ArticlePDF Available

Effect of natural sunflower oil and its components on the skin permeability to water and some drugs

Authors:

Abstract and Figures

Objective: To investigate the effect of natural oils and their components on the water permeability and marker molecules of stratum corneum either when intact or after exposure to mechanical stress. Methods: Full thickness porcine skin was used. The subcutaneous fat was removed with a scalpel. The remaining tissue was dermatomed. A validated tape-stripping procedure was used to induce skin damage. Tritiated water coupled with a scintillation counter was used for measuring the water permeability of skin, caffeine as hydrophilic molecule and testosterone as hydrophobic one. Results: Mean flux values for permeation of tritiated water versus time were monitored for intact and stripped skin treated with the oils and for untreated controls shows reduction of water permeability and retain skin barrier function for stripped skin, on the other hand all tested oils increases the reflux of caffeine and testosterone for both intact and stripped skin. Conclusions: Both sunflower oil and its main components, oleic acid and linoleic acid, significantly decreased the permeability of skin to water. For the damaged skin the oils were effective in reducing the flux to values lower than intact skin. No significant differences between sunflower oil and its components were found to exist, the implication being that either the natural sunflower oil or its components could be employed in skin products.
Content may be subject to copyright.
Research Article
EFFECT OF NATURAL SUNFLOWER OIL AND ITS COMPONENTS ON THE SKIN PERMEABILITY
TO WATER AND SOME DRUGS
HASSAN M. GHONAIM*1,2, MASSIMO G. NORO3, AND JAMSHED ANWAR1,4
1Computational Chemistry Laboratory, Institute of Life Sciences Research, University of Bradford, Bradford, W. Yorkshire BD7 1DP U.K.,
2Department of Pharmaceutics, Faculty of Pharmacy, Suez Canal University, Ismailia, Egypt, 3Physical and Chemical Insights Group,
Unilever Port Sunlight, U.K., 4Dept of Chemistry, Lancaster University, Bailrigg, Lancaster, LA1 4YB, UK.
Email: hassan_ghonaim@pharm.suez.edu.eg
Received: 16 Dec 2013, Revised and Accepted: 11 Feb 2014
ABSTRACT
Objective: To investigate the effect of natural oils and their components on the water permeability and marker molecules of stratum corneum
either when intact or after exposure to mechanical stress.
Methods: Full thickness porcine skin was used. The subcutaneous fat was removed with a scalpel. The remaining tissue was dermatomed. A
validated tape-stripping procedure was used to induce skin damage. Tritiated water coupled with a scintillation counter was used for measuring the
water permeability of skin, caffeine as hydrophilic molecule and testosterone as hydrophobic one.
Results: Mean flux values for permeation of tritiated water versus time were monitored for intact and stripped skin treated with the oils and for
untreated controls shows reduction of water permeability and retain skin barrier function for stripped skin, on the other hand all tested oils
increases the reflux of caffeine and testosterone for both intact and stripped skin.
Conclusions: Both sunflower oil and its main components, oleic acid and linoleic acid, significantly decreased the permeability of skin to water. For
the damaged skin the oils were effective in reducing the flux to values lower than intact skin. No significant differences be tween sunflower oil and
its components were found to exist, the implication being that either the natural sunflower oil or its components could be employed in skin
products.
Keywords: Stratum corneum, Sunflower oil, Oleic acid, Linoleic acid, Tritiated water
INTRODUCTION
Water permeation is considered to be a good indicator of potential
changes in the barrier integrity of skin. For this reason, and
because tritiated water is one of the most frequently used probes
for permeability experiments in general, we considered it to be
suitable for evaluating the efficacy of the oils [1,2]. The hypothesis
tested being do the oils ‘heal’ the stratum corneum and restore the
water barrier function [3]. To investigate the effect of natural oils
and their components on the water and marker molecules
permeability of stratum corneum either when intact or after
exposure to mechanical stress[4]. Water permeation is considered
to be a good indicator of potential changes in the barrier integrity
of skin. For this reason, and because tritiated water is one of the
most frequently used probes for permeability experiments in
general, we considered it to be suitable for evaluating the efficacy
of oils [5].Marker molecules (hydrophilic and lipophilic) also have
been tested to measure the permeability of intact and injured skin
[6-8].The hypothesis tested being do the oils ‘heal’ the stratum
corneum and restore the water barrier.
