Guerrero R O, Guzman A L
School of Pharmacy, University of Puerto Rico, San Juan 00936-5067, USA.
P R Health Sci J. 1998 Dec;17(4):359-64.
This study was conducted to search for xanthine oxidase inhibitors in natural products obtained from plants collected in Puerto Rico and to assess the influence of these extracts in the prevention of cataractogenesis.
Allopurinol is currently a xanthine oxidase inhibitor used in the treatment of gout. New alternatives with increased therapeutic activity and less side effects should be investigated. Preclusion of cataractogenesis in diabetic rats is also the focus of this investigation. Natural products in the form of plant extracts from Puerto Rico offer a rich and relatively untapped source for the discovery of new drugs that may address these kind of problems.
Nineteen collections of Myrtaceae plant extracts were screened for xanthine oxidase inhibition. A spectrophotometrical method was used employing allopurinol as positive control and a blank as negative control. A protocol of the assay with slight modifications was followed from the literature. Two extracts with the highest percentages of xanthine oxidase inhibition were evaluated for possible prevention of cataractogenesis in streptozotocin diabetic rats. The animals were given to drink these plant extracts ad libitum for three months while controls received water. The appearance of cataracts was assessed physically.
Two of the nineteen plant extracts showed high inhibition percentages of xanthine oxidase. Eucalyptus deglupta and Syzygium malaccense displayed 51% and 64% inhibitions (IC50 44.5 micrograms/ml and IC50 51 micrograms/ml), respectively. As for the cataractogenesis inhibition, laboratory animals that drank E. deglupta for three months did not develop cataracts.
Two plant extracts provided positive results with varying degrees of inhibition of xanthine oxidase. S. malaccense demonstrated the greatest xanthine oxidase inhibitory activity whereas E. deglupta presented the best finding for cataractogenesis prevention. The procedures used in this investigation are useful for the in vitro screening of xanthine oxidase inhibition and the in vivo evaluation of cataractogenesis prevention.
本研究旨在从波多黎各采集的植物天然产物中寻找黄嘌呤氧化酶抑制剂，并评估这些提取物对预防白内障形成的影响。
别嘌醇是目前用于治疗痛风的黄嘌呤氧化酶抑制剂。应研究具有更高治疗活性和更少副作用的新替代物。预防糖尿病大鼠白内障形成也是本研究的重点。来自波多黎各的植物提取物形式的天然产物为发现可能解决这类问题的新药提供了丰富且相对未开发的来源。
对19种桃金娘科植物提取物进行黄嘌呤氧化酶抑制筛选。采用分光光度法，以别嘌醇作为阳性对照，空白作为阴性对照。该检测方法遵循文献中略有修改的方案。对两种黄嘌呤氧化酶抑制率最高的提取物进行评估，以确定其对链脲佐菌素诱导的糖尿病大鼠白内障形成的预防作用。动物自由饮用这些植物提取物三个月，而对照组饮用清水。通过肉眼评估白内障的出现情况。
19种植物提取物中有两种显示出较高的黄嘌呤氧化酶抑制率。大叶桉和马六甲蒲桃的抑制率分别为51%和64%（IC50分别为44.5微克/毫升和51微克/毫升）。至于白内障形成抑制，饮用大叶桉三个月的实验动物未出现白内障。
两种植物提取物在黄嘌呤氧化酶抑制方面取得了不同程度的阳性结果。马六甲蒲桃表现出最大的黄嘌呤氧化酶抑制活性，而大叶桉在预防白内障形成方面表现最佳。本研究中使用的方法对于黄嘌呤氧化酶抑制的体外筛选和白内障形成预防的体内评估是有用的。
