The extraction procedure was carried out according to the European Pharmacopoeia procedure(1983). Approximately 50g of black-pepper powder was placed in a round-bottomed flask containing 1200mL of distilled water,which was connected to a Clevenger 0s distillation unit.
The black-pepper powder was then hydro-distilled for 4.5h.The obtained essential oil,which was collected in the side arm, was separated and dried over anhydrous sodium sulfate to eliminate traces of moisture.The extracted essential oil was placed in a glass amber bottle and refrigerated
at 4 C until further analysis.