METHODS AND MATERIALS
Materials
- Franz cells, permegear (USA) for diffusion through the skin
- Scintillation counter (Perkin Elmer's)and Tritiated water
(Perkin Elmer's)for measuring water permeability of skin
tissues.
- Caffeine, testosterone, oleic, conjugated linoleic and monoolein,
Sigma Aldrich, UK.
- Zimmer air dermatome (USA)
Methods
Methods have been developed for the exsiccated skin to introduce
mechanical stress by the use of tape stripping to view of
investigating the effect of the oils on damaged skin tissues.
Skin Tissue preparation
Full thickness porcine skin was obtained from a local
slaughterhouse. The skin was cleaned carefully under cold running
water. The subcutaneous fat was removed with a scalpel. The
remaining tissue was dermatomed to a thickness of ~750 μm using
Zimmer dermatome then cut into 2 cm ×2 cm pieces. Finally, the skin
samples were washed under cold running water, dried and sealed in
plastic bags at -20°C until used[9].
Application of oils
Skin samples (about 2.7×2.7 cm2) were soaked by sunflower oil,
oleic acid and linoleic acid for 1, 8 or 24 hours then wiped with soft
tissue prior to run the permeation experiment. A control experiment
was also conducted using an untreated skin pieces.
SC tape-stripping
A validated tape-stripping procedure was used to mechanical
damage to the skin by removing top layers.
Pieces of 2.7×2.7 cm square tapes were prepared using transparent
Scotch® No.845 Book Tapes (3M Media, Broken, Germany). To
delimit a fixed area for tape stripping, a 5×5 cm square mask was
prepared with a cut central aperture of 2 cm in diameter. A strip of
adhesive tape was pressed firmly onto the skin surface, and then
removed in a single movement. The direction of stripping was
changed with each tape to ensure a more uniform removal of the SC
with fewer tape-strips. Then, given that the area stripped is kept at
known, constant value[9,10].
Water permeability studies using Tritiated water
By using Franz cells 10 μL of tritiated water was applied to the
epidermal skin surface of the donor compartment to examine the skin
water barrier function and for the next 5 hours. Tritiated water
coupled with a scintillation counter were used for measuring the
water permeability of skin tissues after 1, 8 and 24 hours exposure to
sunflower oil, oleic acid, and linoleic acid by using of Franz cells.
Buffer/tritiated water was collected from the acceptor chambers at 1
International Journal of Pharmacy and Pharmaceutical Sciences
ISSN- 0975-1491 Vol 6, Suppl 1, 2014
A
Ac
ca
ad
de
em
mi
ic
c
S
Sc
ci
ie
en
nc
ce
es
s
Ghonaim et al.
Int J Pharm Pharm Sci, Vol 6, Suppl 2, 630-636
631
hour intervals for a total of 5 hours and counted in a liquid scintillation
counter. The data collected and analysed using excels sheets.
Permeation studies for oils:
The permeability studies of the skin to caffeine (hydrophilic drug)
testosterone (hydrophobic drug) were investigated by means of
Franz type diffusion cells (diffusion area of 1.00 cm2, donor
compartment 2 ml and receptor compartment 8 ml. The
dermatomed skin were mounted in the diffusion cells and hydrated
with sodium citrate buffer (pH 5.5) for caffeine and PBS (pH 7.4) for
testosterone for prior to the experiment. The diffusion cells were
placed in a hot plate with the temperature being maintained at 32 C
throughout the experiment.
