Phenolic Compounds from Psidium guajava (Linn.) Leaves: Effect of the Extraction-Assisted Method Upon Total Phenolics Content and Antioxidant Activity

Abstract

The aim of this study was to investigate the influence of the extraction method on the dry extract yield of guava leaves, correlating the total phenolic content (TPC) with the antioxidant activity. The dry extracts were obtained from hydroethanolic (50 and 70%) extract using the ultrasound-assisted method. Folin-Ciocalteau reagent was used to determine the content of TPC. DPPH (2,2-diphenyl-1-picrylhydrazyl) in vitro assay was used to determine the ability to scavenge free radicals. The results analyses demonstrated that the ultrasound-assisted method produced a higher yield in both dry extracts (11%), in contrast to the conventional method. The 50% hydroethanolic solvent was more efficient in the extraction of bioactive compounds. Both extracts showed a positive correlation of phenolic content with antioxidant activity. The FTIR spectrograms showed changes in the chemical groups, as well as determining the aromaticity index of the extracts, indicating a higher aromatic prevalence to the solvent 50%, although it presented simpler phenolic structures. In conclusion, the results provide an important basis for the use of phenolic compounds extracted from guava leaves, not only due to the antioxidant activity exerted, however, for potential use as a crosslinking agent of sulfated and non-sulfated glycosaminoglycan (GAG).