Optimal collision energy is an eligible molecular descriptor to boost structural annotation: An application for chlorogenic acid derivatives-focused chemical profiling.

Tandem mass spectrometry (MS/MS), in particular high-resolution MS/MS, is able to provide element compositions and substructures for the detected signals. However, it is still challenging to configure the whole structures via linking those substructures. Efforts were devoted here to propose and validate optimal collision energy (OCE) to be an auxiliary structural clue to mass-to-charge ratios (m/z), and online energy-resolved MS was developed to yield OCEs. Chlorogenic acid derivatives (CADs) were utilized as the proof-of-concept because diverse isomers usually initiated by the different linkage manners between the quinic acid/shikimic acid and cinnamoyl substituents(s), i.e. caffeoyl group, coumaroyl group, etc. Liquid chromatography-hybrid ion trap-time of flight MS (LC-IT-TOF-MS) was implemented to capture CADs in two well-known herbal medicines namely Lonicerae japonicae Flos and Inulae Flos. Afterwards, hybrid triple quadrupole-linear ion trap MS (Qtrap-MS) was deployed to acquire OCEs for the primary fragmentation pathways of all detected CADs through online energy-resolved MS. On the other side, structural calculations were conducted to figure out the relationships between OCEs and bond properties. Isomeric differences occurred for OCEs, and LC elution program as well as ionization parameters could not affect OCEs. Twenty-four and thirty-one CADs were hunted and putatively identified by LC-IT-TOF-MS in Lonicerae japonicae Flos and Inulae Flos, respectively, and the structural annotation was advanced by applying the OCE-bond property relationships. To verify the structures, CADs-of-interest were purified from Lonicerae japonicae Flos using an automated fraction collector and definitely identified with NMR spectroscopy. Exact consistence occurred for the structural identification of mono-caffeoylquinic acid isomers between LC-MS/MS and NMR analyses. Consequently, OCE is an inherent physicochemical parameter of a given compound and is an eligible structural descriptor to offset the ability of LC-MS/MS towards the chemical profiling of complex matrices.

Chlorogenic and caffeic acids in 64 fruits consumed in Brazil.

This study presents unpublished data on the chlorogenic acid and caffeic acid content in fruits. Sixty-four fruits consumed in Brazil, most of which were produced domestically, were evaluated based on their levels of 3-caffeoylquinic acid, 4-caffeoylquinic acid, 5-caffeoylquinic acid, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid, 4,5-dicaffeoylquinic acid and caffeic acid. The study investigated 15 fruits that have not been reported in the literature in relation to these compounds, including several native species. The highest concentration of mono-caffeoylquinic acid was observed in strawberry, cherry, bilberry, quince and mulberry, while the dicaffeoylquinic acid was present with highest concentration in kumquat, passion fruit and sweet granadilla. Regarding caffeic acid, the highest content was found in bilberry and yellow pitaya. Considering the sum of the concentrations of these compounds, quince, cherry, bilberry, mulberry and sweet granadilla were exceptional, with concentrations between 200.0 and 569.7 mg kg-1.