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At least 1,135 records · Page 63Linked to original sources
PubMed2005

Rapid access to the Welwitindolinone alkaloid skeleton by cyclization of indolecarboxaldehyde substituted cyclohexanones.

[reaction: see text] A very rapid access to cyclohexanone-bridged indole systems was established by an acid-mediated ring closure of appropriately substituted indole aldehydes, which involved an apparent disproportionation of an aldol-like intermediate. One of the bridged indole intermediates was further transformed into an oxindole having the essential skeleton of the Welwitindolinone alkaloids.

Aldehydes↗
PubMed2005

Kadlongilactones A and B, two novel triterpene dilactones from Kadsura longipedunculata possessing a unique skeleton.

[structure: see text] Two novel triterpene dilactones with an unprecedented rearranged hexacyclic skeleton, kadlongilactones A (1) and B (2), have been isolated from the leaves and stems of Kadsura longipedunculata Finet et Gagnep (Schisandraceae). Their structures were established by comprehensive 1D and 2D NMR spectroscopic analysis, coupled with single-crystal X-ray crystallographic diffraction. Compounds 1 and 2 exerted significant inhibitory effects against human tumor K562 cells with IC(50) = 1.40 and 1.71 microg/mL, respectively.

Cell Line, Tumor↗
PubMed2006

TESOTf-induced rearrangement of quinols. Efficient construction of the fully functionalized carbon skeleton of the griseusins by a divergent-reconvergent approach.

[reaction: see text] The "reverse polarity" or "umpolung" strategy for the total synthesis of aryl C-glycosides was developed in the context of the antibiotic (-)-griseusin B. Although a key reaction in a model sequence for the total synthesis produced two structurally divergent products, both were converted to the same advanced model intermediate that contains the complete carbon skeleton and (except for the extraneous oxygen substituent in the model series) the functional group pattern of the griseusins.

Glycosides↗
PubMed2006

Physanolide A, a novel skeleton steroid, and other cytotoxic principles from Physalis angulata.

[reaction: see text] A novel withasteroid, physanolide A (1), with an unprecedented skeleton containing a seven-membered ring, and two new physalins, physalins U (2) and V (3), were isolated from Physalis angulata. The structures were elucidated from spectroscopic analysis, and plausible biosynthetic pathways were postulated. Physalins B (4), D (5), and F (6) showed strong cytotoxicity against multiple tumor cell lines, including KB, A431, HCT-8, PC-3, and ZR751, with EC(50) values less than 4 microg/mL.

Animals↗
PubMed2006

Skeleton-rearranged pentacyclic diterpenoids possessing a cyclobutane ring from Euphorbia wallichii.

[structure: see text] Two novel rearranged trachylobane diterpenoids, designated as wallichanol A (2) and wallichanol B (3), consisting of an unprecedented pentacyclic skeleton named wallichane with a cyclobutane ring, and a new ent-trachylobane diterpenoid, 3-oxo-ent-trachyloban-17-oic acid (1), were isolated from the roots of Euphorbia wallichii. Their structures were elucidated by comprehensive analysis of 2D-NMR spectroscopic data, with the stereochemistry of 1 confirmed by X-ray crystallographic study. All of these compounds potently block osteoclastogenesis in vitro, suggesting a potential therapeutic application in prevention of osteoporosis.

Bone Resorption↗
PubMed2006

Przewalskin A: A new C23 terpenoid with a 6/6/7 carbon ring skeleton from Salvia przewalskii maxim.

Przewalskin A (1), a novel C23 terpenoid with a 6/6/7 carbon ring skeleton, was isolated from Salvia przewalskii. Its structure was determined by comprehensive 1D NMR, 2D NMR, and MS spectroscopic analysis and subsequently confirmed by a single-crystal X-ray diffraction study of its PDC oxidation derivative (2). Compounds 1 and 2 showed modest anti-HIV-1 activity with EC50 = 41 and 89 microg/mL, respectively.

Carbon↗
PubMed2006

Maoecrystal Z, a cytotoxic diterpene from Isodon eriocalyx with a unique skeleton.

