Inhibition of porcine liver carboxylesterase by a new flavone glucoside isolated from Deverra scoparia

An endemic North African Saharan plant from of the Apiaceae family, Deverra scoparia, used locally for medicinal preparations, showed a strong inhibitory effect on porcine liver carboxylesterase. The active compound from the aerial part of the plant was purified by semi-preparative HPLC and photodiode array detection, and structurally determined by 1H, 13C NMR and mass spectroscopy methods. This compound was identified as flavone-3,4′,7-trihydroxy-3′-methoxy-7-glucoside and it was found to be a powerful competitive inhibitor of porcine liver carboxylesterase with a inhibition constant value of 16 μM. Based on the structural features of the inhibitor and the enzyme active site region, it seems that the flavonoside binds to the surface of the enzyme. The low Ki value suggests some physiological significance of such inhibitory activity, especially concerning the bio-transformation of xenobiotics.