The present study has tentatively elucidated the structure of two acylated polyoxypregnane glycosides from Caralluma quadrangula (Forssk.) N.E.Br. (CQ). The analyses were performed using an electrospray-ionization quadrupole time-of-flight (ESI-Q-TOF) mass spectrometer in positive ionization modes to explore fragmentation pathways. The used ionization mode provided consistent and/or complementary information for most of the pregnane glycosides, their fragmentation sequences, and their aglycones. Presumably, this is due to higher efficiency, sensitivity, and better selectivity of the mass spectrometry-based method. The present experimental and theoretical report deals with the characteristic fragmentation behaviors of two acylated polyoxypregnane glycosides CQ1 and CQ2 from the aerial parts of C. quadrangular. A DFT Study was performed to elucidate the position of ikemoyl, and benzoyl residues in compounds CQ1 and CQ2, respectively.
Keywords: Caramulla quadrangula; DFT; UPLC-ESI-Q-TOF; acylated polyoxypregnane glycosides.