Identification and Quantification of Fructoborate Ester Complex Using Liquid Chromatography Coupled with Q Exactive Orbitrap Mass Spectrometry

Abstract

The identification of fructoborate complex in food matrices using liquid chromatography coupled with quadrupole Orbitrap mass spectrometry was investigated in this study. The LC/MS method was established by optimization of mobile phases and direct infusion of FruiteX-B ® brand calcium fructoborate (CaFB) solution to Q Exactive Orbitrap mass spectrometer to obtain MS operation parameters. The precursor ion m/z 367.10522 was dissociated further for conformation analysis of fructoborate complex. The method was applied to identify and quantify fructoborate in freeze dried apricot fruit and raisins. It was found that fructose-11 B-fructose di-ester complex was present in these fruits. The results were further verified by multinuclear solid and liquid states NMR spectroscopy analysis.

The Fructoborates: Part of a Family of Naturally Occurring Sugar–Borate Complexes—Biochemistry, Physiology, and Impact on Human Health: a Review

“…Plant-based materials do not serve as a primary source of inorganic B-containing molecules. CaFB, the most common form of FBE, is naturally found in fresh fruits, vegetables and honey, and in dried fruits (plums, raisins, apricots) [ 20 ]. Fructoborate is found as a protonated diester fructoborate (PFB) resulting from the sorbitol metabolic pathway in the phloem and extracellular peach nectar [ 19 , 21 ].…”

“…This industrially produced CaFB is being widely used as a dietary supplement for joint health, specifically for modulation of the symptoms of age-related joint discomfort and degeneration [ 17 , 19 ]. CaFB has been presented in numerous published papers that report its chemistry [ 20 , 33 , 46 , 47 ]. Additionally, it has been repeatedly reported to significantly reduce pain and improve flexibility in a clinical setting as evidenced by improvements in Western Ontario and McMaster Universities Arthritis Index (WOMAC) and McGill Indices [ 27 – 30 ].…”

“…The results of the thermal assay (TGA), combined with those of XRD, FTIR and Raman spectroscopies, high-performance thin-layer chromatography (HPTLC) [ 61 ], and liquid chromatography–multistage accurate mass spectrometry (LC-MSn) [ 20 ], led to the conclusion that an industrially produced CaFB is a similar product to the diester fructoborate anion (Fig. 1 ), and identical to the fructoborate molecule found in nature, including 2.5 ± 0.1% B and 4.6 ± 0.1% Ca [ 33 ].…”

“…Some studies have identified three types of B-containing molecules of CaFB in aqueous solutions: free BA, the diester, and the monoester complex (the speciation of fructoborates is highlighted in Fig. 2 ) [ 20 , 33 ]. Subsequently, fructoborate species may possess a biological role such as functioning as a coenzyme or cofactor (Fig.…”

“…Generally, as boric acid/borate enters the human/animal cell, it blocks other biomolecules that contain cis -diols, for example, nicotinamide adenine dinucleotide (NAD), S -adenosyl methionine (SAM), flavin adenine dinucleotide (FAD), and ribonuclease (RNase) [4, 13]. Sugar–borate complexes that occur naturally in plants are perhaps the most recognized biogenic cis -diol organic B species [4, 14–20]. Various surveys [21–24] have demonstrated that sugar–borates are crucial in the development of plants (for example, the normal cell wall growth, membrane functions, and the biosynthesis of lignin), but more recently, sugar–borates have been demonstrated to be potentially important modulators of human health [17, 18, 25, 26].…”