Terpene Compound Composition and Antioxidant Activity of Essential Oils from Needles of Pinus densiflora, Pinus koraiensis, Abies holophylla, and Juniperus chinensis by Harvest Period

Plant resources are used as raw materials in various industries related to humans, such as edible, medicinal, taste, and flavor industries, depending on processes such as drying, processing, and collection period. In this study, we investigated the terpene compound composition and antioxidant activity of essential oils extracted from the needles of Pinus densiflora, Pinus koraiensis, Abies holophylla, and Juniperus chinensis collected in the harvest period (February, April, July, and October) planted on the campus of Chungbuk National University. The essential oil was separated by hydrodistillation. According to the analysis results of gas chromatography-mass spectrometry, the terpene compounds changed depending on the season and tree species. The proportions of monoterpene and sesquiterpene classes in the needles of P. densiflora, P. koraiensis, A. holophylla, and J. chinensis changed depending on the harvest period. The antioxidant activity by DPPH and ABTS assays varied depending on the species and seasons, and needles harvested from P. koraiensis showed the highest activity in all harvest periods. High antioxidant activity has been confirmed even at low concentrations in pine trees, so it is expected to play a role as a natural antioxidant. Additionally, since the composition of terpene compounds varies depending on the harvesting time and species, it is expected to have various uses in the pharmaceutical, cosmetics, and food industries.