The donor compartment was filled with 1.5 ml of caffeine solution in
citrate buffer (pH 5.5) at a 25 mg/ml or 1.5 ml of testosterone
solution in PBS (pH 7.4) at a 2.0 mg/ml concentration. The receptor
compartment was completely filled with the respective buffer (8 ml)
and gently stirred using a magnetic stirrer throughout the
experiment. The donor compartment was covered with a paraffin
film to avoid evaporation of the solution. Sample fractions were
collected from the receptor compartment at 1 hour intervals for 5
hours. The total volume of the receptor compartment was
maintained by replenishing with fresh buffer. The amount of drug
permeated through the model membrane was determined by UV
analysis in standard quartz cells after suitable dilution using a
Perkin Elmer UV-Vis spectrometer at 273 nm for caffeine and 250
nm after suitable dilution. A control experiment was also conducted
using an untreated skin.
RESULTS AND DISCUSSION
Water permeability studies
Mean flux values for permeation of tritiated water versus time were
monitored for intact and stripped skin treated with the oils and for
untreated controls (Figures 1-7).
Fig. 1: Standard calibration plot of tritiated water with scentillation counter.
Fig. 2: Effect of oil and oil components on the water permeability through skin after 1hour exposure.
Ghonaim et al.
Int J Pharm Pharm Sci, Vol 6, Suppl 2, 630-636
632
Fig. 3: Effect of oil and oil components on the water permeability through skin after 8hours exposure.
Fig. 4: Effect of oil and oil components on the water permeability through skin after 24hours exposure.
Fig. 5: Effect of oil and oil components on the water permeability through stripped skin after 1hour exposure.
Ghonaim et al.
Int J Pharm Pharm Sci, Vol 6, Suppl 2, 630-636
633
Fig. 6: Effect of oil and oil components on the water permeability through stripped skin after 8hours exposure.
Fig. 7: Effect of oil and oil components on the water permeability through stripped skin after 24hours exposure.
The mean steady state fluxes (15 h) for tritiated water (average of
three exposure times, 1, 8 and 24 hours ) showed that the oils
significantly reduced the water flux values from 111.65 μl/cm2hr for
the untreated intact skin to 102.99 μL/cm2hr for sunflower oil, 103.38
μL/cm2hr for oleic acid, and 103.54 μL/cm2hr for linoleic acid. For the
stripped skin (Table 2) the water flux was 117.82 μL/cm2hr, which
reduced to 108.70 μL/cm2hr for sunflower oil, 107.36 μL/cm2hr for
oleic acid, and 107.16 μL/cm2hr for linoleic acid.
Measure the permeability of the stratum corneum to marker molecules as a function of addition of applied oil and oil components.
Caffeine permeability
0
500
1000
1500
2000
2500
3000
3500
0123456
Cumulative amount of caffeine (ug/cm2)
Time (hr)
Skin
Sunflower
Linoleic a.
Fig. 8: Effect of oil and oil components on the Permeation of caffeine through the excicated porcine skin after 1 hour exposure.
Ghonaim et al.
Int J Pharm Pharm Sci, Vol 6, Suppl 2, 630-636
634
Fig. 9: Effect of oil and oil components on the Permeation of caffeine through the excicated porcine skin after 8 hours exposure.
Fig. 10: Effect of oil and oil components on the Permeation of caffeine through the excicated porcine skin after 24 hours exposure.
Fig. 11: Effect of oil and oil components on the Permeation of testosterone through the excicated porcine skin after 1 hour exposure.
Ghonaim et al.
Int J Pharm Pharm Sci, Vol 6, Suppl 2, 630-636
635
Fig. 12: Effect of oil and oil components on the Permeation of testosterone through the excicated porcine skin after 8 hours exposure.
Fig. 13: Effect of oil and oil components on the Permeation of testosterone through the excicated porcine skin after 24 hours exposure.
The mean steady state fluxes (15 h) for caffeine (figures 8:11)
showed that the oils significantly increase the caffeine flux
values(average of three exposure times, 1, 8 and 24 hours ) from
187.62μg/cm2hr for the untreated intact skin to 270.29μg/cm2hr for
sunflower oil, 403.22μg/cm2hr for oleic acid, and 262.73μg/cm2hr
for linoleic acid after 1 hour exposure, and 359.15μg/cm2hr and
220.53μg/cm2hr for sunflower oil, 387.67μg/cm2hr and
398.58μg/cm2hr for oleic acid, and 299.98μg/cm2hr and
217.70μg/cm2hr for linoleic acid after 8 and 24 hours exposure
respectively. The oleic acid is the most effective in increasing the
caffeine permeability followed by sunflower oil then oleic acid. The
exposure of skin to oils for 8 hours is much more effective in
increasing the permeability than 1 and 24 hour exposure.
