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PubMed1982

[Antitumor effects of organic silicone compounds (IV). Antitumor effects of SDK-50 and SDK-47].

From the results of the 1st and 2nd screening as to the antitumor effect of organosilica compounds, two compounds, namely, SDK-50 (2-piperidinoethyl-phenyldimethyl-silane) and SDK-47 (3-N-2-propenylamino) propyltrimethyl-silane were selected. These two compounds were further tested by using the solid form cancer of Ehrlich, sarcoma-180 and Lewis lung carcinoma in mice and moreover the rats bearing ascites hepatomas. AH-13, 130, 272, 44, 66F, 66, 7974, 41-C, 60-C and 109A. From the summarized data, it may be said that the effect of SDK-50 is relatively superior to SDK-47. In addition of the inhibitory effect on cancer cells, it was found that SDK-50 possesses an activating effect of delayed type hypersensitivity. This effect of SDK-50 was equivalent to PSK or SPG.

Adjuvants, Immunologic↗
PubMed2003

Bis[bis(trimethylsilyl)amino]silylene, an unstable divalent silicon compound.

The title compound, [(Me3Si)2N]2Si: (1), was prepared by the reduction of [(Me3Si)2N]2SiBr2 (2) with potassium graphite at -78 degrees C. Unlike the corresponding germanium and tin compounds, 1 is unstable, but it can be studied in solution at low temperatures. The 29Si NMR chemical shift of 1 measured at -20 degrees C was 223.9 ppm, in good agreement with a value obtained from model calculations of 233 ppm. Reaction of solutions of 1 with methanol or phenol gave the trapping products expected for the silylene, [(Me3Si)2N]2Si(H)OR (R = CH3, C6H5).

Journal Article↗
PubMed2003

Fluoride-promoted rearrangement of organo silicon compounds: a new synthesis of 2-(arylmethyl)aldehydes from 1-alkynes.

A new approach to 2-(arylmethyl)aldehydes 4 based upon a 1,2-anionotropic rearrangement of an aryl group is presented. The synthetic sequence begins with a silylformylation reaction of terminal acetylenes 5 with aryl and heteroaryl silanes 6, followed by treatment of the products (Z)-1 with TBAF. The optimization of the experimental conditions of the fluoride-promoted step is described, together with the synthetic potentialities of the process. A plausible mechanism of the rearrangement reaction is reported that suggests the addition of the fluoride ion to the arylsilicon moiety of beta-silylalkenals (Z)-1 and the consequent migration of the aryl group to the adjacent carbon atom. Both aryl and heteroaryl substituents can rearrange without any loss of configuration. Bromo-functionalized substrates undergo an intramolecular reaction that affords exclusively carbacyclobenzyl aldehydes, further enhancing the high synthetic value of this method.

Journal Article↗
PubMed1989

[Antitumor effects of 5-fluorouracil-bound organic silicon compound].

5-fluoro-3,4-dihydro-2,4-dioxo-N-[2-2- (dimethylphenylsilyl)ethylthioethyl]-1(2H)-pyrimidinocarb oxamide (SDK-12B-5), a novel antitumor agent, is covalently linked with 5-fluorouracil (5-FU) and 2-[(2-dimethylphenylsilyl)ethylthio] ethylamine(SDK-103) which possesses itself antitumor activity against murine solid tumors. It has a broad antitumor spectrum in experimental tumor systems including murine leukemias. Furthermore, SDK-12B-5 administered p.o. with various treatment schedules inhibited significantly the tumor growth of human breast cancer (MX-1), colon cancer (Co-4) and lung cancer (LX-1 and OAT) cells in BALB/c nu/nu mice and the chemotherapeutic index was about 10 for 4 different human cancer xenografts. In the Lewis lung carcinoma (LLC) metastasis model, SDK-12B-5 in combination with amputation of tumors inhibited significantly both the lymph node metastases and lung metastases of LLC and prolonged the life span (%ILS:91%) of BDF1 mice. We also found that the cell killing effect of SDK-12B-5 was affected by both concentration and exposure time in cultured human lung cancer (OAT) cells using soft-agar colony assay. A significant augmentation of delayed type hypersensitivity (DTH) response induced by SDK-12B-5 in comparison with the mixture of SDK-103 and 5-FU was seen when it was administered p.o. simultaneously with the immunization of sheep red blood cell (SRBC) in retired CD1 mice. From the studies on tissue distribution and pharmaco-kinetics of SDK-12B-5 by HPLC and ICP analysis. the persistence of SDK-12B-5 levels in serum and tumors was correlated with the findings that a maximum chemotherapeutic effect was obtained when SDK-12B-5 was administered p.o. repeatedly with every other day to avoid the cumulative toxicity.

Animals↗
PubMedDate not supplied

Release and skin distribution of silicone-related compound(s) from a silicone gel sheet in vitro.

