Evaluation of fractions extracted from Polycladia myrica: biological activities, UVR protective effect, and stability of cream formulation based on it

Phlorotannins are polyphenolic compounds in brown algae and can be used as a natural UV filter in sunscreen formulations. The aim of the present study was to characterize the biological activities of phlorotannins-rich fractions from the brown alga Polycladia myrica and to validate the protective effect as well as stability of cream formulation with phlorotannins against UVR. With respect to antioxidant properties, the ethyl acetate fraction (EF) possessed the highest DPPH radical scavenging (65 +/- 0.2%), and the highest antioxidant activity (11.2 +/- 0.2 mu g ASA mg(-1)). The EF was active against Gram-positive bacteria with EF effectively reducing UVB-induced cytotoxicity in HaCaT keratinocytes. The cream formulation with 5% EF revealed a high sun protective factor (31.79 +/- 4.73), UVA/PF (24.67 +/- 4.03), critical wavelength (383.2 +/- 0.1 nm), and UVA/UVB ratio (0.98 +/- 0.01). The cream formulation was completely homogeneous and had a pH close to human skin pH. The cream was stable in the cooling-heating cycle and the DPPH scavenging activity of the cream was not altered for 30 days of storage at temperatures of 4-40 degrees C. These findings are promising for the use of brown alga P. myrica extract as a valuable source of sunscreen protective substance for pharmaceutical and cosmetic applications.

Automated summary

This study characterized the biological activities of phlorotannins-rich fractions from brown algae and tested the protective effect and stability of a cream formulation containing phlorotannins against UV radiation. The results showed that the brown algae extract has potential application as a sunscreen protective substance.