Optimization of Ultrasound-assisted extraction of polyphenols, tannins and epigallocatechin gallate from barks of Stryphnodendron adstringens (Mart.) Coville bark extracts

Background: Stryphnodendron adstringens (Mar.) Coville is a native plant from Brazil, rich in phenolic compounds and used on popular medicine as a wound healing agent, in the treatment of gastric lesions and as antimicrobial. Materials and Methods: Ultrassound-assisted extraction (UAE) was applied to extraction of epigallocatechin gallate (EGCG), total polyphenols (TP) and total tannins (TT) content from barks of Stryphnodendron adstringens (Mar.) Coville. Several operating parameters, namely extraction time (min), liquid to solid ratio (mg/mL), ethanolic strength (%, v/v), were optimized using response surface methodology (RSM) with a Box-Behnken design. Results: By using the desirability function approach, the optimum UAE conditions to obtain desirable extraction yields for all these metabolites simultaneously were found at the extraction time of 30 min, solid to liquid ratio of 4 mg/mL and ethanolic strength of 65. Under these conditions, the epigallocatechin gallate, total polyphenols and total tannins content were 0.31; 22.95 and 11.95 % (w/w), respectively. Conclusion: The results indicated that knowledge gained from this study should be helpful to further exploit and apply this resource and also showed the feasibility of ultrasound-assisted extraction for obtaining GEGC, TP and TT from barks of S. adstrigens.