Xanthine Oxidase Inhibitory Activity of Vietnamese Medicinal Plants

Abstract

Natural products are excellent sources of lead compounds in the search for new medicaments for the treatment of diseases. The largest present underexplored source of such materials lies in tropical and subtropical regions of the world. In these areas, a long tradition of ethnobotanical medicine often exists and offers a rich and relatively untapped source for the discovery of new drugs from natural products. Vietnam, a tropical Southeast Asian country, also has a long history of traditional medicine systems. 1) However, systematic exploitation of these natural resources for their human health benefits has not been carried out to a significant degree.Gout is a common disease with a worldwide distribution. Hyperuricemia, which is associated with gout, results from the overproduction or underexcretion of uric acid and is greatly influenced by a high dietary intake of foods rich in nucleic acids, such as meats (especially organ meats), leguminous seeds, some types of seafood, and food yeasts. 2,3) During the last step of purine metabolism, xanthine oxidase (XO) catalyses the oxidation of xanthine and hypoxanthine into uric acid. 4) Uricosuric drugs which increase the urinary excretion of uric acid, or XO inhibitors which block the terminal step in uric acid biosynthesis, can lower the plasma uric acid concentration, and are generally employed for the treatment of gout.5) Allopurinol is a clinically used XO inhibitor in the treatment of gout, but this drug suffers from many side effects such as hepatitis, nephropathy, and allergic reactions.6) Thus, new alternatives with increased therapeutic activity and less side effects are desired. Moreover, superoxide anion radicals generated by XO are involved in various pathological states such as hepatitis, inflammation, ischemiareperfusion, carcinogenesis, and aging.2,7) Thus, the search for novel XO inhibitors would be beneficial not only to treat gout but also to combat various other diseases.To identify potential XO inhibitory agents from natural sources, we have tested 288 extracts prepared from 96 selected medicinal plants, which are used by the indigenous people in Vietnam for the treatment of gout or diseases associated with symptoms such as rheumatism, arthritis and inflammation. In addition, the active constituents of Chrysanthemum sinense, which showed the most potent XO inhibitory activity, have been determined. Chemicals Xanthine oxidase (EC 1.2.3.2) from bovine milk (10 units/ml) and xanthine were obtained from Sigma Chemical Co. (St. Louis, MO, U.S.A.). Allopurinol was purchased from Wako Pure Chemical Industries, Ltd. (Osaka, Japan). Other reagents were of the highest grade available. MATERIALS AND METHODS Plant MaterialsPreparation of Samples Each medicinal plant (10-213 g) was cut into small pieces and extracted successively with MeOH (200-300 ml, reflux, 2 h, ϫ3), MeOH-H 2 O (1 : 1, 200-300 ml, reflux, 2 h, ϫ2), and water (200-300 ml, reflux, 2 h). The MeOH solution was evaporated under reduced pressure to give a MeOH extract, while MeOH-H 2 O (1 : 1) and w...

<i>IN VITRO</i> INHIBITION OF CELERY (<i>Apium graveolens</i> L.) EXTRACT ON THE ACTIVITY OF XANTHINE OXIDASE AND DETERMINATION OF ITS ACTIVE COMPOUND

“…5). The high inhibition effect was comparable with other research related to Iranian medicinal plants [8], Vietnamese traditional medicines [9] and selected Philippine medicinal plants [17]. Therefore, the ethanol extract of herb was obtained to be separated using column chromatography and tested further on their toxicity toward shrimp larvae as well as on their enzymatic activity.…”

“…The medicinal value of these plants lies in some chemical substances that produce a definite physiological action on the human body. XO inhibitors have been found in a wide variety of plants from Iran [8], and Vietnam [9]. Celery root and leave juices applied alone or with doxorubicin, increased XO activity [10].…”

Securidaca longipedunculata Fresen (Polygalaceae): A review of its ethnomedicinal uses, phytochemistry, pharmacological properties and toxicology

“…XO catalyses the oxidation of xanthine and hypoxanthine into uric acid, which may lead to a disease known as gout (Kong et al, 2000). Some drugs and plant-derived extracts which serve as XO inhibitors may block uric acid biosynthesis, lower the plasma uric acid concentration and are used to treat gout (Nguyen et al, 2004). The tested S. longipedunculata extracts revealed negligible inhibition of AChE, CES and XO.…”

Cytotoxic constituents from the seeds of VietnameseCaesalpinia sappan

“…Many reports showed that the main components in the heartwood of C. sappan are phenolics with anti-inflammatory, antibacterial, and anti-influenza activities (Choi et al, 2007;Cuong et al, 2012;Kim et al, 2012;Namikoshi et al, 1987;Shimokawa et al, 1985;Washiyama et al, 2009). Nguyen et al (2004) reported that the methanolic extract of the heartwood of C. sappan collected in Vietnam exhibited significant XO inhibitory activity. However, limited information is available concerning the principles of the seeds of C. sappan.…”