The oral route of administration remains the preferred route of administrating drugs due to patient acceptance and compliance. Therapeutic proteins are currently mainly administered by means of the parenteral route because of its low intestinal epithelial permeation capability. The major challenges for oral delivery of proteins and peptides are pre-systemic enzymatic degradation and poor penetration of the intestinal mucosa. The latter can be overcome by including safe and effective absorption enhancers in dosage forms. Aloe vera, Aloe ferox and Aloe marlothii gel materials as well as N-trimethyl chitosan chloride (TMC) were shown to be capable of increasing peptide drug transport across in vitro models such as Caco-2 cell monolayers. The purpose of this study is to investigate binary combinations of chemical drug absorption enhancers and to determine if synergistic drug absorption enhancement effects exist. A. vera, A. ferox and A. marlothii leaf gel materials as well as with N-trimethyl chitosan chloride (TMC) were combined in different ratios and their effects on the transepithelial electrical resistance (TEER) as well as the transport of FITC-dextran across Caco-2 cell monolayers were measured. The isobole method was applied to determine the type of interaction that exists between the absorption enhancers combinations. The TEER results showed synergism existed for the combinations between A. vera and A. marlothii, A. marlothii and A. ferox as well as A. vera and TMC. Antagonism interactions also occurred and can probably be explained by chemical reactions between the chemical permeation enhancers such as complex formation. In terms of FITC-dextran transport, synergism was found for combinations between A. vera and A. marlothii, A. marlothii and A. ferox, A. vera and TMC, A. ferox and TMC and A. marlothii and TMC, whereas antagonism was observed for A. vera and A. ferox. The combinations where synergism was obtained have the potential to be used as effective drug absorption enhancers at lower concentrations compared to single components. / MSc (Pharmaceutics), North-West University, Potchefstroom Campus, 2015

The oral route of administration remains the preferred route of administrating drugs due to patient acceptance and compliance. Therapeutic proteins are currently mainly administered by means of the parenteral route because of its low intestinal epithelial permeation capability. The major challenges for oral delivery of proteins and peptides are pre-systemic enzymatic degradation and poor penetration of the intestinal mucosa. The latter can be overcome by including safe and effective absorption enhancers in dosage forms. Aloe vera, Aloe ferox and Aloe marlothii gel materials as well as N-trimethyl chitosan chloride (TMC) were shown to be capable of increasing peptide drug transport across in vitro models such as Caco-2 cell monolayers. The purpose of this study is to investigate binary combinations of chemical drug absorption enhancers and to determine if synergistic drug absorption enhancement effects exist. A. vera, A. ferox and A. marlothii leaf gel materials as well as with N-trimethyl chitosan chloride (TMC) were combined in different ratios and their effects on the transepithelial electrical resistance (TEER) as well as the transport of FITC-dextran across Caco-2 cell monolayers were measured. The isobole method was applied to determine the type of interaction that exists between the absorption enhancers combinations. The TEER results showed synergism existed for the combinations between A. vera and A. marlothii, A. marlothii and A. ferox as well as A. vera and TMC. Antagonism interactions also occurred and can probably be explained by chemical reactions between the chemical permeation enhancers such as complex formation. In terms of FITC-dextran transport, synergism was found for combinations between A. vera and A. marlothii, A. marlothii and A. ferox, A. vera and TMC, A. ferox and TMC and A. marlothii and TMC, whereas antagonism was observed for A. vera and A. ferox. The combinations where synergism was obtained have the potential to be used as effective drug absorption enhancers at lower concentrations compared to single components. / MSc (Pharmaceutics), North-West University, Potchefstroom Campus, 2015

