Chemical composition and antioxidant activity of black pepper (<i>Piper nigrum</i> L.) fructus essential oil hydrodistillation fractions

The aim of this study was to examine the effect of hydrodistillation time on the chemical composition and antioxidant activity of collected essential oils’ (EOs’) fractions from black pepper fructus for five hydrodistillation periods: I (0-15 min), II (15-30 min), III (30-60 min), IV(60-90 min) and V (90-120 min). In this way, an essential oil with the desired chemical composition and antioxidant activity can be selected. The essential oil was obtained by Clevenger-type hydrodistillation (CHD). The qualitative and quantitative composition of the collected EOs’ fractions was determined by GC-MS and GC-FID analysis. The efficiency of EOs’ fractions to scavenge DPPH radicals was evaluated spectrophotometrically. Essential oil yield was 3.0 ± 0.050 ml/100 g of plant material after 120 min of CHD. The content of monoterpene hydrocarbons and aromatic compounds decreased, while the content of oxygenated monoterpenes, sesquiterpene hydrocarbons and oxygenated sesquiterpenes increased with the time of CHD. The most abundant compound of EOs’ fractions was (E)-caryophyllene, whose content increased with the time of CHD (I-V: 24.9-36.6%). Results indicated that all collected EOs’ fractions exhibited antioxidant activity (EC50 values were in the range I-V: 81.27±0.327–8.02±0.044 mg/ml), where fraction V showed the highest activity. This study proved that CHD time and fractionation affect the composition and antioxidant activity of black pepper essential oil. Future research may be extended to examine other biological activities of black pepper EOs’ fractions, as well as synergistic effects of other identified active components of the essential oil, in addition to (E)-caryophyllene, that would affect biological activities.