Summary: A coumarin derivative possessing properties as a spasmolytic, choleretic and light-protective agent. It is also used in ANALYTICAL CHEMISTRY TECHNIQUES for the determination of NITRIC ACID.

Top Publications

  1. Yoshihara S, Kon A, Kudo D, Nakazawa H, Kakizaki I, Sasaki M, et al. A hyaluronan synthase suppressor, 4-methylumbelliferone, inhibits liver metastasis of melanoma cells. FEBS Lett. 2005;579:2722-6 pubmed
    ..These HA knock-down mice displayed suppressed liver metastasis. Thus, both cell surface HA of melanoma cells and recipient liver HA can promote liver metastasis, indicating that MU has potential as an anti-metastatic agent. ..
  2. Kakizaki I, Kojima K, Takagaki K, Endo M, Kannagi R, Ito M, et al. A novel mechanism for the inhibition of hyaluronan biosynthesis by 4-methylumbelliferone. J Biol Chem. 2004;279:33281-9 pubmed
    ..We propose a novel mechanism for the MU-mediated inhibition of HA synthesis involving the glucuronidation of MU by endogenous UGT resulting in a depletion of UDP-GlcUA. ..
  3. Morohashi H, Kon A, Nakai M, Yamaguchi M, Kakizaki I, Yoshihara S, et al. Study of hyaluronan synthase inhibitor, 4-methylumbelliferone derivatives on human pancreatic cancer cell (KP1-NL). Biochem Biophys Res Commun. 2006;345:1454-9 pubmed
    ..Next, cell surfaces of cancer cells were analyzed by particle-exclusion assay. In conclusion, both hydroxy and methyl groups are necessary for HA inhibition by MU, and two hydroxy groups inhibited HA synthesis more strongly than MU. ..
  4. Urakawa H, Nishida Y, Wasa J, Arai E, Zhuo L, Kimata K, et al. Inhibition of hyaluronan synthesis in breast cancer cells by 4-methylumbelliferone suppresses tumorigenicity in vitro and metastatic lesions of bone in vivo. Int J Cancer. 2012;130:454-66 pubmed publisher
    ..HA accumulation in bone metastatic lesions was perturbed peripherally. These data suggest that MU might be a therapeutic candidate for bone metastasis of breast cancer via suppression of HA synthesis and accumulation. ..
  5. Piccioni F, Malvicini M, Garcia M, Rodriguez A, Atorrasagasti C, Kippes N, et al. Antitumor effects of hyaluronic acid inhibitor 4-methylumbelliferone in an orthotopic hepatocellular carcinoma model in mice. Glycobiology. 2012;22:400-10 pubmed publisher
    ..Importantly, 4-MU induced the apoptosis of HSCs in vitro and decreased the amount of activated HSCs in vivo. In conclusion, our results suggest a role for 4-MU as an anticancer agent for HCC associated with advanced fibrosis. ..
  6. Tofuku K, Yokouchi M, Murayama T, Minami S, Komiya S. HAS3-related hyaluronan enhances biological activities necessary for metastasis of osteosarcoma cells. Int J Oncol. 2006;29:175-83 pubmed
    ..These results suggest that HAS3-related HA enhances crucial biological activities necessary for metastasis and that HAS2-related HA offers an advantageous environment for osteosarcoma cells. ..
  7. Funahashi M, Nakamura T, Kakizaki I, Mizunuma H, Endo M. Stimulation of small proteoglycan synthesis by the hyaluronan synthesis inhibitor 4-methylumbelliferone in human skin fibroblasts. Connect Tissue Res. 2009;50:194-202 pubmed publisher
    ..Furthermore, the two decorins had galactosaminoglycan chains of different sizes. These results suggest that MU inhibits the synthesis of hyaluronan and accelerates production of the larger decorin in the extracellular matrix. ..
  8. Kultti A, Pasonen Seppänen S, Jauhiainen M, Rilla K, Kärnä R, Pyöriä E, et al. 4-Methylumbelliferone inhibits hyaluronan synthesis by depletion of cellular UDP-glucuronic acid and downregulation of hyaluronan synthase 2 and 3. Exp Cell Res. 2009;315:1914-23 pubmed publisher
  9. Kudo D, Kon A, Yoshihara S, Kakizaki I, Sasaki M, Endo M, et al. Effect of a hyaluronan synthase suppressor, 4-methylumbelliferone, on B16F-10 melanoma cell adhesion and locomotion. Biochem Biophys Res Commun. 2004;321:783-7 pubmed
    ..Thus, preventing the formation of cell surface HA reduced both the adhesion and locomotion of melanoma cells, suggesting that MU may act as an inhibitor of tumor metastasis. ..

