Two penetrating carrier systems analysed

Carrier systems with the ability to transport actives into the skin have long played an important role in cosmetics. The most well-known are the liposomes and nanosomes – vesicles that consist of purified phospholipids from the soy plant.1 While with liposomes the vesicle is internally aqueous, the core of nanosomes consists of oils and lipophilic actives. Thus liposomes are more suitable for the encapsulation of hydrophilic substances and nanosomes are best suited for use with lipophilic actives. The soy plants, and thus the soy lipids, nevertheless still carry the stigma of ‘genetic modification’ and cultivation that has a ‘negative impact’ on nature. Rainforests and savannah in South America must vanish, as the Neue Zürcher Zeitung newspaper recently wrote.2 Sophi-Hydro-Tops and Sophi-Lipo-Tops, the two new penetrating carrier systems, are particularly suitable for use in natural cosmetics.

Carrier system alternative to liposomes

Sophi-Hydro-Tops (now referred to as ‘the new sunflower lipids’) are a new carrier system which exhibits similar or better characteristics than the older, well-known liposome systems. With the tiny unilamellar vesicles, which have an unusually homogenous particle size distribution, both hydrophilic and amphiphilic actives can be encapsulated. In comparison with liposomes the new sunflower lipids have a greater encapsulation efficiency for certain substances. So, depending on the active, between 50 and 100 per cent more of, for example, green tea extract (Teavigo) can be encapsulated in the new sunflower lipids. The penetration and antioxidative efficacy of the green tea extract in the skin – epidermis and dermis – at a concentration of 2% was measured with the help of ESR.3 The skin has its own natural protection against free radicals. A radical scavenging active applied onto the skin that has the ability to penetrate through the skin barrier (the stratum corneum) will increase the antoxidative potential in the deeper viable skin layers. The percentage increase in skin protection against radicals is measured in the form of SAP values (skin antioxidative power). Figure 1 shows a significantly better penetration and the duration of efficacy of the antioxidants is prolonged by several times when the green tea is encapsulated in the new sunflower lipids. When the vesicles are incorporated into a cream with lamellar structures also an enhanced penetration and improved efficiency is observed (Fig. 2). While the liposomes cannot keep their membrane stabilities in the cream, the green tea extract is released from the vesicles. This can be observed by the decreased penetration and efficacy level.