Time-dependent bioactivity of preparations from cactus pear (Opuntia ficus indica) and ice plant (Mesembryanthemum crystallinum) on human skin fibroblasts and keratinocytes

Abstract Ethnopharmacological relevance Traditionally and nowadays preparations from two xerophytic plants, the ice plant and cactus pear are used in dermatologic and cosmetic preparations. In spite of their daily use, little is known concerning the bioactivity of such extracts on skin cells. The purpose of this study was to investigate the effect of pressed juices from ice plant (McP) and two cactus pear polysaccharides (cold water soluble, NwPS; non swelling pectin, NPec) on the cell physiology of normal human dermal fibroblasts (NHDF) and HaCaT-keratinocytes due to composition, concentration and incubation time. Materials and methods Cactus pear polysaccharides were analyzed by high performance anion exchange chromatography with pulsed amperometric detection after hydrolysis with trifluoroacetic acid. Ice plant pressed juices were filtrated through a 1.2 μm (McPI) and 0.2 μm filter (McPII). Cell proliferation was measured with BrdU incorporation assay. Reduction of tetrazolium salts was applied to determine the metabolic activity (MTT) while necrotic effects were assessed by LDH-release measurements. Results Cactus pear polysaccharides differed predominantly in their glucose and uronic acid content. The filtration of pressed juices altered the amounts of high molecular weight compounds. The proliferation of NHDF and HaCaTs was significantly stimulated by cactus pear polysaccharides and ice plant pressed juices not until 72 h of incubation. McPI significantly increased the proliferation of NHDF and HaCaTs while significant effect of McPII was only observed in case of HaCaT-keratinocytes. A dependence on concentration was not observed. Metabolic activity was neither influenced by McPI nor by McPII independent of incubation time. The HaCaT proliferation was not significantly influenced by low concentrations of cactus pear polysaccharides however it was inhibited by 100 μg/mL NPec. 100 μg/mL of NwPS and 1 μg/mL NPec stimulated the proliferation of fibroblasts. The metabolic activity of NHDF was not affected neither by NPec nor by NwPS. Independent of the used concentration NwPS significantly enhanced the metabolic activity of HaCaTs after 48 h of incubation. Conclusions Pressed juices of common ice plant and polysaccharides of cactus pear influenced the cell physiology of human keratinocytes and fibroblasts predominantly in a time-dependent manner. The effect was also be related to the concentration and composition as well as the investigated cell type.