More Information


  1. Uchakina O, Ban H, McKallip R. Targeting hyaluronic acid production for the treatment of leukemia: treatment with 4-methylumbelliferone leads to induction of MAPK-mediated apoptosis in K562 leukemia. Leuk Res. 2013;37:1294-301 pubmed publisher
    ..Treatment of tumor-bearing mice with 4-MU led to a significant reduction in tumor load which was mediated through the induction of apoptosis. ..
  2. Nakazawa H, Yoshihara S, Kudo D, Morohashi H, Kakizaki I, Kon A, et al. 4-methylumbelliferone, a hyaluronan synthase suppressor, enhances the anticancer activity of gemcitabine in human pancreatic cancer cells. Cancer Chemother Pharmacol. 2006;57:165-70 pubmed
    ..These data strongly suggest that a combination of MU and gemcitabine is effective against human pancreatic cancer cells. MU may have potential as a chemosensitizer and may provide us with a new anticancer strategy. ..
  3. Mahaffey C, Mummert M. Hyaluronan synthesis is required for IL-2-mediated T cell proliferation. J Immunol. 2007;179:8191-9 pubmed
    ..Our results strongly suggest that HA synthesized by T cells themselves is critical for their IL-2-mediated proliferation and have revealed a previously unrecognized role for endogenous HA in T cell biology. ..
  4. Rilla K, Pasonen Seppänen S, Rieppo J, Tammi M, Tammi R. The hyaluronan synthesis inhibitor 4-methylumbelliferone prevents keratinocyte activation and epidermal hyperproliferation induced by epidermal growth factor. J Invest Dermatol. 2004;123:708-14 pubmed
    ..At any rate, 4-MU and equivalent hyaluronan synthesis inhibitors might be considered for situations where suppression of epidermal activation and hyperproliferation is warranted. ..
  5. Jokela T, Jauhiainen M, Auriola S, Kauhanen M, Tiihonen R, Tammi M, et al. Mannose inhibits hyaluronan synthesis by down-regulation of the cellular pool of UDP-N-acetylhexosamines. J Biol Chem. 2008;283:7666-73 pubmed publisher
    ..Mannose is a potentially useful tool in studies on hyaluronan-dependent cell functions, as demonstrated by reduced rates of keratinocyte proliferation and migration, functions known to depend on hyaluronan synthesis. ..
  6. Vigetti D, Rizzi M, Viola M, Karousou E, Genasetti A, Clerici M, et al. The effects of 4-methylumbelliferone on hyaluronan synthesis, MMP2 activity, proliferation, and motility of human aortic smooth muscle cells. Glycobiology. 2009;19:537-46 pubmed publisher
    ..Besides the decrease in HA synthesis and cell migration, 4-MU reduced AoSMCs proliferation, indicating that 4-MU may exert a vasoprotective effect. ..
  7. Kakizaki I, Takagaki K, Endo Y, Kudo D, Ikeya H, Miyoshi T, et al. Inhibition of hyaluronan synthesis in Streptococcus equi FM100 by 4-methylumbelliferone. Eur J Biochem. 2002;269:5066-75 pubmed
    ..These results suggest that MU treatment may cause a decrease in hyaluronan synthase activity by altering the lipid environment of membranes, especially the distribution of different cardiolipin species, surrounding hyaluronan synthase...
  8. Lokeshwar V, Lopez L, Munoz D, Chi A, Shirodkar S, Lokeshwar S, et al. Antitumor activity of hyaluronic acid synthesis inhibitor 4-methylumbelliferone in prostate cancer cells. Cancer Res. 2010;70:2613-23 pubmed publisher
    ..Therefore, the anticancer effects of 4-MU, an orally bioavailable and relatively nontoxic agent, are primarily mediated by inhibition of HA signaling. ..