Aloe marlothii is a winter-flowering succulent that is widespread in the savanna biome of northern and north-eastern South Africa. Plants grow up to 8 m in height and are commonly found on rocky north-facing slopes. Nectar production occurs through a 24 h period with flowers producing copious amounts (c. 250 µl) of dilute nectar (c. 12%). This abundant nectar supply, that is available for a 5-10 week period during June-August, is utilised by numerous opportunistic avian nectarivores. At a study site in Suikerbosrand Nature Reserve, 60 km south-east of Johannesburg, at least 59% (38 species) of birds recorded during census transects fed on nectar; throughout the range of A. marlothii at least 85 species feed on nectar. This diversity surely far exceeds the number of species ever recorded feeding on nectar of a single plant. During the flowering period an influx of birds at the aloe forest occurred, with an overall increase in abundance and diversity. Pollinator exclusion experiments supported the hypothesis that A. marlothii is pollinated by generalist birds; specialist nectarivores are possibly excluded as inefficient pollinators by the nectar of low concentration and high volume. Fruit set was higher in plants that had avian visitors and very low when pollinators were absent. Stable carbon isotope analysis of whole blood was used to quantify the importance of nectar sugars for opportunistic nectarivores. During flowering there was an enrichment in the δ13C isotopic signature of whole blood of nectar-feeding birds towards that of nectar (δ13C = -12.6‰). This shift was most prominent in frugivores, insectivores and omnivores that typically fed on a diet depleted in 13C when nectar was not available. The C4 grass seed diet of granivores was similar to the isotopic signature ofA. marlothii nectar, so we were unable to determine to what degree granivores benefitted from nectar. Stable nitrogen isotopes in whole blood may suggest that many nectar-feeding birds shift their trophic position during flowering. However, we interpret these results with caution because of insufficient knowledge on diet-tissue fractionation factors of wild birds and/or temporal changes in vegetation isotopic values. Stable carbon isotope analysis of breath samples was used to show that A. marlothii nectar is a readily available income energy source for nectar-feeding birds. Because A. marlothii nectar is so dilute we expected it to be an important water source for many opportunistic nectar-feeding bird species. There was no correlation between the enrichment of δ13C of breath CO2 (representing metabolised nectar sugars) and the δ18O in breath CO2 (representing a highly evaporated water source in nectar); for most birds the δ18O in breath CO2 was more similar to that of free-standing water sources. However, because our knowledge on the relationship between δ18O of ingested water and body water, and fractionation processes when CO2 is exhaled is limited, we were unable to quantify water obtained from nectar. The sugars of A. marlothii nectar are probably more important, as a food source for opportunistic nectarivores during dry winter months when insect abundance is low, than the water in nectar, because birds are able to source water from other drinking sites. / Thesis (PhD)--University of Pretoria, 2010. / Zoology and Entomology / unrestricted

The most popular and convenient route of drug administration remains the oral route, however, protein and peptide drugs such as insulin have poor membrane permeability and stability in the gastrointestinal tract. Absorption enhancers can be added to drug delivery systems to overcome the epithelial cell membrane permeability problem. Although previous studies have shown that aloe leaf materials improve the transport of drugs across intestinal epithelia, their performance in solid oral dosage forms has not yet been investigated. Beads containing insulin and each of the selected absorption enhancers (i.e. Aloe ferox, Aloe marlothii and Aloe vera gel materials) were produced by extrusion-spheronisation, using a full factorial design to optimise the formulations based on transepithelial electrical resistance (TEER) reduction of Caco-2 cell monolayers as response. The optimum bead formulations were evaluated in terms of friability, mass variation, particle surface texture, shape, size and dissolution. The transport of insulin across excised pig intestinal tissue from the optimised bead formulations was determined over a 2 h period. The samples obtained from the transport studies were analysed for insulin content by means of high-performance liquid chromatography (HPLC). The results showed that the TEER reduction, as an indication of tight junction modulation, obtained for the bead formulations containing aloe materials was concentration dependent. Furthermore, inclusion of croscarmellose sodium (Ac-di-sol®) as a disintegrant showed an enhanced TEER reduction effect in combination with the aloe gel materials. Dissolution profiles indicated that the beads containing aloe leaf materials in conjunction with insulin, released the insulin within an hour. In accordance with the TEER reduction results, the A. marlothii and A. vera materials containing beads showed similar increased insulin delivery across excised pig intestinal tissue, which was pronouncedly higher than that of the control group (insulin alone). It can be concluded that beads containing aloe leaf materials have high potential as effective delivery systems for protein therapeutics such as insulin via the oral route of administration. / MSc (Pharmaceutics), North-West University, Potchefstroom Campus, 2015

