Lingham R B, Silverman K C, Jayasuriya H, Kim B M, Amo S E, Wilson F R, Rew D J, Schaber M D, Bergstrom J D, Koblan K S, Graham S L, Kohl N E, Gibbs J B, Singh S B
Merck Research Laboratories, P.O. Box 2000, Rahway, New Jersey 07065, and Merck Research Laboratories, Sumneytown Pike, West Point, Pennsylvania 19486, USA.
J Med Chem. 1998 Nov 5;41(23):4492-501. doi: 10.1021/jm980356+.
We have identified a novel fungal metabolite that is an inhibitor of human farnesyl-protein transferase (FPTase) by randomly screening natural product extracts using a high-throughput biochemical assay. Clavaric acid [24, 25-dihydroxy-2-(3-hydroxy-3-methylglutaryl)lanostan-3-one] was isolated from Clavariadelphus truncatus; it specifically inhibits human FPTase (IC50 = 1.3 microM) and does not inhibit geranylgeranyl-protein transferase-I (GGPTase-I) or squalene synthase activity. It is competitive with respect to Ras and is a reversible inhibitor of FPTase. An alkaline hydrolysis product of clavaric acid, clavarinone [2,24,25-trihydroxylanostan-3-one], lacking the 3-hydroxy-3-methylglutaric acid side chain is less active as a FPTase inhibitor. Similarly, a methyl ester derivative of clavaric acid is also inactive. In Rat1 ras-transformed cells clavaric acid and lovastatin inhibited Ras processing without being overtly cytotoxic. Excess mevalonate reversed the effects of lovastatin but not of clavaric acid suggesting that the block on Ras processing by clavaric acid was due to inhibition of FPTase and not due to inhibition of HMG-CoA reductase. Despite these results, the possibility existed that clavaric acid inhibited Ras processing by directly inhibiting HMG-CoA reductase. To directly examine the effects of clavaric acid and clavarinone on HMG-CoA reductase, cholesterol synthesis was measured in HepG2 cells. No inhibition of HMG-CoA reductase was observed indicating that the inhibition of Ras processing by this class of compounds is due to inhibition of FPTase. To date, clavaric acid is the second reported nitrogen-free compound that competes with Ras to inhibit FPTase activity. A series of related compounds derived from computer-based similarity searches and subsequent rational chemical synthetic design provided compounds that exhibited a range of activity (0.04 --> 100 microM) against FPTase. Modest changes in the structures of these inhibitors dramatically change the inhibitory activity of these inhibitors.
我们通过使用高通量生化检测法随机筛选天然产物提取物，鉴定出一种新型真菌代谢产物，它是人类法尼基蛋白转移酶（FPTase）的抑制剂。从截顶棒瑚菌中分离出了棒酸[24,25-二羟基-2-(3-羟基-3-甲基戊二酰基)羊毛甾烷-3-酮]；它特异性抑制人类FPTase（IC50 = 1.3 microM），且不抑制香叶基香叶基蛋白转移酶-I（GGPTase-I）或角鲨烯合酶活性。它对Ras具有竞争性，是FPTase的可逆抑制剂。棒酸的碱性水解产物棒酮[2,24,25-三羟基羊毛甾烷-3-酮]，缺少3-羟基-3-甲基戊二酸侧链，作为FPTase抑制剂的活性较低。同样，棒酸的甲酯衍生物也无活性。在Rat1 ras转化细胞中，棒酸和洛伐他汀抑制Ras加工过程，且无明显细胞毒性。过量的甲羟戊酸可逆转洛伐他汀的作用，但不能逆转棒酸的作用，这表明棒酸对Ras加工过程的阻断是由于抑制FPTase，而非抑制HMG-CoA还原酶。尽管有这些结果，但棒酸通过直接抑制HMG-CoA还原酶来抑制Ras加工过程的可能性仍然存在。为了直接检测棒酸和棒酮对HMG-CoA还原酶的影响，在HepG2细胞中测量了胆固醇合成。未观察到对HMG-CoA还原酶的抑制作用，表明这类化合物对Ras加工过程的抑制是由于抑制FPTase。迄今为止，棒酸是第二种被报道的与Ras竞争以抑制FPTase活性的无氮化合物。一系列基于计算机相似性搜索及后续合理化学合成设计衍生的相关化合物，提供了对FPTase表现出一系列活性（0.04 --> 100 microM）的化合物。这些抑制剂结构的适度变化会显著改变其抑制活性。