  9. Twarock S, Tammi M, Savani R, Fischer J. Hyaluronan stabilizes focal adhesions, filopodia, and the proliferative phenotype in esophageal squamous carcinoma cells. J Biol Chem. 2010;285:23276-84 pubmed publisher
    ..Because RHAMM appears to support both filopodia, FAK, and the proliferative and migratory phenotype, it may be promising to explore RHAMM as a potential therapeutic target in esophageal cancer. ..
  10. Roberts I, Jones S, Premier R, Cox J. A comparison of the sensitivity and specificity of enzyme immunoassays and time-resolved fluoroimmunoassay. J Immunol Methods. 1991;143:49-56 pubmed
    ..001) more sensitive than with p-nitrophenyl phosphate (pNPP). TR-FIA with Eu3(+)-labelled anti-human IgG was equivalent in sensitivity to HRP with TMB and AP with 4MeUP. ..
  11. May M, Kleven S, Brown D. Sialidase activity in Mycoplasma synoviae. Avian Dis. 2007;51:829-33 pubmed
    ..Negligible activity was detected in conditioned culture supernatant fluid. This is the first report of sialidase activity in pathogenic strains of M. synoviae, which suggests a potential enzymatic basis for virulence of the organism. ..
  12. Malosse L, Buvat P, Adès D, Siove A. Detection of degradation products of chemical warfare agents by highly porous molecularly imprinted microspheres. Analyst. 2008;133:588-95 pubmed publisher
  13. Deshmukh M, Pawar P, Joseph M, Phalgune U, Kashalkar R, Deshpande N. Efficacy of 4-methyl-7-hydroxy coumarin derivatives against vectors Aedes aegypti and Culex quinquefasciatus. Indian J Exp Biol. 2008;46:788-92 pubmed
    ..The hatched larvae showed 100% mortality in the successive instars. Compounds 3 and 4 (3-bromo-7-hydroxy-4-methyl-chromen-2-one and 3-bromo-4-methyl-2'-oxo-2H-chromen-7-yl acetate) showed moderate activity against both mosquito species. ..
  14. Köllner K, Carstens D, Keller E, Vazquez F, Schubert C, Zeyer J, et al. Bacterial chitin hydrolysis in two lakes with contrasting trophic statuses. Appl Environ Microbiol. 2012;78:695-704 pubmed publisher
    ..01 to 0.1%), constitutes an important microbial growth substrate in these temperate freshwater lakes, particularly where other easily degradable carbon sources are scarce. ..
  15. Hurtado Guerrero R, van Aalten D. Structure of Saccharomyces cerevisiae chitinase 1 and screening-based discovery of potent inhibitors. Chem Biol. 2007;14:589-99 pubmed
    ..Crystal structures of ScCTS1 in complex with inhibitors from three series reveal striking mimicry of carbohydrate substrate by small aromatic moieties and a pocket that could be further exploited in optimization of these inhibitors. ..
  16. Heffler M, Golubovskaya V, Conroy J, Liu S, Wang D, Cance W, et al. FAK and HAS inhibition synergistically decrease colon cancer cell viability and affect expression of critical genes. Anticancer Agents Med Chem. 2013;13:584-94 pubmed
    ..Dual inhibition of FAK and HAS3 decreases viability to a greater degree than with either agent alone, and suggests that synergistic inhibition of colon cancer cell growth can result from affecting similar genetic pathways. ..
  17. Manevski N, Moreolo P, Yli Kauhaluoma J, Finel M. Bovine serum albumin decreases Km values of human UDP-glucuronosyltransferases 1A9 and 2B7 and increases Vmax values of UGT1A9. Drug Metab Dispos. 2011;39:2117-29 pubmed publisher
    ..Our findings call for further investigations of the BSA effects on different UGTs and the inhibitors that it may remove. ..
  18. Zeng X, Sun Y, Uzawa H. Efficient enzymatic synthesis of 4-methylumbelliferyl N-acetyllactosaminide and 4-methylumbelliferyl sialyl N-acetyllactosaminides employing beta-D-galactosidase and sialyltransferases. Biotechnol Lett. 2005;27:1461-5 pubmed
  19. Sahasrabudhe A, Lawrence L, Epa V, Varghese J, Colman P, McKimm Breschkin J. Substrate, inhibitor, or antibody stabilizes the Glu 119 Gly mutant influenza virus neuraminidase. Virology. 1998;247:14-21 pubmed
    ..Furthermore the presence of high levels of substrate, either cell or virus associated, may be sufficient to stabilize the NA during virus replication. ..
