1 cm/ns (beam energy 0.5 MeV/amu) or higher. The usual length l of experimental chambers rarely exceeds l=1 m. This decay path corresponds to roughly 100ns, and very few experiments on fast ion beams have been done on longer-lived states. Notable examples are the Berkeley measurements on the Ar¹⁶⁺ 1s2s³S₁ lifetime (calculated around τ=210 ns [2, 3], decay path ～8m) which resulted in a lower lifetime result (172±30ns) than expected and which were later shown to suffer from various systematic errors, the most important being the lack of spectral resolution of radiation from the helium-like or from core-excited lithiumlike ions. An alternative approach, a coincidence measurements of x-rays and projectile ions to associate the detected quanta with ions of a given charge state is difficult for high energy and high current ion beams.     

Rejection of a deviant point from a straight-line regression

A statistical procedure is described to help decide whether or not to reject a data point which deviates markedly from a straight-line regression. A Beer's law plot is used to illustrate the procedure.     

Quasistatic detachment of a sphere from a liquid interface

In this paper the problem of removing a spherical particle initially attached to a liquid-gas interface is analytically treated. In particular, the Derjaguin equation for small radii is used to derive a closed-form approximate expression for the work of detachment of the sphere from the interface. Expressions corresponding to the prescribed displacement condition and the applied force condition, which seems to be the relevant condition for the flotation separation process, are presented. A special effort has been made to closely compare analytical results with data obtained through the exact numerical treatment of the detachment process. Results show that proposed expressions are sufficiently accurate to calculate the energy required to detach the sphere from the interface as soon as the sphere radius is small compared to the capillary length. Validity limits are specified.     

Ircinianin,a Novel Sesterterpene from a Marine Sponge

Ircinianin ( 2 ), a new furano-sesterterpenetertronic acid, has been isolated from a marine sponge of the genus Ircinia. Structure 2 has been established by X-ray diffraction methods.     

The field far from a charge and a dipole

We consider the field far from charged and dipolar impurities in a fluid of polarizable non-polar atoms. Comparison with a recent computer simulation shows that classical continuum ideas are adequate for a charge, but not for a non-polarizable dipole; we present a very simple theory which agrees well with the simulation in that case. No simulation exists for a polarizable dipole, which we also discuss.     

Metal fragment exchange from a molybdaborane to a tungstaborane

Reaction of the molybdaborane arachno-2-[Mo(η-C₅H₅)(η⁵:η¹-C₅H₄)B₄H₇] (I) with the electron-rich molecule [W(PMe₃)₃H₆] at 60 °C for 12 h in toluene gives the novel tungstaborane nido-2-W(PMe₃)₃H₂B₄H₇[Mo(η-C₅H₅)(η⁵:η¹-C₅H₄)H₂] (II) in 60% yield. The reaction is almost quantitative when followed by NMR. This is a rare example of metal fragment exchange within a metallaborane cage. The molybdenum atom is retained in the molecule via a σ-bond between the substituted cyclopentadienyl ring and a basal boron atom in the metallaborane cluster.