Extract from barley plants. Can have antioxidant properties when ingested, but there is no research showing this to be the case when applied topically.  Barley and its extracts/derivatives are a source of gluten. When fermented (as it is when used to make beer or when combined with yeast in cosmetics), barley extract has been shown in animal studies to reduce topical inflammation that can lead to atopic dermatitis. 
- Duh P, Yen G, Yen W, Chang L. Antioxidant Effects of Water Extracts from Barley (Hordeum vulgare L.) Prepared under Different Roasting Temperatures. J. Agric. Food Chem. 2001;49(3):1455-1463.
- Iguchi T, Kawata A, Watanabe T, Mazumder T, Tanabe S. Fermented barley extract suppresses the development of atopic dermatitis-like skin lesions in NC/Nga mice, probably by inhibiting inflammatory cytokines. Biosci Biotechnol Biochem. 2009;73(3):489-93.