28 research outputs found
Influence of inhalation anesthetics on a model biological membrane
General anesthesia is defined as impairment of the central nervous system
(UON) caused by intravenous or volatile anesthetics. The state of loss of consciousness
or even amnesia and the disappearance of perception into external stimuli
is achieved by the use of a large group of chemical compounds. The use of nitrous
oxide in 1844 revolutionized surgery and medicine at that time. From that moment,
anesthesiology develops dynamically, allowing more and more complex procedures.
Despite more than 170 years of history of anesthesia, understanding the mechanism
of reversible loss of awareness and sensitivity to pain caused by the action of
general anesthetics is one of the greatest challenges of modern pharmacology and
neuroscience. Incredibly high diversity of anesthetics, including both noble gases
and complex steroids, combined with human sensation makes the above problem
extremely difficult to solve.
The reversibility of the anesthesia phenomenon suggests that the analyzed
phenomenon is based on disturbance of weak intermolecular interactions, such as
hydrogen bond or van der Walls forces. Anesthetic molecules may bind directly
to the hydrophobic region of protein, which causes its conformational changes or
disturb ion channel activity by anesthetic-induced perturbations of lipid bilayers.
The mechanism of anesthesia is thus very often attributed to both protein and lipid
membrane targets. The influence of anesthetic molecules on biomolecular systems
can be studied successfully using many different physico-chemical methods, such
as, infrared, fluorescence or nuclear magnetic resonance spectroscopy. Vibrational
circular dichroism as well as differential scanning calorimetry can also be used
Structure and function of protein-lipid systems
Biomembranes play many structural and functional roles in both prokaryotic
and eukaryotic cells [10]. They define compartments, the communication between
the inside and outside of the cell. The main components of biomembranes are
lipids and proteins, which form protein-lipid bilayer systems [10]. A structure and
physicochemical properties of protein-lipid membranes, which determines biological
activities of biomembranes, are strongly dependent on interactions between
lipid and protein components and external agents such as a temperature, pH, and
a membrane hydration [4]. A lipid bilayer matrix serves as a perfect environment
for membrane proteins (Fig. 1), and it assures activities of these proteins. Because
biomembranes are composed of many different groups of lipids and proteins and
have a complex structure, it is difficult to study in details their physicochemical
properties using physicochemical methods. For these reason, lipid membranes of
liposomes are used in many scientific laboratories for studding processes associated
with a lipid phase transition, a membrane hydration, or protein-membrane interactions.
The structure of liposomes (Fig. 5), and an influence of pH and an ionic
strength on a lipid bilayer structure are discussed in the presented work. The role
of membrane proteins in determination of biological activities of biomembranes is
highlighted. A high variety of a structure and an enzymatic activity of membrane
proteins is responsible for a high diversity of biological functions of cell membranes
[2]. α-Lactalbumin (α-LA) is a peripheral membrane protein (Figs 8 and 9), its
biological function is strongly related to its conformational structure and interaction
with lipid membranes [49]. The complex of α-LA in a molten globule conformational
state with oleic acid, termed as a HAMLET complex, are disused in a context of
its anti-tumor activity
FTIR-ATR and fluorescence studies of protein-lipid systems
Lipid-protein systems paly curtail roles in living systems [49]. Hence, a determination
of their structure at different levels of organization is still one of the most
important tasks in many research projects. A study of lipid-protein systems is based
on many physicochemical techniques, such as spectroscopy of FTIR, Raman, fluorescence,
NMR, EPR, as well as DLS, DSC and TEM methods. In the presented
paper tow of the most frequently used methods, that is FTIR and fluorescence
spectroscopy, will be discussed in details. They are characterized by a relatively low
cost of sample preparation, a short measuring time, and they give a huge number
of structural and physicochemical information about lipid-protein systems. In the
FTIR-ATR spectroscopy many of vibrational bands are commonly used as very precise
vibrational indicators of structural changes in lipids and proteins (Fig. 1) [1–6].
They allows to characterize lipid and protein components separately in mixed systems.
