Resumo

MALPICA-ACOSTA, Sheila Briget; ACOSTA-OSORIO, Andrés Antonio; BENEDITO-FORT, José Javier  e  CASTILLO-ZAMUDIO, Rosa Isela. Effect of three extraction methods on yield, antioxidant activity, total phenols, and stability of extracts from Plectranthus amboinicus leaves. CienciaUAT [online]. 2024, vol.18, n.2, pp.91-106.  Epub 16-Ago-2024. ISSN 2007-7858.  https://doi.org/10.29059/cienciauat.v18i2.1797.

Conventional phytochemicals extraction methods have shown low yields or very long processing times for obtaining. The ultrasound offers alternatives to increase the yields of plant extracts. The objective of this work was to evaluate the effect of three extraction methods on the yield, phenolic compound composition, antioxidant activity and stability of Plectranthus amboinicus (oregano) leaf extracts. The extraction methods used were: conventional heat-assisted extraction (CE), ultrasound water bath assisted (UBAE) and ultrasound probe assisted extraction (UPAE). A 1:10 (w/v) oregano:ethanol ratio was used at 35 ± 2 °C. Yields were calculated as extract dry matter (% ms). A pseudo-second-order model was used to fit the experimental extraction curves of the three methods and obtain the kinetic parameters. Total phenolic compounds (TPC) and antioxidant activity (AA) were determined by Folin-Ciocal-teau and DPPH methods, respectively. The stability of TPC and AA was evaluated during storage. UPAE increased 33.93 % yield in extracts concerning CE. The highest concentration of CFT (P ≤ 0.05) was obtained by UBAE (10.32 mg EAG/ms) and for AA by CE (19.43 mg ET/g ms). The pseudo-second-order kinetic model adequately fitted the experimental kinetics. The highest TPC rate constant (k) was 0.016 g ms/mg EAG·min, for UPAE, this technique being the one that demonstrated a significant decrease in AA with respect to extraction time. The TPC of the extracts obtained by UBAE, UPAE and CE (3.7 mg EAG/g dms, 4.4 mg EAG/g dms and 7.2 mg EAG/g ms, respectively), as well as the AA remained stable and without significant changes (P ≥ 0.05) during the 34 d of storage, again showing the advantage of using the ultrasound extractive technique, as a function of time.

Palavras-chave : oreganon; extraction; antioxidantactivity; phenolic compounds; yield.

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