Visible light catalyzed reaction of α-bromochalcones with chalcones: direct access to the urundeuvine scaffold
作者:Bhupal Singh Karki、Mukund M. D. Pramanik、Ruchir Kant、Namrata Rastogi
DOI:10.1039/c8ob01881b
日期:——
The α-keto vinyl radicals generated from α-bromochalcones under visiblelightphotoredoxcatalyzed conditions were trapped by chalcones. The subsequent intramolecular cyclization of the resulting benzylic radicals led to the synthesis of dihydronaphthalenes, which were conveniently oxidized to the corresponding naphthalenes. The strategy was adopted successfully for synthesizing derivatives of urundeuvine
Sixteen 1,3,5-triphenyl-2-pyrazolines were synthesized and their anti-infective activities (against Mycobacterium tuberculosis H(37)Rv, six bacterial and four fungal strains) were tested. Only compound with SO(2)CH(3) in the para position of the A-ring was active against the tubercular strain at 100 mu g/ml concentration. All compounds showed good anti infective activity against Escherichia coli and poor activity against Staphylococcus aureus. Compounds 4, 12, 13 and 14 exhibited reasonable activity against all the organisms tested (<0.309 mu M except against S. aureus. The activity of these compounds correlated with their lipophilic/hydrophilic nature. Compounds 4, 10 and 16 showed very good activity (>88% reduction) against four fungi studied at 2 mg/ml. All these compounds possess halogen substitutions. Compound 11 showed very high activity (>90%) against three fungi. Majority of the compounds showed more than 90% inhibition against one or two fungi. Since pyrazolines are reported to inhibit the activity of p-glycoprotein, they may prevent drug resistance developed by microorganism. (C) 2010 Elsevier Ltd. All rights reserved.
Synthesis, antioxidant evaluation, and quantitative structure–activity relationship studies of chalcones
作者:P. M. Sivakumar、P. K. Prabhakar、M. Doble
DOI:10.1007/s00044-010-9342-1
日期:2011.5
Synthesis, antioxidant activity, and quantitative structure-activity relationship (QSAR) of 25 of chalcone derivatives is reported here. They were synthesized by Claisen-Schmidt reaction and were characterized by FTIR, NMR, and mass spectroscopy. Antioxidant activity is evaluated through four different methods namely, superoxide radical-scavenging, hydrogen peroxide scavenging, reducing power, and DPPH radical-scavenging assays. Generally, compounds with -SCH3 and -OCH3 in the para position of the A-ring and -OH in the B-ring were more active than others. In few cases some of the compounds were more active than ascorbic acid or butylated hydroxytoluene. QSAR was developed correlating the antioxidant activity with the structural features of the compounds and the predictive capability of the models was estimated using internal and external validation methods. All the predictions were within the 99% confidence level. Spatial, structural, and lipophilic properties of the compounds determine their antioxidant properties.
Synthesis, antimicrobial and antioxidant activities of 2-[1-{3,5-diaryl-4,5-dihydro-1H-pyrazolenyl}]-4-(4-nitrophenyl)-[1,3]-thiazoles
作者:Prajwal Lourdes Lobo、Boja Poojary、Manjunatha Kumsi、Vinaya Chandra、Nalilu Sucheta Kumari、K. R. Chandrashekar
DOI:10.1007/s00044-012-0154-3
日期:2013.4
In this study, various substituted chalcones, prepared by condensing substituted acetophenones with substituted aldehydes/arylfurfurals, were treated with thiosemicarbazide in basic media to produce 1-thiocarbonyl-3,5-disubstituted pyrazolines which on further reaction with substituted phenacyl bromides afforded the title compounds in good yield. Structures of the newly synthesized compounds were assigned on the basis of elemental analyses, IR, H-1 NMR, and mass spectral studies. The newly synthesized compounds were tested for their in vitro antibacterial and antifungal activities against a variety of microorganisms and antioxidant activities by diphenylpicrylhydrazyl radical scavenging assay. Among the derivatives, compounds 3b, 3e, 6a, and 6h were identified as potent antioxidants. Compounds 3d, 3e, and 6a-f have emerged as the most promising antimicrobial agents displaying the maximum activity against all the tested microorganisms.