Karmen Brajša

Azithromycin modulates neutrophil function and circulating inflammatory mediators in healthy human subjects

Effects on human neutrophils and circulating inflammatory mediators were studied in 12 volunteers who received azithromycin (500 mg/day, p.o.) for 3 days. Blood was taken 1 h before treatment, 2.5, 24 h and 28 days after the last dose. An initial neutrophil degranulating effect of azithromycin was reflected in rapid decreases in azurophilic granule enzyme activities in cells and corresponding increases in serum. The oxidative response to a particulate stimulus was also acutely enhanced. These actions were associated with high plasma and neutrophil drug concentrations. A continuous fall in chemokine and interleukin-6 serum concentrations, within the non-pathological range, accompanied a delayed down-regulation of the oxidative burst and an increase in apoptosis of neutrophils up to 28 days after the last azithromycin dose. Neutrophils isolated from blood at this time point still contained detectable drug concentrations. Acute neutrophil stimulation could facilitate antibacterial effects of azithromycin, while delayed, potentially anti-inflammatory activity may curtail deleterious inflammation.

Synthesis and biological validation of novel pyrazole derivatives with anticancer activity guided by 3D-QSAR analysis.

Using literature data on anticancer activity of pyrazole derivatives, 3D-QSAR models were developed and 3D-QSAR analysis was performed. The 3D-QSAR analysis enabled identification of molecular properties that have the highest impact on antitumor activity against lung cancer cells. The results of 3D-QSAR analysis were taken into account while new compounds were designed. Obtained 3D-QSAR models were used for prediction of activity of new compounds. In this way, design of new compounds was guided by 3D-QSAR analysis which was performed on literature data. Ten new pyrazole derivatives were synthesised and their antitumor activities against A549 and NCIH23 lung cancer cells were validated. In order to obtain full profile of anticancer activity, cells viability (MTS) assays were combined with cell proliferation (BrdU) assays which measure actively dividing cells in treated sample. Experimental measurements showed good agreement between predicted and measured activities for majority of compounds. Also, anticancer activities of new pyrazole derivatives pointed to the chemical groups that can be useful in designing antitumor molecules. Substitution of hydrazine linker with rigid, 1,2,4-oxadiazole moiety resulted in compound 10, which has low (if any) cytotoxic activity and high potential cytostatic activity. Therefore, compound 10 presents a good starting point for design of new, more potent and safer anticancer therapeutics.

Differential evaluation of excisional non-occluded wound healing in db/db mice.

The full-thickness wound in the genetically diabetic (db/db) mouse is a commonly used model of impaired wound healing. We investigated delayed healing of non-occluded, excisional, full-thickness, dermal wounds in db/db mice in comparison to their normal littermate controls and refined methods for monitoring skin wound re-epithelialization, contraction, granulation tissue formation, and inflammation. We have confirmed with a computer-assisted planimetry method the results of previous studies showing that healing of non-occluded full excision wounds in db/db mice does not occur by contraction as much as in healthy mice. In addition, we have developed separate histological methods for the assessment of re-epithelialization, contraction, granulation tissue (mature, immature, fibrosis), and inflammation (lipogranulomas, secondary, nonspecific). Using a new approach to histological assessment, we have shown that wound closure in db/db mice is delayed owing to: (1) delayed granulation tissue maturation; (2) ‘‘laced,’’ widely distributed granulation tissue around fat lobules; and (3) obstruction by lipogranulomas, whereas the rate of re-epithelialization seems to be the same as in C57Bl/6 mice. This methodology should permit a more precise differentiation of effects of novel therapeutic agents on the wound healing process in db/db mice.

Synthesis of macrolones with central piperazine ring in the linker and its influence on antibacterial activity

Three macrolides, clarithromycin, azithromycin and 11-O-Me-azithromycin have been selected for the construction of a series of new macrolone derivatives. Quinolone-linker intermediates are prepared by Sonogashira-type C(6)-alkynylation of 6-iodoquinolone precursors. The final macrolones, differing by macrolide moiety and substituents at the position N-1 of the quinolone or by the presence of an ethyl ester or free acid on the quinolone unit attached via a linker. The linker comprises of a central piperazine ring bonded to the 4″-O position of cladinose by 3-carbon ester or ether functionality. Modifications of the linker did not improve antibacterial properties compared to the previously reported macrolone compounds. Linker flexibility seems to play an important role for potency against macrolide resistant respiratory pathogens.

The effect of apigenin on cyclophosphamide and doxorubicin genotoxicity in vitro and in vivo

The aim of this study was to investigate the mutagenic and antigenotoxic effects of different doses of the flavonoid, apigenin, alone and in combination with the antitumor drugs, cyclophosphamide and doxorubicin, in vitro and in vivo. Using bacterial reverse mutation inhibition in vitro, with and without metabolic activation, the effect of apigenin (10 – 400 μg/plate) was studied on genotoxicity induced by cyclophosphamide (800 μg/plate) and by doxorubicin (0.2 μg/plate). Subsequent to a dose-finding study in vivo, CD1 mice were treated with either cyclophosphamide (40 mg/kg, i.p.) or doxorubicin (5 mg/kg, i.p.) with or without co-administration of apigenin (1–100 mg/kg, p.o.). Micronuclei were determined microscopically in blood smears and glutathione peroxidase (GPX), superoxide dismutase (SOD) and total antioxidative status (TAS) in whole blood, erythrocytes and plasma, respectively. Apigenin decreased doxorubicin-induced, but not cyclophosphamide-induced mutagenicity in vitro. In vivo, apigenin caused a statistically significant decrease in micronucleus frequency in response to cyclophosphamide, possibly due to active flavonoid metabolite formation or inhibition of cyclophosphamide metabolic activation. In animals treated with apigenin and doxorubicin, a significant decrease in micronucleus frequency was not observed, probably due to interindividual variability. No changes in GPX, SOD or TAS were observed in response to either cytotoxic agents or the flavonoid, possibly due to limited metabolic transformation of the drugs at the doses used. The results of the present study provide further evidence for the chemo-preventative properties of apigenin.

