Establishment of the extraction method for the determination of oligomeric proanthocyanidins in guava leaves

Proanthocyanidin compounds raised a high interest to the scientific community because of their biological activity and healthy effects versus several diseases. For this reason, in the last years the study of new sources has been increased.
\nGuava leaves has been used for tea preparation and they may cause beneficial changes in cholesterol and triglyceride levels, and prevention type 2 diabetes mellitus. These beneficial activities have been attributed to the phenolic composition, among them the flavan-3-ols.
\nBecause of that the experimental Box Behnken design based on response surface methodology has been carried out to fix the best extraction conditions. The optimal conditions have been used to determine the proanthocyanidins content in three oxidative states of the leaves. A high degree of polymerization (DP) has been found (from monomers to tridecamers plus polymers). The total amounts of proanthocyanidins decreased when oxidation state of leaves increased. Briefly, guava leaves result as an interesting source of proanthocyanidins with low degree of polymerization in the range comparable with cocoa and apple.