Pro-inflammatory enzyme inhibition of lipoxygenases by flavonoid rich extract from Artemisia vulgaris

Abstract

The peroxyl radicals generated by the activity of lipoxygenases (LOX) are mediators to trigger inflammatory diseases. Therefore, it is important to investigate potent LOX inhibitor for modulating the occurrence and resolving inflammatory processes. Artemisa vulgaris, is a herbal plant that is known for flavonoids, potentially inhibiting lipid peroxidation and scavenging radicals. The objectives of the present study were to obtain flavonoids rich extract from A. vulgaris, and determine the inhibitory mode of the extract against LOX. The flavonoids rich extract was optimized in an ultrasound assisted extraction using ionic liquids as extraction solvent. The results found that the optimum conditions; ratio of solid-to-liquid (1:10) and 30 min of extraction time could produce the high yield (10.14 %) and flavonoid content (5.30 mg QE/g). The LOX activity was demonstrated to follow a mixed mode of inhibition in the presence of the flavonoid rich extract as an inhibitor. The Michaelis-Menten constant (Km) was increased from 0.283 µM to 0.435 µM, whereas the maximum velocity was reduced from 0.22 µM/min to 0.058 µM/min in the inhibition. The flavonoids rich extract is likely to be a natural potent non-competitive inhibitor which may bind to free LOX or substrate-bound LOX.

Keywords: Artemisia vulgaris; Flavonoids; Ionic liquids; LOX inhibition activity; Ultrasound assisted extraction.