Publications by authors named "Reinhard Neubert"

Based on the structure of the Stratum corneum (SC) the potential penetration/diffusion pathways of drugs and cosmetic actives through the SC are presented and discussed. The well-known lipophilic pathway across the SC is presented and relevant examples are used to show that highly lipophilic molecules such as glucocorticoids, coenzyme Q10 etc. are accumulated in the SC and penetrate into the inner liquid like layer of the SC lipid bilayer by lateral diffusion.

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Free amino acids (FAAs) constitute the largest component (∼40 %) of the so-called natural moisturizing factors of the skin. Their level declines in dry skin conditions and one strategy to overcome this problem may involve the topical delivery of FAAs through appropriate strategy. The objective of the present study was therefore to identify alternative skin models and study the corneocyte-water partition coefficients (K) and permeation coefficient (K) of 18 FAAs.

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The objective of this study was to explore the benefits of transdermal drug delivery systems as an alternative option for patients who are unable to tolerate oral administration of drugs, such as ibuprofen (IB). To achieve this, nonionic surfactants and three cosolvents were employed to develop new microemulsions (MEs) that contained IB as nanocarriers. The aim was to enhance the solubility and bioavailability of the drug after transdermal administration.

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Introduction: Heparin is a commonly used anti-coagulant administered either by intravenous or subcutaneous injection for a systemic effect or topically for the treatment of peripheral vascular disorders.

Objective: This study aimed to formulate heparin in non-ionic colloidal carrier systems (CCSs) having enhanced percutaneous absorption for systemic and topical administration.

Methods: Five CCSs were developed and characterized for their rheological properties, droplet size, and drug loading.

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The human skin provides a physiochemical and biological protective barrier due to the unique structure of its outermost layer known as the Stratum corneum. This layer consists of corneocytes and a multi-lamellar lipid matrix forming a composite, which is a major determining factor for the barrier function of the Stratum corneum. A substantiated understanding of this barrier is necessary, as controlled breaching or modulation of the same is also essential for various health and personal care applications such as topical drug delivery and cosmetics to a name few.

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In this study, insulin was loaded into non-ionic colloidal carrier systems (CCS) to be used as nano-sized drug delivery systems for transdermal administration. The CCS were characterized for their rheological properties, droplet size and drug loading. Also, the transdermal flux of insulin was estimated using Franz diffusion cells through the epidermis and all the layers of the rats' skin.

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The stratum corneum (SC) is the largest physical barrier of the human body. It protects against physical, chemical and biological damages, and avoids evaporation of water from the deepest skin layers. For its correct functioning, the homeostasis of the SC lipid matrix is fundamental.

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Article Synopsis
  • The stratum corneum is a crucial barrier in the skin, primarily composed of lipids, particularly ceramides (CERs), which protect against damage.
  • Research focused on the α-OH phytosphingosine CER class to examine the differences between the naturally occurring d-form and the synthetically produced l-form in terms of their structural and chemical properties.
  • The study found that the d-form creates a beneficial hydrogen bonding network, forming a stable supramolecular lattice, while the l-form lacks this ability, affecting how these CERs behave in both 2D and 3D model systems.
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Free amino acids (FAAs), the major constituents of the natural moisturizing factor (NMF), are very important for maintaining the moisture balance of human skin and their deficiency results in dry skin conditions. There is a great interest in the identification and use of nature-based sources of these molecules for such cosmeceutical applications. The objective of the present study was, therefore, to investigate the FAA contents of selected Ethiopian plant and fungi species; and select the best sources so as to use them for the stated purpose.

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Introduction: Coenzyme Q10 (CoQ10) has been widely used in topical and cosmeceutical products due to its cutaneous antioxidant and energizer effects. CoQ10 is found in a higher concentration in the epidermis compared to dermis. The epidermal level of CoQ10 can be reduced due to several factors such as skin UV irradiation and photoaging.

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Transdermal drug delivery is a passive diffusion process of an active compound through the skin which is affected by drug solubility in the multilamellar lipidic matrix of the stratum corneum (SC). Widely used non-ionic surfactants (NIS) can be added into transdermal formulations to enhance the penetration of drugs by influencing the packing of the stratum corneum lipidic matrix. Objective of our study was to analyse the interaction between selected NIS and a simple SC lipidic matrix model system using a variety of surface-sensitive techniques based on the application of Langmuir monolayers.

