Development of a nanoemulsion ofPhyllanthus emblicaL. branch extract

For potential topical administration, we formulated a nanoemulsion containing phenolic constituents of Phyllanthus emblica branch extract. The nanoemulsion has high entrapment efficiency, small particle size, is stable, and can release its main chemical components. Branches of P. emblica were extracted with 50% ethanol (EPE) with 5.4% yield. HPLC analysis indicated several phenolic compounds, including gallic acid, vanillic acid, epigallocatechin (EGC), epigallocatechin gallate (EGCG) and ellagic acid. These were selected as chemical markers of EPE in the nanoemulsion development. The nanoemulsion was prepared by microemulsion techniques with hot high pressure homogenization. A ternary phase diagram was constructed to obtain the optimized nanoemulsion. The obtained transparent EPE nanoemulsion is composed of isopropyl myristate (0.6% w/w), Brij® 78 (0.35% w/w), and 0.15% (w/w) EPE. The optimized EPE nanoemulsion had a median particle size of 191.63 ± 4.07 nm with a narrow particle size distribution, a zeta potential of -10.19 ± 0.54 mV, high entrapment efficiency at 67.99 ± 0.87% and good stability at 4 °C after 90 d of storage. The release of active ingredients from the EPE nanoemulsion was slower than that of the EPE aqueous formulation. The loading ratios of the five phenolic compounds were high, with relative order of EGC > EGCG > vanillic acid > gallic acid > ellagic acid, resulting in slow release profiles of EGC and EGCG in the EPE nanoemulsion. In conclusion, the obtained EPE nanoemulsion has good characteristics for future clinical trials.