Hydrodistillation: Essential oils were extracted by hydrodistillation, and all operations were carried
out at room temperature. The fresh rhizomes of Zingiberaceae were washed to remove soil, peeled and
sliced. Sliced rhizomes of fresh Zingiberaceae (2 kg) were mixture with distilled water (5 L). The
essential oils were extracted by hydrodistillation using a vertical hydrodistillation unit. A flask
containing the homogenate was heated during 24 h and the vapor condensed and separated throughout
an auto-oil/water separator. Each essential oil extraction was running in duplicate.
Solvent extraction: Plant material was oven dried at 50°C for 24 h to reduce water content. Extracts
were prepared by blending preserved plant material (approximately 200 g dry weight) in 99% ethanol
and petroleum ether (1:3 w/v ratio). After 24 h, the mixture was filtered through Whatman filter paper
(No.1) using a Buchner funnel. The solvent was removed with a rotary vacuum evaporator at 40°C
(30 mmHg). The oil was stored in dark vials at 4°C before analyzing. The waste or residue after
extraction of plant materials with petroleum ether was extracted again with ethanol (so-called
secondary extraction, method C), under conditions similar to those described above.