Alkylation by 1,2:5,6-dianhydrogalactitol of deoxyribonucleic acid and guanosine.
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ABSTRACT:
SUBMITTER: Institoris E
PROVIDER: S-EPMC1161443 | biostudies-other | 1980 Mar
REPOSITORIES: biostudies-other
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Project description:Vascular disrupting agents (VDA) represent a novel approach to the treatment of cancer, resulting in collapse of tumor vasculature and tumor death. 5,6-Dimethylxanthenone-4-acetic acid (DMXAA) is a VDA currently in advanced Phase II clinical trials, yet its precise mechanism of action is unknown despite extensive preclinical and clinical investigations. The data presented herein demonstrate that DMXAA is a novel and specific activator of the TBK1-IRF-3 signaling pathway. DMXAA treatment of primary murine macrophages resulted in robust IRF-3 activation, a ~750-fold increase in IFN-beta mRNA and, in contrast to the potent Toll-like receptor 4 (TLR4) agonist, lipopolysaccharide (LPS), signaling was independent of mitogen-activated protein kinase (MAPK) activation and elicited minimal NF-kappaB-dependent gene expression. DMXAA-induced signaling was critically dependent on the IRF-3 kinase, TBK1, and IRF-3, but MyD88-, TRIF-, IPS-1/MAVS-, and IKKbeta-independent, thus excluding all known TLRs and cytosolic helicase receptors. DMXAA pretreatment of murine macrophages induced a state of tolerance to LPS and vice versa. In contrast to LPS stimulation, DMXAA-induced IRF-3 dimerization and IFN-beta expression were inhibited by salicylic acid (SA). These findings detail a novel pathway for TBK-1-mediated IRF-3 activation and provide new insights into the mechanism of this new class of chemotherapeutic drugs. Keywords: DMXAA, IRF-3, TBK1, IFN-beta, Salicylic acid, TLR
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Project description:An efficient synthesis of a variety of 1,2-disubstituted-5,6-dihydropyrrolo[2,1-α]isoquinoline derivatives via an acid-promoted cyclization reaction between 1,2,3,4-tetrahydroisoquinoline (THIQ) and substituted α,β-unsaturated aldehyde derivatives is reported. This cycloaddition allows access to structurally diverse multisubstituted dihydropyrrolo[2,1-α]isoquinolines in moderate to good yields, which was the core scaffold of marine natural alkaloid lamellarins.
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Project description:Spontaneous S-alkylation of methimazole (1) with 1,2-dichloroethane (DCE) into 1,2-bis[(1-methyl-1H-imidazole-2-yl)thio]ethane (2), that we have described recently, opened the question about its formation pathway(s). Results of the synthetic, NMR spectroscopic, crystallographic and computational studies suggest that, under given conditions, 2 is obtained by direct attack of 1 on the chloroethyl derivative 2-[(chloroethyl)thio]-1-methyl-1H-imidazole (3), rather than through the isolated stable thiiranium ion isomer, i.e., 7-methyl-2H, 3H, 7H-imidazo[2,1-b]thiazol-4-ium chloride (4a, orthorhombic, space group Pnma), or in analogy with similar reactions, through postulated, but unproven intermediate thiiranium ion 5. Furthermore, in the reaction with 1, 4a prefers isomerization to the N-chloroethyl derivative, 1-chloroethyl-2,3-dihydro-3-methyl-1H-imidazole-2-thione (7), rather than alkylation to 2, while 7 further reacts with 1 to form 3-methyl-1-[(1-methyl-imidazole-2-yl)thioethyl]-1H-imidazole-2-thione (8, monoclinic, space group P 21/c). Additionally, during the isomerization of 3, the postulated intermediate thiiranium ion 5 was not detected by chromatographic and spectroscopic methods, nor by trapping with AgBF4. However, trapping resulted in the formation of the silver complex of compound 3, i.e., bis-{2-[(chloroethyl)thio]-1-methyl-1H-imidazole}-silver(I)tetrafluoroborate (6, monoclinic, space group P 21/c), which cyclized upon heating at 80 °C to 7-methyl-2H, 3H, 7H-imidazo[2,1-b]thiazol-4-ium tetrafluoroborate (4b, monoclinic, space group P 21/c). Finally, we observed thermal isomerization of both 2 and 2,3-dihydro-3-methyl-1-[(1-methyl-1H-imidazole-2-yl)thioethyl]-1H-imidazole-2-thione (8), into 1,2-bis(2,3-dihydro-3-methyl-1H-imidazole-2-thione-1-yl)ethane (9), which confirmed their structures.
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