The most popular and convenient route of drug administration remains the oral route, however, protein and peptide drugs such as insulin have poor membrane permeability and stability in the gastrointestinal tract. Absorption enhancers can be added to drug delivery systems to overcome the epithelial cell membrane permeability problem. Although previous studies have shown that aloe leaf materials improve the transport of drugs across intestinal epithelia, their performance in solid oral dosage forms has not yet been investigated. Beads containing insulin and each of the selected absorption enhancers (i.e. Aloe ferox, Aloe marlothii and Aloe vera gel materials) were produced by extrusion-spheronisation, using a full factorial design to optimise the formulations based on transepithelial electrical resistance (TEER) reduction of Caco-2 cell monolayers as response. The optimum bead formulations were evaluated in terms of friability, mass variation, particle surface texture, shape, size and dissolution. The transport of insulin across excised pig intestinal tissue from the optimised bead formulations was determined over a 2 h period. The samples obtained from the transport studies were analysed for insulin content by means of high-performance liquid chromatography (HPLC). The results showed that the TEER reduction, as an indication of tight junction modulation, obtained for the bead formulations containing aloe materials was concentration dependent. Furthermore, inclusion of croscarmellose sodium (Ac-di-sol®) as a disintegrant showed an enhanced TEER reduction effect in combination with the aloe gel materials. Dissolution profiles indicated that the beads containing aloe leaf materials in conjunction with insulin, released the insulin within an hour. In accordance with the TEER reduction results, the A. marlothii and A. vera materials containing beads showed similar increased insulin delivery across excised pig intestinal tissue, which was pronouncedly higher than that of the control group (insulin alone). It can be concluded that beads containing aloe leaf materials have high potential as effective delivery systems for protein therapeutics such as insulin via the oral route of administration. / MSc (Pharmaceutics), North-West University, Potchefstroom Campus, 2015

Microcrystalline cellulose (MCC) is the most commonly used excipient in the manufacture of spherical particles or beads by extrusion spheronisation. However, the use of MCC in beads has its limitations such as prolonged release of drugs due to lack of disintegration. The aim of this study was to determine if Aloe vera and Aloe marlothii leaf materials can be used as excipients in the production of beads prepared by extrusion spheronisation. A 23 full factorial design was employed for optimisation and to explore the effects of the concentration of MCC, polyvinylpyrrolidone and aloe materials on the sphericity and release rate of ketoprofen. Scanning electron microscopy revealed more porous beads when aloe materials were included in the bead formulations compared to the formulation with MMC alone. The bead formulations containing aloe materials exhibited faster drug release compared to that of the formulation containing MCC alone. Dissolution data of the optimised formulations were analysed in terms of mean dissolution time (MDT) as well as fit factors (f1 and f2). The optimised bead formulations had dissolution profiles comparable to that of the formulation containing MCC alone at pH 1.2 and 4.5 (f2 values > 70), but less comparable to the reference at pH 6.8 (50 < f2< 65) due to faster drug release. Aloe vera and Aloe marlothii leaf materials can be used successfully together with MCC in the production of beads by extrusion spheronisation. / Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

Microcrystalline cellulose (MCC) is the most commonly used excipient in the manufacture of spherical particles or beads by extrusion spheronisation. However, the use of MCC in beads has its limitations such as prolonged release of drugs due to lack of disintegration. The aim of this study was to determine if Aloe vera and Aloe marlothii leaf materials can be used as excipients in the production of beads prepared by extrusion spheronisation. A 23 full factorial design was employed for optimisation and to explore the effects of the concentration of MCC, polyvinylpyrrolidone and aloe materials on the sphericity and release rate of ketoprofen. Scanning electron microscopy revealed more porous beads when aloe materials were included in the bead formulations compared to the formulation with MMC alone. The bead formulations containing aloe materials exhibited faster drug release compared to that of the formulation containing MCC alone. Dissolution data of the optimised formulations were analysed in terms of mean dissolution time (MDT) as well as fit factors (f1 and f2). The optimised bead formulations had dissolution profiles comparable to that of the formulation containing MCC alone at pH 1.2 and 4.5 (f2 values > 70), but less comparable to the reference at pH 6.8 (50 < f2< 65) due to faster drug release. Aloe vera and Aloe marlothii leaf materials can be used successfully together with MCC in the production of beads by extrusion spheronisation. / Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

Thesis (MSc. (Zoology)) --University of Limpopo, 2008 / Refer to document / National Research Foundation - Thuthuka programme

