CHEMICAL CHARACTERIZATION OF METABOLITES OF MEDICINAL PLANTS USING LIQUID CHROMATOGRAPHY MASS SPECTROMETRY (LC-MS) AND GAS CHROMATOGRAPHY MASS SPECTROMETRY (GC-MS)

Abstract

The objectives of this study were to characterize metabolites of medicinal plants using Liquid Chromatography Mass Spectrometry (LC-MS) and Gas Chromatography and Mass Spectrometry (GC-MS). Centotheca lappacea (L.) Desv. and Bacopa monnieri (L.) Wettst. were selected as model plants for the study.

C. lappacea or “Ya hee yum” a grass in Poaceae family that has long been used in Thailand for postpartum care of women. Elemental analysis was undertaken using Wavelength Dispersive X-ray fluorescence, identification of antioxidants was done with online liquid chromatography–electrospray ionization-quadrupole-time of flight-mass (LC-ESI-QTOF-MS) spectrometer coupled with DPPH assay, and the volatile constituents of C. lappacea were investigated using headspace GC-MS. The elemental analysis showed the presence of macro and micro elements including silicon, potassium, and calcium. Twelve antioxidants, including C-and O-glycosides of luteolin and apigenin, were identified from the 50 % ethanolic extract of the aerial parts of the plant. Nineteen compounds were identified in the roots and twenty-five compounds were found in the aerial parts of C. lappacea. The sample material from both the roots and aerial parts were directly burned using a headspace GC-MS in the same process of obtaining smoke during traditional treatment. The antioxidants and volatile constituents in the C. lappacea plant material are reported for the first time in this study.

B. monnieri or Brahmi has long been proven to improve memory and intellect. Brahmi essence has been developed for many years from B. monnirei standardize extract and mulberry juice to be used as a dietary supplement. In our study, a group of elderly healthy participants were given a course of Brahmi essence over a 12-week period, and their speed of memory was found to have significantly improved over that period. In this study, untargeted LC-MS metabolomics approach was used to characterize metabolites found in plasma, urine and feces that might relate to and contributed to this outcome. From OPLS-DA plots, 15 features (metabolites) were tentatively identified in the plasma, 7 in urine and 17 in feces samples by comparing with data in an on-line data base and in the literature. The metabolites in the plasma samples were in the class of amino acids and their derivatives, acylcarnitine and phospholipids, which were mainly involved in aminoacyl-tRNA biosynthesis, aromatic amino acid biosynthesis and branched chain amino acid biosynthesis pathways. Benzeneactamide-4-O-sulphate and 3-hydroxyhippuric acid together with other metabolites were tentatively identified in urine samples. Amino acids and their derivatives were tentatively identified in fecal samples and the altered metabolic pathways in the fecal samples were similar to those of the plasma samples. Also, jujubogenin/isomer and pseudojujubogenin aglycones were tentatively identified in the feces samples. These metabolites might be directly or indirectly involved with the improvement of speed of memory.

-