Amphotericin B (AmB) is a polyene antibiotic used to treat deep-seated mycoses. Both the therapeutic action and the toxic side effects of this drug are dependent on its molecular organization. AmB appears as a zwitterion at neutral pH owing to -NH 3 + and -COO -groups.The results obtained with electronic absorption, fluorescence, resonance light scattering and infrared absorption spectroscopic analyses show that in the aqueous medium at pH above 10 AmB appears in the monomeric form owing to the negative net electric charge of the molecule. On the contrary, anomalously high aggregation level has been observed at pH below 2, despite the positive net electric charge. The effect is interpreted in terms of the permanent polarization of the polyene chain at low pH, associated with relative rotational freedom of the charged mycosamine fragment of the molecule. The pH-dependent aggregation of AmB is discussed in aspect of pharmacological action of the drug.

Amphotericin B (AmB) is considered the gold-standard in the treatment of serious systemic mycoses despite its numerous adverse effects. Both the mechanism of antifungal action and the toxicity of this drug are dependent on its molecular organization. The effect of AmB on the organization of lipid membranes formed with dipalmitoylphosphatidylcholine (DPPC) was studied with application of the Langmuir-Blodgett technique and ATR-FTIR spectroscopy. The aim of this research was to analyze the physical interactions leading to the formation of aggregated forms of AmB molecules in one-component monolayers and lipid multibilayers. Analysis of FTIR spectra of two-component multibilayers suggests the possibility the mutual reorientation of the amino-sugar moiety (mycosamine) and macrolide ring. This effect may be significant in the explanation of the aggregation processes of AmB in biological systems.

2-(4-Fluorophenylamino)-5-(2,4-dihydroxybenzeno)-1,3,4-thiadiazole (FABT) is a biologically active compound. It forms planar molecules and cations. Single crystals of the FABTH þ chloride grown from water solutions of different alcohols, such as methanol, propan-2-ol, and butanol, show structural changes induced mostly by hydrogen bond interactions with chloride anions and solvent molecules. For structures with the alcohol molecules built in the crystal lattice, the FABTH þ moiety takes the conformation with the o-OH (ortho position) group from the resorcin ring on the same side of the molecule as the sulfur atom in the thiadiazole ring, whereas, in the alcohol free crystals growth from a butanol-water mixture, this group is situated on the other side of the thiadiazole ring. The incorporation of the alcohol molecules into the crystal structures formed by FABTH þ cations strongly depends on their size, and it influences the properties of crystal lattices. In the case of the FABTH þ Clcrystallized from butanol, the crystal structure consists of columns of FABTH þ cations forming intermolecular channels containing two water molecules and two chloride anions related by centers of symmetry. The crystal structure of FABTH þ Clcrystallized from methanol is built of two separate layers consisting of FABTH þ cations and methanol and chloride anions repeating periodically. FABTH þ Clcrystallized from propan-2-ol forms a 3D structure with separate water and propan-2-ol molecules glued by chloride anions and layers of the FABTH þ cations. The Hirshfeld surface analysis is a very useful tool in identifying subtle differences between the solvates. The DFT computations allow us to estimate the energy difference between the two conformers to be 3.2 kcal/mol and the rotational barrier to be 12.6 kcal/mol.

This study was focused on analyzing the effects of dietary inclusion of raw chickpea seed as a replacement of soybean meal as a primary protein source on bone structure in broiler chickens. Broiler chickens (n = 160) received in their diet either soybean meal (SBM) or raw chickpea seeds (CPS) as a primary protein source throughout the whole rearing period (n = 80 in each group). On the 42th day randomly selected chickens from each group (n = 8) were slaughtered. Collected tibiotarsus were subjected to examination of the biomechanical characteristics of bone mid-diaphysis, microstructure of the growth plate and articular cartilages; the analysis of mineral content and crystallinity of mineral phase, and the measurements of thermal stability of collagen in hyaline cartilage were also carried out. The inclusion of chickpea seeds resulted in increase of bone osteometric parameters (weight, length and mid-diaphysis cross-sectional area) and mechanical endurance (yield load, ultimate load, stiffness, Young modulus). However, when loads were adjusted to bone shape (yield and ultimate stress) both groups did not differ. Mineral density determined by means of densitometric measurements did not differ between groups, however the detailed analysis revealed the differences in the macro- and microelements composition. The results of FT-IR and XRD analyses showed no effect of diet type on mineral phase crystallinity and hydroxyapatite nanocrystallites size. In trabecular bone, the increase of real bone volume (BV/TV) and number of trabeculae was observed in the CPS group. Total thickness of articular cartilage was the same in both groups, save the transitional zone, which was thicker in the SBM group. The total thickness of the growth plate cartilage was significantly increased in the CPS group. The area of the most intense presence of proteoglycans was wider in the SBM group. The structural analysis of fibrous components of bone revealed the increase of fraction of thin, immature collagen content in articular cartilage, trabeculae and compact bone in the CPS group. The dietary inclusion of CPS affected the thermal stability of collagen, as decrease of net denaturation enthalpy was observed. This study showed a beneficial effect of CPS on the skeletal development, improving the overall bone development and the microarchitecture of cancellous bone. It suggests that CPS can be a promising replacement for SBM in broilers feeding in the aspect of animal welfare related to the development of the skeletal system.