Additionally, structural changes in lipid membranes can be monitored in one
FTIR-ATR experiment simultaneously in a region of hydrophilic lipid head-groups
(Fig. 5) [17, 18], in a hydrophobic part composed of hydrocarbon lipid chains (see
Figures 2 and 3) [7–9], and in a lipid membrane interface represented by ester lipid
groups (Fig. 4) [4, 6, 11, 12]. A secondary structure of proteins and peptides in different
experimental conditions can be defined in the FTIR-ATR spectroscopy on the
base of amide I bands (Fig. 6 and Tabs 1, 2 and 3) [20–22]. A fluorescence spectroscopy
is a complementary methods to FTIR spectroscopy in a study of lipid-protein
systems. It competes information about time-dependent and very fast (in a scale
of femtoseconds) structural processes in both lipids [41–45] and proteins [23, 27,
48]. The folding, denaturation, and aggregation of proteins and lipid membranes
accompanied by changes in an order, packing and hydration of the system under
study [23, 27, 41–45, 48]
Ethosomal Gel for Topical Administration of Dimethyl Fumarate in the Treatment of HSV-1 Infections
The infections caused by the HSV-1 virus induce lesions on the lips, mouth, face, and eye. In this study, an ethosome gel loaded with dimethyl fumarate was investigated as a possible approach to treat HSV-1 infections. A formulative study was conducted, evaluating the effect of drug concentration on size distribution and dimensional stability of ethosomes by photon correlation spectroscopy. Ethosome morphology was investigated by cryogenic transmission electron microscopy, while the interaction between dimethyl fumarate and vesicles, and the drug entrapment capacity were respectively evaluated by FTIR and HPLC. To favor the topical application of ethosomes on mucosa and skin, different semisolid forms, based on xanthan gum or poloxamer 407, were designed and compared for spreadability and leakage. Dimethyl fumarate release and diffusion kinetics were evaluated in vitro by Franz cells. The antiviral activity against HSV-1 was tested by plaque reduction assay in Vero and HRPE monolayer cells, while skin irritation effect was evaluated by patch test on 20 healthy volunteers. The lower drug concentration was selected, resulting in smaller and longer stable vesicles, mainly characterized by a multilamellar organization. Dimethyl fumarate entrapment in ethosome was 91% w/w, suggesting an almost total recovery of the drug in the lipid phase. Xanthan gum 0.5%, selected to thicken the ethosome dispersion, allowed to control drug release and diffusion. The antiviral effect of dimethyl fumarate loaded in ethosome gel was demonstrated by a reduction in viral growth both 1 h and 4 h post-infection. Moreover, the patch test demonstrated the safety of the ethosomal gel applied on the skin
Physicochemical Properties, Fatty Acid Composition, Volatile Compounds of Blueberries, Cranberries, Raspberries, and Cuckooflower Seeds Obtained Using Sonication Method
Every year, thousands of tons of fruit seeds are discarded as agro-industrial by-products around the world. Fruit seeds are an excellent source of oils, monounsaturated fatty acids, and n-6 and n-3 polyunsaturated essential fatty acids. This study aimed to develop a novel technology for extracting active substances from selected seeds that were obtained after pressing fruit juices. The proposed technology involved sonification with the use of ethyl alcohol at a low extraction temperature. Seeds of four species—blueberry (Vaccinium myrtillus L.), raspberry (Rubus idaeus), cranberry (Vaccinium macrocarpon), and cuckooflower (Cardamine pratensis)—were used for extraction. Following alcohol evaporation under nitrogen, the antioxidant activity, chemical composition, and volatile compounds of the obtained extracts were analyzed using chromatographic methods, including gas chromatography (GC)–mass spectrometry (MS) (GC–MS/MS), and high-performance liquid chromatography–MS. We analyzed physicochemical properties, fatty acid, and volatile compounds composition, sterol and tocochromanol content of blueberry, cranberry, raspberry, and cuckooflower seed oils obtained by sonication. This method is safe and effective, and allows for obtaining valuable oils from the seeds