Piper cubeba L. fruit is an important species used in folk medicine for different types of pains such as rheumatism, chills, flu, colds, muscular aches, and fever. This study examines the chemical constituents, antioxidant activity, and potential inhibitory effect against human peroxiredoxin 5, a key enzyme of P. cubeba essential oil from fruits. Using gas chromatography coupled with mass spectrometry (GC-MS), the principal components were methyleugenol (41.31%) and eugenol (33.95%), followed by (E)-caryophyllene (5.65%), p-cymene-8-ol (3.50%), 1,8-cineole (2.94%), and α-terpinolene (1.41%). Results showed similar scavenging activity via 2,2-diphenyl-1-picrylhydrazyl DPPH radical scavenging activity (IC50 = 110.00 ± 0.08 μg/mL), as well as very potent antioxidant activity against both ferric reducing/antioxidant power (FRAP) (106.00 ± 0.11 μg/mL) and β-carotene bleaching (IC50 = 315.00 ± 2.08 μg/mL) assays when compared to positive butylated hydroxytoluene and ascorbic acid. The molecular docking approach has also been performed to screen the antioxidant activities of the major and potent compounds against human protein target peroxiredoxin 5. Results showed good binding profiles and attributed the strongest inhibitory activity to β-caryophyllene oxide (-5.8 kcal/mol), followed respectively by isocembrol and α-selinene (-5.4 kcal/mol), and viridiflorol (-5.1 kcal/mol). Furthermore, ADME (absorption, distribution, metabolism and excretion)-related physicochemical and pharmacokinetic properties have been assessed and support our in vitro findings. This work demonstrates the powerful antioxidant potency of cubeba pepper and paves the way for the discovery and development of antioxidant agent with high potency.
Keywords: DPPH assay; Piper cubeba L.; human peroxiredoxin 5; in silico computational study; volatile oil; β-carotene assay.