In recent years, Hoodia plant and the preparations of Hoodia have become increasingly popular. These dietary
supplements are promoted for weight loss. The limited availability of this plant material and its increasing popularity leads to
the possibility of adulterations by other species or even genera. Previous results of screenings give rise to serious concerns
about the safety of commercial products claimed to be Hoodia, as a considerable amount seems to lack Hoodia. There is a
strong need to develop an effective analytical protocol that can be routinely used to authenticate either plant extracts or
commercial products that claimed to contain Hoodia gordonii.
Fourteen samples were used for this analysis. Of these fourteen samples, one known to be authentic Hoodia gordonii
from South Africa, three Hoodia species from Missouri Botanical Garden, USA, three Hoodia gordonii samples from
commercial source, five were commercially obtained dietary supplements claimed to contain Hoodia gordonii, and two were
Opuntia species (spp.), an adulterant which grows quickly with no appetite suppressing activity associated. Samples were
analyzed by an ACQUITY UPLC/Synapt G2 MS system with an UPLC HSS T3 column (100mm!2.1mm). The flow rate was
rate was 0.6 mL/min with water with 0.05% formic acid (A) and acetonitrile (B) as mobile phase. ESI+ and ESI- experiments
were performed with data acquired over a range of m/z 100 to 1700.
The first step of this workflow was to analyze these samples using a typical plant metabolomics analysis
protocol, i.e.: UPLC/oaTOF MS with data indepent acquisition (no less than 3 injections per sample) for the entire sample set.
Multi-Variate Statistical Analysis data processing strategy was used so that as initial results, a group of chemical markers can
be generated, these markers are characteristics of Hoodia gardonii and were identified based on comprehensive chemical
fingerprinting. If samples were analyzed in both positive and negative ionization modes, then two lists of chemical markers can
be obtained, one from positive ESI and other from negative ESI. Some markers will be on both lists which help the
confirmations; some markers will be on only one mode as compounds ionization behaviors differ. Our preliminary results were
obtained based on PCA analysis for the entire sample set, followed by OPLS-DA analysis of authentic Hoodia gordonii vs
different samples. There are a group of markers consistently appeared to be the key markers for Hoodia gordonii regardless
what was the other group the Hoodia gordonii was compared against. In our results, in ESI-, we identified 11 markers as
Hoodia gordonii markers, and in ESI+, we identified 30 markers as Hoodia gardonii markers. The second step of this
workflow was to create a Hoodia gordonii LC/MS authentication method using the identified marker information. This method
contains the name of the marker compound along with its expected LC retention time, exact molecular mass information, and
MS-MS fragment information (optional). In this project, two methods were created, one based on ESI+ results, and one based
on ESI- results. Each method can be used to test unknown samples based on which ionization mode was used during testing.
For unknown sample that claims to contain Hoodia gordonii as an ingredient, one UPLC/MS injection was made, an
application manager from the mass spec vendor allows east application of the Hoodia authentication method, as a result, a
report was automatically generated to indicate how many of the essential markers were present in the unknown sample at what
concentration level so that the authentication of the unknown sample can be easily accomplished.
A generic workflow based on comprehensive chemical fingerprinting using UPLC/TOF MSE with novel
informatics solution for plant authentication (Hoodia gordonii)