Optimisation of microwave-assisted extraction from Phyllanthus amarus for phenolic compounds-enriched extracts and antioxidant capacity

Phyllanthus amarus is known as a healing herb which has traditionally been used in the treatment of various diseases such as hepatitis, diabetes and cancer. The extraction parameters have great effects on the extraction efficiency of bioactive compounds and pharmacological activity of the extracts. This study sought to optimise the microwave-assisted extraction parameters for phenolic compounds-enriched extracts and antioxidant capacity from P. amarus using response surface methodology (RSM). The results showed that the optimal microwave-assisted extraction parameters were an extraction time of 30 min, an irradiation time of 14 s min−1 and a ratio of solvent to sample of 150 mL g−1. The total phenolic content, phenolic extraction efficiency, saponin content, 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging capacity, 2,2-diphenyl-1-picryl-hydrazil (DPPH) radical scavenging capacity and ferric reducing antioxidant power of the P. amarus achieved under these optimal parameters were 87.3 mg of gallic acid equivalents (GAE) per gram of dried sample, 69.7 %, 134.9 mg of escin equivalents (EE) per gram of dried sample, 997.8, 604.7 and 437.3 all in mg of trolox equivalents (TE) per gram of dried sample, respectively, which were not significantly different from the predicted values (86.9 mg of GAE per gram of dried sample, 67.3 %, 123.5 mg of EE per gram of dried sample, 1013.3 mg of TE per gram of dried sample, 530.6 mg of TE per gram of dried sample and 423.5 mg of TE per gram of dried sample, respectively). Accordingly, the optimal microwave-assisted extraction parameters of 30 min, 14 s min−1 and 150 mL g−1 are recommended for the extraction of enriched phenolics from P. amarus for potential application in the nutraceutical and pharmaceutical industries.