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610 result(s) for "Langer, Peter"
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Domino reactions of chromones with activated carbonyl compounds
Domino reactions of chromones with activated carbonyl compounds, such as dimethyl acetone-1,3-dicarboxylate and 1,3-diphenylacetone, and with 1,3-bis(silyloxy)-1,3-butadienes, electroneutral equivalents of 1,3-dicarbonyl dianions, allow for a convenient synthesis of a great variety of products. The regioselectivity and course of the reaction depends of the substituent located at carbon C3 of the chromone moiety and also on the type of nucleophile employed.
N -Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity
Indigo, indirubin, and isoindigo derivatives have been used for centuries as pigments. Since the 1990s, a new aspect of the chemistry of this type of compounds is their activity against various types of cancer. N -Glycosides of indigo, indirubin, and isoindigo, blue, red, and yellow sugars, turned out to be of special interest because of their high cancerostatic activity and structural novelty. The present article provides an account on the synthesis and anticancer activity of these compounds.
Divergent Synthesis of 5,7-Diazaullazines Derivatives through a Combination of Cycloisomerization with Povarov or Alkyne–Carbonyl Metathesis
Ullazines and their π-expanded derivatives have gained much attention as active components in various applications, such as in organic photovoltaic cells or as photosensitizers for CO2 photoreduction. Here, we report the divergent synthesis of functionalized diazaullazines by means of two different domino-reactions consisting of either a Povarov/cycloisomerization or alkyne–carbonyl metathesis/cycloisomerization protocol. The corresponding quinolino-diazaullazine and benzoyl-diazaullazine derivatives were obtained in moderate to good yields. Their optical and electronic properties were studied and compared to related, literature-known compounds to obtain insights into the impact of nitrogen doping and π-expansion.
Differences in the Composition of Colostrum and Milk in Eutherians Reflect Differences in Immunoglobulin Transfer
Colostrum is a special type of milk produced in eutherian mammals during the end of pregnancy and during the 1st few days after birth. It supplies passive immunity to the offspring. The composition of colostrum and mature milk is compared in this study. In species with prenatal passive immunization (humans, baboons, and rabbits), immunoglobulin transfer via colostrum is of little importance and the difference in relative protein concentration between colostrum and mature milk can be small. In ungulates, on the other hand, colostrum has to supply the offspring postnatally with passive immunity and colostrum is relatively rich in immunoglobulin. Large differences between relative protein concentration in colostrum and milk can be observed in ungulates. Compositions of colostrum and milk thus reflect differences in immunoglobulin transfer.
Synthesis and Properties of 1H-Pyrrolo3′,2′:3,4fluoreno9,1-ghquinolines and 7H-Pyrrolo2′,3′,4′:4,10anthra1,9-fgquinolines
We report the synthesis of pyrrolo[3′,2′:3,4]fluoreno[9,1-gh]quinoline and pyrrolo[2′,3′,4′:4,10]anthra[1,9-fg]quinoline derivatives. This novel class of N-doped polycyclic heteroaromatic compounds was synthesized by a site-selective cross-coupling reaction followed by acid-mediated cycloisomerization and Pd-catalyzed CH arylation as the final ring-closing reactions. Preliminary optical and aromatic properties were studied by means of steady-state absorption and fluorescence spectroscopy and DFT calculation. Special emphasis was placed on the impact of ring alternation and position of the N-doping within the scaffold.
Asymmetric synthesis of non-proteinogenic amino acids
Authored by two internationally recognized experts with an excellent track record, this much-needed reference summarizes latest research in the rapidly developing field of stereoselective synthesis of enantiomerically enriched amino acids, particularly of non-proteinogenic origin.