[structure: see text] A novel diterpene with an unprecedented tetracyclic 6,7:8,15-di-seco-7,20-olide-6,8-cyclo-ent-kaurane skeleton, named maoecrystal Z (1), has been isolated from the leaves of a Chinese medicinal herb, Isodon eriocalyx (Labiatae). Its structure was determined by comprehensive NMR and MS spectroscopic analysis coupled with single-crystal X-ray crystallographic diffraction. Compound 1 exhibited comparable inhibitory effect against human K562 leukemia, MCF7 breast, and A2780 ovarian tumor cells with IC(50) = 2.90, 1.63, and 1.45 microg/mL and with camptothecin and paclitaxel as the positive controls.

Antineoplastic Agents, Phytogenic↗
PubMed2006

Tandem semipinacol/Schmidt reaction leading to a versatile and efficient approach to azaquaternary alkaloid skeletons.

[Structure: see text] A TiCl4-promoted tandem semipinacol/Aubé's type intramolecular Schmidt reaction of alpha-siloxy-epoxy-azide has been designed and developed to be a general method for efficient construction of azaquaternary carbon units. As applicable examples, some key tricyclic azaquaternary skeletons incorporated in many important alkaloids, such as cephalotaxine, stemonamine, erythrinan, and homoerythrinan alkaloids, have been constructed.

Journal Article↗
PubMed2006

New procedure to mask the 2,3-pi bond of the indole nucleus and its application to the preparation of potent opioid receptor agonists with a Corynanthe skeleton.

Treatment of indole alkaloids with hypervalent iodine in the presence of ethylene glycol provides 2,3-ethylene glycol bridged adducts that could be converted into the original indoles under mild reductive conditions. This procedure, which involves masking of the reactivity of the indole nucleus at the beta-position, was utilized for the modification of the benzene ring of the indoline derivative and was applied to the preparation of potent opioid receptor agonists with the Corynanthe skeleton. [reaction: see text]

Alkaloids↗
PubMed2007

Przewalskin B, a novel diterpenoid with an unprecedented skeleton from Salvia przewalskii maxim.

Przewalskin B (1), a novel diterpenoid possessing a unique skeleton, was isolated from a Chinese medicinal plant Salvia przewalskii. Its structure and relative stereochemistry were elucidated by extensive NMR analysis and a single-crystal X-ray study. A possible biosynthetic pathway for 1 was proposed. Compound 1 exhibited modest anti-HIV-1 activity with EC50 = 30 microg/mL. [structure: see text].

Anti-HIV Agents↗
PubMed1999

Enzymatic selective dehydration and skeleton rearrangement of paclitaxel precursors.

[formula: see text] Enzymatic dehydration reactions to remove selectively the chemically least reactive 13-hydroxyl group of 10-deacetylbaccatin III and its derivatives 2a-c are described. The elimination of the 13-OH takes place with skeleton rearrangement, allowing us to synthesize some interesting diterpenoids in good yields.

Antineoplastic Agents, Phytogenic↗
PubMed1999

Cytotoxic polyprenylated benzoylphloroglucinol derivatives with an unusual adamantyl skeleton from Hypericum sampsonii (Guttiferae).

[formula: see text] The structures of sampsoniones I and J, isolated from the aerial parts of the Chinese medicinal plant Hypericum sampsonii, have been elucidated by detailed spectral analysis. They are complex adamantyl derivatives, and sampsonione I is the first polyprenylated benzoylphloroglucinol derivative with the unique caged tetracyclo[7.3.1.1.0]tetradecane-2,12,14-trione skeleton. Cytotoxic sampsonione I has also been obtained by the biomimetic transformation of sampsonione J.

Adamantane↗
PubMed2000

Effect of single chemotherapeutic agents on the growing skeleton of the rat.

