GC-MS Analysis and Antioxidant Evaluation of Essential Oils from Chimonanthus salicifolius and Chimonanthus nitens

Chimonanthus salicifolius and Chimonanthus nitens are widely used in the food and pharmaceutical industries. Traditionally, their stems and leaves have been consumed as herbal tea substitutes in folk practices, possessing both medicinal and edible values. They represent typical dual-purpose plants for both medicinal and tea applications and are distinctive ethnic She medicinal resources. This study used the flowers, stems, and leaves of C. salicifolius and C. nitens as materials to analyze the chemical components of six essential oils and evaluate their antioxidant and antibacterial activities. We extracted their essential oils through steam distillation, followed by an analysis of their volatile chemical components using gas chromatography–mass spectrometry (GC-MS). Hydroxyl radical (•OH), 1,1-diphenyl-2-picryl hydrazyl (DPPH) and the ferric reducing ability of plasma (FRAP) were used to evaluate the antioxidant activities of the different essential oils. The results showed that the extraction rates of both Chimonanthus species followed the order of leaf > flower > stem. Among them, the essential oil extraction rate from the leaves of C. salicifolius was the highest (2.22%), followed by that from the leaves of C. nitens (0.84%). A total of 83 volatile components were identified from the six extracted essential oils, demonstrating significant compositional differences (p < 0.05). Eucalyptol is the main component and has the highest relative content in the essential oils of both plant leaves, with (54.65 ± 1.03%) in C. salicifolius and (52.28 ± 1.03%) in C. nitens. Antioxidant experiments revealed that the leaf essential oil exhibited the strongest •OH scavenging activity (IC50 = 39.47 ± 5.57 μL·mL−1), while the stem of C. salicifolius showed the highest DPPH scavenging activity (IC50 = 20.78 ± 3.86), and the flower part demonstrated the best FRAP power. Additionally, a preliminary evaluation of the antibacterial activity of these two Chimonanthus leaf essential oils indicated that their minimum inhibitory concentration (MIC) against Staphylococcus aureus, Bacillus pumilus, and Bacillus subtilis was consistently 50 µL·mL−1. This study systematically analyzed the chemical composition, antioxidant activity, and antibacterial activity of essential oils from different parts of C. salicifolius and C. nitens, revealing differences in yield, component composition, and biological activity between the two species. The findings provide scientific evidence for the development and application of essential oils from Chimonanthus plants.