  20. Garcia Armisen T, Lebaron P, Servais P. Beta-D-glucuronidase activity assay to assess viable Escherichia coli abundance in freshwaters. Lett Appl Microbiol. 2005;40:278-82 pubmed
    ..coli by the culture-based method. GLUase activity is a reliable parameter for the rapid quantification of viable E. coli in waters. ..
  21. Bock K, Raschko F, Gschaidmeier H, Seidel A, Oesch F, Grove A, et al. Mono- and Diglucuronide formation from benzo[a]pyrene and chrysene diphenols by AHH-1 cell-expressed UDP-glucuronosyltransferase UGT1A7. Biochem Pharmacol. 1999;57:653-6 pubmed
    ..1 microM) than UGT1A6 (10 microM). The results suggest that the two PAH-inducible UGTs may cooperate in conjugating PAH metabolites, but that UGT1A7 is more efficient. ..
  22. Leuschner R, Bew J. A medium for the presumptive detection of Enterobacter sakazakii in infant formula: interlaboratory study. J AOAC Int. 2004;87:604-13 pubmed
    ..e., 66.7% (66.7% accordance, 53.9% concordance). For the medium level the sensitivities were 96.7% (93.3% accordance, 93.5% concordance) for VRBGA and 98.3% (96.9% accordance, 96.9% concordance) for NA + alpha-MUG. ..
  23. Pastula C, Johnson I, Beechem J, Patton W. Development of fluorescence-based selective assays for serine/threonine and tyrosine phosphatases. Comb Chem High Throughput Screen. 2003;6:341-6 pubmed
    ..Inhibition of LAR and PP-2A in these assays is demonstrated using known inhibitors. Both of these assays are sensitive, robust, kinetic assays that can be used to quantify enzyme activity. ..
  24. Kashima Y, Takahashi M, Shiba Y, Itano N, Izawa A, Koyama J, et al. Crucial role of hyaluronan in neointimal formation after vascular injury. PLoS ONE. 2013;8:e58760 pubmed publisher
    ..VSMC-derived HA promotes neointimal formation after vascular injury, and HA may be a potential therapeutic target for cardiovascular disease. ..
  25. Sim M, Ham J, Lee H, Seo K, Lee M. Long-term supplementation of umbelliferone and 4-methylumbelliferone alleviates high-fat diet induced hypertriglyceridemia and hyperglycemia in mice. Chem Biol Interact. 2014;216:9-16 pubmed publisher
    ..These results indicate that UF and mUF similarly ameliorate hypertriglyceridemia and hyperglycemia partly by modulating hepatic lipid metabolism and the antioxidant defense system along with increasing adiponectin levels. ..
  26. Shibata S, Takagaki K, Ishido K, Konn M, Sasaki M, Endo M. HNK-1-Reactive oligosaccharide, sulfate-O-3GlcAbeta1-4Xylbeta1-MU, synthesized by cultured human colorectal cancer cells. Tohoku J Exp Med. 2003;199:13-23 pubmed
    ..Since HNK-1-reactive sugar chains are known to be involved in cell adhesion in the nervous system, the present results suggest that epithelium-derived colorectal cancer cells might also be able to utilize them in cell adhesion. ..
  27. Takagaki K, Nakamura T, Shibata S, Higuchi T, Endo M. Characterization and biological significance of sialyl alpha 2-3galactosyl beta 1-4xylosyl beta 1-(4-methylumbelliferone) synthesized in cultured human skin fibroblasts. J Biochem. 1996;119:697-702 pubmed
    ..Addition of CDP, an inhibitor of sialytransferase, to the cell culture medium increased the secretion of GAG-MU. These results suggest that SA-Gal-Xyl-MU production may be related to the regulation of GAG-MU biosynthesis. ..
  28. Schelwies M, Brinson D, Otsuki S, Hong Y, Lotz M, Wong C, et al. Glucosamine-6-sulfamate analogues of heparan sulfate as inhibitors of endosulfatases. Chembiochem. 2010;11:2393-7 pubmed publisher
  29. Zhang W, Sun Z, Lu B, Wang Y, Ding P, Zheng P, et al. [Detection of Salmonella in water by using MUCAP test]. Wei Sheng Yan Jiu. 2010;39:381-3 pubmed
    ..the sensitivity of MUCAP method was 100%, the specification was 80.8%, and the detection limit was 1 cfu/100 ml. MUCAP method can effectively identify Salmonella in water and the testing time was shortening from 72h to 48h. ..
