Cosmetochem International AG has encapsulated bioflavonoids extracted from citrus fruits (citroflavonoids) in liposomes to create an active that brightens skin tone, increases skin luminosity and fades age spots. Citrolumine 8 (INCI: Glycerin (and) Water (aqua) Lecithin (and) Citrus Paradisi (Grapefruit) Fruit Extract (and) Citrus Aurantium Amara (Bitter Orange) Fruit Extract (and) Sodium Ascorbate (and) Tocopherol (and) Helianthus Annuus (Sunflower) Seed Oil) reportedly exhibits antioxidant and anti-inflammatory benefits due to its flavonoid content; high-performance liquid chromatography found the active to contain four citroflavonoids: naringin (66%), neohesperidin (16%), narirutin (15%) and hesperidin (3%).
To assess skin lightening benefits, an in vitro cellular inhibition assay was used to evaluate the active's ability to inhibit tyrosinase. It found the active to demonstrate a concentration-dependent effect. Kojic acid was used as the positive control to validate the method and in comparison, 1% of the active reduced tyrosinase activity 20% less than kojic acid but 40% greater than the untreated control.
The company also used a chromameter and high resolution imaging to study the effect of the active on skin tone and age spots. A formulation containing 1% of the active was applied on nine Caucasian and six Asian female volunteers in a double-blind, placebo-controlled pilot study for two months. It was reported that 1% of the active on Caucasian skin lightened the age spots by 9.2% and brightened the skin tone by 5% after 56 days of use. Preliminary tests on Asian skin also showed that 1% of the active caused a marked lightening after 56 days.
When incorporating the active into a formulation: it should be added below 40°C using low shear mixing after emulsifying, as the last step in the manufacturing process; the ethyl alcohol concentration should be kept below 5% and solvents below 10%; surfactants should be avoided; low levels of nonionic, high HLB surfactants (up to 1%) are well-tolerated; high levels of salts (> 0.5%) should be avoided; and the active should be stored at 2–8°C.
The active is recommended at 1% in antiaging products to brighten the skin tone and increase skin luminosity and radiance. The average liposome size in the active is 100–150 nm.