Aleksandra Misicka

Comparison of performance of Chirobiotic T, T2 and TAG columns in the separation of β2-and β3-homoamino acids

The enantiomers of eight unusual beta(2)- and beta(3)-homoamino acids were separated on chiral stationary phases containing the macrocyclic glycopeptide antibiotic teicoplanin (Chirobiotic T or T2) or teicoplanin aglycone (Chirobiotic TAG) as chiral selectors. The effects of the organic modifier, the mobile phase composition, and temperature on the separations were investigated. Linear vant Hoff plots were observed in the studied temperature range, 280-318 K, and the changes in enthalpy, Delta(DeltaH(o)), entropy, Delta(DeltaS(o)), and free energy, Delta(DeltaG(o)) were calculated. The values of the thermodynamic parameters depended on the nature of the selectors, the structures of the analytes, and especially the positions of the substituents on the analytes. A comparison of the separation performances of the macrocyclic glycopeptide stationary phases revealed that the Chirobiotic TAG column exhibited much better selectivity for beta(2)-homoamino acids, while the separation of beta(3)-homoamino acid enantiomers was better on Chirobiotic T or T2. The elution sequence was determined in some cases and was observed to be R < S.

Certain aspects of silver and silver nanoparticles in wound care: a minireview

Resistance to antimicrobial agents by pathogenic bacteria has emerged in recent years and is a major health problem. In this context silver and silver nanoparticles (AgNP) have been known to have inhibitory and bactericidal effects and was used throughout history for treatment of skin ulcer, bone fracture, and supporting wound healing. In all of these applications prevention and treatment of bacterial colonized/infected wounds are critical. In this context silver and its derivatives play an important role in health care. Silver is widely used in clinical practice in the form of silver nitrate and/or silver sulfadiazine. In the last few years silver nanoparticles entered into clinical practice as both antimicrobial and antifungal agents. In addition, nanosilver is used in coating medical devices (catheters) and as component of wound dressings. In this paper we present summarized information about silver and nanoparticles made of silver in the context of their useful properties, especially antibacterial ones, being of a great interest for researchers and clinicians.

Adjuvant vaccination with melanoma antigen-pulsed dendritic cells in stage III melanoma patients

Dendritic cells may be successfully used to induce in vivo-specific anti-tumor responses when combined with the appropriate antigen in the appropriate context. The purpose of this study was to evaluate efficacy of peptide-loaded DC vaccine in high-risk stage III melanoma patients after lymph node dissection (LND). HLA-A2+, -A1+, or -A3+ melanoma patients (Nxa0=xa022), stage III, N1b-N3, received 5–16 (median: 11) DC vaccines loaded with MHC class-I-restricted melanoma peptides respective to the patient’s haplotype, and with autologous tumor lysate, if available. Vaccinated patients were matched to unvaccinated stage III controls (22 of 869) by sex, number of metastatic lymph nodes, extracapsular involvement, LND type, Breslow stage, and ulceration. Vaccination elicited cutaneous delayed-type hypersensitivity (DTH) or/and IFN-γ-producing CD8+ cell response to melanoma peptides in 15 of 22 patients. Three-year overall survival (OS) rate was 68.2% in the vaccinated group versus 25.7% in the control group, P value accounting for matching: 0.0290. In a Cox regression model, hazard ratio (HR) for death of vaccinated patients was 0.31 [95% confidence interval (CI): 0.10–0.94]. The corresponding values for 3-year disease-free survival rate were 40.9 versus 14.5%, Pxa0=xa00.1083; HR of recurrence for vaccinated, 0.46 (95% CI: 0.18–1.22). There was no grade >1 toxicity. The DC/peptide vaccine was well tolerated and elicited immune responses to melanoma antigens. Vaccinated patients had significantly longer OS after LND than the matched controls, but a significant improvement in the primary endpoint DFS was not achieved.

High-performance liquid chromatographic chiral separation of β2-homoamino acids

Reversed-phase high-performance liquid chromatographic methods were developed for the separation of enantiomers of eleven unnatural beta(2)-homoamino acids on chiral stationary phases containing macrocyclic glycopeptides (teicoplanin-containing Chirobiotic T and T2) or the macrocyclic peptide teicoplanin aglycone (Chirobiotic TAG) as chiral selectors. The effects of the organic modifier, the mobile phase composition, temperature, and the structures of the analytes on the separations were investigated. Separations were carried out at constant mobile phase compositions in temperature range 7-45 degrees C and the changes in enthalpy, Delta(DeltaH(o)), entropy, Delta(DeltaS(o)), and free energy, Delta(DeltaG(o)), were calculated. The -Delta(DeltaG(o)) values obtained on the three columns indicated that Chirobiotic TAG, without sugar units, may promote the interactions of the enantiomers of beta(2)-homoamino acids with branched alkyl or aryl side-chains, whereas for beta(2)-homoamino acids with alkyl side-chains Chirobiotic T and T2 seem to be more favorable. The elution sequence was determined in some cases and was observed to be R < S.

Design, synthesis and in vitro biological evaluation of a small cyclic peptide as inhibitor of vascular endothelial growth factor binding to neuropilin-1.

Neuropilin-1 (NRP-1) is a co-receptor of VEGFR (vascular endothelial growth factor receptor), but it is also suggested that NRP-1 in tumour cells may serve as a separate receptor for VEGF165. Therefore molecules interfering with VEGF165 binding to NRP-1 seem to be promising candidates as new anti-angiogenic and anti-tumour drugs. Here, we report the design, synthesis, biological evaluation and molecular modelling of the small cyclic peptide, which shows a good inhibitory effect on VEGF165/NRP-1 binding (IC50=0.18μM). The reported compound could be considered as one of the smallest cyclic peptides (MW=510) interfering with VEGF165/NRP-1 binding presented up to now.

