Ligand quercetin

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Basic Ligand Information

Molecular Structure
Picture of quercetin (click for magnification)
Molecular Formula
BRENDA Name
InChIKey
C15H10O7
quercetin
CYHOMWAPJJPNMW-JIGDXULJSA-N
Synonyms:
2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-1-benzopyran-4-one, 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-chromen-4-one, 2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-4H-1-benzopyran-4-one, 2R,3S-cis-dihydroquercetin, 3,3',4',5,7-pentahydroxy flavone, 3,3',4',5,7-pentahydroxyflavone, 3,5,7,3',4'-pentahydroxyflavone, pppAACAG, quercetin[side 1], quercetin[side 2]

Roles as Enzyme Ligand

In Vivo Substrate in Enzyme-catalyzed Reactions (25 results)

EC NUMBER
PROVEN IN VIVO REACTION
REACTION DIAGRAM
LITERATURE
ENZYME 3D STRUCTURE
S-adenosyl-L-methionine + quercetin = S-adenosyl-L-homocysteine + tamarixetin
show the reaction diagram
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S-adenosyl-L-methionine + quercetin = S-adenosyl-L-homocysteine + 3,3',5,7-tetramethoxyquercetin
show the reaction diagram
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S-adenosyl-L-methionine + quercetin = S-adenosyl-L-homocysteine + isorhamnetin
show the reaction diagram
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S-adenosyl-L-methionine + quercetin = S-adenosyl-L-homocysteine + 7-O-methylquercetin
show the reaction diagram
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UDP-alpha-D-glucose + quercetin = UDP + quercetin 3-O-beta-D-glucoside
show the reaction diagram
3'-phosphoadenylylsulfate + quercetin = adenosine 3',5'-bisphosphate + quercetin 3-sulfate
show the reaction diagram
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In Vivo Product in Enzyme-catalyzed Reactions (9 results)

EC NUMBER
PROVEN IN VIVO REACTION
REACTION DIAGRAM
LITERATURE
ENZYME 3D STRUCTURE
kaempferol + [reduced NADPH-hemoprotein reductase] + O2 = quercetin + [oxidized NADPH-hemoprotein reductase] + H2O
show the reaction diagram
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-
(2R/3R)-dihydroquercetin + 2-oxoglutarate + O2 = quercetin + succinate + CO2 + H2O
show the reaction diagram
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-
quercitrin + H2O = quercetin + L-rhamnose
show the reaction diagram
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quercitrin + H2O = quercetin + L-rhamnose
show the reaction diagram
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Substrate in Enzyme-catalyzed Reactions (136 results)

EC NUMBER
REACTION
REACTION DIAGRAM
LITERATURE
ENZYME 3D STRUCTURE
quercetin + O2 = ?
show the reaction diagram
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quercetin + H2O = ?
show the reaction diagram
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quercetin + H2O2 = oxidized quercetin + H2O
show the reaction diagram
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quercetin + O2 = ?
show the reaction diagram
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S-adenosyl-L-methionine + quercetin = S-adenosyl-L-homocysteine + 4'-methoxyquercetin
show the reaction diagram
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S-adenosyl-L-methionine + quercetin = S-adenosyl-L-homocysteine + ?
show the reaction diagram
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S-adenosyl-L-methionine + quercetin = ?
show the reaction diagram
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S-adenosyl-L-methionine + quercetin = S-adenosyl-L-homocysteine + isorhamnetin
show the reaction diagram
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UDP-alpha-D-glucose + quercetin = UDP + quercetin 7-O-beta-D-glucoside
show the reaction diagram
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UDP-alpha-D-glucose + quercetin = UDP + quercetin 7-O-beta-D-glucoside
show the reaction diagram
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UDPglucose + quercetin = UDP + 4-O-beta-D-glucosyl-quercetin
show the reaction diagram
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UDP-glucose + quercetin = UDP + ?
show the reaction diagram
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sucrose + quercetin = ?
show the reaction diagram
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UDP-L-rhamnose + quercetin = quercetin-3-O-rhamnoside + UDP
show the reaction diagram
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UDP-glucose + quercetin = UDP + quercetin 7-O-beta-D-glucoside
show the reaction diagram
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UDP-alpha-D-glucose + quercetin = UDP + quercetin 3-O-beta-D-glucoside
show the reaction diagram
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UDP-alpha-D-glucose + quercetin = UDP + ?
show the reaction diagram
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UDP-alpha-D-glucose + quercetin = ?
show the reaction diagram
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UDP-alpha-D-glucose + quercetin = UDP + ?
show the reaction diagram
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sucrose + quercetin = D-fructose + quercetin glucoside
show the reaction diagram
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sucrose + quercetin = D-fructose + isoquercitrin
show the reaction diagram
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quercetin + UDP-glucuronate = quercetin 3-O-glucuronate + UDP
show the reaction diagram
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UDP-alpha-D-glucose + quercetin = UDP + quercetin 4'-O-glucoside
show the reaction diagram
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UDP-alpha-D-xylose + quercetin = UDP + quercetin 3-O-beta-D-xyloside
show the reaction diagram
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3,3-dimethylallyl diphosphate + quercetin = diphosphate + ?
show the reaction diagram
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pppAACAG + GDP = diphosphate + guanosine 5'-pppAACAG
show the reaction diagram
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3'-phosphoadenylylsulfate + quercetin = adenosine 3',5'-bisphosphate + ?
show the reaction diagram
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4-nitrophenyl sulfate + quercetin = 4-nitrophenol + quercetin 3'-O-sulfate
show the reaction diagram
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3'-phosphoadenylylsulfate + quercetin = adenosine 3',5'-bisphosphate + quercetin 3-sulfate
show the reaction diagram
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adenosine 3'-phosphate 5'-phosphosulfate + quercetin = adenosine 3',5'-bisphosphate + quercetin 7-sulfate
show the reaction diagram
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3'-phosphoadenylylsulfate + quercetin = adenosine 3',5'-bisphosphate + ?
show the reaction diagram
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ATP + H2O + quercetin[side 1] = ADP + phosphate + quercetin[side 2]
show the reaction diagram
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Product in Enzyme-catalyzed Reactions (47 results)

