Abstract
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.
Highlights
Allergic diseases are mainly caused by hypersensitive response to external materials, including bronchial asthma, allergic rhinitis, and atopic dermatitis, and they are one of the most common chronic diseases worldwide [1]
Yield and chemical composition The yield of the essential oil extracted from P. densiflora wood was 0.75% (g/g)
The yield of the pine wood oil was higher than that of the essential oil extracted from the leaves of the Pinus species [17, 18]
Summary
Allergic diseases are mainly caused by hypersensitive response (allergy) to external materials, including bronchial asthma, allergic rhinitis, and atopic dermatitis, and they are one of the most common chronic diseases worldwide [1]. The most common pharmacological therapies for allergic diseases include inhibitors of chemical mediators that are involved in the allergic reaction or anti-inflammatory drugs that suppress the tissues’ inflammation [2]. These pharmacological therapies can only improve symptoms when the drug is administered continuously, Pinus densiflora Pine needles have been used for the treatment of adult diseases such as neuralgia, diabetes mellitus, hypertension, and skin disease in herbal or folk medicine [8]. Pine leaf extracts have been reported to be useful for treating oxidative damage [9]
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