Abstract:

A novel polyphenolic compound, named oxovitisin, with unique lactone pyranone ring and non-oxonium
structures was prepared. In this study, oxovitisin A was synthesized by two-step reactions in micro-oxygenation system
by using carboxypyranoanthocyanins (vitisin A) as a precursor, which was formed from pyruvic acid and anthocyanins.
The preparation conditions of oxovitisin A, namely temperature, pH, ethanol and reaction time, were optimized using
combination of single factor and orthogonal array experiments. High performance liquid chromatography-with diodearray
detection (HPLC-DAD) was used to monitor the reaction process and the main adduct was qualitatively and
quantitatively analyzed by HPLC-DAD combined with electron ionization tandem mass spectrometry (HPLC-DAD-EIMS/
MS). The sulforhodamine B (SRB) assay was employed to evaluate the anti-tumor effects of oxovitisin A, vitisin A,
methyl-pyranoanthocyanin and malvidin-3-O-glucoside against Caco-2 and MCF-7 cells in vitro. The results showed that
the optimal preparation conditions were found to be reaction at 45 ℃ for 21 d with 20% ethanol acidified to pH 3.6 using
1.0 mg/mL of vitisin A. The effects of four important variables on oxovitisin A yield followed the decreasing order: pH >
reaction temperature > reaction duration > ethanol concentration. The main reaction product was confirmed by HPLCMS/
MS to be oxovitisin A with a yield of 26.59% after 21 d. The SRB assay showed that oxovitisin A displayed obvious
inhibitory effect on the proliferation of Caco-2 and MCF-7 cells with an IC50 value of (238.8 ± 24.6) and (85.7 ± 9) μg/mL,
respectively, obviously stronger than that of vitisin A and methyl-pyranoanthocyanin.

Key words: anthocyanin derivatives, oxovitisin A, orthogonal array experiment, HPLC-MS/MS, anti-tumor effect