The efficacy of topical silicone gel sheeting in prevention and/or reduction of keloids and hypertrophic scars is well recognized. In the present study, we reexamined the possible release of silicone-related compound(s) from a commercially available silicone gel sheet (Cica-Care, Smith and Nephew, Hull, England) in aqueous media in vitro. The silicone gel sheet was also applied on the excised skin surface to examine the possible distribution of silicone-related compounds into the skin in vitro. Silicone-related compounds were measured as silicon by an inductively coupled plasma-atomic emission spectrophotometer. When a piece of silicone gel sheet was placed in phosphate buffer solution (pH 3-9) at 37 degrees C for 7 days, the concentration of silicon in the medium increased with time, depending on the pH of the medium. This indicates that the released silicone-related compounds are water-soluble. When Cica-Care was applied on the surface of excised rat skin, human axilla skin and hypertrophic scars under hydrated conditions in vitro, silicon was detected in all skin samples. Greater distribution was observed in rat skin than in human axilla skin and hypertrophic scars. The release of silicone-related compounds from a silicone gel sheet (Cica-Care) and their distribution into the skin were demonstrated in vitro. Silicone-related compounds distributed into the skin may have pharmacological effects on the skin. Further investigation will be necessary to investigate in detail the action of silicone-related compounds on the proliferation of fibroblasts and excessive production of collagen.

Adolescent↗
PubMed2000

Lithium, Sodium, and Copper(I) Supersilylphosphanediides M(2)PSitBu(3): Compounds with Novel Spherical (M(2)P)(n) Frameworks Compounds of Silicon, Part 133; Supersilyl Compounds of Phosphorus, Part 6. This work was supported by the Deutsche Forschungsgemeinschaft and by the Fonds der Chemischen Industrie. Part 132: N. Wiberg, T. Passler, S. Wagner, J. Organomet. Chem. 2000, 598/2, 304; Part 5: N. Wiberg, A. Wörner, H.-W. Lerner, K. Karaghiosoff, H. Nöth, Z. Naturforsch. B 1998, 53, 1004.

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Journal Article↗
PubMed2000

Spectra and structure of silicon containing compounds. XXVII. Raman and infrared spectra, conformational stability, vibrational assignment and ab initio calculations of vinyldichlorosilane.

The infrared (3200-30 cm(-1) spectra of gaseous and solid and the Raman spectra of liquid (3200-30 cm(-1), with quantitative depolarization values, and solid vinyldichlorosilane, CH2=CHSiHCl2, have been recorded. Both the gauche and the cis conformers have been identified in the fluid phases. Variable temperature (105-150 degrees C) studies of the infrared spectra of the sample dissolved in liquid krypton have been carried out. From these data the enthalpy difference has been determined to be 20 +/- 5 cm(-1) (235 +/- 59 J mol(-1) with the gauche conformer the more stable rotamer. It was not possible to obtain a single conformer in the solid even with repeated annealing of the sample. The experimental enthalpy difference is in agreement with the prediction from MP2/6-311 + G(2d,2p) ab initio calculations with full electron correlation. However, when smaller basis sets, i.e. 6-31G(d) and 6-311 + G(d,p) were utilized the cis conformer was predicted to be the more stable form. Complete vibrational assignments are proposed for both conformers based on infrared contours, relative infrared and Raman intensities, depolarization values and group frequencies, which are supported by normal coordinate calculations utilizing the force constants from ab initio MP2/6-31G(d) calculations. From the frequencies of the Si-H stretches, the Si-H bond distance of 1.474 A has been determined for both the gauche and the cis conformers. Complete equilibrium geometries have been determined for both rotamers by ab initio calculations employing the 6-31G(d), 6-311 + G(d,p) and 6-311 + (2d,2p) basis sets at level of Hartree-Fock (RHF) and/or Moller Plesset to the second order (MP2) with full electron correlation. The potential energy terms for the conformer interconversion have been obtained from the MP2/6-31G(d) calculations. The results are discussed and compared with those obtained for some similar molecules.

Molecular Conformation↗
PubMed2001

R$\rm{^{{\ast}}_{4}}$Tl(3)Cl and R$\rm{^{{\ast}}_{6}}$Tl(6)Cl(2) (R*=SitBu(3))-The First Compounds with Larger Clusters Containing Covalently Linked Thallium Atoms Compounds of Silicon, Part 143. Supersilyl Compounds of Boron and Its Homologues, Part 12. This work was supported by the Deutsche Forschungsgemeinschaft and by the Fonds der Chemischen Industrie. Part 42: N. Wiberg, W. Niedermayer, J. Organomet. Chem. 2001, in press; Part 11. M. Kehrwald, W. Köstler, A. Rodig, G. Linti, T. Blank, N. Wiberg, Organometallics 2001, in press.

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Journal Article↗
PubMed1989

[Characteristics in antitumor effects of organic silicon related compounds].