  30. Strassburg C, Kneip S, Topp J, Obermayer Straub P, Barut A, Tukey R, et al. Polymorphic gene regulation and interindividual variation of UDP-glucuronosyltransferase activity in human small intestine. J Biol Chem. 2000;275:36164-71 pubmed
  31. Hendel B, Marxsen J, Fiebig D, Preuss G. Extracellular enzyme activities during slow sand filtration in a water recharge plant. Water Res. 2001;35:2484-8 pubmed
  32. Kostova I, Manolov I, Karaivanova M. Synthesis, physicochemical characterization, and cytotoxic screening of new zirconium complexes with coumarin derivatives. Arch Pharm (Weinheim). 2001;334:157-62 pubmed
    ..Among these compounds the zirconium complex of mendiaxon showed highest cytotoxic activity against human promyelocytic leukemic HL-60 cells. The inorganic salt was found to be active against this cell line. ..
  33. Peters W, Te Morsche R, Roelofs H. Combined polymorphisms in UDP-glucuronosyltransferases 1A1 and 1A6: implications for patients with Gilbert's syndrome. J Hepatol. 2003;38:3-8 pubmed
  34. Mano Y, Usui T, Kamimura H. Effects of beta-estradiol and propofol on the 4-methylumbelliferone glucuronidation in recombinant human UGT isozymes 1A1, 1A8 and 1A9. Biopharm Drug Dispos. 2004;25:339-44 pubmed
    ..This study therefore indicates that the use of beta-estradiol as a specific inhibitor for UGT1A1 should be used with care in the identification of UGT isozymes responsible for glucuronidation in human liver microsomes. ..
  35. Xu N, Zhang S. Identification, expression and bioactivity of a chitotriosidase-like homolog in amphioxus: dependence of enzymatic and antifungal activities on the chitin-binding domain. Mol Immunol. 2012;51:57-65 pubmed publisher
    ..It is also the first study showing the presence of a ChT-like homolog with both chitinolytic activity and fungistatic activity in non-vertebrate species. ..
  36. Ni L, Swingle M, Bourgeois A, Honkanen R. High yield expression of serine/threonine protein phosphatase type 5, and a fluorescent assay suitable for use in the detection of catalytic inhibitors. Assay Drug Dev Technol. 2007;5:645-53 pubmed
  37. Hoffmann R, Schwarz G, Pohl C, Ziegenhagen D, Kruis W. [Bile acid-independent effect of hymecromone on bile secretion and common bile duct motility]. Dtsch Med Wochenschr. 2005;130:1938-43 pubmed
    b>Hymecromone (4-methyl-umbiliferone) has been used for more than 20 years for the treatment of functional and obstructive spasms of the biliary tract. Its mode of action however is still largely unknown...
  38. García Vilas J, Quesada A, Medina M. 4-methylumbelliferone inhibits angiogenesis in vitro and in vivo. J Agric Food Chem. 2013;61:4063-71 pubmed publisher
    ..Taken together, the results suggest that 4-MU may have potential as a new candidate multitargeted bioactive compound for antiangiogenic therapy. ..
  39. Forteza R, Casalino Matsuda S, Falcon N, Valencia Gattas M, Monzon M. Hyaluronan and layilin mediate loss of airway epithelial barrier function induced by cigarette smoke by decreasing E-cadherin. J Biol Chem. 2012;287:42288-98 pubmed publisher
  40. Fang W. Quantification of Staphylococcus aureus and Escherichia coli in the liquid medium by fluorimetry and its use in phagocytosis assay. J Appl Bacteriol. 1996;80:577-82 pubmed
    ..The fluorimetric technique, in general, gave a higher percentage of phagocytosis than the plate counting method with statistical significance for E. coli. ..
  41. Huang T, Fang Z, Yang L. Strong inhibitory effect of medroxyprogesterone acetate (MPA) on UDP-glucuronosyltransferase (UGT) 2B7 might induce drug-drug interactions. Pharmazie. 2010;65:919-21 pubmed
    ..The [I]/Ki value was calculated to be 0.31, which suggested that DDIs might occur when MPA was co-administered with drugs which mainly undergo UGT2B7-mediated metabolism. ..
