In vitro antioxidant and anti-cholinesterase properties of essential oils from pepper fruits (Dennettia tripetala g. baker)

Abstract

Essential oils from different plant species have been reported to possess various biological activities. Thus, this study is aimed at investigating the antioxidant and anti-cholinesterase properties of essential oils from ripe and unripe pepper fruits (Dennettia tripetala G. Baker). Essential oil was extracted from ripe and unripe pepper fruits (100 g each) using a Clevenger apparatus. Thereafter, the antioxidant activities of the essential oil were assessed through several antioxidant assays. In addition, the effect of the essential oil on cholinesterases; acetycholinesterase (AChE) and butyrylcholinesterase (BChE) was assessed using spectrophotometric method. The results revealed that both ripe and unripe pepper fruits essential oils showed strong antioxidant activities and there was no significant difference in their antioxidant activities except for ferric reducing antioxidant power where unripe pepper fruit essential oil showed higher antioxidant activity (16.33 mgAAE/g) than ripe pepper fruit essential oil (12.55 mgAAE/g). In addition, unripe pepper fruit essential oil had a stronger inhibitory effect on AChE (IC50 = 1.67 mg/mL) than that of ripe pepper fruit (IC50 = 2.69 mg/mL), whereas there was no significant difference in their BChE inhibitory properties. Essential oils from both ripe and unripe pepper fruits had antioxidant properties and inhibited AChE and BChE activities in vitro. However, findings in this study revealed that ripening could reduce the biological activities of pepper fruit essential oils, most especially ferric reducing antioxidant property and acetylcholinesterase inhibition.