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PubMed2001

N-methoxy-N-acylnitrenium ions: application to the formal synthesis of (-)-TAN1251A.

[structure: see text]. A formal synthesis of the muscarinic M(1) receptor antagonist (-)-TAN1251A (7) from L-tyrosine is described. Central to this venture has been the construction of the 1-azaspiro[4.5]decane skeleton present in the natural product by an N-methoxy-N-acylnitrenium ion-induced spirocyclization. The dienone generated in this transformation, 10, was converted to (-)-TAN1251A via tricycle 9, an intermediate in Kawahara's recent synthesis of racemic 7.

Aza Compounds↗
PubMed2003

New oxidative tools for the functionalization of the cephalostatin north 1 hemisphere.

Dimethyldioxirane (DMDO) C-H oxidation of ketone 17 to hemiketal 18 (82%), bis-dehydration to vinyl ether 21 (77%), and DMDO again provides C-23 axial alcohol 23 (99%). Routine processing, including a double-stereoselective Sharpless AD reaction (de >98%), gives alcohols 7 and 32. C-23 deoxy substrate 7 undergoes Suarez hypoiodite oxidative cyclization to (natural) beta spiroketal 34, but compound 32, bearing a C-23 silyl ether, generates unnatural spiroketal 33. [reaction: see text]

Cyclization↗
PubMed1987

Preliminary study on the suppression of experimental autoimmune encephalomyelitis in the Lewis rat with spirogermanium.

Spirogermanium (SG) is an azaspirane compound that incorporates the element germanium into a heterocyclic ring structure. It is currently being tested in phase II clinical trials as an anti-neoplastic agent and, in experimental animals, has suppressed adjuvant arthritis. In this study, SG suppressed experimental autoimmune encephalomyelitis in the Lewis rat. Suppression was a dose-dependent phenomenon and doses of 28 mg/kg and 40 mg/kg given intraperitoneally five through 14 days postinoculation gave significant protection. Perivascular inflammation in the central nervous system was also suppressed in animals receiving effective doses. Although these doses were well tolerated, cytoplasmic lamellar-bodies were found in the central nervous system of all SG-treated animals. Also, animals treated with SG developed diarrhea and weight loss, although histologic study of the gastrointestinal tract revealed no lesions.

Animals↗
PubMed2006

Antimalarial activity of a synthetic endoperoxide (RBx-11160/OZ277) against Plasmodium falciparum isolates from Gabon.

OZ277 is a newly developed, fully synthetic endoperoxide antimalarial that we tested against field isolates from Gabon. A comparison of activities of OZ277 with artesunate, mefloquine, and chloroquine showed OZ277 to be highly active against all parasite isolates. Artesunate and mefloquine also showed potent antiparasitic activity, but all isolates were chloroquine resistant.

Animals↗
PubMed2003

EI-2128-1, a novel interleukin-1beta converting enzyme inhibitor produced by Penicillium sp. E-2128.

EI-2128-1, a novel interleukin-1beta converting enzyme (ICE) inhibitor, was isolated from the culture broths of Penicillium sp. E-2128. EI-2128-1 selectively inhibited human recombinant ICE activity with IC50 value of 0.59 microM, without inhibiting elastase and cathepsin B. EI-2128-1 also inhibited mature interleukin-1beta secretion from THP-1 cells induced by LPS with IC50 value of 0.28 microM.

Caspase Inhibitors↗
PubMed1988

Effect of spirogermanium and radiation therapy on the 9L rat brain tumor model.

Spirogermanium (SPG) was investigated in the 9L rat brain tumor model in vivo and in vitro. Used at a single ip dose of 50 or 60 mg/kg or at 5 daily doses of 10 mg/kg, SPG was ineffective in prolonging survival of rats burdened with the intracerebrally implanted tumor, i.e., the median survival time (MST) was the same as that for the controls. Only a schedule of 3 X 20 mg SPG/kg every other day improved the MST compared with controls. Single-dose (20-Gy) radiation therapy (RT, cesium-137 whole-head irradiation) did prolong survival. However, when single-dose SPG was combined with RT (1 hr or 1 day before, or 1 hr after RT), the survival response was worse than after RT alone. When the daily SPG was combined with daily RT (5 doses of 6 Gy), survival was no better than after daily RT alone. In vitro, SPG produces a concentration-dependent, exponential decrease in cell survival as measured by colony formation assay. When combined with radiation, there is an additive effect on cell lethality. Aside from the possibility that SPG does not penetrate the rat brain tumor itself, we have no explanation why SPG shows some activity against human brain tumors and is cytotoxic against 9L cells in vitro, yet is both ineffective by itself and fails to potentiate RT in the 9L rat brain tumor model.