  42. Ishii Y, Iwanaga M, Nishimura Y, Takeda S, Ikushiro S, Nagata K, et al. Protein-protein interactions between rat hepatic cytochromes P450 (P450s) and UDP-glucuronosyltransferases (UGTs): evidence for the functionally active UGT in P450-UGT complex. Drug Metab Pharmacokinet. 2007;22:367-76 pubmed
    ..Thus, CYP2C11/13 could associate with UGTs, but the affinity is assumed to be weaker than that of CYP2B/3As. These results suggest that there is isoform specificity in the interaction between P450s and UGTs. ..
  43. Kerby M, Legge R, Tripathi A. Measurements of kinetic parameters in a microfluidic reactor. Anal Chem. 2006;78:8273-80 pubmed
    ..The study provides a basis for appropriate use of mass-transfer and reaction arguments in successful application of enzymatic microreactors. ..
  44. Slonim A, Bulone L, Minikes J, Hays A, Shanske S, Tsujino S, et al. Benign course of glycogen storage disease type IIb in two brothers: nature or nurture?. Muscle Nerve. 2006;33:571-4 pubmed
  45. Nasonova S. [A case of successful use of odeston in the diagnostics and treatment of biliary dysfunctional disorders]. Voen Med Zh. 2003;324:55-7 pubmed
  46. Hughes C, Malki G, Loo C, Tanner A, Ganeshkumar N. Cloning and expression of alpha-D-glucosidase and N-acetyl-beta-glucosaminidase from the periodontal pathogen, Tannerella forsythensis (Bacteroides forsythus). Oral Microbiol Immunol. 2003;18:309-12 pubmed
    ..The N-acetyl-beta-D-glucosaminidase has a Mr of 87,787 and is homologous to an N-acetyl-beta-D-glucosaminidase in Porphyromonas gingivalis W83. ..
  47. Knights K, Bowalgaha K, Miners J. Spironolactone and canrenone inhibit UGT2B7-catalyzed human liver and kidney microsomal aldosterone 18beta-glucuronidation: a potential drug interaction. Drug Metab Dispos. 2010;38:1011-4 pubmed publisher
  48. Zhao J, Wang G, Chen M, Cheng L, Ji X. Demethylzeylasteral exhibits strong inhibition towards UDP-glucuronosyltransferase (UGT) 1A6 and 2B7. Molecules. 2012;17:9469-75 pubmed publisher
  49. Wegner A, McConnell J, Blakely R, Wadzinski B. An automated fluorescence-based method for continuous assay of PP2A activity. Methods Mol Biol. 2007;365:61-9 pubmed
  50. Garg A, Manidhar D, Gokara M, Malleda C, Suresh Reddy C, Subramanyam R. Elucidation of the binding mechanism of coumarin derivatives with human serum albumin. PLoS ONE. 2013;8:e63805 pubmed publisher
    ..This study will provide insights into designing of the new inspired coumarin derivatives as therapeutic agents against many life threatening diseases. ..
  51. McKallip R, Hagele H, Uchakina O. Treatment with the hyaluronic acid synthesis inhibitor 4-methylumbelliferone suppresses SEB-induced lung inflammation. Toxins (Basel). 2013;5:1814-26 pubmed publisher
    ..Taken together, these results suggest that use of 4-MU to target hyaluronic acid production may be an effective treatment for the inflammatory response following exposure to SEB. ..
  52. Kostova I, Manolov I, Nicolova I, Danchev N. New metal complexes of 4-methyl-7-hydroxycoumarin sodium salt and their pharmacological activity. Farmaco. 2001;56:707-13 pubmed
    ..zinc (II), nickel (II), cobalt (II) and iron (III) with 4-methyl-7-hydroxycoumarin sodium salt (Mendiaxon, Hymecromone) were synthesized by mixing of equimolar amounts of the respective metal nitrates and 4-methyl-7-..
  53. Purba E, Oguro A, Imaoka S. Isolation and characterization of Xenopus soluble epoxide hydrolase. Biochim Biophys Acta. 2014;1841:954-62 pubmed publisher
    ..The epoxide hydrolase activity of sEH seemed to be similar to that of human sEH, while Xenopus sEH did not have phosphatase activity toward several substrates that human sEH metabolizes. ..