Commercially processed dry ginger (Zingiber officinale): Composition and effects on LPS-stimulated PGE₂ production

Using techniques previously employed to identify ginger constituents in fresh organically grown Hawaiian white and yellow ginger varieties, partially purified fractions derived from the silica gel column chromatography and HPLC of a methylene chloride extract of commercially processed dry ginger, Zingiber officinale Roscoe, Zingiberaceae, which demonstrated remarkable anti-inflammatory activity, were investigated by gas chromatography-mass spectrometry. In all, 115 compounds were identified, 88 with retention times (R_t) >21 min and 27 with <21 min. Of those 88 compounds, 45 were previously reported by us from fresh ginger, 12 are cited elsewhere in the literature and the rest (31) are new: methyl [8]-paradol, methyl [6]-isogingerol, methyl [4]-shogaol, [6]-isoshogaol, two 6-hydroxy-[n]-shogaols (n = 8 and 10), 6-dehydro-[6]-gingerol, three 5-methoxy-[n]-gingerols (n = 4, 8 and 10), 3-acetoxy-[4]-gingerdiol, 5-acetoxy-[6]-gingerdiol (stereoisomer), diacetoxy-[8]-gingerdiol, methyl diacetoxy-[8]-gingerdiol, 6-(4′-hydroxy- 3′-methoxyphenyl)-2-nonyl-2-hydroxytetrahydropyran, 3-acetoxydihydro-[6]- paradol methyl ether, 1-(4′-hydroxy-3′-methoxyphenyl)-2-nonadecen-1- one and its methyl ether derivative, 1,7-bis-(4′-hydroxy-3′- methoxyphenyl)-5-methoxyheptan-3-one, 1,7-bis-(4′-hydroxy-3′- methoxyphenyl)-3-hydroxy-5-acetoxyheptane, acetoxy-3-dihydrodemethoxy-[6]- shogaol, 5-acetoxy-3-deoxy-[6]-gingerol, 1-hydroxy-[6]-paradol, (2E)-geranial acetals of [4]- and [6]-gingerdiols, (2Z)-neral acetal of [6]-gingerdiol, acetaldehyde acetal of [6]-gingerdiol, 1-(4-hydroxy-3-methoxyphenyl)-2,4- dehydro-6-decanone and the cyclic methyl orthoesters of [6]- and [10]-gingerdiols. Of the 27 R_t < 21 min compounds, we had found 5 from fresh ginger, 20 others were found elsewhere in the literature, and two are new: 5-(4′-hydroxy-3′-methoxyphenyl)-pent-2-en-1-al and 5-(4′-hydroxy-3′-methoxyphenyl)-3-hydroxy-1-pentanal. Most of the short R_t compounds are probably formed by thermal degradation during GC (which mimics cooking) and/or commercial drying. The concentrations of gingerols, the major constituents of fresh ginger, were reduced slightly in dry ginger, while the concentrations of shogaols, the major gingerol dehydration products, increased.