Xanthine Oxidase Inhibitory Activity on Selective Medicinal Plants

Abstract

Gout is a form of inflammatory arthritis that develops in some people who have high levels of uric acid in blood. The acid can form needle like crystals in a joint and cause sudden, severe episodes of pain, tenderness, redness, warmth and swelling. Gout is a metabolic disease associate with over productions of uric acid. Uric acid is found in a more soluble from as sodium urate. In severe hyperuricemia, crystals of sodium urate get deposited in the soft tissues, particularly in the joints. Such deposits are known as tophi. This causes inflammation in the joints resulting painful gouty arthritis. Gout is a common disorder with a worldwide distribution. Hyperuricemia, associated with gout, is present in 5-30% of the general population. Hyperurecemia results from the over production or under the excretion of uric acid and is greatly influenced by the high dietary intake of food rich in nucleic acids, such as meats, leguminous seeds and some types of seafood. During the last step of purine metabolism, XO catalyses the oxidation of Xanthine and hypoxanthine into uric acid. Medicinal plants were evaluated for their Xanthine Oxidase (XO) inhibitory potential. Their aqueous extracts prepared from used parts were tested in vitro at 100μg/ml concentration for their inhibition potencies expressed as percentage (%) inhibition of Xanthine oxidase activity. Totally 12 plants were found inhibition (%) activity of Xanthine oxidase namely Achyranthes aspera (leaves), Aegle marmelos (pulp), Aerua lanata (leaves), Amaranthus viridis (leaves), Beta vulgaris (vegetable), Boerhavia diffusa (leaves), Canthium parviflorum (leaves), Cissus quadrangularis (fruit), Coriandrum sativum (leaves), Decalepis hamiltonii (root), Moringa oleifera (leaves), and Momordica charantia (pulp). The above plants tested for XO inhibition activity. Allopurinol it is used as a positive control. The aqueous, methanolic and alcoholic extractions of these plants were used for experiments of the 12 plant extracts assays, 10 extracts demonstrated xanthine oxidase activity at 100 μg/ml, among 8 extracts showed an inhibition greater than 50% inhibition and IC₅₀ values below 100 μg/ml. The methanol extracts of Canthium parviflorum, Boerhavia diffusa, Cissus quadrangularis, Beta vulgaris, showed more than 50% inhibition. The most active was the methanol extract of the pulp of Momordica charantia (Cucurbitaeae) (IC₅₀, 40 μg/ml), the IC₅₀ value of allopurinol used as a positive control. The study demonstrated that the effect of medicinal plants used for the gout treatment was based at least in part on the XO inhibitory action.