Influence of some physical properties of 5-fluorouracil on encapsulation efficiency in liposomes

The aim of this study is to encapsulate two drugs: 5-fluorouracil (5-FU) with the hydrophobic properties and 1-b-D-arabinofuranosylcytosine (Ara-C) with the amphiphilic properties into liposomes prepared by the modified reverse-phase evaporation method (mREV) from L-a-phosphatidylcholine dipalmitoyl (DPPC). We studied the thermotropic phase behavior of liposome entrapped 5-FU and Ara-C. It is known that the stability of liposomes depends not only on the method of chemical gradient loading, the use of membrane stabilizer such as sterols, but also on the phase transition temperature (Tc) of phospholipids, which undergoes an alteration after encapsulation of drugs to liposomes. The competition of these two drugs entrapped in liposomes was analyzed by the use of two spectroscopies: 1H NMR and UV on the basis of the analysis of the signals of each drug in the liposome- drug system. The percent of encapsulation in DPPC/Ara-C/5-FU liposome obtained by the use of UV spectroscopy amounted 93.84 and 96.05% for 5-FU and Ara-C, respectively. Phase transition temperature Tc of liposomes containing Ara-C did not significantly change while for the liposomes containing 5-FU it increased in comparison with Tc of the reference liposomes formed from DPPC

Effect of temperature on tolbutamide binding to glycated serum albumin

Glycation process occurs in protein and becomes more pronounced in diabetes when an increased amount of reducing sugar is present in bloodstream. Glycation of protein may cause conformational changes resulting in the alterations of its binding properties even though they occur at a distance from the binding sites. The changes in protein properties could be related to several pathological consequences such as diabetic and nondiabetic cardiovascular diseases, cataract, renal dysfunction and Alzheimer's disease. The experiment was designed to test the impact of glycation process on sulfonylurea drug tolbutamide-Albumin binding under physiological (T = 309 K) and inflammatory (T = 311 K and T = 313 K) states using fluorescence and UV-VIS spectroscopies. It was found in fluorescence analysis experiments that the modification of serum albumin in tryptophanyl and tyrosyl residues environment may affect the tolbutamide (TB) binding to albumin in subdomain IIA and/or IIIA (Sudlow's site I and/or II), and also in subdomains IB and IIB. We estimated the binding of tolbutamide to albumin described by a mixed nature of interaction (specific and nonspecific). The association constants (Lmol-1) for tolbutamide at its high affinity sites on non-glycated albumin were in the range of 1.98-7.88 × 104 Lmol-1 (λex = 275 nm), 1.20-1.64 × 104 Lmol-1 (λex = 295 nm) and decreased to 1.24-0.42 × 104 Lmol-1 at λex = 275 nm (T = 309 K and T = 311 K) and increased to 2.79 × 104 Lmol-1 at λex = 275 nm (T = 313 K) and to 4.43-6.61 × 104 Lmol-1 at λex = 295 nm due to the glycation process. Temperature dependence suggests the important role of van der Waals forces and hydrogen bonding in hydrophobic interactions between tolbutamide and both glycated and non-glycated albumin. We concluded that the changes in the environment of TB binding of albumin in subdomain IIA and/or IIIA as well as in subdomains IB and IIB influence on therapeutic effect and therefore the studies of the binding of tolbutamide (in diabetes) to transporting protein under glycation that refers to the modification of a protein are of great importance in pharmacology and biochemistry. This information may lead to the development of more effective drug therapy in people with diabetes

Methotrexate and cytarabine - loaded nanocarriers for multidrug cancer therapy : spectroscopic study

