In this study, the interaction between benzothiazole (BTA, concentration of a drug required for 50% inhibition in vitro (IC50) = 0.77 mM) and benzimidazole (BIA, IC50 = 2.14 mM) with urease was quantitatively assessed, using UV-Vis, molecular fluorescence, and circular dichroism. The results showed that both compounds interact with urease by a static fluorescence quenching mechanism with a non-fluorescent complex formation. The main forces responsible for stabilizing the supramolecular complex between BTA and urease were hydrophobic while, for BIA, van der Waals interactions and hydrogen bonds were the main ones. Urease conformation changes due to the interaction process were analyzed by circular dichroism and synchronous fluorescence. Besides, a competitive assay with substrate and inhibitors was used to evaluate the preferential urease site of interaction with BTA and BIA. Our experimental and theoretical studies supported that both, BTA and BIA, are mixed-inhibitors of ureases with a slight preference to the active site of such enzymes. Finally, both BTA and BIA showed to possess anti-H. pylori (one reference strain and six clinical isolates) activity, presenting minimal inhibitory concentration (MIC) values ranging from 38-150 and 20-164 μM, respectively. The urease inhibitors omeprazole and hydroxyurea showed MIC values in the range of 46-185 μM and 1683-> 3366 μM, respectively.

Biophysical, theoretical and biological in vitro studies were carried out to evaluate the interaction of the main allergen protein of egg white (ovalbumin, OVA) with sulphonamides (SA): sulphathiazole (S1), sulfaquinoxaline (S2), sulfadimethoxine (S3) and sulfamethazine (S4). The binding constants for the OVA-SA supramolecular complexes ranged from 1.20 to 30.66 x 10(5) M-1, observing the following order of affinity: S1 > S2 > S4 > S3. The preferential forces in the stabilization of the OVA complexes with S2 and S3 were hydrogen bonds and Van der Waals forces, whereas for OVA-S1 and OVA-S4, were electrostatic interactions. Interaction process led to a change in the native structure of the protein, which may potentiate its natural allergenicity. Cations Ca (II), Mg(II) and Fe(III) favor the interaction of OVA with S1 and S2. The theoretical studies performed were consistent with the spectroscopic data. Finally, it was found that the interaction process for sulfonamides evaluated with OVA change the inhibition activity profile these antibiotics against strains of Escherichia coli ATCC 25922 and Bacillus megaterium APFSG3isox, but not the minimal inhibitory concentration values. (c) 2019 Elsevier B.V. All rights reserved.

Assessment of phosphorus in fruit juices is of great interest due to its essentiality and nutritional properties. This study applied sample treatment strategies to determine phosphorus in fractions of juices. Firstly, total phosphorus (P-total) was determined from digestion and sample suspension exploring direct analysis by inductively coupled plasma optical emission spectrometry. which presented no significant difference, for 95% of confidence level. Then, free phosphorus (P-free) was determined by spectrophotometry and represented 30-90% of P-total with an inverse relationship respecting P-total concentration. Fractioning according to particle size evidenced highest fraction of P-free in samples after filtration. Fractioning of phosphorus based on its charge was also performed and the high percentages of P in the anionic fraction (from 91.2 to 95.9%) are related to free inorganic phosphate in equilibrium with its protonated forms. Thus, it is more assailable after consumption, giving this food great functionality on human diet.

ChemInformVolume 46, Issue 36 Heterocyclic Compounds ChemInform Abstract: Thermolysis of 1-(Thiophen-2-yl)-1H-tetrazoles: A Route to Thiophene-Fused Imidazoles and Pyrimidines. Maria I. L. Soares, Maria I. L. Soares Dep. Chem., Univ. Coimbra, P-3004 Coimbra, Port.Search for more papers by this authorAna C. F. de Lyra, Ana C. F. de Lyra Dep. Chem., Univ. Coimbra, P-3004 Coimbra, Port.Search for more papers by this authorMarta S. C. Henriques, Marta S. C. Henriques Dep. Chem., Univ. Coimbra, P-3004 Coimbra, Port.Search for more papers by this authorJose A. Paixao, Jose A. Paixao Dep. Chem., Univ. Coimbra, P-3004 Coimbra, Port.Search for more papers by this authorTeresa M. V. D. Pinho e Melo, Teresa M. V. D. Pinho e Melo Dep. Chem., Univ. Coimbra, P-3004 Coimbra, Port.Search for more papers by this author Maria I. L. Soares, Maria I. L. Soares Dep. Chem., Univ. Coimbra, P-3004 Coimbra, Port.Search for more papers by this authorAna C. F. de Lyra, Ana C. F. de Lyra Dep. Chem., Univ. Coimbra, P-3004 Coimbra, Port.Search for more papers by this authorMarta S. C. Henriques, Marta S. C. Henriques Dep. Chem., Univ. Coimbra, P-3004 Coimbra, Port.Search for more papers by this authorJose A. Paixao, Jose A. Paixao Dep. Chem., Univ. Coimbra, P-3004 Coimbra, Port.Search for more papers by this authorTeresa M. V. D. Pinho e Melo, Teresa M. V. D. Pinho e Melo Dep. Chem., Univ. Coimbra, P-3004 Coimbra, Port.Search for more papers by this author First published: 20 August 2015 https://doi.org/10.1002/chin.201536199Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume46, Issue36September, 2015 RelatedInformation

Thermal reactions of 1-(thiophene-2-yl)-1H-tetrazoles are reported for the first time. The solution thermolysis of 1-(thiophene-2-yl)-1H-tetrazoles under conventional heating and microwave irradiation afforded the unexpected new thieno[2,3-d]pyrimidines incorporating two thiophene rings, which were obtained as major or only product. The synthesis of these heterocycles was rationalized considering the initial nitrogen elimination to generate imidoylnitrene followed by rearrangement to the corresponding carbodiimide and subsequent cyclization triggered by the nucleophilic attack of the in situ generated 2-aminothiophene. The flash vacuum pyrolysis and solution thermolysis of 1-(thiophene-2-yl)-1H-tetrazoles also gave thieno[2,3-d]imidazoles via intramolecular formal insertion into a C–C bond of the corresponding imidoylnitrene intermediate.