Use of high pressure techniques to produce Mangifera indica L. leaf extracts enriched in potent antioxidant phenolic compounds

Pressurized liquid extraction (PLE) and enhanced solvent extraction (ESE) were used for the first time to extract antioxidant compounds from mango leaves. The effects of pressure (4–20MPa), temperature (40–100°C) and concentration of ethanol (0–100%) on PLE of phenolic compounds from mango leaves were optimized according to a multilevel factorial design. The global yield, phenolic yield, total phenolic content (TPC), and antioxidant activity (AA) were used as response variables. Pressure and temperature had a positive effect (p<0.05) on the global and phenolic yields, while ethanol concentration had a positive influence on the TPC (p<0.01). Ethanol improved the selectivity of PLE process so extracts present the highest TPC (414.9–854.7mg/g dry extract). AA of PLE and ESE extracts (3.55–5.64μgDPPH/μg) was superior to that of (+)-α-tocopherol (3.87μgDPPH/μg). Mangiferin and iriflophenone 3-C-β-d-glucoside were the predominant polyphenols identified by HPLC-ESI-MS. Furthermore, ESE and PLE proved to be more efficient than Soxhlet extraction in terms of the yield and antioxidant activity of extracts; however, ESE had the advantages of minimizing solvent consumption thus reducing undesired concentration steps.Mango leaves present potent antioxidant phenolic compounds such as mangiferin, flavonols, benzophenones, and gallotannis highly valued in food, cosmetic, and pharmaceutical applications. At industrial scale, the production of extracts from mango by-products is realized using conventional solvent extraction techniques. But, there is an increasing demand for greener and more efficient techniques. In this work, two environmentally friendly methods (PLE and ESE) to obtained mango leaf extracts enriched in potent phenolic compounds were optimized. The addition of high concentrations of CO2 to hydroalcoholic mixtures yielded extracts with TPC similar to those obtained by PLE and AA superior to (+)-α-tocopherol. Moreover, ESE processes reduced the consumption of liquid solvents, diminished undesired evaporation steps, and inhibited native enzymes which degrade phenolic compounds.