Nanoencapsulated vitamin C: guaranteed efficacy and stability

Vitamin C has a beneficial effect on the skin, acting as a reducing agent, capturing and combating free radicals, making it much used in cosmetics It has an internationally known capacity for lightening the skin, reducing spots and improving the skin’s overall appearance. Vitamin C also increases collagen production and prevents a series of pathologies such as skin cancer and dermatitis. However, its use in cosmetics formulations is limited as it has low stability, the result of its photo-sensitivity.

Nanoencapsulated vitamin C is more stable and its cutaneous penetration is increased, thanks to its reduced particle size (100 – 200 nm). The vehicle of the nanoencapsulated form is Ascorbyl Tetraisopalmitate (oily vitamin C) in high-performance nanoparticles.Ascorbyl Tetraisopalmitate is a lot more stable than ascorbic acid, thanks to the esters that stabilize the molecule, leaving it soluble in lipids, which also increases its permeability in skin, allowing for a more efficient vitamin C action in the skin structure matrix, the site of important biochemical reactions for the maintenance of the skin’s integrity. In addition, this form of vitamin C has a less acid pH, which, associated to the special coating conferred by the nanoparticle, gives better cutaneous tolerance and compatibility, and doesn’t irritate the skin. Vitamin C is a powerful antioxidant that inhibits lipidic peroxidation, and is thus important in neutralizing free radicals. Vitamin C is also important for its action in stimulating collagen production. It acts as a skin lightener as it inhibits melanogenesis.

Nanoencapsulated vitamina C gives long-term hydration, with a silky, agreeable feel and with no granular residue. Its nanometric size forms a monolayer on the skin surface and guards against the transepidermal water loss that is a mechanism closely bound up with cutaneous drying and aging. It looks like a liquid colloidal suspension, white and opaque, which can be used in the preparation of various cosmetics and thus can be a vehicle for several types of base for the face, eye area and body.

Tests have analyzed non-encapsulated vitamin C (Ascorbyl Tetraisopalmitate) and vitamin C (Ascorbyl Tetraisopalmitate) vehicle in lipidic nanoparticles in aristoflex gel with 2% Kogic acid, to verify the antioxidant action. It was seen that after a month of being stored on a shelf, the nanoencapsulated vitamin C had a greater antioxidant action than the non-nanoencapsulated vitamin C, as it inhibited the yellow color characteristic of oxidation, as we can see in the image below. Here number 1 is aristoflex gel with 2% Kogic acid; number 2 aristoflex gel with 2% Kogic acid and 0.4% non-nanoencapsulated vitamin C and number3 aristoflex gel with 2% Kogic acid and 10% nanoencapsulated vitamin C.

Capsulated vitamin C’s stability was evaluated across freezing/thawing cycles with the temperature changed from -4 °C to 40 °C 3 times. After this stress there was no change in dose of vitamin C nor alteration in the mean diameter of the particle.

Encapsulated vitamin C’s stability was also evaluated in solutions with pH varying from 3 to 8 and maintained for 3 months at room temperature. Following this, there was no significant change in dose nor particle diameter. These results lead us to conclude that nanoencapsulated vitamin C can be used in bases of varying pH, with surety in the maintenance of the dose of vitamin.

Also evaluated were encapsulated vitamin C’s potential for primary skin irritability, accumulated skin irritability, skin sensitivity and photoallergy. Volunteers received an application on the skin of the back and evaluated themselves, and were also assessed by dermatologists following a determined period of contact with the skin and after receiving UV radiation on the spot for a determined period. Encapsulated vitamin C did not induce detectable irritation during the study period and is thus considered safe for topical use. Further, no volunteer presented phototoxicity and photoallergy. Encapsulated vitamin C was also assessed as to ocular acceptability by an eye care professional after the test period. there was no eye irritation; thus the product was considered appropriate to use in the eye area.

In collaboration with Dr. Patrícia Andrei Saslavsky

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