Marek Murias

Folic acid-conjugated core/shell ZnS:Mn/ZnS quantum dots as targeted probes for two photon fluorescence imaging of cancer cells.

This work presents a novel approach to producing water soluble manganese-doped core/shell ZnS/ZnS quantum dots (ZnS:Mn/ZnS). The Mn-doped ZnS core was prepared through a nucleation doping strategy and a ZnS shell was grown on ZnS:Mn d-dots by decomposition of Zn(2+)-3-mercaptopropionic acid (MPA) complexes at 100 °C. It was found that the Mn2+(4)T1→6A1 fluorescence emission at ∼590 nm significantly increased after growth of the shell when the Mn2+ doping content was 4.0 at.%. A photoluminescence quantum yield of ∼22% was obtained for core/shell nanocrystals. The nanoparticles were structurally and compositionally characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and dynamic light scattering. The surface MPA molecules favor the dispersion of ZnS:Mn/ZnS QDs in aqueous media and make possible conjugation with targeting folic acid molecules. The folate receptor-mediated delivery of folic acid-conjugated ZnS:Mn/ZnS QDs was demonstrated using confocal microscopy with biphotonic excitation. Bare and folate-conjugated QDs exhibit only weak cytotoxicity towards folate receptor-positive T47D cancer cells and MCF-7 cells, used as a reference, at high concentrations (mmolar range) after 72h incubation.

Thioglycerol-capped Mn-doped ZnS quantum dot bioconjugates as efficient two-photon fluorescent nano-probes for bioimaging

Water-dispersible 1-thioglycerol (TG)-capped Mn-doped ZnS quantum dots were prepared in aqueous solution using the nucleation-doping strategy. Using 4% Mn relative to Zn and a Zn(OAc)2/Na2S ratio of 0.9, Mn:ZnS nanocrystals with an average diameter of 3.9 ± 0.5 nm, with pure Mn2+-related photoluminescence (PL) at 585 nm, and with a PL quantum yield of 13.2% were obtained. Transmission electron microscopy, X-ray powder diffraction, electron spin resonance, X-ray photoelectron spectroscopy, UV-visible spectroscopy and spectrofluorometry have been used to characterize the crystal structure, the doping status, and the optical properties of the doped-dots. Folic acid (FA) was linked to TG-capped Mn:ZnS nanocrystals to produce Mn:ZnS@TG-FA nanobioconjugates that were used for targeted in vitro delivery to a human cancer cell line. Folate receptor mediated cellular uptake of FA-functionalized dots is proven via confocal and two-photon imaging.

In vitro antileishmanial activity of resveratrol and its hydroxylated analogues against Leishmania major promastigotes and amastigotes

Resveratrol, a natural phytoalexin found mainly in grapes, possesses a variety of beneficial activities including anticancer, antimicrobial and antiviral. However, there is no information about its effects on kinetoplastid parasites such as Leishmania. Leishmania is a human pathogen responsible for a spectrum of diseases known as leishmaniases and a significant health problem in many parts of the world. In this study, we investigated effects of resveratrol and its hydroxylated analogues on Leishmania major, a causative agent of zoonotic cutaneous leishmaniasis in the Old World. Resveratrol showed antileishmanial activity against promastigotes in vitro and, more importantly, was effective against intracellular amastigotes, a parasite life stage infectious in humans, as detected in in vitro macrophage assay. The hydroxylated stilbenes tested in this study also showed antileishmanial activity against promastigotes, the most promising being 3,4,4′,5′-tetrahydroxy-trans-stilbene. This compound showed excellent antileishmanial activity against extracellular promastigotes in vitro but not intracellular amastigotes. Our results suggest that resveratrol may be useful as a therapeutic agent to treat leishmaniasis and warrant its further assessment in animal models of disease.

Different Effects of Resveratrol on Dose-Related Doxorubicin-Induced Heart and Liver Toxicity

The aim of the study was to evaluate the effect of resveratrol in doxorubicin-induced cardiac and hepatic toxicity. Doxorubicin was administered once a week throughout the period of 7 weeks with 1.0 or 2.0 mg/kg body weight or concomitantly with resveratrol (20 mg/kg of feed). Heart and liver toxicity was histologically and biochemically evaluated. Resveratrol protected from the heart lipid peroxidation caused by 1 mg doxorubicin and it sharply diminished superoxide dismutase activity. An insignificant effect of resveratrol on the lipid peroxidation level and the superoxide dismutase activity was observed in the hearts of rats administered a higher dose of doxorubicin. However, resveratrol attenuate necrosis and other cardiac histopathological changes were induced by a high dose of doxorubicin. Interestingly, it slightly intensified adverse cardiac histological changes in rats receiving a lower dose of doxorubicin. Resveratrol did not have any protective effect on the hepatic oxidative stress, while exerting a mild beneficial effect on the morphological changes caused by doxorubicin. All in all, this study has shown different effects of resveratrol on dose-related doxorubicin-induced heart and liver toxicity. Resveratrol may modulate the hepatic and cardiac effect of doxorubicin, depending on the drug dose.

