Isolation and identification of the five major sesquiterpene hydrocarbons of ginger

Abstract

Forty-eight different ginger oils from nine countries spanning four continents have been investigated by dual capillary gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). All oils were found to contain the same five major sesquiterpene hydrocarbons. Two of them were isolated in one step from an Indian oil by an efficient reversed phase high performance liquid chromatographic (RP-HPLC) separation. The other three were isolated by a combination of RP-HPLC and preparative capillary GC. They were identified by UV, MS, 'H NMR and I3C NMR as a-zingiberene (I), P-hisabolene (2), (E,E)-a-farnesene (3), P-sesquiphellandrene (4) and ar-curcumene (5). The reported absence of some of these compounds in earlier studies could in many cases be explained by unsatisfactory separations, misidentifications and confusion in the nomenclature. a-zingiberene;/3-bisabolene; ( E , E)-a-farnesene;decided therefore to investigate a larger range of oils, to isolate and identify unequivocally the main sesquiterpene hydrocarbons and to study the published reports in closer detail to see whether the reported variation was valid or not. This paper reports the results of these studies. EXPERIMENTALPlant material. Zingiber oficinafe Roscoe rhizomes were collected (Vietnam, Indonesia, Ciskei) or bought (Thailand, Malaysia) locally. Brazilian ginger was purchased fresh in the Netherlands. Almost all of the above rhizomes were hydrodistilled in our laboratory with the apparatus described in the European Pharmacopoeia. A few of the larger Indonesian samples were steam-distilled in our laboratory. The other oil from Ciskei and the Australian and Nepalese oil were steamdistilled locally. The Indian oil was bought commercially. GC. A Varian 3300 gas chromatograph equipped with one split/splitless injection system, a 1 : 1 inlet splitter, two columns and two FI detectors was used. The two columns were a J&W 60 m DB-1,0.25 mm i.d. and 0.25 ym film thickness and a J&W 60m DB-WAX, 0.25 mm i.d. and 0.25 pm film thickness, respectively. Split ratio 1 : 100, carrier gas HZ, inlet pressure 20 psi, linear velocity 35cm/s; temp. prog. 50°C (Omin hold) to 238°C (8 min hold) at 4"/min; inj. temp. 220°C; det. temp. 260°C. Retention indices. All indices are Kovats indices. They were calculated by comparing the retention times of the compounds of interest with those of the C(7-23) alkanes. SESQUII'ERPENE IIYDROCARBONS OF GINGER OIL 1 2 3 4 5 6 7

Chemical Composition and Cytotoxicity Evaluation of Essential Oil from Leaves of Casearia Sylvestris, Its Main Compound α-Zingiberene and Derivatives

“…Additional peaks ranging from δ 1.16 to δ 2.14 correspond to remaining hydrogens (H-1, H-6, H-7, H-8 and H-9). The 13 C-NMR spectrum showed fifteen signals, being six at the region of double bonds (δ 120–135), referring to carbons C-2, C-3, C-4 C-5, C10 and C-11, besides signals at δ 26.2, 17.9, 17.8 and 21.3 corresponding to methyl groups in C-12, C-13, C14 and C-15 respectively, thus confirming its structure as α-zingiberene (Figure 1) [32,33].…”

Laboratory Evaluation of Products to Reduce Settling of Sweetpotato Whitefly Adults

“…Cedar oil formulated with 1% Tween 20 resulted in a SR 50 value of 1.1, whereas the commercial product NOCDOWN III, which is 67% cedar oil, had a SR 50 value of 3810 and thus had no effect on adult settling. Ginger oil, which had a SR 50 value of 0.4 in the current study, contains sesquiterpenes, including bisabolene, farnesene, sesquiphellandrene, zingeberene and curcumene (van Beck and Lelyveld 1991). These latter two compounds are volatile constituents of the glandular trichomes of accessions of the wild tomato species Lycopersicon hirsutum f. typicum Humb.…”

Is Low-field NMR a Complementary Tool to GC-MS in Quality Control of Essential Oils? A Case Study: Patchouli Essential Oil

“…2), but it is not known for the 10 investigated EOs. As we possessed a significant collection of ginger oils [33], we preliminary investigated this aspect also for ginger oil (▶ Fig. 6).…”