Effects of cactus pear polysacchairdes on human skin cells as a function of incubation time and monosaccharide composition

Cactus pear (Opuntia ficus-indica L., Cactaceae) is a famous food plant originating from Mexico characcterizted by high amounts of polysaccharides. While these polysaccharides are well investigated concerning their physico-chemical properties less is known about their biologic activity. To obtain a more complete insight into the dermopharmaceutical properties, a pectic polysaccharide (NPec) and a water soluble polysaccharide (NwPS) from cactus pear mainly differing in their glucose and glucuronic acid amounts were chosen for the present investigation. To achive this, human skin fibroblasts (NHDF) and keratinocytes (HaCaT) were incubated with different concentrations of the cactus pear polysaccharides for 48h and 72h, respectively. Afterwards their effect on cell proliferation and metabolic activity was determined by BrdU incorporation and MTT reduction assays. While the metabolic activity of NHDF was neither affected by NPec nor by NwPS, independent of incubation time or concentration, the metabolic activity of HaCats was increased after incubation with NwPS for 48h. The HaCaT proliferation was not significantly influenced by low levels of cactus pear polysaccharides; however, it was inhibited by 100µg/mL NPec. 100µg/mL of NwPS and1µg/mL NPec stimulated the proliferation of NHDF. In conclusion, cactus pear polysaccharides affected skin cell metabolism depending on their specific composition, concentration and incubation time.