The effect of intracerebroventricular infusion of morphine, methionine-enkephalin and D-Ala2-Met-enkephalinamide on body temperature of rabbits

The effect of intracerebroventricular infusions of two synthetically obtained peptides: Met-enkephalin hydrochloride and D-Ala2-Met-enkephalinamide hydrochloride, and of morphine hydrochloride on rectal temperature was investigated in conscious rabbits. Morphine hydrochloride in a dose of 240 micrograms and D-Ala2-Met-enkephalinamide hydrochloride in doses of 240 and 3000 micrograms produced a hyperthermia which was accompanied by ear vasoconstriction and shivering. No such effect ensued after Met-enkephalin, possibly due to rapid enzymatic degradation of this compound. The concept of opioid involvement in the central thermoregulatory mechanism is discussed.

Biphalin protects against cognitive deficits in a mouse model of mild traumatic brain injury (mTBI)

Traumatic brain injury (TBI) is often a result of traffic accidents, contact sports or battlefield explosions. A mild form of traumatic brain injury (mTBI) is frequently underestimated, as the immediate physical symptoms decrease rapidly and conventional neuroimaging studies often do not show visible evidence of brain lesions. However, cognitive impairments persist for weeks, months or even years after the incident. Endogenous opioids were documented to play a role in thmodulation of mTBI pathology, whereas exogenous opioids were shown to possess neuroprotective properties. In the present study, biphalin, a dimeric enkephalin analog, improved cognitive performance in the Morris Water Maze and Novel Object Recognition tests in a mouse weight-drop model of mTBI. The effect of a single systemic injection of 10 mg/kg biphalin immediately after trauma was reversed by naltrexone, suggesting an opioid receptor-mediated mechanism. Biphalin also reduced cortical and hippocampal neurodegeneration, as shown by silver staining. Our data indicates that opioid receptor activation by biphalin may provide neuroprotection of post-traumatic neurodegeneration processes and may protect against memory impairments.

Structure-activity relationship study of a small cyclic peptide H-c[Lys-Pro-Glu]-Arg-OH: a potent inhibitor of Vascular Endothelial Growth Factor interaction with Neuropilin-1

Inhibition of angiogenesis is one of the most promising approaches in anticancer therapy. It was recently suggested that Neuropilin-1 (NRP-1) in tumour cells may serve as a separate receptor for Vascular Endothelial Growth Factor-165 (VEGF165) which is one of the main pro-angiogenic agents in the organism. Therefore molecules inhibiting VEGF165 binding to NRP-1 could be potential candidates for new antiangiogenic and anticancer drugs. Here we present a structure-activity relationship study of the peptide H-c[Lys-Pro-Glu]-Arg-OH which showed high inhibitory effect on VEGF165/NRP-1 binding (IC50=0.18μM) in our previous study. We report the design, synthesis, in vitro assays and docking analysis of four small cyclic peptides (14-,15-membered ring) and one bigger cyclic compound (30-membered ring). Our study shows that both the ring size and configuration of amino acid residues present in the structure are crucial for high inhibitory effect.

Peptide analog of fibronectin that inhibits cell migration and ERK 1/2 activity

Two analogs of the peptide mimicking the 1977-1991 C- terminal part of fibronectin have been synthesized and tested. AWLI simulated human fibronectin fragment 1977-1991, whereas AWLII hybridized to both RGD and 1977-1991 fragments. AWLI and AWLII peptides inhibited the migration of the ovarian carcinoma cell line OVP10 regardless of the presence RGD. AWLI peptide inhibited spontaneous and fibronectin-activated cell migration and ERK1/2 activity. Neither AWLI nor fibronectin induced changes in FAK proteins, as could be judged from Western blots. In conclusion, it seems that the C-terminal fragment of fibronectin inhibits ERK1/2-dependent (random) migration of ovarian carcinoma cells.

Biphalin preferentially recruits peripheral opioid receptors to facilitate analgesia in a mouse model of cancer pain - A comparison with morphine

The search for new drugs for cancer pain management has been a long-standing goal in basic and clinical research. Classical opioid drugs exert their primary antinociceptive effect upon activating opioid receptors located in the central nervous system. A substantial body of evidence points to the relevance of peripheral opioid receptors as potential targets for cancer pain treatment. Peptides showing limited blood-brain-barrier permeability promote peripheral analgesia in many pain models. In the present study we examined the peripheral and central analgesic effect of intravenously administered biphalin - a dimeric opioid peptide in a mouse skin cancer pain model, developed by an intraplantar inoculation of B16F0 melanoma cells. The effect of biphalin was compared with morphine - a golden standard in cancer pain management. Biphalin produced profound, dose-dependent and naloxone sensitive spinal analgesia. Additionally, the effect in the tumor-bearing paw was largely mediated by peripheral opioid receptors, as it was readily attenuated by the blood-brain-barrier-restricted opioid receptor antagonist - naloxone methiodide. On the contrary, morphine facilitated its analgesic effect primarily by activating spinal opioid receptors. Both drugs induced tolerance in B16F0 - implanted paws after chronic treatment, however biphalin as opposed to morphine, showed little decrease in its activity at the spinal level. Our results indicate that biphalin may be considered a future alternative drug in cancer pain treatment due to an enhanced local analgesic activity as well as lower tolerance liability compared with morphine.