D-Optimal Mixture Design in Sonication-Maceration Solvent Extraction of Total Phenolic and Antibacterial Activity from Acanthus ilicifolius Leaves

Abstract

Acanthus ilicifolius is a widely recognized traditional medical herb in Indonesia. The objective of this study is to determine the optimal combination of solvents (water, ethanol, and acetone) for the extraction yield, total phenolic content, and antibacterial activity from A. ilicifolius leaves. The sonication-maceration solvent extraction was employed to acquire Acanthus ilicifolius leaves extract yield, phenolic content and antibacterial activity. Total phenolic content (TPC) was calculated using the Folin–Ciocalteu colorimetric method. The agar disk diffusion method was used to test the extracts for antibacterial activity against Staphylococcus aureus. The extraction method was optimized, the experimental data was modeled, and the design of experiments were all carried out using a D-optimal mixture design. The maximum extraction yield (4.10%) was reached by water-acetone extract. The ethanol-acetone, water-ethanol, water-acetone, and water-ethanol-acetone (41.67-16.66-41.67%) extracts were the highest TPC with values of 10.09, 10.13, 10.42 and 10.42 mg GAE/g dry weight, respectively. Finally, the optimum zone inhibition against S. aureus (2.25 mm) was showed by water-ethanol-acetone (16.67-66.66-16.67%) extract. The ideal conditions based on D-optimal mixture design were highly accurate at 61% attractiveness with a mixed solvent of water (49.52%) and ethanol (50.48%), predicting extraction yield, TPC, and antibacterial activity of 2.67%, 7.86 mg GAE/g DW, and 1.49 mm, respectively. Results showed the water-ethanol mixture were the best solvent in the sonication-maceration extraction for antibacterial properties of phenolic compounds, and extraction yield from A. ilicifolius leaves.