Sorellin und Hobartin,zwei neue Indolalkaloide aus Aristotelia peduncularis (LABILL.) HOOK. F. 173. Mitteilung über organische Naturstoffe

Sorelline and Hobartine, Two New Indole Alkaloids from Aristotelia peduncularis (LABILL .) HOOK . F. From Aristotelia peduncularis (LABILL .) HOOK . F. two new indole alkaloids, sorelline ( 1 ) and hobartine ( 2 ), have been isolated. Their structures were elucidated on the basis of spectroscopic data (the formulae represent their relative configurations). The alkaloids 1 and 2 have closely related structures with a monosubstituted indole moiety and an unrearranged monoterpene unit in the aliphatic part.     

A mass spectrometric investigation of non-covalent interactions between ruthenium complexes and DNA

Electrospray ionisation mass spectrometry was used to investigate reactions between six ruthenium compounds and three different non self-complementary duplex oligonucleotides containing 16 base pairs. Each of the compounds studied formed non-covalent complexes containing between one and five ruthenium molecules bound to DNA. Competition experiments involving duplex 16mers and pairs of ruthenium compounds were used to determine the order of relative binding affinities of the metal compounds. Other competition experiments involving ruthenium compounds, and the organic DNA binding agents daunomycin and distamycin, provided information about the sites and modes of DNA binding of the ruthenium compounds.     

Natural benzofurans. Synthesis of medicagol methoxybenzofuran

A general route to 2-arylbenzofurans, consisting of reaction of an o-halogenophenol ester with a cuprous arylacetylide, was employed to synthesize medicagol methoxybenzofuran. 2,4-Diraethoxyacetophenone was converted to 2,4-dimethoxyphenylacetylene in three steps and reaction of the cuprous salt with 2-iodo-4,5-methylenedioxyphenyl acetate gave the desired 2-(2′,4′-dimethoxyphenyl)-5,6-methylenedioxybenzofuran.     

Design, synthesis, and binding affinities of pyrrolinone-based somatostatin mimetics

[structure: see text] Tetrapyrrolinone somatostatin (SRIF) mimetics (cf. 1), based on a heterochiral (D,L-mixed) pyrrolinone scaffold, were designed, synthesized, and evaluated for biological activity. The iterative synthetic sequence, incorporating the requisite functionalized coded and noncoded amino acid side chains, comprised a longest linear synthetic sequence of 23 steps. Binding affinities at two somatostatin receptor subtypes (hsst 4 and 5) reveal micromolar activity, demonstrating that the d,l-mixed pyrrolinone scaffold can be employed to generate functional mimetics of peptide beta-turns.     

Predicting adsorption isotherms of low-volatile compounds by temperature programmed desorption: iodine on carbon

Equilibrium adsorption isotherms for low-volatile compounds are extremely difficult to measure. A simple technique using temperature programmed desorption (TPD) is proposed. It is demonstrated that the two parameters needed for constructing the Langmuir isotherm can be derived with data from the TPD technique alone. Thus, the Langmuir isotherms of iodine on AX-21 super-activated carbon were obtained with this technique. A series of TPD experiments for samples with different initial loadings of iodine were carried out by varying the heating rates which resulted in different peak desorption temperatures. The peak desorption temperature decreased as the initial loading was increased because of the re-adsorption effect. The Langmuir constant was derived from kinetic theory with the activation energy for desorption obtained from the experiment. The activation energy for desorption was 12.3 kcal/mol. The Langmuir constants determined by this technique were in comparable order of magnitude to the reported values for iodine on activated carbon. The saturation capacity of AX-21 for iodine could also be determined from the TPD data obtained from samples with different initial loadings. The estimated saturation capacity from the TPD experiment was 2.96 g I(2)/g AX-21, which was close to the experimentally measured saturation capacity of 3.25 g I(2)/g AX-21 for the same system.     

Processes of flats induced by higher dimensional processes III

Stationary processes of k-flats in ^d can be thought of as point processes on the Grassmannian _k ^d of k-dimensional subspaces of ^d . If such a process is sampled by a (d–k+ j)-dimensional space F, it induces a process of j-flats in F. In this work we will investigate the possibility of determining the original k-process from knowledge of the intensity measures of the induced j-processes. We will see that this is impossible precisely when 1<k<d–1 and j=0,...,2[r/2]–1, where r is the rank of the manifold _k ^d . We will show how the problem is equivalent to the study of the kernel of various integral transforms, these will then be investigated using harmonic analysis on Grassmannian manifolds.The research of the first and third authors was supported in part by NSF grants DMS-9207019 and DMS-9304284. The research of the second author was supported in part by NFR contract number R-RA 4873-306 and the Swedish Academy of Sciences.     

Boundary and Lens Rigidity of Lorentzian Surfaces

Let be a Lorentzian metric on the plane that agrees with the standard metric outside a compact set and so that there are no conjugate points along any time-like geodesic of . Then and are isometric. Further, if and are two dimensional compact time oriented Lorentzian manifolds with space--like boundaries and so that all time-like geodesics of maximize the distances between their points and and are ``boundary isometric', then there is a conformal diffeomorphism between and and they have the same areas. Similar results hold in higher dimensions under an extra assumption on the volumes of the manifolds.

     

Carbon-13 and nitrogen-15 nuclear magnetic resonance of physostigmine (eserine)

The ¹⁵N and ¹³C nmr spectra of physostigmine are discussed along with complete assignment of the signals. This alkaloid ¹⁵ N nmr spectrum is notable because it contains nitrogens in three different environments.