Citrus cultivars have remarkable health benefits, but only the anti-inflammatory activities of the major varieties have been studied. This study investigated the anti-inflammatory effects of various citrus cultivars and their active anti-inflammatory components. The essential oils of 21 citrus peels were extracted via hydrodistillation using a Clevenger-type apparatus, and the chemical compositions of the essential oils were analyzed. D-Limonene was the most abundant constituent. To evaluate the anti-inflammatory effects of the citrus cultivars, the gene expression levels of an inflammatory mediator and proinflammatory cytokines were investigated. Among the 21 essential oils, those extracted from C. japonica and C. maxima exhibited superior anti-inflammatory activities, being able to inhibit the expression of the inflammatory mediators and proinflammatory cytokines in lipopolysaccharide-stimulated RAW 264.7 cells. The essential oils of C. japonica and C. maxima were distinguished into seven distinct constituents, α-pinene, myrcene, D-limonene, β-ocimene, linalool, linalool oxide, and α-terpineol, compared with other essential oils. The anti-inflammatory activities of the seven single compounds significantly inhibited the levels of inflammation-related factors. In particular, α-terpineol exhibited a superior anti-inflammatory effect. This study showed that the essential oils from C. japonica and C. maxima exhibit high anti-inflammatory activity. In addition, α-terpineol is an active anti-inflammatory compound that contributes to inflammatory responses.

Essential oils from citrus cultivars are widely used in food, cosmetic, and pharmaceutical industries, and they have been extensively studied in the last decades. This study investigates the antioxidant activities of essential oils from 21 citrus cultivars and the active antioxidant constituents of the oils. Essential oils are extracted from the peels of citrus cultivars via hydrodistillation, and their chemical compositions are analyzed by gas-chromatography–mass-spectroscopy. The antioxidant activities of the citrus cultivars are determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), and ferric-reducing antioxidant potential (FRAP) assays. Based on the results, the major constituent of the oils is d-limonene (50.88–97.19%). The essential oil from Citrus junos shows the highest phenolic content (360.04 ± 24.75 mg GAE/100 g), followed by that from Citrus × latifolia (339.42 ± 31.14 mg GAE/100 g), [(Citrus unshiu × Citrus sinensis) × Citrus reticulata] × Citrus reticulata (327.05 ± 14.29 mg GAE/100 g), and [(Citrus unshiu × Citrus sinensis) × Citrus reticulata] × Citrus reticulata (322.92 ± 21.43 mg GAE/100 g). The essential oil from [(Citrus unshiu × Citrus sinensis) × Citrus reticulata] × Citrus reticulata shows the highest DPPH and ABTS radical scavenging activity, with an EC₅₀ of 86.17 ± 4.87 and 0.16 ± 0.06 mg/mL, respectively. The essential oil from Citrus reticulata and [(Citrus unshiu × Citrus sinensis) × Citrus reticulata] × Citrus reticulata shows the highest ferric-reducing activities (2302.55 ± 237.26 and 2213.12 ± 35.54 mg/100 g, respectively). These results indicate that the essential oil from [(Citrus unshiu × Citrus sinensis) × Citrus reticulata] × Citrus reticulata has a higher antioxidation effect than that from other cultivars. By comparing the chemical compositions of the essential oils, 12 compounds are selected as the major contributors to the antioxidant activities of the oils, and α-phellandrene and α-terpinene are the most active constituents of the oils.

Citrus is one of the most popular and widely grown fruit crops in the world. However, the bioactivity of only certain species of citrus cultivars is studied. In this study, the effects of essential oils from 21 citrus cultivars on melanogenesis were investigated in an effort to identify active anti-melanogenesis constituents. The essential oils from the peels of 21 citrus cultivars obtained by hydro-distillation were analyzed using gas chromatography–mass spectrometry. Mouse melanoma B16BL6 cells were used in all assays conducted in this study. The tyrosinase activity and melanin content were determined using the lysate of α-Melanocyte-stimulated B16BL6 cells. In addition, the melanogenic gene expression was determined by quantitative reverse transcription-polymerase chain reaction. Overall, the essential oils of (Citrus unshiu X Citrus sinensis) X Citrus reticulata, Citrus reticulata, and ((Citrus unshiu X Citrus sinensis) X Citrus reticulata) X Citrus reticulata provided the best bioactivity and comprised five distinct constituents compared to other essential oils such as limonene, farnesene, β-elemene, terpinen-4-ol, and sabinene. The anti-melanogenesis activities of the five individual compounds were evaluated. Among the five essential oils, β-elemene, farnesene, and limonene showed dominating properties. The experimental results indicated that (Citrus unshiu X Citrus sinensis) X Citrus reticulata, Citrus reticulata, and ((Citrus unshiu X Citrus sinensis) X Citrus reticulata) X Citrus reticulara are potential candidates with anti-melanogenesis activity for use as cosmetics and pharmaceutical agents against skin hyperpigmentation.

The Journal of the Korean Wood Science and Technology (JKWST) launched in 1973 as an official publication of the Korean Society of Wood Science and Technology has been served as a core of knowledges on wood science and technology.

The aim of this study is to identify the active compounds of the essential oil extracted from the Pinus densiflora (Sieb. et Zucc.) wood using the hydrodistillation method and evaluate their anti-inflammatory activity. The chemical composition of the oil was identified by GC–MS analysis, and its anti-inflammatory activity was assessed by investigating its effect on the expression of interleukin-4 (IL-4), interleukin-13 (IL-13), and β-hexosaminidase in lipopolysaccharide (LPS)-stimulated RBL-2H3 cells. Treatment of the LPS-stimulated RBL-2H3 cells with the oil and its fractions downregulated the production of pro-inflammatory cytokines such as IL-4 and IL-13 and further attenuated the secretion of β-hexosaminidase out of the cells to a significant level. Among the five obtained fractions, fraction E exhibited the best anti-inflammatory activity, and its main constituent, longifolene, was considered as the active compound. Moreover, the inhibitory effect of longifolene on the expression levels of IL-4 and IL-13 and the β-hexosaminidase secretion was similar to that of the P. densiflora wood oil, indicating longifolene as the active constituent of the P. densiflora wood oil with immunosuppressive effects on inflammation.