|dc.description.abstract||The progression of skin ageing in individuals is multifaceted and provoked by various aspects, including hereditary and a variety of environmental causes, for instance UV (ultra violet) radiation, resulting in the morphological modifications in the dermal layer of the skin (Makrantonaki & Zouboulis, 2007:40) Transformations caused by ageing skin, in which degenerative alterations exceed regenerative alterations are recognised by the thinning and wrinkling of the epidermis in conjunction with the appearance of lines, creases, crevices and furrows, particularly emphasised in lines of facial expressions (Aburjai & Natsheh, 2003:990).
For human beings to continue to exist in a terrestrial atmosphere, the loss of water from the skin must be cautiously synchronised by the epidermis, a task dependent on the multifaceted character of the stratum corneum (Rawlings & Harding, 2004:43). The stratum corneum (SC) is responsible for the main resistance to the penetration of most compounds; nevertheless the skin represents as an appropriate target for delivery. The target site for anti-ageing treatment includes the epidermal and dermal layers of the skin. Therefore, the need to apply fatty materials to the skin is practically intuitive and may perhaps be as old as man’s existence itself (Lodén, 2005:672). Natural therapies have been used for several decades for taking care of skin illnesses and a wide variety of dermatological disorders, such as inflammation, phototoxicity, atopic dermatitis and alopecia areata (Aburjai & Natsheh, 2003:988).
Using the skin as an alternative route for the administration of honeybush extracts for the treatment of ageing skin may be beneficial. Tea contains more than 500 chemical compounds, including, tannins, flavonoids, amino acids, vitamins, caffeine and polysaccharides. Tea polyphenols (flavonoids) have proven anti-inflammatory, antioxidant, antiallergic, antibacterial and antiviral effects (Aburjai & Natsheh, 2003:990). Unfortunately using the skin as an alternative route for administering drugs (transdermal drug delivery) has numerous limitations.
One of these limitations is the barrier function of the skin (Naik et al., 2000:319). Because of the skin’s outstanding ability to protect the body against unwanted substances from its surroundings, it is necessary to use methods to enhance drug penetration through the skin.
The aim of this study was to formulate two 2% semisolid formulations containing two different honeybush extracts as the active ingredient, and to determine which of the formulations deliver mangiferin and hesperidin best to the target site (dermis). Cosmetic formulations of a natural origin, is designed to protect the skin against exogenous or endogenous harmful agents, as well as to balance the dermal homeostatis lipids altered by dermatosis and ageing (Aburjai & Natsheh, 2003:988).
Stability tests over a three month period were also performed on the different formulations. To determine the stability of the different semi-solid formulations, the formulated products were stored at 25 °C/60% RH (relative humidity), 30 °C/60% RH and 40 °C/75% RH. HPLC analysis was used to determine the concentrations of the ingredients in all the formulated products.
Other stability tests included appearance, pH, viscosity, mass loss, zeta potential and particle size determination. Unfortunately a change in colour, viscosity, zeta potential, mass loss, particle size and concentration of the ingredients in both the formulations, indicated that the products were unstable from the first month of stability testing. A 2% Cyclopia maculata cream as well as a 2% Cyclopia genistoides cream was formulated.
Franz cell diffusion studies as well as membrane release studies were performed over a 12 h period, followed by tape stripping experiments to determine which semi-solid formulation delivered mangiferin and hesperidin the best to the dermal layer of the skin. The results of the different formulations were compared. Unfortunately there was no significant penetration by any of the honeybush extracts. Results were inconclusive and unquantifiable due to unconvincing penetration results.
The antioxidant properties of both the extracts and the active ingredients were calculated. Antioxidant studies by the use of the TBA-assay method were done to determine whether the honeybush extracts, mangiferin and hesperidin as well as their semisolid formulations had any antioxidant activities. Both the honeybush extracts and the semisolid formulations showed promising results. Mangiferin and hesperidin did not show any antioxidant activity on their own, therefore the assumption can be confirmed that plants do function synergistically.
A clinical study was also conducted to see whether honeybush extracts have the potential to hydrate the skin, counteracting the symptoms and signs of skin ageing. Clinical efficacy studies were done to determine whether the honeybush formulations had any skin hydrating effects in the treatment against skin ageing. The results were statistically inconclusive and variations between the subjects were very high due to skin variations at different skin sites. There was however a trend that Cyclopia genistoides performed the best.||en_US