Yuzu (Citrus junos Tanaka) has been used as a traditional medicine in Japan. We investigated in vitro anti-inflammatory effects of limonene from yuzu peel on human eosinophilic leukemia HL-60 clone 15 cells. To examine anti-inflammatory effects of limonene on the cells, we measured the level of reactive oxygen species (ROS), monocyte chemoattractant protein-1 (MCP-1), nuclear factor (NF) kappa B, and p38 mitogen-activated protein kinase (MAPK). We found that low concentration of limonene (7.34 mmol/L) inhibited the production of ROS for eotaxin-stimulated HL-60 clone 15 cells. 14.68 mmol/L concentration of limonene diminished MCP-1 production via NF-kappa B activation comparable to the addition of the proteasomal inhibitor MG132. In addition, it inhibited cell chemotaxis in a p38 MAPK dependent manner similar to the adding of SB203580. These results suggest that limonene may have potential anti-inflammatory efficacy for the treatment of bronchial asthma by inhibiting cytokines, ROS production, and inactivating eosinophil migration.

Yuzu (Citrus junos Sieb. ex Tanaka) peel oils were extracted by cold‐pressing. The flavour components of yuzu were quantitatively determined by use of two internal standards with GC and GC–MS. Characteristic flavour components of yuzu were examined by GC–olfactometry. The contents of hydrocarbons (34 compounds), alcohols (37 compounds) and aldehydes (16 compounds) in weight percent were about 96.55%, 2.03% and 0.1%, respectively. The terpenes were the major components of yuzu peel oil, but they contributed little to the characteristic flavour of yuzu. Methyltrisulfide, borneol, n‐octanol, trans‐undec‐2‐enal, (+)‐p‐mentha‐1‐en‐9‐ol, eugenol and carvacrol were found to be strongly involved in the characteristic flavour of yuzu, together with 6‐methyl‐5‐hepten‐2‐ol and methyltrisulfide having the highest FD‐factor. Copyright © 2000 John Wiley & Sons, Ltd.

The volatile components of Tosa-buntan (Citrus grandis Osbeck forma Tosa) cold-pressed peel oil were studied by GC and GC-MS. The characteristic aroma compounds were investigated by GC-olfactometry in which a semi-bore capillary column, DB-Wax, was used for effective separation of the volatile components of the oil. Hydrocarbons including mono and sesquiterpenes of the oil accounted for about 98% of the volatile components. The characteristic flavor was also present in the oxygenated fraction. Flavor dilution (FD) factors of the volatile flavor components of the cold-pressed oil were determined by aroma extraction dilution analysis. The relative flavor activity derived from FDfactor and peak area percent was used in this experiment. It was suggested that compounds with higher relative flavor activity such as decanoic acid, heptyl acetate, a a a a-bisabolol, nonanal, cis, trans-farnesol, trans-nerolidol and 2-dodecenal would contribute to Tosa-buntan flavor. Careful sniff testing revealed 2-dodecenal to be a characteristic or key compound of Tosa-buntan aroma. A solution of this authentic compound below 2 ppm gave a pleasant and refreshing aroma similar to Tosa-buntan flavor.

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Antioxidative activities of thirty kinds of citrus essential oils and their fourteen components against linoleic acid oxidation were examined by a thiocyanate method. The tocopherol contents of these oils were determined by high-performance liquid chromatography monitored at 290 nm. All the citrus essential oils and the flavor components showed inhibitory effects against linoleic acid oxidation. Highest antioxidative ability was observed in the essential oils of yuzu, lemon, hassaku, sudachi, mochiyu, yuko and Tarocco orange. Antioxidative activities of ␤-pinene, myrcene, ␣-terpinene, ␥-terpinene and decanal were higher or similar to that of d d d d-tocopherol. Tocopherols were contained abundantly in the essential oils of limes, Valencia orange, yuzu and lemons. However, there was little correlation between tocopherol contents and antioxidative activities in citrus essential oils. The composition of terpene compounds seems to be a major factor in the antioxidative activities of these oils.