Determining the properties of nanoparticles obtained by novel methods and defining the scope of their application as drug carriers has important practical significance. This article presents the pioneering studies concerning high degree incorporation of cytarabine (AraC) and methotrexate (MTX) into liposome vesicles. The main focus of this study were cytarabine-methotrexate-dipalmitoylphosphatidylcholine (DPPC) interactions observed in the gel and fluid phases of DPPC bilayers. The proposed new method of use the Transmittance2919/2850 ratio presented in our research is sensitive to subtle changes in conformational order resulting from rotations, kinks and bends of the lipid chains. The transition temperatures characterized by Fourier Transform Infrared Spectroscopy (FT-IR) were consistent with the results obtained by Differential Scanning Calorimetry (DSC). Transmission Electron Microscopy (TEM) was used in order to determine the size and shape of the liposomes obtained. The mutual interactions occurring between the drugs studied and the phospholipids were analyzed using the Nuclear Magnetic Resonance (NMR)

A comprehensive spectroscopic analysis of the ibuprofen binding with human serum albumin. Part 2

Human serum albumin (HSA) is the most abundant human plasma protein. HSA plays a crucial role in many binding endos- and exogenous substances, which affects their pharmacological effect. The innovative aspect of the study is not only the interaction of fatted (HSA) and defatted (dHSA) human serum albumin with ibuprofen (IBU), but the analysis of the influence of temperature on the structural modifications of albumin and the interaction between the drug and proteins from the temperature characteristic of near hypothermia (308 K) to the temperature reflecting inflammation in the body (312 K and 314 K). Ibuprofen is a non-steroidal anti-inflammatory drug. IBU is used to relieve acute pain, inflammation, and fever. To determine ibuprofen’s binding site in the tertiary structure of HSA and dHSA, fluorescence spectroscopy was used. On its basis, the fluorescent emissive spectra of albumin (5 106 mol/dm3) without and with the presence of ibuprofen (1 105–1 104 mol/dm3) was recorded. The IBU-HSA complex’s fluorescence was excited by radiation of wavelengths of ex 275 nm and ex 295 nm. Spectrophotometric spectroscopy allowed for recording the absorbance spectra (zero-order and second derivative absorption spectra) of HSA and dHSA under the influence of ibuprofen (1 104 mol/dm3). To characterize the changes of albumin structure the presence of IBU, circular dichroism was used. The data obtained show that the presence of fatty acids and human serum albumin temperature influences the strength and type of interaction between serum albumin and drug. Ibuprofen binds more strongly to defatted human serum albumin than to albumin in the presence of fatty acids. Additionally, stronger complexes are formed with increasing temperatures. The competitive binding of ibuprofen and fatty acids to albumin may influence the concentration of free drug fraction and thus its therapeutic effect

The Advances and Challenges of Liposome-Assisted Drug Release in the Presence of Serum Albumin Molecules: The Influence of Surrounding pH

The aim of this study is to prepare a liposomal delivery system for 5-methyl-12 (H)- quino[3,4-b]-1,4-benzothiazine chloride (5-MBT) and study the in vitro release characteristics. The release of 5-MBT from a liposomal complex with human serum albumin (HSA) [LDPPC/5-MBT]:HSA was examined using the spectrophotometric method and differential scanning calorimetry (DSC). Electronic paramagnetic resonance was used to assess the influence of the pH of the environment on the conformation of phospholipids, the latter determining the degree of release of the encapsulated compound. The applied mathematical models made it possible to determine the necessary analytical parameters to facilitate the process of potential drug release from liposomes. The complexes formed by liposomal 5-MBT with serum albumin (HSA) particles allowed for the description of the Fick process. The change in the polarity of the phospholipid membrane resulting from the changes in the pH of the surroundings, significantly influenced the percentage of 5-MBT entrapment in the liposomes. It also affected the release percentage

A Comprehensive Spectroscopic Analysis of the Ibuprofen Binding with Human Serum Albumin, Part I

