Ultrasound-assisted and pressurized liquid extraction of phenolic compounds from Phyllanthus amarus and its composition evaluation by UPLC-QTOF

• Phyllanthus amarus extracts were obtained by ultrasound-assisted extraction and pressurized liquid extraction.
• Ultrasound-assisted extraction and pressurized liquid extraction yielded higher gallic acid content compared to conventional extraction.
• The extracts were analyzed by ultra-performance liquid chromatography/quadrupole time of flight mass spectrometry.
• Hydrolysable tannins, flavonoids, and lignans were the main compounds detected.

Phyllanthus amarus Schum & Thonn is an herb rich in bioactive compounds, mainly phenols, and it is widely used for its medicinal properties. In this study, aqueous extraction from aerial parts of P. amarus was performed using ultrasound-assisted extraction (UAE), pressurized liquid extraction (PLE), and conventional extraction (CE). Response surface methodology was used to assess the effect of the time, ultrasonic intensity, and liquid/solid (L/S) ratio in UAE and of time and temperature in PLE on total phenolics and gallic acid extraction. The chemical composition of the extracts obtained through the three techniques was also analyzed using UPLC-ESI-QTOF-MS/MS. The UAE operational condition that afforded the highest phenolic content (27.23 mg/g plant) used time of 7 min, ultrasonic intensity of 301 W/cm2, and L/S ratio of 40 mL/g. This value was lower than the one obtained by the conventional extraction method (42.78 mg/g plant). However, PLE at 192.4 °C and time of 15 min yielded the highest total phenolic content (52.97 mg/g plant). Regarding the extraction of gallic acid, the non-conventional methods yielded contents three times higher than the conventional extraction. The chemical composition of P. amarus extracts had mainly hydrolysable tannins, flavonoids, and lignans. The most significant difference was found in UAE, which proved to be inefficient to extract ellagitannins.

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