Antitumor activity of amidino-substituted benzimidazole and benzimidazo[1,2-a]quinoline derivatives tested in 2D and 3D cell culture systems.

Abstract Due to a poor clinical predictive power of 2D cell cultures, standard tool for in vitro assays in drug discovery process, there is increasing interest in developing 3D in vitro cell cultures, biologically relevant assay feasible for the development of robust preclinical anti-cancer drug screening platforms. Herein, we tested amidino-substituted benzimidazoles and benzimidazo[1,2-a]quinolines as a small platform for comparison of antitumor activity in 2D and 3D cell culture systems and correlation with structure–activity relationship. 3D cell culture method was applied on a human cancer breast (SK-BR-3, MDA-MB-231, T-47D) and pancreatic cancer cells (MIA PaCa-2, PANC-1). Results obtained in 2D and 3D models were highly comparable, but in some cases we have observed significant disagreement indicating that some prominent compounds can be discarded in early phase of researching because of compounds with false positive result. To confirm which of cell culture systems is more accurate, in vivo profiling is needed.

Porphyrins as new endogenous anti-inflammatory agents.

A series of porphyrins, tetrapyrrole natural organic compounds, are evaluated here as endogenous anti-inflammatory agents. They directly inhibit the activity of Fyn, a non-receptor Src-family tyrosine kinase, triggering anti-inflammatory events associated with down-regulation of T-cell receptor signal transduction, leading to inhibition of tumor necrosis factor alpha (TNF-α) production. This is one of the major pro-inflammatory cytokines, associated with diseases such as diabetes, tumorigenesis, rheumatoid arthritis, and inflammatory bowel disease. Porphyrins, as a chemical class, inhibited Fyn kinase activity in a non-competitive, linear-mixed fashion. In cell-based in vitro experiments on polymorphonuclear cells, porphyrins inhibited TNF-α cytokine production, T-cell proliferation, and the generation of free radicals in the oxidative burst, in a concentration-related manner. In vivo, lipopolysaccharide-induced TNF-α production in mice was inhibited by several of the porphyrins. These findings may be very important for the overall understanding of the role(s) of porphyrins in inflammation and their possible application as new anti-inflammatory agents.

Baicalin and Baicalein Inhibit Src Tyrosine Kinase and Production of IL-6

Flavonoids play an important role in the treatment of various diseases, as they are able to inhibit reactive oxygen species, which cause damage to cells and tissues which may lead to increased risk of inflammatory diseases. Baicalin and baicalein, two flavonoids found in the roots of Scutellaria baicalensis, in the leaves of Thymus vulgaris and Oroxylum indicum, were tested for their anti-inflammatory activity as well as for their cytotoxicity. Thereby the two compounds were investigated on Src tyrosine kinase inhibition and inhibition of production of interleukin (IL-6) in lipopolysaccharide- (LPS-) stimulated THP-1 cells. Additionally, the THP-1 cell line was used for the determination of the cytotoxicity. Both baicalin and baicalein showed some anti-inflammatory properties, while baicalein turned out to be the more active compound with higher inhibitory activities on both Src tyrosine kinase and production of cytokine IL-6. Baicalin and baicalein showed no signs of cytotoxicity in the MTS cytotoxicity assay in THP-1 cells.

Relative potencies of three glucocorticoids to induce hypoplasia of the physis and concomitant biochemical alterations in the rat

Abstract Although inhaled glucocorticoids are known to have systemic effects on bone metabolism, there is little comparative information on their relative potencies. The effects of three standard glucocorticoids in causing changes in bone metabolism and growth, therefore, were investigated in relation to other systemic effects in the rat. Given to male Sprague-Dawley rats, 4.5–5.5 weeks old, subcutaneously (s.c.), at doses of 0.3–10 mg/kg daily for 7 days, beclomethasone dipropionate, prednisolone and ciclesonide all dose-dependently inhibited thymus body mass index (BMI) (by 57%, 44% and 76% at 3 mg/kg). Ciclesonide, potently and prednisolone, less effectively, also repressed femoral bone growth (by 41% and 18% at 10 mg/kg), significantly reducing body weight gain (both by 100% at 10 mg/kg), and serum concentrations of acid phosphatase (ACP) and tartarate resistant acid phosphatase (TRACP) (by >30% at 10 mg/kg); both increased serum glucose and triglycerides levels. Serum alkaline phosphatase (ALP) was not affected. Beclomethasone dipropionate had little or no effect on these additional variables. In conclusion, ciclesonide showed pronounced bone growth inhibiting activity after s.c. administration to the rat while other two glucocorticoids showed differences in activity on bone metabolism. However, this model is sufficiently sensitive and specific for testing the effect of glucocorticoids on bone metabolism.