Use of fingerprinting technique for mass spectrometry for the analysis of extracts of natural products

Author(s)

Elaine Cristina Cabral

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
• Defense date: 2010-12-20

Examining board members

Jose Manuel Riveros; Pio Colepicolo; Fábio Cesar Gozzo; Humberto Marcio Santos Milagre; Luiz Alberto Beraldo de Moraes

• Advisor: Jose Manuel Riveros

Abstract

A new analytical methodology for the analysis of medicinal plant parts and extracts via direct infusion mass spectrometry (MS) has been developed. This analytical approach, named chemical fingerprinting, involves minimal sample preparation and was applied in this work with the aim to detect optimal culture conditions, culture periods and harvest times for obtaining raw natural products with highest active principle and concentrations, as well as to understand and recognizing ecological interactions between plant and its surrounding environment. The analytical methodology included MS with electrospray ionization (ESI) in the positive (+) and negative (-) modes, as well as fragmentation of ions of interest (MS/MS) experiments. The diluted extract and active fractions of Maytenus ilicifolia, extracts of Arrabidaea chica from diverse geographic origins (accesses), as well as the oil from Pterodon pubescens and nuts of various clones of Anacardium occidentale were introduced by direct injection. Characterization of nuts and stems from A. occidentale, as well as of its respective clones by their chemical constituents has been successfully performed. After ether extraction of nuts, it was possible to characterize the triacylglycerols (TAG) by ESI(+) and free fatty acids by ESI (-). After extraction of stem juice with isopropanol, diverse ions were identified as anacardic acids by ESI(-). Also, parameters influencing to the ionization process, such as capillary voltage, cone voltage and cone extraction voltage, have been evaluated for the stem juice at ESI(-). For A. chica, the proposed methodology has been proven to efficiently bioprospect the anthocyanins, and among the nine accesses evaluated, it has been possible to identify the one producing higher amounts of dying material proportionally to the biomass. We also evaluated the enzymatic treatment extraction methodology, which resulted in the increase of aglycones content, probably due to anthocyanins hydrolysis. The occurrence of hydrolysis has been also observed when leaves have been water-sprayed while drying in the sun. Seasonal influence on the production of secondary metabolite has been observed in the samples collected on the experiments performed from 2007 to 2009. For M. ilicifolia, it has been possible to characterize a series of compounds related to the anti ulcer activity and already reported in the literature, such as dulcitol, catechin and derivatives and flavonoid glycosides. The proposed methodology has been applied in the evaluation of genetic improvement of M. ilicifolia by comparing the identified compounds profiles. The developed methodology aimed at direct analyzing P. pubescens has successfully detected and identified bioactive compounds of the seed oil, allowing the fast characterization. In conclusion, the proposed MS fingerprinting methodology allows in an informative, straightforward and with minimal sample preparation the chemical characterization and quality control of natural products. (AU)