Premium
8‐Hydroxydaidzein is unstable in alkaline solutions
Author(s) -
Chang T. S.
Publication year - 2010
Publication title -
international journal of cosmetic science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 62
eISSN - 1468-2494
pISSN - 0142-5463
DOI - 10.1111/j.1468-2494.2010.00549_5.x
Subject(s) - chemistry , phosphate buffered saline , dpph , phosphate , nuclear chemistry , substrate (aquarium) , reaction rate constant , chromatography , kinetics , medicinal chemistry , organic chemistry , antioxidant , oceanography , physics , quantum mechanics , geology
J. Cosmet. Sci., 60, 353–357 (May/June 2009) Accepted for publication December 29, 2008. Synopsis 8‐Hydroxydaidzein is a suicide substrate of mushroom tyrosinase with potent irreversible inhibitory activity. Despite its high potential in the cosmetics industry, it was found that 8‐hydroxydaidzein was unstable in a formulated cream. In this technical note, the stability of 8‐hydroxydaidzein in various solutions is investigated. The compound was dissolved in a series of solvents, and the residual 8‐hydroxydaidzeins in the prepared solutions were sequentially determined during storage by HPLC. As a result, the loss in time of 8‐hydroxydaidzein in both pH 6.8 phosphate buffer and DMSO showed typical first‐order kinetics, and the loss rate constant of the compound in pH 6.8 phosphate buffer (4.48 × 10 ‐3 h ‐1 ) was 18‐fold higher than that in DMSO (2.5 × 10 ‐4 h ‐1 ). The stabilities of the compound in different buffers with pH values ranging from pH 5 to pH 9 were determined in advance. The results showed that the compound was completely degraded in one day in the pH 8 and pH 9 buffers. In contrast, 8‐hydroxydaidzein remained stable above 85% after 20 days’ storage in the pH 5 and pH 6 buffers. In addition to the residual 8‐hydroxydaidzein analysis, the residual bioactivities, including tyrosinase inhibitory activity and DPPH‐radical scavenging activity of the 8‐hydroxydaidzein solutions after 20 days’ storage in different pH values, were also determined, and the results correlated well with those of the stability experiments. All the results demonstrated that 8‐hydroxydaidzein is unstable in alkaline solutions. According to the data in the present report, it is recommended that 8‐hydroxydaidzein be formulated in an acid solution for its applications.