Synthesis of conjugated bile acids/azastilbenes as potential antioxidant and photoprotective agents

• Conjugated bile acids/azastilbenes: bile amides + aromatic aldehydes.
• Conjugates showed promising antioxidant activity (IC50: 19.60–31.83 μg mL−1).
• Photoprotective activity: SPF, UVAPF and Critical Wavelength.
• The majority of the conjugates showed photoprotective activity similar to or greater than free azastilbene.

A series of 14 bile acids/azastilbenes conjugates (1a–g and 2a–g) was prepared through the condensation of bile amides (1 and 2) and aromatic aldehydes. The newly synthesized conjugates were evaluated in vitro for their antioxidant and photoprotective activities. Six compounds (1, 1a, 1b, 2, 2a and 2b) showed promising antioxidant activity with IC50 values of 19.60–31.83 μg mL−1. The synthesized compounds presented a varied photoprotection profile, with the SPF ranging from 2 to 9. Among the 16 compounds tested for the protection against UVB sunrays, 3 compounds (2c, 2e and 2g) presented more significant protection than resveratrol and the free azastilbene 3; while the UVAPF increased from 2 in resveratrol and 5 in 3 to 5–11 in the majority of the conjugates.

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