Kinetic study on the inhibition of xanthine oxidase by acylated derivatives of flavonoids synthesised enzymatically

Abstract

Studies have reported that flavonoids inhibit xanthine oxidase (XO) activity; however, poor solubility and stability in lipophilic media limit their bioavailability and applications. This study evaluated the kinetic parameters of XO inhibition and partition coefficients of flavonoid esters biosynthesised from hesperidin, naringin, and rutin via enzymatic acylation with hexanoic, octanoic, decanoic, lauric, and oleic acids catalysed by Candida antarctica lipase B (CALB). Quantitative determination by ultra-high performance liquid chromatography–mass spectrometry (UHPLC–MS) showed higher conversion yields (%) for naringin and rutin esters using acyl donors with 8C and 10C. Rutin decanoate had higher partition coefficients (0.95), and naringin octanoate and naringin decanoate showed greater inhibitory effects on XO (IC₅₀ of 110.35 and 117.51 μM, respectively). Kinetic analysis showed significant differences (p < .05) between the flavonoids before and after acylation regarding K_m values, whereas the values for V_max were the same, implying the competitive nature of XO inhibition.

Keywords:

• Acylation
• lipase
• flavonoids
• xanthine oxidase

Acknowledgements

We thank financial support from FAPESP and CAPES (postgraduate scholarships). This work was performed in partial fulfilment of the requirements for the PhD in Postgraduate Program in Health Sciences of M. E. M. B. Araújo, in São Francisco University (Bragança Paulista, Brazil).

Disclosure statement

The authors declare no conflict of interests.

Additional information

Funding

We thank financial support from FAPESP and CAPES (postgraduate scholarships).