BACKGROUND: To establish the effect of chemotherapeutics on the growing skeleton, male Wistar rats were studied. DESIGN: Between the ages of 4 and 13 weeks the rats were given i.v. doxorubicin 15 mg/m2 body surface area (BSA), methotrexate 60 mg/m2 BSA or cisplatin 7.5 mg/m2 BSA. For each group of drug-treated rats there was a diet-matched control group that was injected with a placebo only. Rats fed ad libitum served as the basic control group for length and weight growth. Body weight and tibial length were measured weekly. Kidney and liver weight were determined at the end of the study. RESULTS: Weight gain and length growth were significantly decreased in the diet controlled groups (P < 0.05). Doxorubicin reduced length growth with 4.12 mm or 18% (P < 0.05). Methotrexate reduced length growth with 1.11 mm or 5% (P < 0.05). Length growth in the cisplatin treated rats did not differ from the diet controls. CONCLUSIONS: Doxorubicin and methotrexate decrease length growth in the rat tibia by, respectively, 18% and 5%. Cisplatin does not affect length growth. The decrease in growth might be a direct effect of doxorubicin and methotrexate on the tibial growth plate and metaphysis, but may be more pronounced due to the malnutrition.

Animals↗
PubMed2002

Histological examinations of bone and cartilage in the axial skeleton of human triploidy fetuses.

The aim of this study was to examine histologically bone and cartilage in vertebral corpora of axial skeletons of eight human triploid fetuses, gestational ages 14-25 weeks, CRL 100-200 mm. The results were compared to earlier studies on vertebral development in trisomies 21, 18, 13, and to normal corpora development. After radiography in frontal and lateral projections, the vertebral column was sectioned into cervical, thoracic and lumbar segments, decalcified, dehydrated, and embedded in paraffin. The blocks were serially sectioned in the vertical plane and stained with Toluidine blue and Alcian blue/van Gieson. The radiographic characteristics of the vertebral corpora observed in frontal and lateral projection varied from small cleft vertebral corpora to fusions between the individual corpora. Histological examination of the vertebral corpora confirmed the abnormal pattern of ossification seen radiographically. As a new finding abnormal metachromasia of the ground substance was observed in the cartilage. Marked borderlines were registered in the cartilage between regions with differences in metachromasia. These borderlines were similar but more extensive than borderlines observed previously in trisomies 21, 18 and 13.

Cartilage↗
PubMed2001

The effect of shared structure and content on reading nonwords: evidence for a CV skeleton.

Four experiments examined the effect of shared skeletal structure versus content overlap on naming printed nonwords. Experiments 1-2 compared priming among nonwords sharing either skeletal structure and content (e.g., dus-DUS) or structure alone (e.g., pid-BAF) with controls that differed from the target in the number of skeleton slots (e.g., pid-BAF vs. plid-BAF). Conversely, in Experiments 3-4, same-versus different-structure primes contrasted only in the ordering of CV skeletal slots (e.g., fap-DUS vs. ift-DUS). Priming effects were modulated by shared content and skeletal similarity. The sensitivity of skeletal priming to the abstract arrangement of consonants and vowels suggests that skeletal representations assign distinct slots for consonants and vowels. Readers' sensitivity to skeletal structure in nonword identification indicates that assembled phonological representations are constrained by linguistic knowledge.

Adult↗
PubMedDate not supplied

Synthesis of the skeleton of the morphine molecule by mammalian liver.

The possibility that morphine could be synthesized in animals has long been considered and a pathway in mammalian brain analogous to that in the opium poppy has been proposed. Substances have been detected in mammalian brain that are recognized by antisera raised against morphine. Recently we reported the presence of three such immunoreactive substances in bovine hypothalamus and adrenal, and in rat brain, and the definitive identification of two of them by gas chromatography-mass spectrometry as morphine and codeine. Incorporation of a labelled precursor has demonstrated the biosynthesis of morphine in the opium poppy from tyrosine-derived units (see Fig. 1). Intramolecular coupling of reticuline to form salutaridine is the critical step that generates the morphine skeleton (morphinan) and the stereochemistry of the morphinan series. We now report the conversion in vivo and in vitro of reticuline to salutaridine by rat liver, but this conversion is not detectable in rat brain and bovine adrenal. This is the first direct demonstration of the synthesis of a morphinan in an animal tissue and also supports the hypothesis that morphine and codeine in brain and adrenal are of endogenous origin.

Adrenal Glands↗