EC NUMBER
REACTION
REACTION DIAGRAM
LITERATURE
ENZYME 3D STRUCTURE
kaempferol + [reduced NADPH-hemoprotein reductase] + O2 = quercetin + [oxidized NADPH-hemoprotein reductase] + H2O
show the reaction diagram
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-
quercitrin + H2O = quercetin + L-rhamnose
show the reaction diagram
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quercetin 3-O-beta-D-glucuronide + H2O = quercetin + D-glucuronate
show the reaction diagram
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ATP + H2O + quercetin[side 1] = ADP + phosphate + quercetin[side 2]
show the reaction diagram
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Activator in Enzyme-catalyzed Reactions (8 results)

EC NUMBER
COMMENTARY
LITERATURE
ENZYME 3D STRUCTURE
significantly increases serum xanthine oxidase activities, and decreases liver xanthine oxidase activities significantly
induces enzyme expression
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EC50 value of 0.99 mM
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0.05 mM, stimulates GTPase activity about 8fold, but inhibits polymerization of microtubules and specifically inhibits colchicine binding to tubulin
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0.05 mM, 7fold increase in DNA-cleavage activity for isoform II beta, 4fold increase for isoform II alpha
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3fold induction of the heavy subunit gene promotor and heavy subunit expression, best at 0.05 mM, induction even of a distal part of the promotor sequence containing only 2 antioxidant-response/electrophile-response elements, i.e. ARE/EpRE
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stimulates transport of rhodamine 123
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Inhibitor in Enzyme-catalyzed Reactions (243 results)