Protective Effect of Red Beetroot against Carbon Tetrachloride- and N-Nitrosodiethylamine-Induced Oxidative Stress in Rats

The aim of the study was to investigate the potential protective effect of beetroot juice in a model of oxidative stress induced by N-nitrosodiethylamine (NDEA) and carbon tetrachloride (CCl(4)). Male Wistar rats were treated with beetroot juice per os, 8 mL/kg/day for 28 days, and a single i.p. dose of the xenobiotics: 150 mg/kg NDEA or 2 mL/kg CCl(4). Simultaneously, two groups of rats not pretreated with juice were given only each of the xenobiotics. The level of microsomal lipid peroxidation in the liver, expressed as TBARS concentration, was increased several fold in rats administered only NDEA or CCl(4). TBARS were decreased by 38% only in rats pretreated with beetroot juice before the administration of CCl(4). In animals pretreated with juice and receiving NDEA, a further increase in TBARS occurred. All of the investigated antioxidant enzymes were inhibited by the administration of either toxicant alone by 26%-77% as compared to controls. Pretreatment with juice caused a partial recovery in the activity of glutathione peroxidase and glutathione reductase, by 35% and 66%, respectively. Superoxide dismutase activity was increased about 3-fold in animals pretreated with juice. Both xenobiotics caused a rise in plasma protein carbonyls, which were reduced by 30% in rats pretreated with juice and then injected with NDEA. Similarly, DNA damage in blood leukocytes caused by either toxicant was slightly diminished, by 20%, in the rats treated with juice before NDEA administration. It could be concluded that pretreatment with beetroot juice can counteract, to some extent, xenobiotic-induced oxidative stress in rats.

Phthalocyanine Derivatives Possessing 2-(Morpholin-4-yl)ethoxy Groups As Potential Agents for Photodynamic Therapy

Three 2-(morpholin-4-yl)ethoxy substituted phthalocyanines were synthesized and characterized. Phthalocyanine derivatives revealed moderate to high quantum yields of singlet oxygen production depending on the solvent applied (e.g., in DMF ranging from 0.25 to 0.53). Their photosensitizing potential for photodynamic therapy was investigated in an in vitro model using cancer cell lines. Biological test results were found particularly encouraging for the zinc(II) phthalocyanine derivative possessing two 2-(morpholin-4-yl)ethoxy substituents in nonperipheral positions. Cells irradiated for 20 min at 2 mW/cm(2) revealed the lowest IC50 value at 0.25 μM for prostate cell line (PC3), whereas 1.47 μM was observed for human malignant melanoma (A375) cells. The cytotoxic activity in nonirradiated cells of novel phthalocyanine was found to be very low. Moreover, the cellular uptake, localization, cell cycle, apoptosis through an ELISA assay, and immunochemistry method were investigated in LNCaP cells. Our results showed that the tested photosensitizer possesses very interesting biological activity, depending on experimental conditions.

Cytotoxicity, acute and subchronic toxicity of ionic liquid, didecyldimethylammonium saccharinate, in rats.

The aim of this study was to investigate cytotoxicity, acute and subchronic oral toxicity of an ionic liquid didecyldimethylammonium saccharinate [DDA][Sac] in rat. IC(50) values tested on six human cell lines varied from 1.44 microM to 5.47 microM. The compound tested was classified to the 4th toxicity class with a fixed LD(50) cut-off value 500 mg/kg. Organ pathology induced by [DDA][Sac] in an acute experiment included exfoliation of the surface layer of the colon and alveolar septa in lung parenchyma. In a subchronic experiment rats were administered 10, 30 and 100 mg/kg/day [DDA][Sac] for 28 days. Reduced body weight gain and slightly reduced food consumption was observed particularly in high-dose rats. Slight hematology changes were found only in mid-dose females. Statistically significant changes in clinical chemistry parameters included: increases in the ALT, SDH, ALP and GGT activities, and in glucose, blood urea nitrogen and creatinine concentrations. However, these changes did not occur in both sexes and were not dose-related with the exception of ALP in females. No treatment-related microscopic changes were observed in a subchronic experiment. Under the condition of this study the lowest-observed-adverse-effect level of [DDA][Sac] was considered to be 10 mg/kg/day.

