COSMECEUTICAL PROPERTIES OF LEVAN 403 120 115 110 105 � ca 100 · Q) 95 85 80 0 20 40 60 80 100 120 Concentration (ug/ml) Figure 5. Cytotoxicity of levan against human fibroblast cell line. The data are expressed as mean values (± standard deviations) of four experiments. 150 140 130 e... 120 � ca 110 · Q) 100 90 80 70 10 100 1000 Concentration (ug/ml) Figure 6. Cell proliferation effect of levan against human keratinocytes. The data are expressed as mean values (± standard deviations) of four experiments. line-above 30% at high concentrations ( 1 mg/ml). This suggests levan's safety with regard to cosmetic applications. CELL PROLIFERATION TEST WITH 3-DIMENSIONAL ARTIFICIAL SKIN After inducing skin irritation in 3-D artificial skin using 0.05% of SLS, which is used widely as a skin irritant (27), we applied 0.01 mg/ml and 0.05 mg/ml of levan solution, and observed the results. When we compared cell viability in the presence and the absence of levan (SLS only) (Figure 7) we determined that the artificial skin that had been treated with levan exhibited substantially greater cell proliferation (more than a 30% enhancement).

404 JOURNAL OF COSMETIC SCIENCE 110 .....-----------------------, - 100 � ·s: :1 □ I I I □ J (a) (b) (c) (d) Concentration (w/v°/4) Figure 7. Cell proliferation effect of levan in 3-D artificial skin: (a) control (b) 0.05% SDS (c) 0.05% SDS + 0.01 mg/ml of levan (d) 0.05% SDS + 0.05 mg/ml of levan. The data are expressed as mean values (± standard deviations) of four experiments. ANTI-INFLAMMATION TEST WITH 3-DIMENSIONAL ARTIFICIAL SKIN Interleukin-la. (IL-lu) is known to function as a proinflammatory mediator during intercellular signal transport, and has also been shown to induce the proliferation of some cells, including osteoblasts, m·onocytes, macrophages, keratinocytes, hepatocytes, and fibroblasts, via stimuli such as inflammation or infection (30). IL-lu is also known to stimulate the increase of arachidonic acid lipoxygenase metabolites, including leukotri­ ene B4, 5-, 12-, and 15-HETE, and also functions as a potential inducer of reepitheli­ alization in wounded skin (31). Therefore, measurement of the quantity of IL-lu se­ creted in the culture medium is just one of a host of methods for the evaluation of the anti-inflammatory effects of levan. After inducing primary skin irritation with 0.05% SLS in 3-D artificial skin, 0.01 mg/ml and 0.05 mg/ml of levan solution were applied, and we subsequently measured the quantity of interleukin-la. secreted. Artificial skin treated with 0.01 mg/ml and 0.05 mg/ml of levan exhibited decrements in the quantity of IL-lu, as opposed to the artificial skin, which had not been treated with levan (Figure 8). Taking the above into account, our results suggest that levan exerts an emollient effect during skin irritation caused by irritants. However, the exact mechanism underlying this phenomenon is currently unclear. Despite the high molecular weight of levan, it still exhibits cell proliferation and anti-inflammatory effects. This may be attributable to its penetrative ability, which is in itself due to a much smaller particle size distribution (ranging from about 170 to 300 nm) than is associated with other polysaccharides. CONCLUSIONS In this study, we have determined some of the relevant cosmeceutical properties of levan, including its moisturizing effect, cell cyrotoxicity, cell proliferation effect, and anti­ inflammation effect. Levan manifested a moisturizing effect highly reminiscent of that