EC NUMBER
COMMENTARY
LITERATURE
ENZYME 3D STRUCTURE
22% inhibition at 0.01 mM
-
12.0% at 0.1 mM
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inhibition pattern for AKR1C21, overview
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0.02 mM inhibits by ca. 50%
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flavonol that can be an inhibitor of the activity of DFR towards dihydroflavonols
shows a competitive inhibition and a mixed-type inhibition with respect to UDP-glucose and NAD+, decreases specific activities of UGDH, but does not affect UGDH protein expression, thus UGDH activity is inhibited by polyphenols at the post-translational level. Quercetin exerts strong antiproliferative activity in breast cancer cells. Heat inactivation of UGDH is accelerated to a greater degree by quercetin than by gallic acid. In the presence of quercetin, the activity remaining after 30 min is 20% that of control
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about 25% inhibition at 0.0025 mM
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inhibits by 52%
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78% inhibition at 0.1 mM
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0.1 mM, 94% inhibition
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incubation of the LPO/H2O2/acetonitrile system with 0.1 mM quercetin is associated with the highest rate of inhibition amounting to 40.2% of the control
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noncompetitive inhibition by initially reducing the ferric form of the enzyme to an inactive ferrous form
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remarkable noncompetitive inhibition
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i.e. 3,3',4',5,7-pentahydroxyflavone, isolated from air-dried powdered leaves of Vitex negundo, a lipophilic metal chelator, that interferes with the parasite's iron metabolism inhibiting Fe2+ acquisition from an endogenous source, combination of quercetin with serum albumin increases its bioavailability, the inhibitor causes deprivation of the enzyme of iron which in turn destabilized the critical tyrosyl radical required for its catalysing activity
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molecular docking studies. Quercetin is stabilized by two hydrogen bonds with the amino acids Ala198 and Pro253
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strong inhibition
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IC50: 1.5 microM
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0.01 mM
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flavonol, non-competitive with both NADPH and GSSG, influence on glutathione recognition
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0.05 mM, strong inhibitory effect, IC50: 0.97 mM
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uncompetitive inhibitor, molecular dynamics simulations carried out to elucidate the binding mode of quercetin reveal that this small molecule binds at the trimer-trimer interface of hexameric CysE, a site physically distinct from the active site of the enzyme, overview. Binding of quercetin to CysE leads to conformation changes in the active site loops and proximal loops that affect its internal dynamics and consequently its affinity for substrate/co-factor binding, justifying the reduced enzyme activity. Quercetin binding kinetics and analysis provide mechanistic understanding of allosteric modulation. The ligand is involved in hydrophilic as well as hydrophobic interactions with Kpn CysE, 62% inhibition at 0.005 mM with 500 ng enzyme
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the enzyme is tolerant to quercetin up to a concentration of 1.5 mM
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the formation of ethylglucuronoside is inhibited by the flavonoids for all enzymes except for UGT2B15, mechanism-based inhibition; the formation of ethylglucuronoside is inhibited by the flavonoids for all UGT enzymes except for UGT2B15, mechanism-based inhibition; the formation of ethylglucuronoside is inhibited by the flavonoids for all UGT enzymes except for UGT2B15, mechanism-based inhibition; the formation of ethylglucuronoside is inhibited by the flavonoids for all UGT enzymes except for UGT2B15, mechanism-based inhibition; the formation of ethylglucuronoside is inhibited by the flavonoids for all UGT enzymes except for UGT2B15, mechanism-based inhibition; the formation of ethylglucuronoside is inhibited by the flavonoids for all UGT enzymes except for UGT2B15, mechanism-based inhibition; the formation of ethylglucuronoside is inhibited by the flavonoids for all UGT enzymes except for UGT2B15, mechanism-based inhibition
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0.1 mM: 93% inhibition, 0.01 mM: 55% inhibition
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0.1 mM, 41% inhibition of DGK I and 15% inhibition of DGK IV
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50% inhibition at 0.1 mM
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inhibition of p56lck
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at high concentrations
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IC50: 0.006 mM
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ATP does not reverse
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a less potent flavonoid inhibitor of CDK6, CDK5, and CDK1
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mechanism, role of radicals
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high affinities with the RNA-polymerase active site; strong binding affinity to the enzyme (RdRp)
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IC50: 0.0007 mM, competitive
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a flavonol, 0.888 mM, pH 6.0, room temperature, 82.1% maximum inhibition
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1 mM, 75% inhibition
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18.1% inhibition at 0.03 mM
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IC50 for recombinant SrtA(DELTA24): 0.0527 mM, no antibacterial activity against Staphylococcus aureus
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IC50 for recombinant SrtB(DELTA30): 0.03328 mM, no antibacterial activity against Staphylococcus aureus
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flavonoid
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0.1 mM, about 70% inhibition
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slight inhibition
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very strong inhibition
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naturally occurring flavone, binds to the free enzyme and also intercalates into the DNA at a very high concentration (300 mM) without binding to the minor grove
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i.e. 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-2,3-dihydro-4H-1-benzopyran-4-one
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an F1 inhibitor, also inhibits Fe2+ uptake
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3D Structure of Enzyme-Ligand-Complex (PDB) (100 results)

EC NUMBER
ENZYME 3D STRUCTURE

Enzyme Kinetic Parameters

kcat Value (Turnover Number) (39 results)

EC NUMBER
TURNOVER NUMBER [1/S]
TURNOVER NUMBER MAXIMUM [1/S]
COMMENTARY
LITERATURE
193
-
-
0.027
-
pH 7.5, 37C
0.16
-
pH 7.5, temperature not specified in the publication
0.000113
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in 100 mM Tris-HCl pH 8.0, at 30C
0.58
-
pH 7.5, 30C, with UDP-glucose, recombinant enzyme
59.8
-
pH 7.5, 43C, forward reaction
0.41
-
at pH 7.2 and 30C
0.1
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isoform UGT88E19, cosubstrate UDP-glucose, pH 7.5, 30C

KM Value (80 results)