Human serum albumin (HSA) plays a fundamental role in the human body. It takes part in the transport of exogenic and endogenic substances, especially drugs. Ibuprofen (IBU) is one of the most commonly used non-steroidal anti-inflammatory drugs, used for pain relief, fever relief, and for anti-inflammatory purposes. The binding of ligands with HSA is a significant factor which determines the toxicity and the therapeutic dosages of these substances. The aim of this study was to compare the degree of ibuprofen binding with human serum albumin at various temperatures and protein solution pH values. In order to evaluate conformational changes in HSA caused by interaction with ibuprofen, spectrophotometric (first and second derivatives of the UV-VIS spectrum), and spectrofluorometric analyses were performed concerning the mutual interactions of IBU-HSA. The use of fluorescent spectroscopy allowed for recording fluorescent emissive spectra of HSA (5 × 10−6 mol/dm3) without and with the presence of ibuprofen (1 × 10−5–1 × 10−4 mol/dm3) at temperatures of 308, 310, 312, and 314 K at pH values of 6.5, 6.8, 7.4, 7.8, and 8.1. System fluorescence was excited by radiation of wavelengths of λex = 275 nm and λex = 295 nm. Based on this, original and modified Stern-Volmer, Scatchard, Klotz and Hill curves were determined. The data that were obtained showed a significant effect of temperature and pH of the human serum albumin solution on the strength and type of interaction of ibuprofen with HSA

Methotrexate and Cytarabine—Loaded Nanocarriers for Multidrug Cancer Therapy. Spectroscopic Study

Determining the properties of nanoparticles obtained by novel methods and defining the scope of their application as drug carriers has important practical significance. This article presents the pioneering studies concerning high degree incorporation of cytarabine (AraC) and methotrexate (MTX) into liposome vesicles. The main focus of this study were cytarabine-methotrexate-dipalmitoylphosphatidylcholine (DPPC) interactions observed in the gel and fluid phases of DPPC bilayers. The proposed new method of use the Transmittance2919/2850 ratio presented in our research is sensitive to subtle changes in conformational order resulting from rotations, kinks and bends of the lipid chains. The transition temperatures characterized by Fourier Transform Infrared Spectroscopy (FT-IR) were consistent with the results obtained by Differential Scanning Calorimetry (DSC). Transmission Electron Microscopy (TEM) was used in order to determine the size and shape of the liposomes obtained. The mutual interactions occurring between the drugs studied and the phospholipids were analyzed using the Nuclear Magnetic Resonance (NMR)

In Vitro Investigation of the Interaction of Tolbutamide and Losartan with Human Serum Albumin in Hyperglycemia States

Serum albumin is exposed to numerous structural modifications which affect its stability and activity. Glycation is one of the processes leading to the loss of the original properties of the albumin and physiological function disorder. In terms of long lasting states of the hyperglycemia, Advanced Glycation End-products (AGEs) are formed. AGEs are responsible for cellular and tissue structure damage that cause the appearance of a number of health consequences and premature aging. The aim of the present study was to analyze the conformational changes of serum albumin by glycation—“fructation”—using multiple spectroscopic techniques, such as absorption (UV-Vis), fluorescence (SFM), circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopy and evaluate of possible alteration of binding and competition between tolbutamide (TB, a first-generation sulfonylurea oral hypoglycemic drug) and losartan (LOS, an angiotensin II receptor (AT1) blocker used in hypertension (1st line with a coexisting diabetes)) in binding to non-glycated (HSA) and glycated (gHSAFRC) human serum albumin in high-affinity binding sites. The studies allowed us to indicate the structural alterations of human serum albumin as a result of fructose glycation. Changes in binding parameters, such as association ( K a ) or Stern-Volmer ( K S V ) constants suggest that glycation increases the affinity of TB and LOS towards albumin and affects interactions between them. The process of albumin glycation influences the pharmacokinetics of drugs, thus monitored pharmacotherapy is reasonable in the case of diabetes and hypertension polypharmacy. This information may lead to the development of more effective drug treatments based on personalized medicine for patients with diabetes. Our studies suggest the validity of monitored polypharmacy of diabetes and coexisting diseases