Nair Vipin D P, Dairam A, Agbonon A, Arnason J T, Foster B C, Kanfer I
Division of Pharmaceutics, Faculty of Pharmacy, Rhodes University, Grahamstown, South Africa.
J Agric Food Chem. 2007 Mar 7;55(5):1707-11. doi: 10.1021/jf0619838. Epub 2007 Feb 13.
African potato (AP) is widely used as an immune booster for the treatment of various ailments. The norlignan glycoside hypoxoside, a major phytoconstituent of AP, its aglycon rooperol, and an aqueous preparation of lyophilized AP corms were screened for in vitro antioxidant activity using the DPPH (1,1-diphenyl-2-picryl hydrazine) and FRAP (ferric reducing ability of plasma) tests. Inhibition of quinolinic acid (QA) induced lipid peroxidation in rat liver tissue was studied in vitro using the thiobarbituric assay (TBA). Superoxide free radical scavenging activity was determined by the nitroblue tetrazolium assay. An isocratic HPLC method was developed to quantitatively determine both hypoxoside and rooperol concurrently. While rooperol and AP extracts reduced QA-induced lipid peroxidation in rat liver homogenates and significantly scavenged the superoxide anion at pharmacological doses, in comparison, hypoxoside was virtually devoid of activity. Since hypoxoside is converted to rooperol in vivo following administration of AP, the results indicate that the hypoxoside component in AP could have value as an antioxidant prodrug.
非洲土豆（AP）被广泛用作免疫增强剂来治疗各种疾病。使用DPPH（1,1-二苯基-2-苦基肼）和FRAP（血浆铁还原能力）试验，对AP的主要植物成分诺木脂素苷hypoxoside、其苷元罗珀醇以及冻干AP球茎的水性制剂进行了体外抗氧化活性筛选。使用硫代巴比妥酸测定法（TBA）在体外研究了喹啉酸（QA）诱导的大鼠肝组织脂质过氧化的抑制作用。通过氮蓝四唑测定法测定超氧阴离子自由基清除活性。开发了一种等度高效液相色谱法以同时定量测定hypoxoside和罗珀醇。虽然罗珀醇和AP提取物在大鼠肝匀浆中降低了QA诱导的脂质过氧化，并在药理剂量下显著清除超氧阴离子，但相比之下，hypoxoside几乎没有活性。由于在给予AP后hypoxoside在体内会转化为罗珀醇，结果表明AP中的hypoxoside成分作为抗氧化前药可能具有价值。
