Pyrogallol: An Alternative Trapping Agent in Proanthocyanidins Analysis

The use of pyrogallol as trapping reagent in proanthocyanidin (PA) analysis was investigated. PAs are antioxidants and disease-preventing agents, the efficiency of which depends on their composition and size. Different nucleophilic compounds are usually used for acid-catalyzed depolymerization of proanthocyanidins: benzyl mercaptan, phloroglucinol, and cysteamine. Each nucleophile has different characteristics and typical reaction temperatures that ranges from 50 to 90 °C. Pyrogallol is more reactive than these compounds, so it was possible to apply a minor reaction temperature that was finally reduced from 50 to 30 °C, compared to phloroglucinol, but maintaining a significant yield. The results, compared to those obtained using phloroglucinol as trapping nucleophile, indicated that pyrogallol is an effective and interesting reagent for this analysis.