What is Algae Extract?

In cosmetics, algae act as thickening agents (see alginates), water-binding agents, and antioxidants. Some algae are also potential skin irritants. For example, the phycocyanin present in blue-green algae has been suspected of allergenicity and of causing dermatitis on the basis of patch tests. Other forms of algae, such as Irish moss and carrageenan, contain proteins, vitamin A, sugar, starch, vitamin B1, iron, sodium, phosphorus, magnesium, copper, and calcium. Most of these are beneficial for skin, either as emollients or antioxidants.

In 2008 there was a study done on cosmetic formulations with marine compounds.

“The serum enriched in marine compounds showed a better moisturizing effect in short term. The cream appeared more active later, particularly following repeat applications. A sustained tensor (firming) effect was observed during treatment with both the lotion and the cream. However, no remnant firming effect was perceived after stopping treatment.”

Astaxanthin extract

Carotenoid (a carotene pigment) found in plants, algae, and fish, particularly salmon, that functions as a potent antioxidant. Research also suggests that astaxanthin may be able to prevent the oxidative damage to skin after exposure to UVA radiation. Real astaxanthin in skincare products are known to stain the skin temporarily.

Haematococcus pluvialis is a freshwater species of Chlorophyta from the family Haematococcaceae. This species is well known for its high content of the strong antioxidant astaxanthin, which is important in aquaculture, and cosmetics.

Sources
Current Issues in Molecular Biology, January 2002, pages 1–11
 Journal of Agricultural Food Chemistry, February 2002, pages 840–845
International Journal of Cosmetic Science; Kinetics of moisturizing and firming effects of cosmetic formulations 2008 Apr;30(2):131-8. doi: 10.1111/j.1468-2494.2008.00436.x.
Kleinová M, Hewitt M, Brezová V, Madden J, Cronin M, Valko M. Antioxidant properties of carotenoids: QSAR prediction of their redox potentials. Gen Physiol Biophys..2007;26(2):97-103.
Niwano T, Terazawa S, Nakajima H, Wakabayashi Y, Imokawa G. Astaxanthin and withaferin A block paracrine cytokine interactions between UVB-exposed human keratinocytes and human melanocytes via the attenuation of endothelin-1 secretion and its downstream intracellular signaling. Cytokine.. 2015;72(2):184-97.