Testosterone permeability
The mean steady state fluxes (15 h) for testosterone (figures 11:13)
showed that the oils significantly increase the testosterone flux
values (average of three exposure times, 1, 8 and 24 hours ) from
10.98 μg/cm2hr for the untreated intact skin to 12.67 μg/cm2hr for
sunflower oil, 11.06 μg/cm2hr for oleic acid, and 14.80 μg/cm2hr for
linoleic acid after 1 hour exposure, which increases to 17.36
μg/cm2hr and 17.24 μg/cm2hr for sunflower oil, 15.29 μg/cm2hr and
16.14 μg/cm2hr for oleic acid, and 19.22 μg/cm2hr and 22.45
μg/cm2hr for linoleic acid after 8 and 24 hours exposure
respectively. The linoleic acid is the most effective in increasing the
testosterone permeability followed by sunflower oil then oleic acid.
The exposure of skin to oils for 8 hours is much more effective in
increasing the permeability than 1 hour exposure, while no big
difference between 8 and 24 hours exposure.
CONCLUSIONS
We demonstrated that both sunflower oil and its main components,
oleic acid and linoleic acid, significantly decreased the permeability
of skin to water. For the damaged skin the oils were effective in
reducing the flux to values lower than intact skin. No significant
differences between sunflower oil and its components were found to
exist, the implication being that either the natural sunflower oil or
its components could be employed in skin products. Both sunflower
oil and its main components, oleic acid and linoleic acid, significantly
increased the permeability of skin to caffeine as an example of
hydrophilic drug and testosterone as an example of hydrophobic
drug. For caffeine permeability oleic acid was the most effective then
sunflower oil and linoleic acid with no significant differences
between them were found to exist while for testosterone linoleic
acid was the most effective then sunflower oil and oleic acid with no
significant differences between them were found to exist. The
exposure time for 8 hours is the optimum time for the permeability
of both drugs, the implication being that either the natural sunflower
Ghonaim et al.
Int J Pharm Pharm Sci, Vol 6, Suppl 2, 630-636
636
oil or its components could be employed in skin products to restore
skin barrier functions.
REFERENCES
1. Marta Machado, Teresa M. Salgado, Jonathan Hadgraft, Majella
E. Lane. The relationship between transepidermal water loss
and skin permeability. Int. J. Pharm. 2010;384: 73-77.
2. Pieter van der,BijlArmorel D.,Jacques Cilliers, Ilse A. Standercet.
Diffusion of Water across Human Skin in the Presence of Two
Barrier Creams, Skin PharmacolAppl Skin Physiol2000;13:
104-110.
3. Darmstadt GL; Mao-Qiang M Chi E; E Chi, SK Saha, VA Ziboh, RE
Black,et al. Impact of topical oils on the skin barrier: possible
implications for neonatal health in developing countries.
actapaediatrica. 2002;91.5:546-554.
4. Joke A. Bouwstra, Maria Ponec. The skin barrier in healthy
and diseased state. Biochim. Biophys. Acta 2006; 1758: 2080-
2095.
5. S. Gattu a H.I. Maibach. Enhanced Absorption through Damaged
Skin: An Overview of the in vitro Human Model. Skin
PharmacolAppl Skin Physiol2010;23: 171-176.
6. Shuji Kitagawa and Hui Li. Effects of Removal of Stratum
Corneum, Delipidization and Addition of Enhancers, Ethanol
and l-Menthol, on Skin Permeation of Benzoic Acid and Its 4-n-
Alkyl Substituents in Excised Guinea Pig Dorsal Skin Chem.
Pharm. Bull. 1999;47(1):44-47.
