Hancornia speciosa Gomes (Apocynaceae), vulgarly known as mangaba, has its antihypertensive activity demonstrated previously by us, being the activity ascribed to polyphenols and cyclitols like L-(+)-bornesitol (1). We herein investigated the stability of the bioactive marker bornesitol submitted to forced degradation conditions.
Bornesitol employed in the study was isolated from H. speciosa leaves, and its purity was confirmed by LC-MS, 1H and 13C NMR analysis.
To evaluate bornesitol stability, a HILIC-UHPLC-ESI-MS/MS method was developed based on MRM (Multiple Reaction Monitoring) acquisition mode and negative ionization mode, employing both specific (m/z 193 →161 Da) and confirmatory (m/z 193 →175 Da) transitions. A gradient elution of 0.1% formic acid in water and acetonitrile was performed in a HILIC column.
The method was validated and showed adequate linearity (r2>0.99), selectivity, specificity, accuracy, and precision (RSD < 2.9%). The method was robust for deliberate variations on dessolvation temperature, but not for changes in the flow rate and dessolvation gas.
The results from the stability studies allowed us to classify bornesitol as labile for acidic and alkaline hydrolysis, but as very stable for oxidative and neutral hydrolysis exposure. Bornesitol was categorized as practically stable under photolysis degradation, whereas a considerable reduction on its contents was induced by metal ions and thermolysis exposure.
Degraded samples from neutral hydrolysis and thermolysis were assayed in vitro for ACE inhibition and showed a substantial decrease in biological activity as compared to intact bornesitol (Figure 1). myo-Inositol was identified as the major degradation product in both matrices (Figure 2). This is the first report on bornesitol stability under different stress conditions and the obtained data are relevant for the development and quality control of standardized products from H. speciosa leaves.