Synergistic effect of plasma-activated medium and novel indirubin derivatives on human skin cancer cells by activation of the AhR pathway
Due to the increasing number of human skin cancers and the limited effectiveness of therapies, research into innovative therapeutic approaches is of enormous clinical interest. In recent years, the use of cold atmospheric pressure plasma has become increasingly important as anti-cancer therapy. The combination of plasma with small molecules offers the potential of an effective, tumour-specific, targeted therapy. The synthesised glycosylated and non glycosylated thia-analogous indirubin derivatives KD87 and KD88, respectively, were first to be investigated for their pharmaceutical efficacy in comparison with Indirubin-3'-monoxime (I3M) on human melanoma (A375) and squamous cell carcinoma (A431) cells. In combinatorial studies with plasma-activated medium (PAM) and KD87 we determined significantly decreased cell viability and cell adhesion. Cell cycle analyses revealed a marked G2/M arrest by PAM and a clear apoptotic effect by the glycosylated indirubin derivative KD87 in both cell lines and thus a synergistic anti-cancer effect. I3M had a pro-apoptotic effect only in A431 cells, so we hypothesize a different mode of action of the indirubin derivatives in the two skin cancer cells, possibly due to a different level of the aryl hydrocarbon receptor and an activation of this pathway by nuclear translocation of this receptor and subsequent activation of gene expression.
Synthesis of benzo f quinazoline-1,3(2 H ,4 H )-diones
We report the synthesis of polycyclic uracil derivatives. The method is based on palladium-catalysed Sonogashira–Hagihara and Suzuki–Miyaura cross-coupling reactions followed by Brønsted acid-mediated cycloisomerisation. The developed methodology tolerates various functional groups and leads to moderate up to quantitative yields of the final products. The impact of different functional groups on the optical properties was studied by UV–vis and fluorescence spectroscopy.
Synthesis and properties of 6-alkynyl-5-aryluracils
The development of a new and straightforward chemoselective method for the synthesis of uracil-based structures by combining Suzuki–Miyaura and Sonogashira–Hagihara cross-coupling is reported. The methodology was applied to synthesize a series of novel compounds. The tolerance of the combination of different functional groups was tested. The influence of different functional groups on the physical properties was studied by ultraviolet–visible (UV–vis) and fluorescence spectroscopy, providing new insights into the potential applications of uracil-based structures.
Familial pancreatic cancer—current knowledge
Familial pancreatic cancer (FPC) is a rare, hereditary tumour syndrome. High morbidity and mortality is associated with development of pancreatic cancer in these high-risk individuals and, as outlined in this Review, screening of FPC families seems appropriate. Here, Bartsch and colleagues describe the current knowledge of FPC, including phenotype, underlying genetic causes and clinical management (including genetic counselling and screening). Familial pancreatic cancer (FPC) describes families with at least two first-degree relatives with confirmed exocrine pancreatic cancer that do not fulfil the criteria of other inherited tumour syndromes with increased risks of pancreatic cancer, such as Peutz–Jeghers syndrome, hereditary pancreatitis, and hereditary breast and ovarian cancer. The inheritance of FPC is mostly autosomal dominant and with a heterogeneous phenotype. The major gene defect is yet to be identified, although germline mutations in BRCA2, PALB2 and ATM are causative in some FPC families. Expert consensus conferences considered it appropriate to screen for pancreatic cancer in high-risk individuals using a multidisciplinary approach under research protocol conditions. However, neither biomarkers nor reliable imaging modalities for the detection of high-grade precursor lesions are yet available. Most screening programmes are currently based on findings from endoscopic ultrasonography and MRI, and data has demonstrated that precursor lesions of pancreatic cancer can be identified. No consensus exists regarding the age to initiate or stop screening and the optimal intervals for follow-up. Timing and extent of surgery as a treatment for FPC are debated. This Review focuses on the clinical phenotype of FPC, its histopathological characteristics, known underlying genetic changes and associated genetic counselling and screening. Key Points Familial pancreatic cancer (FPC) is a rare, but established, tumour syndrome About 15–20% of FPC families carry germline mutations in BRCA2 , PALB2 and ATM , but the major underlying gene defect(s) are yet to be identified Smoking triples the risk of pancreatic cancer in members of FPC families Screening for pancreatic cancer in high-risk individuals under research protocol conditions in a multidisciplinary setting is considered appropriate by experts; current screening programmes are based on endoscopic ultrasonography and MRI Available data demonstrate that precursor lesions to pancreatic cancer can be identified using current screening protocols Timing and extent of surgery in the treatment of FPC are still a matter of debate