Amphotericin B (AmB) is a life-saving polyene antibiotic used to treat deep-seated mycotic infections. Both the mode of therapeutic action as well as toxic side effects are directly dependent on molecular organization of the drug. Binding of AmB to lipid monolayers formed with dipalmitoylphosphatidylcholine, pure and containing 40 mol% cholesterol or ergosterol, the sterols of human and fungi respectively, has been examined by means of

The aim of the work was to compare glycation-related changes in thermal denaturation of collagen in naturally ageing and in vitro ribosylated tissues. Samples of cornea, meniscus and Achilles tendon from young adult and from ageing rabbits were compared. Moreover, in vitro glycated samples (ribose, 100 mg mL -1 , 14 days) were prepared for both age groups. Collagen in tissues was characterized in terms of thermal denaturation parameters obtained from differential scanning calorimetry. The level of pentosidine and other fluorescent advanced glycation end products (AGEs) in the papain-digested tissue samples was evaluated using spectrofluorimetry (k ex/em : 335/385 and 370/440 nm). In naturally ageing tissues, changes in properties of extracellular matrix collagen expressed in terms of parameters of thermal denaturation and fluorescent AGEs levels were tissue dependent and were related to differences in organization of matrix components. No signs of increased level of AGEs were found in the naturally ageing cornea, unlike in the tendon and meniscus. In vitro ribation proved by gains of fluorescent AGEs affected thermal stability of collagen in all tissues, both in young adult and in the ageing ones. The effects of ribation were considerably greater than the effects of natural ageing. The increase in denaturation temperature was similarly strong in all tissues and did not correlate with the increase in fluorescent AGEs. As a conclusion, parameters of collagen thermal denaturation are tissue and age dependent and an amount of fluorescent AGEs is not the only determinant of increasing thermal stability of glycated collagen.

The normal and the preresonance Raman effects (NR and PRR) of spectroscopy have been used to monitor and explain the aggregation processes of amphotericin B (AmB) in aqueous solution at different pH values and containing the K(+) and Na(+) ions. The resonance-enhanced and normal vibrational Raman spectra were recorded with a semiconductor laser (ex 785 nm) and an argon laser (ex 514.5 nm) for investigation of interactions between AmB chromophores. The essential difference between the samples stimulated by resonance-enhanced and by near-infrared was in the C=C stretching mode region of polyene chain. The processes connected with the aggregation of AmB led to changes in the chromophore, which were only visible as a remarkable broadening of the band centered at 1558 cm(-1). The understanding of possible physical mechanisms responsible for the molecular aggregation of the drug is important from the pharmaceutical applicability standpoint.

Xanthohumol (XN) is the major prenylated flavonoid found in hop resin. It has attracted considerable attention in recent years due to its wide spectrum of biological activities and the beneficial effect on human health. Since lipid membrane is first target for biologically active compounds, we decided to investigate the influence of XN on the dipalmitoylphosphatidylcholine (DPPC) multibilayers. Interactions of XN with DPPC were investigated as a function of temperature and its concentration by using X-ray diffraction and the ATR-FTIR spectroscopy techniques. The aim of understanding the mechanisms of molecular interactions between XN and DPPC was to indicate the localization of the XN with respect to the membrane and the type of interaction with phospholipids. The results revealed that XN changes the physical properties of the DPPC multibilayers in the form of dry film. A new complex formation between XN and DPPC is reported. The detailed analysis of refraction effect indicates the changes in electron density ratio between hydrophobic and hydrophilic zones of lipid at phase transition. This is in compliance with reported changes in FTIR spectra where at pretransition XN moves from interface region between polar heads to the neighborhood of phosphate groups.