Extensive research has already been performed on Aloe vera therefore it is important that researchers include other aloe species, such as Aloe marlothii and Aloe ferox, in studies involving aloe plant materials (Loots et al., 2007:6891). The use of natural products has regained popularity and in recent years the demand for alternative medication has risen considerably (Walji & Wiktorowicz, 2013:86). The hydration state of the human skin is fundamental for its normal functioning (Verdier-Sévrain & Bonté, 2007:75), with healthy skin possessing a water content higher than 10% (w/v) (Blank, 1952:439). This demonstrates the importance of the topical application of skin moisturisers as part of basic skin care regime (Verdier-Sévrain & Bonté, 2007:75). The first part of this project focused on the in vivo skin hydration effects of the precipitated polysaccharide components of A. vera, A. ferox and A. marlothii leaf gel materials (3% (w/v)) after single (30, 90 and 150 min after application) and multiple applications (twice daily application over a period of four weeks) on healthy volunteers, respectively. The anti-erythema effects of these aloe materials on sodium lauryl sulphate irritated skin were also examined. The skin hydration effects of the aloe materials were determined with the Corneometer® CM 825 and Visioscan® VC 98 during the short term study (single application) and longer term study (multiple applications). In addition, as an indirect measurement of skin hydration, the Cutometer® dual MPA 580 was used to measure skin elasticity during the longer term study. To determine the anti-erythema effects of the aloe materials when applied to irritated skin areas, the haemoglobin content of the skin was measured with a Mexameter® MX 18. The results from the in vivo study indicated that A. ferox gel material dehydrated the skin, whereas A. vera and A. marlothii gel materials hydrated the skin during the short term study. Results from the longer term study showed that all the aloe leaf materials have skin dehydration effects, probably due to the aloe absorbing moisture from the skin into the applied gel layer upon drying. From the anti-erythema study, it was seen that A. vera and A. ferox materials had the potential to reduce erythema on the skin similar to that of the positive control group (i.e. hydrocortisone gel) after six days of treatment. The skin possesses exceptional barrier properties which can mostly be ascribed to the outermost layer of the skin, the stratum corneum (SC). Due to the physical barrier the skin has against drug permeation, the delivery of drug molecules into and across the skin continues to be challenging (Lane, 2013:13) and to overcome this barrier, penetration enhancers can be used to efficiently deliver drugs across the skin (Barry, 2002:522). The aim of the second part of this project was to determine the skin penetration enhancing effects of the gel and whole leaf materials of A. vera, A. marlothii and A. ferox. Ketoprofen was used as the marker compound and a high performance liquid chromatography (HPLC) method was developed and validated to determine the amount of ketoprofen present in the samples. Prior to the skin diffusion studies, membrane release studies were performed to test whether the solutions containing different concentrations of the aloe leaf materials (i.e. 3.00%, 1.50% and 0.75% (w/v)) released ketoprofen from their gel-like structures. From these studies, it was evident the 0.75% (w/v) concentration had the highest average percentage ketoprofen release, which was subsequently chosen as the concentration for the aloe leaf materials tested in the transdermal skin diffusion studies. The in vitro permeation study was conducted across dermatomed (400 μm thick) skin in Franz diffusion cells. Tape stripping was performed after completion of the diffusion studies to determine the concentration ketoprofen present in the SC-epidermis and epidermis-dermis layers of the skin. Results from the in vitro permeation study showed that A. vera gel enhanced the flux of ketoprofen to the highest extent (20.464 μg/cm2.h) when compared to the control group (8.020 μg/cm2.h). Aloe marlothii gel (12.756 μg/cm2.h) and A. ferox whole leaf material (12.187 μg/cm2.h) also enhanced the permeation of ketoprofen across the skin compared to the control group. A. vera gel material was the most efficient transdermal drug penetration enhancer of the selected aloe species investigated. In order to determine by which mechanism the aloe leaf materials enhanced the skin permeation of ketoprofen (Hadgraft et al., 2003:141), the permeation profiles were analysed using a non-linear curve-fitting procedure (Díez-Sales et al., 1991:3) to obtain α, β and kp values. A change in the α-value indicated the aloe leaf material influenced the partition coefficient (K), whereas a change in β indicated the aloe leaf material influenced the diffusivity (D) (with the assumption that h, the diffusional path length is constant) (Otto et al., 2010:278). The calculated α-values indicated the drug permeation enhancing effect of A. vera gel can be ascribed to an increased partitioning of the drug into the skin. The calculated β-values showed A. ferox whole leaf altered the diffusion characteristics of the skin for ketoprofen. The tape stripping results showed A. marlothii whole leaf delivered the highest concentration of the ketoprofen into the SC-epidermis and epidermis-dermis layers of the skin. / PhD (Pharmaceutics), North-West University, Potchefstroom Campus, 2014

