ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Eine doppelt stereodifferenzierende Crotylierung des Aldehyds 1 mit dem Silan (S)-2 zum Homoallyl... more Eine doppelt stereodifferenzierende Crotylierung des Aldehyds 1 mit dem Silan (S)-2 zum Homoallylalkohol 3 ist der diastereoselektive Schlusselschritt (anti:syn >30:1) einer effizienten asymmetrischen Synthese von (+)-Lactacystin. (+)-Lactacystin ist ein aus Streptomyces sp. OM-6519 isolierter Metabolit mit bemerkenswerter neurotropher Aktivitat. Ein weiterer wichtiger Schritt der Synthese ist eine katalytische asymmetrische Aminohydroxylierung als entscheidender Schritt bei der Synthese des (2R,3S)-Hydroxyleucin-Synthons.
Porphyromonas gingivalis (P.g.)-induced TNF-α can be affected by muramyl dipeptide (MDP) in a bip... more Porphyromonas gingivalis (P.g.)-induced TNF-α can be affected by muramyl dipeptide (MDP) in a biphasic concentration-dependent manner. We found that in P.g.-exposed macrophages, treatment with 10 μg/mL of MDP (MDP-low) up-regulated TNF-α by 29%, while 100 μg/mL or higher (MDP-high) significantly decreased it (16% to 38%). MDP-high was found to affect the ubiquitin-editing enzyme A20 and activator protein 1 (AP1). An AP1 binding site was found in the promoter region of A20. A20 promoter activity was up-regulated after transfection of AP1 cDNA in cells. Four analogues of MDP (3-6) were prepared through a convergent strategy involving the synthesis of two unique carbohydrate fragments, 7a and 7b, using the peptide coupling reagents, EDCI and HOAt. Analogue 4 improved MDP function and P.g.-induced activities. We propose a new signaling pathway for TNF-α induction activated after exposing macrophages to both P.g. and MDP-high or analogue 4.
[structure: see text] Herbimycin A (HA) belongs to a class of antibiotics known as the benzoquino... more [structure: see text] Herbimycin A (HA) belongs to a class of antibiotics known as the benzoquinoid ansamycins. Members of this class have shown promising biological activity as Hsp90 inhibitors. An enantioselective synthesis of HA is described, employing asymmetric syn-crotylation methodology to introduce the C10, C11, C14, and C15 stereocenters. The C6-C7 stereocenters were introduced using Brown's alpha-pinene-derived gamma-methoxy allylborane reagent. The C12 stereocenter was established by diastereoselective hydroboration.
Callystatin A is a prominent member of a class of natural products which display promising growth... more Callystatin A is a prominent member of a class of natural products which display promising growth inhibition of cancer cells in their biological profile. The challenging structure and the interesting biological activity of (-)-callystatin A fueled our interest in the synthesis of this marine natural product. We achieved the total synthesis using a highly convergent approach joining four subunits together with a Wittig olefination, a selective Heck reaction and an aldol reaction as the pivotal steps. The aldol reaction as one of the final transformations during the synthesis opens fast access to a variety of structural analogues and circumvents tedious protecting group manipulations. Here we report an improved synthesis utilizing a modified vinyl iodide which shortens the synthesis by two steps. Additionally, first biological results will be reported.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Eine doppelt stereodifferenzierende Crotylierung des Aldehyds 1 mit dem Silan (S)-2 zum Homoallyl... more Eine doppelt stereodifferenzierende Crotylierung des Aldehyds 1 mit dem Silan (S)-2 zum Homoallylalkohol 3 ist der diastereoselektive Schlusselschritt (anti:syn >30:1) einer effizienten asymmetrischen Synthese von (+)-Lactacystin. (+)-Lactacystin ist ein aus Streptomyces sp. OM-6519 isolierter Metabolit mit bemerkenswerter neurotropher Aktivitat. Ein weiterer wichtiger Schritt der Synthese ist eine katalytische asymmetrische Aminohydroxylierung als entscheidender Schritt bei der Synthese des (2R,3S)-Hydroxyleucin-Synthons.
Porphyromonas gingivalis (P.g.)-induced TNF-α can be affected by muramyl dipeptide (MDP) in a bip... more Porphyromonas gingivalis (P.g.)-induced TNF-α can be affected by muramyl dipeptide (MDP) in a biphasic concentration-dependent manner. We found that in P.g.-exposed macrophages, treatment with 10 μg/mL of MDP (MDP-low) up-regulated TNF-α by 29%, while 100 μg/mL or higher (MDP-high) significantly decreased it (16% to 38%). MDP-high was found to affect the ubiquitin-editing enzyme A20 and activator protein 1 (AP1). An AP1 binding site was found in the promoter region of A20. A20 promoter activity was up-regulated after transfection of AP1 cDNA in cells. Four analogues of MDP (3-6) were prepared through a convergent strategy involving the synthesis of two unique carbohydrate fragments, 7a and 7b, using the peptide coupling reagents, EDCI and HOAt. Analogue 4 improved MDP function and P.g.-induced activities. We propose a new signaling pathway for TNF-α induction activated after exposing macrophages to both P.g. and MDP-high or analogue 4.
[structure: see text] Herbimycin A (HA) belongs to a class of antibiotics known as the benzoquino... more [structure: see text] Herbimycin A (HA) belongs to a class of antibiotics known as the benzoquinoid ansamycins. Members of this class have shown promising biological activity as Hsp90 inhibitors. An enantioselective synthesis of HA is described, employing asymmetric syn-crotylation methodology to introduce the C10, C11, C14, and C15 stereocenters. The C6-C7 stereocenters were introduced using Brown's alpha-pinene-derived gamma-methoxy allylborane reagent. The C12 stereocenter was established by diastereoselective hydroboration.
Callystatin A is a prominent member of a class of natural products which display promising growth... more Callystatin A is a prominent member of a class of natural products which display promising growth inhibition of cancer cells in their biological profile. The challenging structure and the interesting biological activity of (-)-callystatin A fueled our interest in the synthesis of this marine natural product. We achieved the total synthesis using a highly convergent approach joining four subunits together with a Wittig olefination, a selective Heck reaction and an aldol reaction as the pivotal steps. The aldol reaction as one of the final transformations during the synthesis opens fast access to a variety of structural analogues and circumvents tedious protecting group manipulations. Here we report an improved synthesis utilizing a modified vinyl iodide which shortens the synthesis by two steps. Additionally, first biological results will be reported.
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