Resveratrol and its synthetic derivatives exert opposite effects on mesothelial cell-dependent angiogenesis via modulating secretion of VEGF and IL-8/CXCL8

We examined the effect of resveratrol (RVT) and its two derivatives (3,3′,4,4′-tetrahydroxy-trans-stilbene and 3,3′,4,4′,5,5′-hexahydroxy-trans-stilbene) on human peritoneal mesothelial cell (HPMC)-dependent angiogenesis in vitro. To this end, angiogenic activity of endothelial cells (HUVEC, HMVEC, and HMEC-1) was monitored upon their exposure to conditioned medium (CM) from young and senescent HPMCs treated with stilbenes or to stilbenes themselves. Results showed that proliferation and migration of endothelial cells were inhibited in response to indirect (HPMC-dependent) or direct RVT activity. This effect was associated with decreased secretion of VEGF and IL-8/CXCL8 by HPMCs treated with RVT, which confirmed the experiments with recombinant forms of these angiogenic agents. Angiogenic activity of endothelial cells treated with CM from HPMCs exposed to RVT analogues was more effective. Improved migration was particularly evident in cells exposed to CM from senescent HPMCs. Upon direct treatment, RVT derivatives stimulated proliferation (but not migration) of HUVECs, and failed to affect the behaviour of HMVEC and HMEC-1 cells. These compounds stimulated production of VEGF and IL-8/CXCL8 by HPMCs. Studies with neutralizing antibodies against angiogenic factors revealed that augmented angiogenic reactions of endothelial cells exposed to CM from HPMC treated with RVT analogues were related to enhanced production of VEGF and IL-8/CXCL8. Collectively, these findings indicate that RVT and its synthetic analogues divergently alter the secretion of the angiogenic factors by HPMCs, and thus modulate HPMC-dependent angiogenic responses in the opposite directions. This may have implications for the attempts of practical employment of the stilbenes for treatment of pathologies proceeding with abnormal vascularisation of the peritoneal tissue.

Protective effect of Aquilegia vulgaris L. on aflatoxin B1-induced hepatic damage in rats

The aim of the study was to investigate the effect of ethanol and ethyl acetate extract obtained from Aquilegia vulgaris L. on microsomal lipid peroxidation, reduced glutathione level and antioxidant enzymes activity in the liver of rats intoxicated with aflatoxin B(1) (AFB(1)). Animals were pretreated with 12 daily p.o. doses of the extracts tested (100mg/kg body weight). Then AFB(1) was administered intraperitoneally at a single dose of 1.5mg/kg b.w. to evoke the liver damage. α-Tocopherol was used as a positive control. Reduced glutathione (GSH) was depleted in aflatoxin-treated rats by 80% in comparison with that in the controls. The extracts restored the GSH concentration up to the basal level. Microsomal lipid peroxidation stimulated by Fe(2+)/ascorbate (assessed by measuring TBARS) was enhanced in AFB(1)-treated rats by 28% as compared to that in the control group. The extracts caused a decrease in TBARS level by 40% and 27%. Only two antioxidant enzymes were affected by AFB(1) administration. The activity of catalase was reduced by 24% and the activity of glutathione-S-transferase (GST) was increased by 33%. The pretreatment with ethyl acetate and ethanol extract reduced the GST activity by 76% and 30%, respectively. No significant changes in the activity of other antioxidant enzymes were observed in rats treated with the extracts and AFB(1). It can be concluded that multiple pretreatment with the extracts obtained from A. vulgaris attenuated aflatoxin B(1)-induced hepatic damage as evidenced by inhibition of lipid peroxidation and preventing reduced glutathione depletion.

COX-2 inhibitors: a novel strategy in the management of breast cancer.

Cyclooxygenase-2 (COX-2) inhibitors are common anti-inflammatory drugs with pleiotropic, endogenous actions that could be useful in the management of breast cancer. Here, we provide a complete understanding of the biochemistry of COX-2 and discuss the various molecular mechanisms behind its increased expression in breast cancer. We also analyze the possible mechanisms responsible for the anticancer effect of COX-2 inhibitors and provide an overview of the available preclinical and clinical data on the use of COX-2 inhibitors in breast cancer. Finally, we describe a mathematical model of the relation between the structure and biological potency of promising new COX-2 inhibitors (trans-stilbenes) using a 2D quantitative structure-activity relationship (QSAR) technique.