Extensive research has already been performed on Aloe vera therefore it is important that researchers include other aloe species, such as Aloe marlothii and Aloe ferox, in studies involving aloe plant materials (Loots et al., 2007:6891). The use of natural products has regained popularity and in recent years the demand for alternative medication has risen considerably (Walji & Wiktorowicz, 2013:86). The hydration state of the human skin is fundamental for its normal functioning (Verdier-Sévrain & Bonté, 2007:75), with healthy skin possessing a water content higher than 10% (w/v) (Blank, 1952:439). This demonstrates the importance of the topical application of skin moisturisers as part of basic skin care regime (Verdier-Sévrain & Bonté, 2007:75). The first part of this project focused on the in vivo skin hydration effects of the precipitated polysaccharide components of A. vera, A. ferox and A. marlothii leaf gel materials (3% (w/v)) after single (30, 90 and 150 min after application) and multiple applications (twice daily application over a period of four weeks) on healthy volunteers, respectively. The anti-erythema effects of these aloe materials on sodium lauryl sulphate irritated skin were also examined. The skin hydration effects of the aloe materials were determined with the Corneometer® CM 825 and Visioscan® VC 98 during the short term study (single application) and longer term study (multiple applications). In addition, as an indirect measurement of skin hydration, the Cutometer® dual MPA 580 was used to measure skin elasticity during the longer term study. To determine the anti-erythema effects of the aloe materials when applied to irritated skin areas, the haemoglobin content of the skin was measured with a Mexameter® MX 18. The results from the in vivo study indicated that A. ferox gel material dehydrated the skin, whereas A. vera and A. marlothii gel materials hydrated the skin during the short term study. Results from the longer term study showed that all the aloe leaf materials have skin dehydration effects, probably due to the aloe absorbing moisture from the skin into the applied gel layer upon drying. From the anti-erythema study, it was seen that A. vera and A. ferox materials had the potential to reduce erythema on the skin similar to that of the positive control group (i.e. hydrocortisone gel) after six days of treatment. The skin possesses exceptional barrier properties which can mostly be ascribed to the outermost layer of the skin, the stratum corneum (SC). Due to the physical barrier the skin has against drug permeation, the delivery of drug molecules into and across the skin continues to be challenging (Lane, 2013:13) and to overcome this barrier, penetration enhancers can be used to efficiently deliver drugs across the skin (Barry, 2002:522). The aim of the second part of this project was to determine the skin penetration enhancing effects of the gel and whole leaf materials of A. vera, A. marlothii and A. ferox. Ketoprofen was used as the marker compound and a high performance liquid chromatography (HPLC) method was developed and validated to determine the amount of ketoprofen present in the samples. Prior to the skin diffusion studies, membrane release studies were performed to test whether the solutions containing different concentrations of the aloe leaf materials (i.e. 3.00%, 1.50% and 0.75% (w/v)) released ketoprofen from their gel-like structures. From these studies, it was evident the 0.75% (w/v) concentration had the highest average percentage ketoprofen release, which was subsequently chosen as the concentration for the aloe leaf materials tested in the transdermal skin diffusion studies. The in vitro permeation study was conducted across dermatomed (400 μm thick) skin in Franz diffusion cells. Tape stripping was performed after completion of the diffusion studies to determine the concentration ketoprofen present in the SC-epidermis and epidermis-dermis layers of the skin. Results from the in vitro permeation study showed that A. vera gel enhanced the flux of ketoprofen to the highest extent (20.464 μg/cm2.h) when compared to the control group (8.020 μg/cm2.h). Aloe marlothii gel (12.756 μg/cm2.h) and A. ferox whole leaf material (12.187 μg/cm2.h) also enhanced the permeation of ketoprofen across the skin compared to the control group. A. vera gel material was the most efficient transdermal drug penetration enhancer of the selected aloe species investigated. In order to determine by which mechanism the aloe leaf materials enhanced the skin permeation of ketoprofen (Hadgraft et al., 2003:141), the permeation profiles were analysed using a non-linear curve-fitting procedure (Díez-Sales et al., 1991:3) to obtain α, β and kp values. A change in the α-value indicated the aloe leaf material influenced the partition coefficient (K), whereas a change in β indicated the aloe leaf material influenced the diffusivity (D) (with the assumption that h, the diffusional path length is constant) (Otto et al., 2010:278). The calculated α-values indicated the drug permeation enhancing effect of A. vera gel can be ascribed to an increased partitioning of the drug into the skin. The calculated β-values showed A. ferox whole leaf altered the diffusion characteristics of the skin for ketoprofen. The tape stripping results showed A. marlothii whole leaf delivered the highest concentration of the ketoprofen into the SC-epidermis and epidermis-dermis layers of the skin. / PhD (Pharmaceutics), North-West University, Potchefstroom Campus, 2014