Polyphenol–Aluminum Complex Formation: Implications for Aluminum Tolerance in Plants

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• 作者：Liangliang Zhang ; Ruiqiang Liu ; Benjamin W. Gung ; Steven Tindall ; Javier M. Gonzalez ; Jonathan J. Halvorson ; Ann E. Hagerman
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2016
• 出版时间：April 20, 2016
• 年：2016
• 卷：64
• 期：15
• 页码：3025-3033
• 全文大小：440K
• 年卷期：0
• ISSN：1520-5118

文摘

Natural polyphenols may play an important role in aluminum detoxification in some plants. We examined the interaction between Al³⁺ and the purified high molecular weight polyphenols pentagalloyl glucose (940 Da) and oenothein B (1568 Da), and the related compound methyl gallate (184 Da) at pH 4 and 6. We used spectrophotometric titration and chemometric modeling to determine stability constants and stoichiometries for the aluminum–phenol (AlL) complexes. The structures and spectral features of aluminum–methyl gallate complexes were evaluated with quantum chemical calculations. The high molecular weight polyphenols formed Al₃L₂ complexes with conditional stability constants (β) ∼ 1 × 10²³ at pH 6 and AlL complexes with β ∼ 1 × 10⁵ at pH 4. Methyl gallate formed AlL complexes with β = 1 × 10⁶ at pH 6 but did not complex aluminum at pH 4. At intermediate metal-to-polyphenol ratios, high molecular weight polyphenols formed insoluble Al complexes but methyl gallate complexes were soluble. The high molecular weight polyphenols have high affinities and solubility features that are favorable for a role in aluminum detoxification in the environment.