In vitro metabolism of β‐lapachone (ARQ 501) in mammalian hepatocytes and cultured human cells

Abstract

ARQ 501 (3,4-dihydro-2,2-dimethyl-2H-naphthol[1,2-b]pyran-5,6-dione, beta-lapachone) is an anticancer agent, currently in multiple phase II clinical trials as monotherapy and in combination with other cytotoxic drugs. This study focuses on in vitro metabolism in cryopreserved hepatocytes from mice, rats, dogs and humans using [(14)C]-labeled ARQ 501. Metabolite profiles were characterized using liquid chromatography/mass spectrometry combined with an accurate radioactivity counter. Ion trap mass spectrometry was employed for further structural elucidation. A total of twelve metabolites were detected in the mammalian hepatocytes studied; all of which but one were generated from phase II conjugation reactions. Ten of the observed metabolites were produced by conjugations occurring at the reduced ortho-quinone carbonyl groups of ARQ 501. The metabolite profiles revealed that glucuronidation was the major biotransformation pathway in mouse and human hepatocytes. Monosulfation was the major pathway in dog, while, in rat, it appears glucuronidation and sulfation pathways contributed equally. Three major metabolites were found in rats: monoglucuronide M1, monosulfate M6, and glucuronide-sulfate M9. Two types of diconjugation metabolites were formed by attachment of the second glycone to an adjacent hydroxyl or to an existing glycone. Of the diconjugation metabolites, glucosylsulfate M10, diglucuronide M5, and glucuronide-glucoside M11 represent rarely observed phase II metabolites in mammals. The only unconjugated metabolite was generated through hydrolysis and was observed in rat, dog and human hepatocytes. ARQ 501 appeared less stable in human hepatocytes than in those of other species. To further elucidate the metabolism of ARQ 501 in extrahepatic sites, its metabolism in human kidney, lung and intestine cells was also studied, and only monoglucuronide M1 was observed in all the cell types examined.

Light effect on the stability of β-lapachone in solution: pathways and kinetics of degradation

“…[19] Compound 2 has been identified as the only unconjugated metabolite of bLAP in hepatocytes, a major metabolite in dogs and a minor one in rats and humans. [20] This compound showed low activity against carcinoma walker 256. [21] 13-Hydroxy-lapachol (2-hydroxy-3-(3-hydroxy-3-methylbutyl)-naphthalene-1,4dione): 1 (Figure 2, compounds 3, 4, 5 and 6).…”

The chemotherapeutic effects of lapacho tree extract: β-lapachone

“…β-lapachone has been demonstrated to elicit significant anti-tumor activity against many cancer cells, including leukemia [10,11], prostate cancer [12], osteosarcoma [13], breast cancer [14], bladder cancer [15], lung cancer [16], hepatoma [9], and even the worst pancreatic cancer [17][18][19]. There are at least three phase I and three phase II clinical trials of β-lapachone, as the name of ARQ 501, on treating patients with various cancers (National Cancer Institute) [20][21][22].…”

Potent antileukemic action of naphthoquinoidal compounds: evidence for an intrinsic death mechanism based on oxidative stress and inhibition of DNA repair

“…5,83 With regard to the side effects of chemotherapy, it is essential to know whether a compound exerts a harmful effect on normal dividing cells. In this context, with the exception of nor-β-lapachone (IC 50 for V79 cells was greater than 21.9 µmol L -1 ), all nor-β-lapachone derivatives tested exerted a cytotoxic effect against V79 cells, with the antiproliferative potential ranging from moderate (2 and 3) to high (1 and 4) ( Table 5).…”