Identification of diterpenos flexibiliene from Stillingia loranthaceae, using LC-MS² and Molecular Networking

The genus Stillingia (Euphorbiaceae) is represented by 30 species distributed in the America and islands of the Pacific. In Brazil, seven species are distributed between Caatinga and Atlantic Forest, four of which are predominantly Caatinga. Only four species of Stillingia were studied chemically. Diterpenes with rare flexibilane skeletons have been reported from the roots of S. sanguinolenta. These compounds demonstrated interesting pharmacological activities. The use of hyphenated techniques, such as LC-MS2, coupled with bioinformatics techniques such as Molecular Networking, are able to rapidly identify substances from complex biological extracts. Thus, the objective of the study was the identification of flexibilene diterpenes, using LC-MS2 and Molecular Networking, of root bark of S. loranthaceae. The botanical identification was carried out in the Herbarium Alexandre Leal Costa at the Biology Institute of UFBA. The hexane extract (HE) from the root bark was analyzed by LC-MS2, and the data were used to generate a molecular network in GNPS site. It was possible to observe a cluster represent this diterpene skeleton in the molecular network. This data associated to MS/MS fragmentation approach suggested the presence of several new flexibilene diterpenes and known compounds (tonantzitlolone A-C) already identified from other Stillingia species.