Medicinal Uses Of 2-undecanone

Adapted from Sane et al. (1998).

Adapted from Sane et al. (1998).

Minor differences were noted. In particular, higher amounts of ketones (2-nonanone and 2-undecanone) and 2-heptanol were observed in the oil from India. On the other hand, the absence of bornyl acetate and calamenene isomers in the Indian ginger oil should be noted as well as the presence of two zingiberol isomers in both oils. If we compare the composition of the Indian oil with that studied by Lawrence (1983), Lawrence found higher amounts of monoterpenes and a lower amount of a-zingiberene.

Tomi et al. (1995), using a computer-assisted 13C-NMR analysis in combination with HPGC, determined the major components of ginger oil: camphene (7.9%), P-bisabolene (5.9%), limonene (6.0%), (E,E)-a-farnesene (5.4%), and a-zingiberene (27.2%). Sane et al. (1998) studied geographical variations of ginger oils from the various areas of India

Their results show a greater yield for Gujarat (0.24%) than for the other three areas (0.12%). Rani (1999) studied the formation of sesquiterpene hydrocarbons in Indian ginger oil. The oil contained a-zingiberene (22%), P-zingiberenene (7%), P-bisabolene (14%), ar-curcumene (20%), and the remaining fraction contained a-selinene, P-elemene, P-farnesene, sesquithujene, and sesquisabinene. It also contained some oxygenated mono- and sesquiterpenes. The biosynthesis of the three main sesquiterpene hydrocarbons was established using the isotopic method.

Essential Oils from China

A review of the raw and dry ginger produced in Szechuan shows that the essential oil contains a-zingiberene, ar-curcumene, a-farnesene, P-farnesene, linalool, gingerol, P-sesquiphellandrene, zingerone, dehydrogingerol, hexahydrocurcumin, and other compounds (Chen and Guo, 1980). Dry ginger produced in Szechuan contained 1 to 2% essential oil as compared with 0.2 to 0.4% of raw ginger found in Peikin. TLC indicated that most of the constituents were identical. The citral content for a Chinese oil was very low (0.22%) (Lin and Hua, 1987) compared to that found in Japanese oils or in a Fijian oil (64%) (Smith and Robinson, 1981). Chen and Ho (1988) compared the chemical composition of ginger oils from Taiwan obtained by steam distillation and supercritical CO2 extraction. These results are reported in Table 3.18.

Ginger oils from Taiwan obtained both from steam distillation and liquid CO2 extraction were fractionated into hydrocarbons and oxygenated hydrocarbons using silica gel CC. The two fractions were analyzed by HRGC and HRGC/MS. Monoterpenes, sesquiterpe-nes, aliphatic aldehydes and ketones, and neral and geranial as well as monoterpene and sesquiterpene alcohols were the major categories of ginger components. They were partially affected or generated by thermal-induced degradation during steam distillation. From the results reported in Table 3.18, it appears that the amount of monoterpene hydrocarbons greatly increased with CO2 extraction with the exception of terpinolene. To a smaller extent, the same is true for sesquiterpene hydrocarbons. However, the percentage of ar-curcumene decreased in the fraction obtained with liquid CO2 extraction.

The constituents of ginger oils prepared by different processes (cold dried, hot dried, or baked at 220° C) were compared by column chromatography and mass spectra (Ye et al., 1989). Odor assessments for volatile compounds of ginger essential oils from Taiwan by sniffing GC were carried out by Sheen et al. (1992a). Geranial, (3-sesquiphellandrene

Table 3.18 Comparison of the hydrocarbon fraction of ginger oils from Taiwan obtained by steam distillation and supercritical CO2 extraction

Compound

Steam distillation

Liquid CO2 extraction

Monoterpene hydrocarbons

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