Extraction of lignans from Phyllanthus amarus Schum. & Thonn using pressurized liquids and low pressure methods

•Pressurized liquid and low pressure extractions from Phyllanthus amarus provided extracts rich in lignans.•The binary mixture ethanol + water (50% v/v) is the best solvent to obtain niranthin and phyllanthin.•Seven lignans were identified in the extracts using GC–MS.•The HPLC-DAD method was used to quantify phyllanthin and niranthin.•The influence of temperature on the lignan yield of PLE is negligible in the studied range.

Extracts rich in lignans were obtained from Phyllanthus amarus by Pressurized Liquid Extraction (PLE). The influences of temperature and solvent type on the extraction yield and chemical composition of the extracts were evaluated. Temperature was evaluated from 35 °C to 80 °C and the used solvents were: water, ethanol and a mixture of ethanol + water (50% v/v). All extractions were performed at the pressure of 10 MPa. A low pressure extraction method (LPE) using the Ultra-Turrax disperser and the same solvents, at room temperature and atmospheric pressure, was performed to compare the results with those of PLE. The extracts were analyzed by Gas Chromatography coupled to Mass Spectrometry (GC–MS) and seven lignans were identified: 5-demethoxy-niranthin, phyllanthin, filtetralin, 5-demethoxy-nirtetralin, nirtetralin, hipophyllanthin and niranthin. High Performance Liquid Chromatography (HPLC) was used to quantify the most bioactive lignans, phyllanthin and niranthin, in the extracts. In the PLE method, the effect of temperature was negligible in the studied range for the recovery of these lignans. The binary mixture ethanol + water (50% v/v) was the best solvent for the recovery of high amounts of both lignans, independently of the extraction method. However, PLE with 100% ethanol provided the most concentrated extracts in both lignans. PLE achieved higher global extraction yield than in LPE, but lower lignan recoveries. The contents of the major lignans extracted by each method varied significantly, suggesting that phyllanthin and niranthin are located in different parts of the plant tissue. The selection of the best method to extract lignans form P. amarus depends on the operation costs.

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