4,552 publications from this institution
Abstract The synthesis of a new prodrug system for antiviral nucleosides AZT (1) and ddT (2) based on α-hydroxybenzylphosphonates 3 is described. 3 hydrolyze via different mechanisms yielding the H-phosphonate monoesters 4 or nucleoside monophosphates 5, respectively. 3 were more lipophilic than 1, 2 and showed marked activity against HIV-1/2.
A large variety of natural products have been described as anti-HIV agents, and for a portion thereof the target of interaction has been identified. Cyanovirin-N, a 11-kDa protein from Cyanobacterium (blue-green alga) irreversibly inactivates HIV and also aborts cell-to-cell fusion and transmission of HIV, due to its high-affinity interaction with gp120. Various sulfated polysaccharides extracted from seaweeds (i.e., Nothogenia fastigiata, Aghardhiella tenera) inhibit the virus adsorption process. Ingenol derivatives may inhibit virus adsorption at least in part through down-regulation of CD4 molecules on the host cells. Inhibition of virus adsorption by flavanoids such as (-)epicatechin and its 3-O-gallate has been attributed to an irreversible interaction with gp120 (although these compounds are also known as reverse transcriptase inhibitors). For the triterpene glycyrrhizin (extracted from the licorice root Glycyrrhiza radix) the mode of anti-HIV action may at least in part be attributed to interference with virus-cell binding. The mannose-specific plant lectins from Galanthus, Hippeastrum, Narcissus, Epipac tis helleborine, and Listera ovata, and the N-acetylgl ucosamine-specific lectin from Urtica dioica would primarily be targeted at the virus-cell fusion process. Various other natural products seem to qualify as HIV-cell fusion inhibitors: the siamycins [siamycin I (BMY-29304), siamycin II (RP 71955, BMY 29303), and NP-06 (FR901724)] which are tricyclic 21-amino-acid peptides isolated from Streptomyces spp that differ from one another only at position 4 or 17 (valine or isoleucine in each case); the betulinic acid derivative RPR 103611, and the peptides tachyplesin and polyphemusin which are highly abundant in hemocyte debris of the horseshoe crabs Tachypleus tridentatus and Limulus polyphemus, i.e., the 18-amino-acid peptide T22 from which T134 has been derived. Both T22 and T134 have been shown to block T-tropic X4 HIV-1 strains through a specific antagonism with the HIV corecept or CXCR4. A number of natural products have been reported to interact with the reverse transcriptase, i.e., baicalin, avarol, avarone, psychotrine, phloroglucinol derivatives, and, in particular, calanolides (from the tropical rainforest tree, Calophyllum lanigerum) and inophyllums (from the Malaysian tree, Calophyllum inophyllum). The natural marine substance illimaquinone would be targeted at the RNase H function of the reverse transcriptase. Curcumin (diferuloylmethane, from turmeric, the roots/rhizomes of Curcuma spp), dicaffeoylquinic and dicaffeoylt artaric acids, L-chicoric acid, and a number of fungal metabolites (equisetin, phomasetin, oteromycin, and integric acid) have all been proposed as HIV-1 integrase inhibitors. Yet, we have recently shown that L-c hicoric acid owes its anti-HIV activity to a specific interaction with the viral envelope gp120 rather than integrase. A number of compounds would be able to inhibit HIV-1 gene expression at the transcription level: the flavonoid chrysin (through inhibition of casein kinase II, the antibacter ial peptides melittin (from bee venom) and cecropin, and EM2487, a novel substance produced by Streptomyces. (ABSTRACT TRUNCATED)
The paper gives a survey of the upcoming use of X-ray computed tomography (CT) for dimensional quality control purposes: i.e. for traceable measurement of dimensions of technical (mechanical) components and for tolerance verification of such components. It describes the basic principles of CT metrology, putting emphasis on issues as accuracy, traceability to the unit of length (the meter) and measurement uncertainty. It provides a state of the art (anno 2011) and application examples, showing the aptitude of CT metrology to: (i) check internal dimensions that cannot be measured using traditional coordinate measuring machines and (ii) combine dimensional quality control with material quality control in one single quality inspection run.
Two new monomeric and two new dimeric drimane sesquiterpenes, cinnamacrins A-C (1-3) and cinnafragrin D (4), along with bemadienolide (5), capsicodendrin (6), cinnamodial (7), cinnamolide (8), isopolygodial (9), and delta-tocotrienol (10), were isolated from Cinnamosma macrocarpa. The structures of the new compounds were determined by physical, chemical, and spectroscopic evidence. Capsicodendrin (6) and/or cinnamodial (7) are the major compounds in C. fragrans and C. macrocarpa, which are both widely used in Malagasy traditional medicine. The cytostatic activity as well as alpha-glucosidase inhibition and antiviral activities of the major constituents 6 and 7 and the compounds previously isolated from C. fragrans were evaluated.
Summary The paper gives a state-of-the-art overview of so called rapid prototyping techniques, like stereolithography, selective laser sintering, ballistic particle manufacturing and others. These are new manufacturing techniques in which the part is produced by gradually growing material to the required shape. A tentative classification and nomenclature is proposed. It is shown that those new processes are ideally suited for CIM. The paper tries to compare the different processes and discuss their application and performances.
Phosphonylmethoxyalkylpurines and -pyrimidines exhibit potent activity against a broad spectrum of DNA viruses. We evaluated some of these nucleotide analogues for antitrypanosomal activity in vitro and in mice. The most active compounds were (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl) adenine (HPMPA) and (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)-2,6-diaminopurine (HPMPDAP), which inhibited growth of Trypanosoma brucei brucei by 50% (EC50 value) when incubated in vitro for 24 hr with 0.23-5.69 micrograms drug/ml. Both compounds completely eliminated multidrug-resistant T. b. brucei in culture at 1 microgram/ml after 4-5 days exposure. Mice infected with drug-susceptible T. b. brucei were cured with 2 doses of 10 mg/kg HPMPDAP. Two or 5 doses of 50 mg/kg 9-(2-phosphonylmethoxyethyl) adenine (PMEA) or 9-(2-phosphonylmethoxyethyl)-2,6-diaminopurine (PMEDAP), respectively, were necessary to eliminate T. b. brucei infections in mice. Mice infected with multidrug-resistant T. b. brucei were not cured with the above dosages. The most active compound against Trypanosoma congolense was PMEDAP with an EC50 value of 3.21-11.63 micrograms/ml. Thus, some of the phosphonylmethoxyalkyl purines showed potential as antitrypanosomal compounds at dosages that are below those toxic for mice.