7. SindyTrauer, Alexa Patzelt, Nina Otberg, Fanny Knorr,
ChristelRozycki, Gabor Balizs, Rolf Büttemeyer, Michael
Linscheid, et al. "Permeation of topically applied caffeine
through human skin - a comparison of in vivo and in vitro data.
Br. J. Clin. Pharmacol. 2009; 68:2:181-186.
8. M. Dias, A. Farinha, J. Hadgraft, J. Pais, C. Toscano. Topical
delivery of caffeine from some commercial formulations. Int. J.
Pharm.1999;182: 41-47.
9. Wu Xiao; Griffin Peter;Price Gareth J.; Guy Richard
H.Preparation and in Vitro Evaluation of Topical Formulations
Based on Polystyrene-poly-2-hydroxyl Methacrylate
Nanoparticles. MolPharm.2009;6.5: 1449-1456.
10. Wu Xiao; Biatry Bruno;CazeneuveColett, Guy Richard H. Drug
Delivery to the Skin from Sub-micron Polymeric Particle
Formulations: Influence of Particle Size and Polymer
Hydrophobicity. Pharm Res.2009;26.8:1995-2001.
ResearchGate has not been able to resolve any citations for this publication.
Article
Quantifying percutaneous absorption of topical drugs as well as those compounds relevant to occupational exposure is important for assessing delivery, efficacy and toxicology. Methods for assessing absorption are established for intact skin; however, what may be equally relevant is how much absorption occurs through damaged skin. The Embase database was accessed online in March 2009 in search of human in vitro studies measuring absorption through damaged or diseased skin. Few studies have measured absorption through damaged human skin in vitro but those that have demonstrate a modest but clear enhancement in absorption with enhancement favoring hydrophilic molecules. Damaged or diseased skin may display a modest increase in absorption compared to intact skin; however, more studies with consistent methods and correlations to in vivo data are needed to fully elucidate how much absorption occurs through damaged skin.
Article
Transepidermal water loss (TEWL) is a measure of the steady-state water vapour flux crossing the skin to the external environment and it has been used extensively to characterise skin barrier function. We have previously hypothesised that in vivo TEWL is directly related to the reciprocal of the diffusional permeation pathlength through the stratum corneum (SC). The aim of the present paper is to validate experimentally this hypothesis. Ninety volunteers were recruited and TEWL and corneocyte surface areas were measured for six anatomic sites. The number of cell layers in the SC was calculated for each anatomic site in order to estimate the geometric pathlength for water efflux. Significant anatomic site variability was found for both TEWL and corneocyte surface area which were inversely correlated. A direct reciprocal relationship between TEWL and pathlength was determined, with TEWL values tending to zero when corneocytes are infinitely large. In general, skin sites with smaller corneocytes have fewer cell layers, with shorter permeation pathlengths and higher TEWL values. The results confirm our previous hypothesis and suggest that TEWL may be used to characterise the permeation routes for different anatomic sites.
Article
Due to ethical reasons, in vivo penetration studies are not applicable at all stages of development of new substances. Therefore, the development of appropriate in vitro methods is essential, as well as the comparison of the obtained in vivo and in vitro data, in order to identify their transferability. The aim of the present study was to investigate the follicular penetration of caffeine in vitro and to compare the data with the in vivo results determined previously under similar conditions. The Follicular Closing Technique (FCT) represents a method to investigate the follicular penetration selectively. In the present study, FCT was combined with the Franz diffusion cell in order to differentiate between follicular and intercellular penetration of caffeine into the receptor medium in vitro. Subsequently, the results were compared with the data obtained in an earlier study investigating follicular and intercellular penetration of caffeine in vivo. The comparison of the data revealed that the in vitro experiments were valuable for the investigation of the follicular penetration pathway, which contributed in vivo as well as in vitro to approximately 50% of the total penetration, whereas the kinetics of caffeine penetration were shown to be significantly different. The combination of FCT with the Franz diffusion cell represents a valuable method to investigate follicular penetration in vitro. Nevertheless, in vivo experiments should not be abandoned as in vitro, structural changes of skin occur and blood flow and metabolism are absent, probably accounting for reduced penetration rates in vitro.