Animals↗
PubMed1986

Roles of adroxazine, a new heterocyclic hormone of the adrenals, and leucogenenol, a thymothyroid hormone, in the formation of blood cells.

Treatment of normal rats with the thymothyroid hormone leucogenenol accelerates the rate at which the 'functional' cells, neutrophils, red blood cells and lymphocytes, develop in the bone marrow from their corresponding committed precursor cells. Following the initial treatment of normal rats with leucogenenol, there is a temporary elevation in the bone marrow of the relative concentrations of myeloblasts, rubriblasts and lymphoblasts. It has now been found that bilaterally adrenalectomized rats have a different response from normal rats to treatment with leucogenenol. Although treatment of bilaterally adrenalectomized rats with leucogenenol accelerates the rate of development of their functional cells, the initial injection of leucogenenol is followed by a temporary decrease in the relative concentrations of myeloblasts, rubriblasts and lymphoblasts in their bone marrow. Additionally, adrenalectomized rats treated concurrently with tritiated thymidine and leucogenenol show a significant lower percentage of labeled cells in their bone marrow than do correspondingly treated normal rats. These results indicate that adrenalectomized rats have a lower than normal concentration of stem cells in their bone marrow that can be committed to become functional cells. Treatment with adroxazine, a new recently isolated heterocyclic hormone of the adrenals, causes adrenalectomized rats to respond as normal rats to the injection of leucogenenol. There is a temporary elevation of myeloblasts, rubriblasts and lymphoblasts in their bone marrow as well as a normal increase in the percentage of cells that are labeled following concurrent treatment with tritiated thymidine and leucogenenol. It may be concluded that treatment with adroxazine increases the rate of replication of uncommitted bone marrow stem cells while treatment with leucogenenol increases the rate at which committed cells develop into their respective functional cells. A scheme is presented to show the suggested roles that leucogenenol and adroxazine play in regulating the formation of blood cells.

Adrenal Glands↗
PubMed2005

8-(1-Naphthalen-2-yl-vinyl)-6,7,10-trioxaspiro (4.5) decane, a new 1,2,4-trioxane effective against rodent and simian malaria.

A new series of 8-(1-aryl-vinyl)-6,7,10-trioxaspiro [4.5] decanes 7a-e and 3-(1-aryl-vinyl)-l,2,5-trioxaspiro [5.5] undecanes 8a-e have been prepared and screened against multi-drug resistant Plasmodium yoelii in mice. 8-(1-Naphthalen-2-yl-vinyl)-6,7,10-trioxaspiro [4.5] decane 7b, the most active trioxane of the series, has also shown promising activity against Plasmodium cynomolgi in rhesus monkeys.

Animals↗
PubMed2005

A biomimetically inspired, efficient synthesis of the South 7 hemisphere of cephalostatin 7.

Synthesis of the South 7 hemisphere of cephalostatin 7 is described applying a second-generation synthetic strategy, which retains all the existing carbons in hecogenin acetate 1. TFAT (trifluoroacetyl trifluoromethanesulfonate)-assisted E-ring opening yields the key D-ring cyclopentadiene. A facially selective [4 + 2] cycloaddition between a series of steroidal D-ring dienes and singlet oxygen was conformationally directed by the C21-Me stereochemistry of the side chain. Sharpless asymmetric dihydroxylation of the terminal olefin provides (S)-C25-OH. An acid-catalyzed SN2' intramolecular alkylation of an acetal oxygen was followed by a one-pot sequence of beta-elimination and spiroketalization. The new route provides a practical 16-operation synthesis of the South 7 hemisphere (20% overall), as well as a model for construction of the crucial North 1 hemisphere.

Biomimetic Materials↗
PubMed2004

Synthesis of novel Bi-, Tri-, and tetracyclic nucleosides by reaction of a common cyclic enamine derived from TSAO-T with nucleophiles.

We report here the efficient regio- and stereoselective synthesis of new polycyclic nucleosides using a common cyclic enamine (7) as the starting material. In fact, the reaction of 7, easily prepared by reaction of 5'-O-Tosyl TSAO-T under basic nonnucleophilic conditions (potassium carbonate), with different classes of nucleophiles, for example, nitrogen-, oxygen-, sulfur-, and carbon-based nucleophiles, or with amino acids afforded, with total regio- and stereoselectivity, new bi-, tri-, and tetracyclic nucleosides. This straighforward route represents an original and unambiguously regio- and stereoselective pathway to these compounds. Some of these polycyclic nucleosides may be useful intermediates for a second series of reactions that may lead to the generation of structurally new nucleosides.

Amines↗