Water-in-oil emulsions including water-in-ester oil and water-in-silicone oil (W/O+S) have various advantages such as blocking moisture evaporation and forming air permeable membrane. However, their applications have been limited due to the poor stability under low viscosity condition. In this study, we investigated the effect of synergistic interaction between nonionic surfactant, micro-size particles and cationic surfactant on the stability of W/O+S formulation. The stability of W/O+S emulsions was changed as a function of cationic surfactant concentration where it increased at lower concentration and then started to decrease above a critical point. Finally, emulsion phase inversion occurred at a high concentration. The results suggest that W/O+S emulsions of low viscosity ranging from 2000 to 5000 cps can be stabilized under the conditions where a nonionic surfactant, micro-size particles and a cationic surfactant are used in the range of 1.0 ∼ 4.0 wt%, 2.5 wt% and 0.1 ∼ 0.5 wt%, respectively.

Skin aging is the phenomena finally expressed on the skin surface and related to the changes in the microstructure of the skin texture. Which is resulted in wrinkle formation and uneven tone of skin and so on. In this study, the synergy effect of Cedrol and a collagen-derived peptide in type Ⅲ collagen synthesis was evaluated by in vitro test. The physiological skin state of 22 female volunteers was measured after using the cosmetics for 4 weeks. Results showed that Cedrol and a collagen-derived peptide had the excellent synergy effect in type Ⅲ collagen synthesis. The cosmetics improved skin microrelief, star configurations, skin gloss, skin tone, hydration and elasticity except skin lightening. In conclusion, this study proved that Cedrol and collagen-derived peptide had the synergy effect of type Ⅲ collagen synthesis in the cell level and cosmetics with those was improved skin aging in human volunteer test.