1H NMR simultaneous identification of health-relevant compounds in propolis extracts

AbstractIntroduction- Propolis is a resinous substance collected by bees from exudates of different plantswhich is rich in well-known health-relevant phenolic compounds such as flavonoids and phenolicacids. Propolis extracts are very complex matrices difficult to study. Different analytical methodsare usable to analyse propolis extracts and to obtain chemical fingerprint but at our knowledgeNMR was not previously used for this purpose.Objective- This study aims to demonstrate that it is possible to use the 1H NMR for thesimultaneous recognition of phenolic compounds in complex matrices, such as propolis extracts,using appropriate tools for spectra pre-treatment and analysis.Methodology- In this work twelve typical phenolic propolis compounds (apigenin, chrysin,galangin, kaempferol, quercetin, naringenin, pinocembrin, pinostrobin, caffeic acid, cinnamic acid,p-coumaric acid, ferulic acid) were considered as reference compounds and their presence insamples were verified by HPLC-MS. A simple 1H NMR sequence was used to obtain spectra ofsamples. Spectra were pre-treated by using an appropriate tool for spectra alignment and analysedby using a software for the study of spectra originated from complex matrices. Sixty-five propolissamples were used to test the proposed identification procedure.Results- Ten out of twelve considered compounds were identified as statistically significant in mostof the samples.Conclusion- This work suggests that it is possible to efficiently use the 1H NMR, coupled withappropriate spectral analytical tools, for the simultaneous detection of phenolic compounds incomplex matrices.