Article
The skin disposition of topically applied nanoparticles with varying degrees of hydrophobicity, composed of different proportions of polystyrene (PS) and poly-(2-hydroxyethyl methacrylate) (HEMA), and of an associated, model "active" (Nile Red), was investigated. PS-HEMA copolymer nanoparticles were fluorescently labeled, via the covalent incorporation of a small quantity of fluorescein methacrylate, and characterized by dynamic light scattering, transmission electron microscopy and NMR. The fluorophore, Nile Red, was dispersed into the nanoparticles and its loading was determined by ultracentrifugation. Skin uptake was assessed in vitro following a 6 h application of the nanoparticle formulation, via stratum corneum (SC) tape-stripping and confocal microscopy. Nanoparticle diameters were below 100 nm. Progressive introduction of HEMA decreased particle hydrophobicity and reduced Nile Red loading. Uptake of Nile Red into the skin, as assessed both by the amounts extracted from the SC and by confocal microscopy, decreased as the percentage HEMA increased. Confocal microscopy confirmed that nanoparticles could not move beyond the superficial SC, but did show affinity for hair follicle openings. In conclusion, the loading of a lipophilic "active" into nanoparticles, and its subsequent release when these formulations are applied topically, are sensitive to the composition and relative hydrophobicity of the carrier.
Article
To investigate the influence of particle size and polymer properties on the topical delivery of a lipophilic "active" species (Nile Red (NR)) from sub-micron polymeric particles. Three poly-(epsilon-caprolactone) (CAPA) formulations were examined to assess the impact of particle size. Three other formulations, based on cellulose acetate butyrate (CAB), CAPA and polystyrene were studied to address the role of polymer hydrophobicity. In vitro skin permeation, and confocal microscopy and stratum corneum (SC) tape-stripping were used to evaluate the cutaneous disposition of NR. NR delivery into the SC was greater from the larger particles, the overall smaller surface area of which enhanced the "leaving tendency" of the lipophilic "active". Skin uptake of NR (measured as "%payload released") from polystyrene, CAPA and CAB particles increased with decreasing polymer hydrophobicity (polystyrene > CAPA > CAB) as expected. Confocal microscopy revealed that NR released from the particles accumulated in, and penetrated via, lipid domains between the SC corneocytes. The particles showed affinity for hairs, and concentrated on the skin surface at the follicular openings. Delivery of a model drug to the skin from sub-micron polymeric particle formulations is sensitive to the particle size and the relative hydrophobicity of the carrier.
Article
Skin penetration of benzoic acid and its 4-alkyl substituents (methyl, ethyl, n-propyl and n-butyl) through excised guinea pig dorsal skin was examined, and effects of removal of stratum corneum, delipidization and addition of the penetration enhancers, ethanol and l-menthol plus ethanol, were observed. Permeability coefficients, which increased with the increase in their alkyl chain lengths, depended on the ratio of undissociated form of the derivatives. Removal of stratum corneum by tape stripping and delipidization by a chloroform-methanol mixture, whose effects on the permeation were similar, increased the permeability coefficients of the derivatives, especially those of relatively hydrophilic derivatives. Addition of 1% l-menthol plus 15% ethanol increased the permeability coefficient of benzoic acid, but decreased those of ethyl-, n-propyl- and n-butyl-substituents, and differences in the permeability coefficients among these acids almost disappeared. A similar though weaker tendency was observed for the effects of 15% ethanol itself. Analysis of transfer free energy of the methylene group from vehicle to skin revealed that tape stripping and delipidization induced the reduction of lipophilic barrier property, although it still remained after these treatments. The analysis also showed that the addition of the enhancers made the skin relatively more hydrophilic compared to the vehicle, which induced an increase in permeability coefficient of benzoic acid and decreases in those of its lipophilic substituents.
