Abstract:
Eczema is considered a worldwide concern as more people, particularly children, are affected each year. Side effects of eczema include hyperpigmentation and wrinkle formation. Due to the overexpression of interleukin (IL)-1β and IL-6, large quantities of the tyrosinase enzyme are released causing hyperpigmentation, whereas during wrinkle formation elastase is produced. This study examined the antityrosinase, anti-elastase and immune-modulatory potential of 22 succulent plant extracts. These extracts were prepared from the leaves and gels of 10 plant species, which included four aloes, Bulbine frutescens (L.) Willd. and five aloe hybrids. Five extracts displayed tyrosinase inhibition at a concentration of 200 µg/mL, which included Aloe arborescens gel (AG) (41.38 ± 0.94 %), A. vera leaf (VL) (26.64 ± 1.50 %), Aloe X principis (2) leaf (XL) (33.11 ± 1.29 %), (A. chabaudii x A. petricola) x A. zubb pure leaf (CPL) (18.70 ± 1.40 %) and A. ferox x A. zubb leaf (FZL) (21.82 ± 1.12 %), however, these extracts displayed no elastase inhibition at the highest tested concentration. Furthermore, these extracts displayed no antiproliferative activity on human keratinocyte (HaCaT) cells, with fifty percent inhibitory concentrations (IC50) >400 µg/mL. The AG and XL extracts, which showed the highest tyrosinase inhibition, were selected for cytokine modulatory activity using peripheral blood mononuclear cells (PBMC's) to evaluate the effect on interleukin-8 (IL-8), 1β, 6, 10, 12p70 and TNF-α production. Aloe arborescens gel inhibited IL-8 (54.69 ± 3.42 pg/mL) and IL-1β (8.78 ± 0.80 pg/mL) production at a concentration of 3.125 µg/mL, while Aloe X principis (2) leaf reduced the production of all the cytokines at the highest concentration (50 µg/mL). In conclusion, this study showed that Aloe X principis (2) leaf extract, which inhibited tyrosinase and cytokine production, should be considered for further investigation as a potential treatment for side effects associated with eczema.
