UV Light Stability of α-Cyclodextrin/Resveratrol Host–Guest Complexes and Isomer Stability at Varying pH

Kerrilee E. Allan; Claire E. Lenehan; Amanda V. Ellis

doi:10.1071/CH08506

RESEARCH ARTICLE

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UV Light Stability of α-Cyclodextrin/Resveratrol Host–Guest Complexes and Isomer Stability at Varying pH

Kerrilee E. Allan ^A , Claire E. Lenehan ^A and Amanda V. Ellis ^A ^B

+ Author Affiliations

- Author Affiliations

^A School of Chemistry, Physics and Earth Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia.

^B Corresponding author. Email: Amanda.Ellis@flinders.edu.au

Australian Journal of Chemistry 62(8) 921-926 https://doi.org/10.1071/CH08506
Submitted: 18 November 2008 Accepted: 15 January 2009 Published: 13 August 2009

Abstract

trans-Resveratrol is an antioxidant that readily isomerizes to the cis isomer under UV irradiation. Here we report on the UV-Visible analysis of the stability of both trans- and cis-resveratrol isomers in the presence of UV light over a pH range of 2.0–9.0 in a phosphate-borate buffer that contains sodium dodecyl sulphate and acetonitrile. The molar absorptivity of the trans-resveratrol solution absorbing at 320 nm (3.88 eV) and 305 nm (4.07 eV) was 33000 and 34000 M^–1 cm^–1, respectively. Results indicate that trans-resveratrol has a slower isomerization within a pH range of 5.0–8.0. A pH > 8.0 results in almost immediate isomerization of the sample, whereas at pH 2.0 a photo-degradation product appears at 260 nm (4.77 eV). This was not apparent at pH 8.0. By including trans-resveratrol into a trans-resveratrol/α-cyclodextrin host–guest inclusion complex in pH 8.0 buffer isomerization was greatly reduced, with enhanced trans-resveratrol photostability.

References

UV Light Stability of α-Cyclodextrin/Resveratrol Host–Guest Complexes and Isomer Stability at Varying pH

Abstract

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