Farnesol-derived Dicarboxylic Acids in the Urine of Animals Treated with Zaragozic Acid A or with Farnesol

Abstract

Farnesyl diphosphate, the substrate for squalene synthase, accumulates in the presence of zaragozic acid A, a squalene synthase inhibitor. A possible metabolic fate for farnesyl diphosphate is its conversion to farnesol, then to farnesoic acid, and finally to farnesol-derived dicarboxylic acids (FDDCAs) which would then be excreted in the urine. Seven dicarboxylic acids were isolated by high performance liquid chromatography (HPLC) from urine of either rats or dogs treated with zaragozic acid A or rats fed farnesol. Their structures were determined by nuclear magnetic resonance analysis. Two 12-carbon, four 10-carbon, and one 7-carbon FDDCA were identified. The profile of urinary dicarboxylic acids from rats fed farnesol was virtually identical to that produced by treating with zaragozic acid A, establishing that these dicarboxylic acids are farnesolderived. By feeding [1-14 C]farnesol and comparing the mass of the dicarboxylic acids produced with the ultraviolet absorption of the HPLC peaks, a method to quantitate the ultraviolet-absorbing FDDCAs was devised. When rats were treated with zaragozic acid A, large amounts of FDDCAs were excreted in the urine. The high level of FDDCAs that were found suggests that their synthesis is the major metabolic fate for carbon diverted from cholesterol synthesis by a squalene synthase inhibitor. A metabolic pathway is proposed to explain the production of each of these FDDCAs.Squalene synthase is an attractive target for the development of a cholesterol synthesis inhibitor that could serve as a cholesterol lowering agent. Cholesterol synthesis inhibitors, such as lovastatin (1), a 3-hydroxy-3-methylglutaryl-coenzyme A inhibitor, are effective cholesterol-lowering agents in man and/or animals. Squalene synthase catalyzes the first committed step in cholesterol synthesis, and selective inhibition of this enzyme should result in inhibition of cholesterol synthesis without affecting the synthesis of other isoprenoids such as dolichol, ubiquinone, and the prenylated proteins. A novel class of fungal metabolites, known as zaragozic acids, has been recently discovered and characterized as potent inhibitors of squalene synthase (2-8). The zaragozic acids are subnanomolar inhibitors of squalene synthase in vitro, they inhibit cholesterol synthesis from acetate or mevalonate in cell culture and in animal models, and also have been shown to lower plasma cholesterol when administered orally in certain animal species (4, 5,8). Other classes of squalene synthase inhibitors have also been discovered (for a review, see Ref. 9).An important question to be answered for these compounds is the metabolic effect of inhibition of squalene synthase. The squalene synthase reaction consists of the reductive dimerization of two molecules of farnesyl diphosphate (FPP) 1 to form a molecule of squalene (10). The primary consequence of inhibition of this reaction would be an accumulation of FPP. Thus, the metabolic fate of FPP in the presence of a squalene synthase inhibitor is of interest. Previous wor...

Squalene synthase inhibitors suppress triglyceride biosynthesis through the farnesol pathway in rat hepatocytes

“…In animal experiments, SQS inhibitors increased farnesol and farnesol-derived dicarboxylic acids in liver tissues (4,18,19). Bostedor and colleagues identified common dicarboxylic acids that were increased in urine of rats and dogs treated with either zaragozic acid A, a SQS inhibitor, or farnesol (20). The identified diacids included 3,7-dimethyl-2, 6-octadiene-1,8-dioic acid (free acid form of compound 4 in Fig.…”

“…SQS inhibitors increase farnesol and farnesol-derived dicarboxylic acids in vitro (17), and an increase was also reported in mice, rats, and beagle dogs (4,(18)(19)(20). To study the effects of farnesol and its derivatives on triglyceride biosynthesis, we added 100 M farnesol, squalene, farnesyl acetate, 3,7,11-trimethyl-2,6,10-dodecatriene-1,12-dioic acid methylester, 3,7-dimethyl-2,6-decadiene-1,10-dioic acid methylester, 3,7-dimethyl-2,6-octadiene-1,8-dioic acid methylester, 3-methyl-2-hexamonoene-1,6-dioic acid methylester, and suberic acid to hepatocytes, and evaluated their ability to inhibit triglyceride biosynthesis ( Fig.…”

“…SQS inhibitors have been reported to increase farnesol and farnesol-derived dicarboxylic acids owing to the in-crease of FPP utilization in other branching pathways of isoprenoid metabolism (4,(17)(18)(19)(20). Farnesol is produced from FPP by farnesyl pyrophosphatase (21).…”

A novel bisphosphonate inhibitor of squalene synthase combined with a statin or a nitrogenous bisphosphonate in vitro

“…It is currently unknown whether this was due to an enzyme inhibitory class effect or whether it was specifi c to the drug. Inhibition of SQS can result in the accumulation of both FPP and FPP metabolites, such as farnesol-derived dicarboxylic acids ( 13 ), which could be responsible for the possible hepatotoxicity with the high-dose monotherapy of lapaquistat. Farnesol itself can be proapoptotic at high concentrations ( 14 ).…”

Modulation of Neuronal Voltage-gated Calcium Channels by Farnesol

“…Thus, over the time course of a typical neuronal action potential, L-type channels were the most effectively inhibited channel isoform, followed by N-type channels (IC 50 values obtained from dose-response curves for peak current inhibition (32,33). In hepatic tissue, farnesol is catabolized into farnesoic acid and dicarboxylic acids (34) or is re-phosphorylated into farnesyl pyrophosphate by a specific kinase (35,36). Multistep branches of the pathway are marked with dotted arrows for simplicity.…”