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内容記述 |
M. aquatica were imported from the following countries; Belgium, Plantentuin der Rijksuniversiteit to Gent; Belgium, Institut et Jardin de Botanique de I'Universite de Liege; France, Jardin Botanique Ville de Nantes; Italy, Insti-tuto ed Orto Botanico dell' Univ. di Roma; Portugal Hortus Botanicus Coimbra. They were cultivated in Okayama University and Kurashiki Experimental Station for Agriculture. By analyzing the essential oils obtained from aquatica herbs by gas chromatography (column, SAIB 20% on Celite 545; column temp., 155℃; carrier gas, hydrogen; flow rate, 65 ml/min. ), we divided aquatica mint into following three chemical strains. Linalool strain seems to be very similiar to Mentha citrata from chemical and morphological point of view. Menthofuran in the second oil was identified by infrared spectrum, thin-layer chromatography (a purple red spot by vanillin sulfuric acid reagent) and Fluckiger reagent test. It will be surely identical with. American aquatica reported by Reitsema. The essential oil obtained from third strain showed strong absorption at 1700cm-1 and gave semicarbazone of m. p. 232℃ in the yield of 30%. The oil regenerated from this semicarbazone by treatment with acid media showed two peaks in the gas chromatogram, the later of which was determined to coincide with the main peak of aquatica original oil; retention time relative to (-) menthol was 0.88. This indicates that aquatica ketone is sensitive to acid and isomerizes to a stable isomer. The original ketone was isolated purely by silica column chromatography (first eluting solvent, petroleum ether, then followed by ether): b.p. 81℃/5mm., [α]¹⁵D -7.3°. By the reduction with lithium aluminum hydride, a borneol-like smelling crystal (m. p. 42～45℃) was obtained. From the elementary analysis of its 3, 5-dinitrobenzoate (Found: C, 58.70; H, 5.83; Calcd. for C₁₇H₂₀N₂O₆=dinitrobenzoate of C₁₀H₁₈O: C, 58.61; H, 5.79%), the molecular formula for original ketone was established to be C₁₀H₁₆O. It showed no double bond in the infrared spectrum and gave pinonic acid by potassium permanganate oxidation (identified as semicarbazone of m. p. 204℃). From these results aquatica ketone seemed to be a bicyclic ketone such as pinocamphone or isopinocamphone. NMR spectrum of this ketone in deuterio-chlo-roform showed the presence of gem-dimethyl (singlets, 9.12 8.68τ) and one methyl (doublet, 8.85, 8.73τ, J=7 c. p. s.), which support isopinocamphone skeleton. Then, (-)-isopinocamphone was prepared by hydroboration of (-)-pinene, [α]¹⁵D-35° according to Brown's method; b. p. 91～105℃/20mm., after silica chromatography, [α]¹⁵D-8.8°. Infrared spectrum absorption and retention time of (-) -isopinocamphone were found to be completely identical with those of aquatica ketone. This is the first paper which shows the presence of (-)-isopinocamphone in the essential oil of the Genus Mentha, while (-)-pinocamphone was found inn the oil of Hyssopus officinalis L. and ground ivy (Glechoma hederacea L. subsp. grandis (A. Gray) Hara). Then, oils of various interspecific hybrid clones between aquatica and several mint species such as rotundifolia (2n=24), spicata (48), japonica (48), arvensis var. agrestis (72) and arvensis var. piperascens (96) were analyzed by gaschromatography. The results obtained are shown in Table 4. |
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