EC NUMBER
KM VALUE [MM]
KM VALUE MAXIMUM [MM]
COMMENTARY
LITERATURE
0.8
-
-
0.163
-
pH 7.5, 37C
0.0237
-
pH 7.5, temperature not specified in the publication
0.0353
-
-
0.03678
-
pH 7.5, 30C, with UDP-glucose, recombinant enzyme
0.00096
-
pH 7.5, 43C, forward reaction
0.09
-
pH 7.0, 30C
0.0582
-
at pH 7.2 and 30C
0.00119
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pH 7.5, 30C
0.0351
-
pH 6.5, 37C, allozyme SULT1A1*1
0.00085
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pH 7, 25C

Ki Value (43 results)

EC NUMBER
KI VALUE [MM]
KI VALUE MAXIMUM [MM]
COMMENTARY
LITERATURE
0.072
-
pH 9.9
0.012
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at 0.04 mM 2,3-dihydro-2,5-dihydroxy-4H-benzopyran-4-one, at pH 7.0 and 25C
0.00046
-
pH 7.4, 25C, recombinant enzyme
0.088
-
pH 6.8, 30C
0.000021
-
-
0.007
-
-
0.0012
-
pH 7.4, 25C
6.19
-
value for lysed cells
0.0225
-
-
0.035
-
pH 7.5, 25C
0.00058
-
pH 7.4, 37C
0.068
-
-
0.0014
-
pH and temperature not specified in the publication
0.00668
-
-
0.006
-
pH 6.5, 25C
0.3
-
pH not specified in the publication, 30C, value above
0.00149
-
pH 7.5, 40C
0.023
-
in the presence of increasing amounts of inhibitor at different concentrations of the substrates methylglyoxal and glutathione, Dixon plot analysis, significantly lower inhibition than that with curcumin, competitive inhibition, pH 7.0, 30C

IC50 Value (140 results)

EC NUMBER
IC50 VALUE
IC50 VALUE MAXIMUM
COMMENTARY
LITERATURE
0.3048
-
pH 7.0
0.0027
-
pH 7.4, 25C
-999
-
27% inhibition at 0.01 mM, cell-based assay, pH not specified in the publication, 37C
0.000059
-
at pH 7.4 and 37C
0.0022
-
pH 7.4, 25C
0.0188
-
-
0.026
-
pH 7.4, 25C, recombinant enzyme
0.026
-
at 0.04 mM 2,3-dihydro-2,5-dihydroxy-4H-benzopyran-4-one, at pH 7.0 and 25C
0.0015
-
pH 7.4, 25C, wild-type enzyme
0.0026
-
pH 7.4, 25C, recombinant enzyme
0.0014
-
IC50: 0.0014 mM
0.045
-
pH 7.0, 23C
0.00127
-
-
0.0048
-
in 0.1M Tris-HCl (pH 8.0), at 25C
0.00044
-
pH and temperature not specified in the publication
0.142
-
pH 7.5, 25C
0.0015
-
IC50: 1.5 microM
0.0011
-
pH 7.5, 22C
0.97
-
0.05 mM, strong inhibitory effect, IC50: 0.97 mM
0.0037
-
pH 8.0, 25C, recombinant enzyme
0.08
-
IC50: 0.08 mM
0.024
-
at pH 8.0 and 37C
0.0335
-
pH 6.8, 25C
0.007
-
pH 9.0, 36C
0.00059
-
pH not specified in the publication, temperature not specified in the publication
0.006
-
IC50: 0.006 mM
0.064
-
-
0.0007
-
IC50: 0.0007 mM, competitive
0.00472
-
at pH 7.0 and 25C
0.01
-
pH 7.4, 37C, isozyme sPLA2 IB
0.0453
-
pH 7.4, 37C
0.0214
-
a flavonol, pH 6.0, room temperature
0.0039
-
at 37C in 10 mM potassium phosphate buffer, pH 7.4, containing 0.05% (w/v) emulphogen
0.0379
-
at 37C in 10 mM potassium phosphate buffer, pH 7.4, containing 0.05% (w/v) emulphogene
0.035
-
pH and temperature not specified in the publication
0.0082
-
pH and temperature not specified in the publication
0.01803
-
pH 6.5, 25C
0.0527
-
IC50 for recombinant SrtA(DELTA24): 0.0527 mM, no antibacterial activity against Staphylococcus aureus
0.03328
-
IC50 for recombinant SrtB(DELTA30): 0.03328 mM, no antibacterial activity against Staphylococcus aureus
0.0309
-
at pH 2.0 and 37C
0.08
-
pH 6.0, 37C
0.0155
-
pH 11.0, 35C, recombinant His-tagged enzyme
0.001
-
-

References & Links

Links to other databases for quercetin

ChEBI
PubChem
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PubChem