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Ceramides (CERs) play a major role in skin barrier function and direct replacement of depleted skin CERs, due to skin disorder or aging, has beneficial effects in improving skin barrier function and skin hydration. Though, plants are reliable source of CERs, absence of economical and effective method of hydrolysis to convert the dominant plant sphingolipid, glucosylceramides (GlcCERs), into CERs remains a challenge. This study aims at exploring alternative GlcCERs sources and chemical method of hydrolysis into CERs for dermal application.

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This review is the second part of a series which presents the state of the art in stratum corneum (SC) lipid matrix (LM) research in depth. In this part, the various hypothetical models which were developed to describe the structure and function of the SC LM as the skin's barrier will be discussed. New as well as a cumulative assortment of older results which change the view on the different models are considered to conclude how well the different models are holding up today.

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Celluloses were extracted from teff straw (TS), enset fiber (EF), sugarcane bagasse (SB) and coffee hull (CH) agro-industrial byproducts generated in large quantities in Ethiopia. The present study aimed to explore these plant byproducts as alternative sources of cellulose for potential industrial applications, using various eco-friendly chlorine-free treatment conditions to obtain an optimum cellulose extraction condition. The byproducts and the as-extracted celluloses were analyzed for chemical compositions, yield, chemical functionality, crystallinity, thermal stability and morphology.

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The main barrier of the human skin is the stratum corneum (SC). Its properties (also depending on the health and age of the individual) and its influence on improved penetration of active ingredients into the skin are the subject of many research projects. Since the availability of human skin, as the ideal model membrane, is limited, the aim of this study was to find a suitable alternative model membrane from the animal kingdom.

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Background/aims: Free amino acids (FAAs) and urea, present inside the corneocytes, can be important indicators of skin condition. However, due to the lack of a standard extraction protocol for FAAs from corneocytes, conflicting research results have been reported. Therefore, the purpose of this study was (1) to standardize the extraction protocol and (2) to investigate FAA profiles in healthy young and healthy old volunteers, as well as in psoriasis and atopic dermatitis patients.

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This review is summarizing an important part of the state of the art in stratum corneum research. A complete overview on discoveries about the general biophysical and physicochemical properties of the known ceramide species' is provided. The ceramides are one of the three major components of the lipid matrix and mainly govern its properties and structure.

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The control of bleaching reaction is important in hair bleaching and laundry detergents to ensure quality of the final product. A better understanding of the reaction mechanisms is needed to minimize product failures. P NMR-spectroscopy-based spin trap technique was employed to detect and quantify the free radical species that were generated in different bleaching solutions.

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Unlabelled: Dermal application of peptides as drugs is an interesting and growing field in therapeutics. Besides therapy, they are increasingly used as cosmetic agents. Peptide delivery into the skin is highly challenging since they provide disadvantageous properties like a high molecular weight, hydrophilicity, polarity and susceptibility to enzymatic degradation.

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Of particular importance for Stratum corneum (SC) lipids are the free fatty acids (FFAs). Age-related changes of the SC structure lead to diminished capacity for barrier compensation. The aims of this cross-sectional study were to identify even-numbered especially odd-numbered FFAs within the intercorneocytic lamellar lipid structures of the SC and to explore age- and diabetes-related changes in FFAs.

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The pH value is identified as an essential determinant for the lipid synthesis in the stratum corneum (SC). The activity of the enzymes that catalyse the transformation of lipid precursors into ceramides, free fatty acids or cholesterol highly depends on pH value. Additionally, there are substantial indications for pH conditions to have a direct effect on the molecular structure of the membranes and their properties.

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Ceramides (CERs) are the backbone of the intercellular lipid lamellae of the stratum corneum (SC), the outer layer of the skin. Skin diseases such as atopic dermatitis, psoriasis, and aged skin are characterized by dysfunctional skin barrier and dryness which are associated with reduced levels of CERs. Replenishing the depleted epidermal CERs with exogenous CERs has been shown to have beneficial effects in improving the skin barrier and hydration.

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For this study mixtures based on the ceramides [NS] (NS = non-hydroxy-sphingosine) and [AP] (AP = α-hydroxy-phytosphingosine) in a 2:1 and 1:2 ratio, together with cholesterol and lignoceric acid, were investigated. These mixtures are modelling the uppermost skin layer, the stratum corneum. Neutron diffraction, utilizing specifically deuterated ceramide molecules, was used to obtain a maximum amount of experimental detail.

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