Elsevier

Phytochemistry

Volume 66, Issue 13, July 2005, Pages 1614-1635
Phytochemistry

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

https://doi.org/10.1016/j.phytochem.2005.05.007Get rights and content

Abstract

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 (Rt) >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 Rt < 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 Rt 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.

Graphical abstract

Direct analysis of partially purified fractions of commercially processed dry ginger extract by GC-MS resulted in the identification of 115 compounds including 31 new compounds and 3 others previously unreported from ginger.

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Introduction

In our previous report on the gas chromatography-mass spectrometry (GC-MS) analysis of partially purified fractions from two organically grown fresh white and yellow ginger varieties, Zingiber officinale Roscoe (Zingiberaceae) from Hawaii, we described the identification of 63 compounds including 31 compounds previously reported as ginger constituents, 25 new gingerol derivatives and 7 thermal degradation products of gingerols (Jolad et al., 2004). In this paper we report similar findings from the GC-MS analysis of biologically active column chromatography (CC) fractions from the CH2Cl2 extract of commercially processed dry ginger powder with special emphasis on their activity in inhibiting in vitro PGE2 production.

Chronic inflammation has been associated with a number of human diseases including chronic obstructive pulmonary disease, asthma and rheumatoid arthritis. While “conventional” treatments have met with some success, patients suffering from diseases with associated chronic inflammation are turning to alternatives for relief of their symptoms or as prophylactic treatments. These alternatives include dietary supplements that are purported to have anti-inflammatory actions. However, the efficacy and potency of these supplements have not been studied in great detail. Plants (or supplements derived from the plants) that have received attention as being useful for chronic inflammation include ginger.

Inflammation is associated with a large range of mediators that initiate the inflammatory response, recruit and activate other cells to the site of inflammation and subsequently resolve the inflammation (Gallin and Snyderman, 1999). In general, the chemical mediators can be divided into two large classes: cytotoxins and arachidonic acid metabolites. Products produced by the metabolism of arachidonic acid include both cyclooxygenase products (prostaglandins, thromboxanes) and lipooxygenase products (leukotrienes). Products such as LTB4 and PGE2 that are representative of these two pathways can initiate polymorphonuclear (PMN) leukocytes recruitment and changes in vascular tone and blood flow. Increased production of prostaglandins during an inflammatory response is achieved by induction of cyclooxygenase 2 (COX-2).

Several studies have indicated that compounds found in ginger are effective in relief of symptoms from chronic inflammatory diseases. Administration of ginger has resulted in patients relating decreased symptoms of rheumatoid arthritis (Srivastava and Mustafa, 1992). Gingerol (a major component of ginger) has been reported to have anti-inflammatory actions. For gingerol these include suppression of both cyclooxygenase and lipooxygenase metabolites and arachidonic acid (Kiuchi et al., 1992, Srivas, 1984, Tjendraputra et al., 2001). Our own research has found that organic extracts from ginger rhizomes or standards containing gingerols were able to inhibit LPS-induced PGE2 (IC50 < 0.1 μg/ml) production in U937 cells. Extracts containing either predominantly gingerols or shogaols (identified by HPLC) were both highly active at inhibiting LPS-induced PGE2 production (IC50 < 0.1 μg/ml), while extracts that contained unknown compounds were less effective (IC50 < 3.2 μg/ml). Extracts or standards containing predominantly gingerols were capable of inhibiting COX-2 expression while shogaol containing extracts had no effect on COX-2 expression (Lantz et al., 2005).

Section snippets

Results and discussion

Of the 10 final CC fractions analyzed for biological activity (Table 1), the initial two lipophilic fractions (X/1 and X/2) and the final polar fractions (X/9 and X/10), representing 9.0 (22.5%) and 11.2 g (28%), respectively, of the isolate, had insignificant activity and were, therefore, excluded from further analysis. The remaining six fractions (X/3–8), which exhibited high anti-inflammatory activity, were analyzed by GC-MS to detect and identify the constituents present in them. The

PGE2 assay results

The original dry ginger CH2Cl2 extract (X) and 6 (X/3–X/8) out of its 10 CC fractions (X/1–X/10) had high anti-inflammatory activities similar to those exhibited by fresh ginger extract and its CC fractions. As can be seen in Table 1, fractions containing gingerols (X/5 and X/6) and gingerol analogs (X/3, X/4, X/7 and X/8) showed potent inhibition of LPS-stimulated PGE2 production (IC50 = 0.05 0.08 μg/ml), comparable to IC50 for indomethacin in our assay system. Gingerols and ginger analogs have

Plant material

Ginger powder (Z. officinale) was purchased from San Francisco Herb and Natural Food.

Extraction and fractionation

Ginger powder (2500 g) was extracted with CH2Cl2 (7500 ml) for 36 h at 25 °C. After filtration, washing and work-up, a 40 g portion of the total CH2Cl2 extract (X, 159 g, 6.4%) was subjected to column chromatography (CC) on silica gel following the methodology developed in our laboratory for the separation of gingerol fractions in gram quantities for in vivo assays. The CC fractions were pooled into 10

Acknowledgements

This publication was made possible by Grant No. 5 P50 AT000474-05 to B.N.T. from the National Center for Complementary and Alternative Medicine (NCCAM) and the Office of Dietary Supplements (ODS) and its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NCCAM, ODS or the National Institutes of Health. We thank Dr. Aniko Solyom and Veronica Rodriguez for HPLC analyses and Mark Yanagihashi for preparing tables and other technical

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