Antioxidant Activity and Volatile Oil Analysis of Ethanol Extract of Phoebe zhennan S. Lee et F. N. Wei Leaves

The medicinal value of P. zhennan has been documented in traditional Chinese medicine books. The aim of this paper was to study the antioxidant activity of alcoholic extracts of P. zhennan leavesusing 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2-phenyl-4,4,5,5-tetramethylimidazolineoxyl-1-oxyl-3-oxide (PTIO) radical scavenging and ferric ion reducing antioxidant power (FRAP) assays. The active components of the leaves were identified via headspace solid-phase microextraction and gas chromatography–mass spectrometry (HS-SPME-GC-MS). The results showed that the scavenging rate of DPPH was 94.67%with an EC50 value of 0.674 mg/mL at a concentration of 2 mg/mL. The maximum scavenging rate was 47.40% at a Trolox equivalent of 0.33 mg TE/mL for PTIO radicals. The FRAP reached 84.80% at 0.20 mg/mL concentration. The results confirmed the strong antioxidant activity of the extracts. Furthermore, 44 compounds, mostly terpenoids, obtained from the alcoholic extracts of P. zhennan leaves were analyzed using HS-SPME-GC-MS and 15 of these compounds had a relative content exceeding 1%. The strong antioxidant activity of the alcoholic extracts of P. zhennan leaves could be attributed to the presence of copaene (33.97%), β-caryophyllene (4.42%), δ-cadinene (11.04%), γ-muurolene (4.78%), cis-calamenene (2.02%), linalool (1.04%), α-pinene (1.46%), borneol acetate (1.5%), and γ-terpinene (0.66%). This study demonstrates the potential medicinal value of alcoholic extracts of P. zhennan leaves.