Green Algae in Cosmetics: What are the Properties for the Skin?

In a study conducted by Barbara OBERMAYER and Patrick STOLZ, a test was utilised to assess the influence of micro-algae extracts, including thegreen algae C. vulgaris at 15 μg/L, on the collagen I content of human fibroblasts. The extract of C. vulgaris had a positive impact on the synthesis of collagen I, dependent on the concentration of micro-algae.

At a concentration of 0.4%, we observe an increase in collagen synthesis of approximately 30% compared to the control. At a concentration of 1.6%, collagen synthesis increases by 50% compared to the control. The extract of C. vulgaris therefore appears to have a connective tissue strengthening activity and thus slows down skin ageing.

Furthermore, a study conducted by Indah RAYA aimed to analyse the antioxidant activity of Chlorella vulgaris for its use as an antioxidant cream. The cream containing C. vulgaris demonstrated an antioxidant activity of 61.90%, whereas the cream without the algae had an antioxidant activity of 3.46%. C. vulgaris therefore appears to have a significant antioxidant activity , thus enabling it to counteract the effects of oxidative stress on the skin, namely skin ageing.

The extract of green algae would reduce the expression of the matrix metalloproteinase-1 (MMP-1) in human cell lines. MMP-1 is an enzyme that breaks down collagen and associated growth factors. Inhibiting the expression of this enzyme could therefore be one of the mechanisms by which green algae improves skin elasticity.

C. vulgaris is also capable of inhibiting lipid peroxidation and interacts with both enzymatic and non-enzymatic antioxidant systems, mitigating and resisting oxidative stress. The high levels of antioxidants found in C.vulgaris, such as carotenoids, astaxanthin, canthaxanthin, flavoxanthin, loraxanthin, and neoxanthin, may prove to be effective agents in preventing damage, particularly skin damage, caused by oxidation. During oxidative stress (pollution, tobacco, UV, etc.), free radicals are produced, which accelerate the skin ageing process. Antioxidants then capture these free radicals by trapping singlet oxygen and limit the damage.

Pierre-Yves MORVAN wanted to verify the effects of Chlorella vulgaris on the skin's microcirculation. His initial aim was to study the effects on angiogenesis, which is the production of blood vessels, using a model in vitro of human cells. C. vulgaris at 0.1% reduced the length of the vessels by -46% compared to the control.

The researcher then focused on vascular imperfections. Seventeen women applied a cream containing Chlorella vulgaris at 1% twice a day for 84 days. The volunteers had visible lesions: small varicose veins, small spider angiomas, and telangiectasias. C. vulgaris at 1% visibly reduced the redness of the vascular lesions: up to -64% after 28 days of use and up to -77% after 84 days. The treatment has improved the size and colour of the vascular lesions.

C. vulgaris could therefore be of interest for skin conditions related to redness and telangiectasias, such as rosacea for example. One of the mechanisms involved could potentially be the inhibition of angiogenesis, a process associated with the redness of rosacea. The author suggests that this effect could be the result of a reduction in the action of the vascular endothelial growth factor (VEGF), responsible for angiogenesis, by the overexpression of the metalloproteinase-3 inhibitor (TIMP3), being an antagonist of the VEGF receptor.

Furthermore, we had previously observed that C. vulgaris increases collagen synthesis. Collagen is a protein that is believed to have the ability to strengthen the walls of veins, and a deficiency has been linked to the development of varicosities. Weakened and less elastic venous walls would lead to the accumulation of blood in the vein, which widens it and makes it more visible. It can be hypothesised that the produced collagen would form a sort of "sheath" around the blood vessels to reduce their appearance, and therefore also reduce redness.

However, these results should be approached with caution. These effects have only been demonstrated once, in this context only. Further experiments are necessary to validate these points.