Biological Activities and Chemical Constituents of Essential Oils from Piper cubeba Bojer and Piper nigrum L.

In this study, we evaluated antioxidant, antihyperuricemic, and herbicidal activities of essential oils (EOs) from Piper cubeba Bojer and Piper nigrum L.; two pepper species widely distributed in tropics, and examined their chemical compositions. Dried berries of P. cubeba and P. nigrum were hydro-distilled to yield essential oil (EO) of 1.23 and 1.11% dry weight, respectively. In the antioxidant assay, the radical scavenging capacities of P. cubeba EO against DPPH and ABTS free radicals were 28.69 and 24.13% greater than P. nigrum, respectively. In the antihyperuricemic activity, P. cubeba EO also exhibited stronger inhibitory effects on xanthine oxidase (IC₅₀ = 54.87 µg/mL) than P. nigrum EO (IC₅₀ = 77.11 µg/mL). In the herbicidal activity, P. cubeba EO showed greater inhibition on germination and growth of Bidens pilosa and Echinochloa crus-galli than P. nigrum EO. Besides, P. cubeba EO decreased 15.98-73.00% of photosynthesis pigments of B. pilosa and E. crus-galli, while electrolyte leakages, lipid peroxidations, prolines, phenolics, and flavonoids contents were increased 10.82-80.82% at 1.93 mg/mL dose. Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) analyses revealed that P. nigrum and P. cubeba EOs principally possessed complex mixtures of monoterpenes and sesquiterpenes. Terpinen-4-ol (42.41%), α-copaene (20.04%), and γ-elemene (17.68%) were the major components of P. cubeba EO, whereas β-caryophyllene (51.12%) and β-thujene (20.58%) were the dominant components of P. nigrum EO. Findings of this study suggest both P. cubeba and P. nigrum EOs were potential to treat antioxidative stress and antihyperuricemic related diseases. In addition, the EOs of the two plants may be useful to control B. pilosa and E. crus-galli, the two invasive and problematic weeds in agriculture practice.