posted on 2024-02-23, 13:05authored byPaul Besrukow, Alexander Orbach, Ralf Schweiggert
Pharmaceutical, cosmetic,
and agricultural applications of bioactive
stilbenoids are limited due to their poor photostability. We aimed
to modulate the photostability of (E)-resveratrol
in grape cane extract formulations by supplementation with selected
additives and monitoring (E)- and (Z)-resveratrol concentrations by HPLC-DAD during 4 h of exposure to
artificial sunlight. (E)-Resveratrol in liquid formulations
degraded to ca. 13% (0.005 mmol/L) of its initial content (0.040 mmol/L)
during the aforementioned illumination (reaction constant k = 0.54 1/h). Deceleration of (E)-resveratrol
light-decay was most pronounced when supplemented with dispersible
zinc oxide (k = 0.11) or a phenolic apple extract
(k = 0.16). In the dried thin-film state, phenolic
apple extract (k = 0.08) and zinc oxide (k = 0.12) significantly enhanced the photostability of (E)-resveratrol (control: k = 0.19). Overall,
(Z)-resveratrol development was less pronounced than
(E)-resveratrol decay, indicating reactions beyond E/Z-isomerization. Briefly, the addition
of apple polyphenols or zinc oxide at appropriate dosages was shown
to significantly enhance the photostability of (E)-resveratrol in grape cane extract formulations.