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Spectroscopic Means (spectroscopic + mean)
Selected AbstractsIsolation and Characterization of New Bitter Diterpenoids from the Basidiomycete Sarcodon scabrosusHELVETICA CHIMICA ACTA, Issue 11 2004Bing-Ji Ma The novel cyathane-type diterpenoids scabronine G and H (1 and 2, resp.) were isolated from the fruiting bodies of the basidiomycete Sarcodon scabrosus together with four known compounds, allocyathin B2 (3), sarcodonin A (4), sarcodonin G (5), and scabronine F (6). Their structures were determined by spectroscopic means, including 2D-NMR (HMBC, HMQC, ROESY, 1H,1H-COSY). [source] Isolation and Structure Elucidation of Enniatins L, M1, M2, and N: Novel Hydroxy AnalogsHELVETICA CHIMICA ACTA, Issue 8 2004Pornrapee Vongvilai Four new cyclohexadepsipeptides, enniatins L (1), M1 (2), M2 (3), and N (4), have been isolated from an unidentified fungus (BCC 2629), together with the known enniatins B (5), H (6), and I (7), MK1688 (8), and enniatin B4 (9). Compounds 1,4 are the first enniatin analogs with an OH group at the side chain of one of the 2-hydroxycarboxylic acid residues. The structures of 1,4 were elucidated by spectroscopic means and by X-ray crystallography. [source] Two Novel Triterpenes from the Leaves of Ficus microcarpaHELVETICA CHIMICA ACTA, Issue 5 2004Yueh-Hsiung Kuo Two novel triterpenes, 29(20,19)abeolupane-3,20-dione (4) and 19,20-secoursane-3,19,20-trione (5), besides (3,)-3-hydroxy-29(20,19)abeolupan-20-one (2), lupenone, and , -amyrone (6), were isolated from the leaves of Ficus microcarpa and were characterized by spectroscopic means, including 2D-NMR techniques and chemical methods. Compound 4 is the second derivative having the 29(20,19)abeolupane skeleton, and 5 is a novel skeleton. A biosynthetic pathway to 5 is proposed (Scheme). [source] Two Novel 14-Nor-13,14-secopodocarpanes from the Bark of Taiwania cryptomeriodesHELVETICA CHIMICA ACTA, Issue 2 2004Shih-Chang Chien The two novel compounds cryptomelactones A (3) and B (4) were isolated from the bark of Taiwania cryptomeriodes, besides the two known podocarpane derivatives 1,,13,14-trihydroxypodocarpa-8,11,13-trien-7-one (1) and 3,,13,14-trihydroxypodocarpa-8,11,13-trien-7-one (2), and were characterized by spectroscopic means including 2D-NMR techniques. Compounds 3 and 4 are novel-14-nor-13,14-seco-podocarpanes. The absolute configurations of 3 and 4 were determined by the modified Mosher method. The biotransformation mechanism of 3 and 4 is proposed. [source] Isolation of coumarins and ferulate from the roots of Angelica purpuraefolia and the antitumor activity of khellactonePHYTOTHERAPY RESEARCH, Issue 5 2007Hyeong-Kyu Lee Abstract A new coumarin, hydroxylomatin (1), was isolated from the CHCl3 -soluble fraction of the roots of Angelica purpuraefolia, along with one ferulate (2) and three other known coumarins (3,5) including khellactone (3). The structure of hydroxylomatin (1) was determined to be 3,,,5,-dihydroxy-3,,4,-dihydroseselin (1) by spectroscopic means including 2D-NMR. The modified Mosher's method was used to determine the chiral center at C-1 of compound 2. Khellactone (3) is a major compound of the roots of A. purpuraefolia. This study also examined the antitumor activity of khellactone (3) using a LLC mouse lung carcinoma in the BDF-1 mice and a NCI-H460 human lung carcinoma in a human tumor xenograft model in nude mice. This compound (3) inhibited LLC tumor growth with a T/C (mean value of treated group/mean value of control group) value of 12.9% at a dose of 5 mg/kg and 33.2% at a dose of 10 mg/kg, respectively, in a dose-dependent manner. In addition, it suppressed the growth of NCI-H460 tumor cells, accounting for 81.4% at a dose of 10 mg/kg in nude mice. Copyright © 2007 John Wiley & Sons, Ltd. [source] Precursor-derived Si,(B,)C,N ceramics: thermolysis, amorphous state and crystallization,APPLIED ORGANOMETALLIC CHEMISTRY, Issue 10 2001Joachim Bill Abstract The preparation of silicon nitride- and carbide-based ceramics by solid-state thermolysis of polysilazanes and polysilylcarbodiimides is described. Results on the ceramization of the preceramic compounds and the architecture of the corresponding amorphous states obtained by spectroscopic means and by X-ray and neutron scattering are reviewed. Fundamental correlations between the composition and structure of the preceramic compounds and the architecture of the amorphous state are revealed. Furthermore, the crystallization behavior of the amorphous precursor-derived Si,C,N ceramics is treated. Moreover, the influence of boron on the thermal stability of the amorphous state is described. The high-temperature behavior of these Si,B,C,N solids can be correlated with their phase composition. Ceramic materials with compositions located close to the three-phase equilibrium SiC,+,BN,+,C exhibit a high temperature stability up to 2000,°C. This effect is accompanied by the formation of a metastable solid consisting of Si3N4 and SiC nanocrystals that are embedded in a turbostratic B,C,N matrix phase. Based on thermodynamic considerations, a model for the high-temperature stability effect is proposed. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||