Stability, clinical efficacy, and antioxidant properties of Honeybush extracts in semi-solid formulations

BACKGROUND: Honeybush extracts (Cyclopia spp.) can be incorporated into skin care products to treat conditions such as skin dryness and can function as an anti-oxidant. OBJECTIVE: To formulate Honeybush formulations and test it for antioxidant activity, skin penetration, and skin hydrating effects. MATERIALS AND METHODS: Semi-solid formulations containing either Cyclopia maculata (2%) or Cyclopia genistoides (2%) underwent accelerated stability studies. Membrane release studies, Franz cell skin diffusion and tape stripping studies were performed. Antioxidant potential was determined with the 2-thiobarbituric acid-assay and clinical efficacy studies were performed to determine the formulations' effect on skin hydration, scaliness, and smoothness after 2 weeks of treatment on the volar forearm. RESULTS: The formulations were unstable over 3 months. Membrane release, skin diffusion studies, and tape stripping showed that both formulations had inconclusive results due to extremely low concentrations mangiferin and hesperidin present in the Franz cell receptor compartments, stratum corneum-epidermis, and epidermis-dermis layers of the skin. Honeybush extracts showed antioxidant activity with concentrations above 0.6250 mg/ml when compared to the toxin; whereas mangiferin and hesperidin did not show any antioxidant activity on their own. The semisolid formulations showed the potential to emit their own antioxidant activity. Both formulations improved skin smoothness, although they did not improve skin hydration compared to the placebos. C. maculata reduced the skin scaliness to a larger extent than the placebos and C. genistoides. CONCLUSION: Honeybush formulations did not penetrate the skin but did, however, show antioxidant activity and the potential to be used to improve skin scaliness and smoothness.