To investigate the characteristics in antitumor effects of 2-trimethylsilylethylthioethylamine(KAS-010) and its conjugate with 5-FU (KAS-011), the antitumor and immunomodulating activities of these silicon compounds were examined with various systems. Both KAS-010 and KAS-011 administered orally was found to be effective to B 16 melanoma, Meth A sarcoma and MM 46 mammary carcinoma in vivo. On the other hand, KAS-011 administered orally exhibited a marked antitumor activity against L 1210 leukemia bearing mice. Furthermore, these silicon compounds inhibited significantly metastases to the lymph nodes and lung of Lewis lung carcinoma implanted id into the right ear of BDF1 mice. Especially, KAS-011 in combination with tumor amputation resulted in a remarkable prolongation of the survival time (% ILS: 93.8%) in this antimetastatic model. The cell killing effect was mainly dependent on the exposure time of these silicon compounds in cultured KB and human lung cancer (OAT) cells. Moreover, a significant increase of delayed type hypersensitivity reaction (DTHR) to sheep red blood cell (SRBC) induced by KAS-010 was seen in old aged mice. The DTHR in B 16 melanoma and Ehrlich carcinoma bearing mice treated with KAS-010 was significantly higher than those of non-treated tumor bearing mice, indicating an enhanced cellular immunity to KAS-010 possibly resulting in a remarked antitumor effect. We also found that tumor free mice treated these silicon compounds were acquired specific tumor immunity to Meth A sarcoma and MM 46 mammary carcinoma.

Adjuvants, Immunologic↗
PubMed2004

Comparative chemistry of isolable divalent compounds of silicon, germanium, and tin.

Recent studies of the synthesis, structures, spectroscopic properties, and reactions of a series of isolable metallylenes (R2E:, E = Si (1), Ge (2), and Sn (3); R2 = 1,1,4,4-tetrakis(trimethylsilyl)butane-1,4-diyl) are summarized. Because these group-14 metallylenes bear the same helmet-like ligand, a straightforward discussion of the element-dependence of the intrinsic properties of the group-14 element divalent compounds is possible. All these metallylenes were monomeric both in solution and in the solid state, indicating the effective steric protection by the ligand against dimerization. A small sigma-pi conjugation between C-Si(substituent) sigma orbitals and the vacant npz orbitals of divalent atoms in R2E: exists and the extent decreases in the order E = Si > Ge > Sn, as evidenced by UV-vis and NMR spectroscopies and X-ray crystallography. However, the extent of the sigma-pi conjugation in metallylenes 1-3 was much smaller than the electron-donating effects of neighboring nitrogen atoms in known stable cyclic diamino-substituted metallylenes, and hence metallylenes 1-3 are regarded as the least electronically perturbed. Comparative studies of the unique reactions among these metallylenes are also discussed.

Butanes↗
PubMed1954

Silicon metabolism in diatoms. I. Evidence for the role of reduced sulfur compounds in silicon utilization.

1. Cells of the fresh water diatom Navicula pelliculosa may be grown in a mineral medium containing a low concentration of silicon. When transferred to a fresh silicate solution and incubated under non-growing conditions such deficient cells rapidly take up silicon from the medium. 2. The utilization of silicon is an aerobic process. 3. When deficient cells are washed with distilled water or saline, their ability to utilize silicon is impaired whereas respiration is unaffected. 4. The ability of washed cells to take up silicon can be partially restored with sulfate or ascorbic acid, and is completely restored by Na(2)S, Na(2)S(2)O(3), glutathione, l-cysteine, dl-methionine, or ascorbic acid plus sulfate. 5. The sulfhydryl reagent, CdCl(2), inhibits silicon utilization of unwashed cells at concentrations which do not affect respiration. This inhibition similarly is reversed by glutathione or cysteine. 6. However, sodium iodoacetate or sodium arsenite inhibits respiration and silicon utilization at the same concentrations. 7. The silicon taken up by deficient cells is deposited at the cell surface as a thickening of the existing silica frustules. 8. Sulfhydryl groups in the cell membrane may be involved in silicon uptake by diatoms.

Cell Membrane↗
PubMed1992

[Silicone molding compounds and latex gloves. The effect of latex gloves on addition and condensation silicones].

Inhibited setting of addition silicones has been observed using latex gloves in the dental office. Therefore four addition silicones as well as four condensation silicones were mixed with seven latex gloves with different properties (sterility, powder, accelerator, inner layer). The masses were mixed with bare hands as a control and--additionally--with powdered hands. Condensation silicones stayed unaffected when put together in exact amounts, while some addition silicones showed nearly complete inhibition. Mixing the condensation silicones under the conditions of daily practice--one spoon of body plus a distinct amount of catalyst-resulted in hardness differences compared to using the exact dose. Nevertheless the resulting impressions were of satisfying quality. The powder-component (Bio-sorb, Surgikos) leads to an accelerated setting. The general dental practitioner/dental hygienist have to consider these aspects while choosing gloves and silicone putties for taking impressions.

Dental Impression Materials↗