Untargeted metabolomics analysis of Diospyros celebica Bakh. from three different geographical origins in Sulawesi island using UHPLC-Q-Orbitrap HRMS

Diospyros celebica Bakh is known as Sulawesi ebony and is reported to have quinones as the primary metabolite. The metabolites contained in Sulawesi ebony can be influenced by several factors, one of which is the growth location. This study aims to identify which metabolites are present in Sulawesi ebony wood using UHPLC-Q-Orbitrap HRMS and to determine the origin of Sulawesi ebony wood on Sulawesi Island, Indonesia, in combination with principal component analysis (PCA) and orthogonal partial least square-discriminant analysis (OPLS-DA). Forty-five samples of Sulawesi ebony were sonicated using 80% ethanol and analyzed using UHPLC-Q-Orbitrap HRMS. A total of 35 metabolites were identified based on an in-house database (putative identification). The quinone group is the most present among the identified metabolites in the Sulawesi ebony wood. The resulting base peak chromatograms were preprocessed using correlation optimized warping to align all sample chromatograms before being analyzed with PCA and OPLS-DA. The resulting score plot showed that based on the PCA, the origins could not be distinguished, while OPLS-DA was able to discriminate Sulawesi ebony from the three provinces. Diomelquinone A was identified as a marker compound for Sulawesi ebony from West Sulawesi province, while 3-methylplumbagin and kaempferol were markers for South Sulawesi province. These metabolites can be used as diagnostic markers for the growth location of Sulawesi ebony on Sulawesi island, Indonesia.