Article
Permeation of caffeine through human skin and artificial membranes (mounted in modified Franz type diffusion cells) was evaluated, either from saturated solutions or from commercially available topical formulations (all containing 3% caffeine). Data interpretation of the caffeine diffusion through human skin does not implicate transfer through pores despite caffeine being a relatively polar molecule. No correlation was found between transfer though the synthetic membranes (cellulose acetate impregnated with isopropyl myristate and silicone rubber soaked in isopropyl myristate) and that observed through skin. The synthetic membranes can be used for assessing product performance in quality assurance but will give little indication of its performance in vivo. The study investigated the percutaneous permeation of caffeine through human skin in order to obtain a mechanistic interpretation of its route of permeation. Synthetic membranes were also examined to determine if they could be used as models for human skin. Different commercial formulations investigated to determine the significance of enhancement strategies.
Article
The in vitro permeability of tritiated water through fresh and frozen human skin was evaluated in the presence and absence of two different barrier creams. Treated (10 min) and untreated fresh and frozen human skin disks (4 mm in diameter) were mounted in flow cells of a continuous flow-through diffusion apparatus. Buffer/tritiated water was collected from the acceptor chambers at 2-hour intervals for a total of 20 h and counted in a liquid scintillation counter. The results indicated that both barrier creams lowered the average flux rates of tritiated water through fresh and frozen skin, but no significant differences could be detected between the two preparations. However, different results may be obtained when compounds with molecular weights much higher than water are used.
Article
Unlabelled: Topical therapy to enhance skin barrier function may be a simple, low-cost, effective strategy to improve outcome of preterm infants with a developmentally compromised epidermal barrier, as lipid constituents of topical products may act as a mechanical barrier and augment synthesis of barrier lipids. Natural oils are applied topically as part of a traditional oil massage to neonates in many developing countries. We sought to identify inexpensive, safe, vegetable oils available in developing countries that improved epidermal barrier function. The impact of oils on mouse epidermal barrier function (rate of transepidermal water loss over time following acute barrier disruption by tape-stripping) and ultrastructure was determined. A single application of sunflower seed oil significantly accelerated skin barrier recovery within 1 h; the effect was sustained 5 h after application. In contrast, the other vegetable oils tested (mustard, olive and soybean oils) all significantly delayed recovery of barrier function compared with control- or Aquaphor-treated skin. Twice-daily applications of mustard oil for 7 d resulted in sustained delay of barrier recovery. Moreover, adverse ultrastructural changes were seen under transmission electron microscopy in keratin intermediate filament, mitochondrial, nuclear, and nuclear envelope structure following a single application of mustard oil. Conclusion: Our data suggest that topical application of linoleate-enriched oil such as sunflower seed oil might enhance skin barrier function and improve outcome in neonates with compromised barrier function. Mustard oil, used routinely in newborn care throughout South Asia, has toxic effects on the epidermal barrier that warrant further investigation.
Article
The primary function of the skin is to protect the body for unwanted influences from the environment. The main barrier of the skin is located in the outermost layer of the skin, the stratum corneum. The stratum corneum consists of corneocytes surrounded by lipid regions. As most drugs applied onto the skin permeate along the lipid domains, the lipid organization is considered to be very important for the skin barrier function. It is for this reason that the lipid organization has been investigated quite extensively. Due to the exceptional stratum corneum lipid composition, with long chain ceramides, free fatty acids and cholesterol as main lipid classes, the lipid organization is different from that of other biological membranes. In stratum corneum, two lamellar phases are present with repeat distances of approximately 6 and 13 nm. Moreover the lipids in the lamellar phases form predominantly crystalline lateral phases, but most probably a subpopulation of lipids forms a liquid phase. Diseased skin is often characterized by a reduced barrier function and an altered lipid composition and organization. In order to understand the aberrant lipid organization in diseased skin, information on the relation between lipid composition and organization is crucial. However, due to its complexity and inter-individual variability, the use of native stratum corneum does not allow detailed systematic studies. To circumvent this problem, mixtures prepared with stratum corneum lipids can be used. In this paper first the lipid organization in stratum corneum of normal and diseased skin is described. Then the role the various lipid classes play in stratum corneum lipid organization and barrier function has been discussed. Finally, the information on the role various lipid classes play in lipid phase behavior has been used to interpret the changes in lipid organization and barrier properties of diseased skin.