Metal oxide-based dispersive solid-phase extraction coupled with mass spectrometry analysis for determination of ribose conjugates in human follicular fluid

Polycystic ovary syndrome (PCOS) is the most common cause of anovulatory infertility. The pathogenesis of PCOS remains unclear and early diagnosis of PCOS is challenging. Follicular fluid provides a unique window in the critical processes during oocyte and follicular maturation, and the metabolic level of follicular fluid has important impact on the developmental potential of oocytes and subsequent embryos. Previous studies demonstrated some modified ribonucleosides in biological fluids were diseases related metabolites. In this respect, analysis of endogenous modified ribonucleosides in follicular fluids will facilitate the investigation of follicular development. Here, we developed a strategy for determination of ribose conjugates from follicular fluid using metal oxide-based dispersive solid-phase extraction (DSPE) coupled with liquid chromatography multiple reaction monitoring-mass spectrometry analysis (DSPE-LC-MRM-MS/MS). Cerium dioxide (CeO2) was used to selectively recognize and capture cis-diol containing ribose conjugates from complex biological samples under basic environment. The trapped ribose conjugates were then easily released under acidic environment. The results showed that 50 potential ribose conjugates were detected in follicular fluid by the developed DSPE-LC-MRM-MS/MS method. We then further investigated the contents change of the detected ribose conjugates in follicular fluid from PCOS patients. The results indicated that the follicular fluid from healthy controls and PCOS patients can be clearly differentiated with the partial least squares-discriminate analysis (PLS-DA) based on the detected ribose conjugates. In addition, the contents of 8 ribose conjugates were significantly different between PCOS patients and healthy controls, which could potentially serve as the indicator of PCOS.