Modern tools to study traditional medicinal plants: Ginger and turmeric

This dissertation describes three related lines of research concerning the anti-inflammatory botanical dietary supplements ginger ( Zingiber officinale Rosc.) and turmeric (Curcuma longa L.). The first part of this research sought to verify and distinguish relationships between ginger and other Zingiber species, entailing a phylogenetic analysis of 10 ginger (Zingiber officinale) accessions, four Zingiber species, and one Alpinia species, using a combination of unique DNA sequences and chemical signatures. The comparative DNA sequence/chemical signature-based phylogenetic analyses of the studied Zingiber species and accessions yielded nearly identical phylogenetic relationships. The ginger accessions exhibited both indistinguishable DNA sequence and similar chemical composition, when compared to each other, yet they were quite distinct from the other Zingiber species. This led us to conclude that either DNA sequence or chemical characters can be used effectively to authenticate ginger plant material.; The second part of this research investigated the utility of LC-ESI-MS/MS in the analysis of gingerols from ginger and curcuminoids from turmeric. All the three authentic curcuminoid standards demonstrated consistent ionization and fragmentation mechanisms in four different mass spectrometers. In contrast to the curcuminoids, the three authentic gingerol standards did show consistent ionization and fragmentation mechanisms in the same mass spectrometer, but instrument dependent ionization mechanisms were observed in the four different mass spectrometers used in this study. These observations establish a foundation for the use of LC-ESI-MS/MS as a method for the identification of gingerols, curcuminoids, and related compounds via the comparison of MS/MS spectra with the appropriate authentic standards; or alternatively, against each other when analyzed in the same mass spectrometer.; In the third part of this research, LC-ESI-MS/MS was used to identify compounds related to the gingerols and curcuminoids in methanolic crude extracts of fresh ginger and turmeric rhizomes. From ginger rhizomes, 31 gingerol-related compounds and 26 diarylheptanoids (curcuminoid-related compounds) were identified, 18 of which are new compounds. From turmeric rhizomes, 19 diarylheptanoids were identified and 6 of these are new compounds. This type of investigation may therefore provide chemical evidence for authentication of fresh ginger and turmeric rhizome and for biosynthetic pathway study of diarylheptanoids and gingerol related compounds.