Synthesis of novel isothiazolopyridines and their in vitro evaluation against Mycobacterium and Propionibacterium acnes

AbstractIn this paper we describe synthesis, structures and some physicochemical properties of 20 isothiazolopyridines 8–13 substituted differently into an isothiazole ring as well as their in vitro antibacterial assays against Mycobacterium tuberculosis H37Rv, Mycobacterium fortuitum PCM 672 and Propionibacterium acnes PCM 2400. Compound 13a was found to be the most active derivative against M. tuberculosis H37Rv, demonstrating 100% growth inhibition of microorganisms in the primary screen (minimum inhibitory concentration [MIC] 6.25μg/mL). Nineteen of the prepared compounds were evaluated against M. fortuitum PCM 672 and P. acnes PCM 2400 and only compounds 9 and 12d exhibited excellent activity against individual strains of microorganisms with MIC90 <1μg/mL. The inhibitory action of the remaining isothiazolopyridines towards the tested strains of the microorganism was low, absent, or a non-linear correlation prohibited accurate determination of MIC values. Unexpectedly, seven of the remaining isothiazolopyridines tested against M. fortuitum and P. acnes stimulated growth of the microorganisms in the range 10–50% or even more (10b) under experimental conditions

Chemopreventive activity of fluphenazine and its analogues in human lymphocyte cultures preincubated with ceramide synthase inhibitor

Wstęp. Ceramid (cer) jest zazwyczaj produkowany na drodze hydrolizy sfingomieliny przez sfingomielinazy (SMase). Zbadano, że aktywność chemoprewencyjna — propoptotyczna i chemouwrażliwiająca — piperazynowej pochodnej fenotiazyny (Pht), flufenazyny (FPh) i jej nowo syntezowanych analogów — związków 1b i 3f — zależy od stymulacji lizosomalnej, kwaśnej sfingomielinazy (aSMase), niezależnej od Zn2+, jednego z enzymów uczestniczących w powsta­waniu endogennego cer. Innym ważnym szlakiem tworzenia cer w komórce jest synteza de novo z udziałem syntetazy ceramidowej (CerS). Celem pracy była ocena aktywności chemoprewencyjnej FPh i jej analogów: związków 1b i 3f po nieodwracalnym zablokowaniu CerS. Materiał i metody. Aktywność chemoprewencyjną badanych związków (10 μM, 2 godz.) oceniano w hodowlach limfocytów ludzkich uszkodzonych genotoksycznie przez inkubację z benzo[a]pirenem (+B[a]P; 7,5 μM, 48 godz.) i po preinkubacji z selektywnym inhibitorem CerS — fumonizyną B1 (+FB1; 20 μM, 1,5 godz.). W ocenie efektów badanych związków zastosowano metody: mikroskopii fluorescencyjnej, spektrofotometrii i spektrofluorymetrii. Istotność statystyczną uzyskanych rezultatów sprawdzono za pomocą testu t-Studenta. Wyniki. W hodowlach limfocytów w obecności inhibitora CerS (+B[a]P; +FB1) inkubacja hodowli z analogami 1b i 3f prowadziła do istotnie niższego (p &lt; 0,05) odsetka komórek w apoptozie i akumulacji rodaminy 123 (Rod-123) w po­równaniu z hodowlą bez inhibitora CerS (+B[a]P; -FB1). W przypadku macierzystego związku FPh wpływ na hodowle limfocytów nie zależał od obecności inhibitora CerS. Wnioski. Efekty proapoptotyczny i chemouwrażliwiający analogów 1b i 3f są uwarunkowane aktywacją CerS. Nato­miast dla macierzystej FPh wykazano, że jej aktywność chemoprewencyjna nie zależy od stymulacji szlaku syntezy de novo cer z udziałem CerS.Introduction. The ceramide (cer) is generated mainly via hydrolysis of sphingomyelin by sphingomeylinase (SMase). It was previously documented that chemopreventive activity — proapoptotic and chemosensitizng of piperazine phenothiazine derivative, fluphenazine (FPh) and its newly synthesized analogues, 1b and 3f compounds, depends on the activity of lysosomal acidic sphingomyelinase (aSMase), Zn2+-independent, one of the enzymes participating in intracellular ceramide generation. Another important pathway of intracellular formation of ceramide is de novo synthesis with participation of ceramide synthase (CerS). The aim of this research is to assess the chemopreventive activity of FPh and 1b and 3f compounds after irreversible CerS blockade. Material and methods. Chemopreventive activity of the tested compounds (10 μM, 2 h) was evaluated in hu­man lymphocyte cultures, genotoxically damaged by benzo[a]pyrene (+B[a]P; 7,5 μM, 48 h) and preincubated with a selective inhibitor CerS — fumonisin B1 (+FB1; 20 μM, 1,5 h) and inspected with fluorescence microscopy, as well as with spectrophotometric and spectrofluorimetric methods. Student’s t-test was used for testing the statistical significance of the results. Results. It was established that in the presence of the CerS inhibitor (+B[a]P; +FB1) the effects of 1b and 3f analogues on apoptotic cell frequency in lymphocyte cultures and on accumulation of rhodamine 123 (Rod-123), were signifi­cantly (p &lt; 0.05) decreased when compared to the cultures carried out in the absence of the CerS inhibitor (+B[a]P; -FB1). Whereas in the case of the parent compound: the FPh, the presence of the inhibitor did not influence on FPh chemopreventive activity. Conclusions. The proapoptotic and chemosensitizing effects of 1b and 3f compounds were determined in major part by CerS activation. Also the chemopreventive activity of the parent compound: the FPh, was independent of the cer de novo synthesis pathway conducted by CerS

Electrocatalytic water oxidation by CuII complexes with branched peptides

Two mononuclear CuII complexes with tetrapeptides incorporating a L-2,3-diaminopropionic acid (dap) branching unit are reported to undergo PCET and catalyse water oxidation. C-terminal His extension of dap (L = 2GH) instead of Gly (L = 3G) lowers the pKa for CuIIIH-2L (9.36 vs. 9.98) and improves the TOF at pH 11 (53 vs. 24 s-1)

Branched peptide with three histidines for the promotion of CuII binding in a wide pH range – complementary potentiometric, spectroscopic and electrochemical studies

Modifications in linear and cyclic peptides have been widely explored in relation with the associated effects on the coordination of CuII. Branching of peptides is yet another innovative conception to promote metal binding. The three dimensional (3D), quasi-tripodal structure of the new ligand, H-His-Dap(H-His)-His-NH2 (3H, where Dap = L-2,3-diaminopropionic acid), which is created by the vicinal two N-terminal and one C-terminal functions of Dap allows triple-arm extension and offers new options in metal binding. A strategy is presented for the characterization of 3H focusing on the role of structural domains in CuII binding by comparison of analogous tetrapeptides that involve a varying number of His and Gly residues. Potentiometric, spectroscopic (UV-Vis, CD and EPR), mass spectrometric and electrochemical data indicate that in monomeric CuII–3H complexes the metal is bound with higher affinity compared to its structural domains indicating that the effect of 3D branching should be taken as an important factor for future studies on CuII peptide constructs

Self-assembled, nanostructured coatings for water oxidation by alternating deposition of Cu-branched peptide electrocatalysts and polyelectrolytes

This work demonstrates the heterogenization of homogeneous water oxidation electrocatalysts in surface coatings produced by combining the substances with a suitable polyelectrolyte.</p