4- Methyl umbelliferone

Methyl umbelliferone, pH-dependent change of fluorescence 91 Metoxurone 74 Mevinphos (cis/trans) 362 Microwave apparatus 96 ff Mirsol 45... 

Coumarin itself has a poor quantum yield, but appropriate substitution leads to fluorescent compounds emitting in the blue-green region (400-550 nm). Substitution in position 4 by a methyl group leads to umbelliferone. 7-Hydroxycoumarins are very sensitive to pH. For example, 4-methyl-7-hydroxycoumarin (4-methyl-umbelliferone) can be used as a fluorescent pH probe (see Chapter 10). 

Read the fluorescence at excitation wavelength 366 nm and emission wavelength 442 nm. Include a two-point calibration curve of 500 and 1000 pmol 4-methyl-umbelliferone (50 and 100 pi of the 10 pM standard solution) this curve should be linear. 

In practice it is often more convenient to measure the release of a phenol from an aryl phosphomonoester. Standard serum phosphatase methods employ phenyl phosphate (188), p-nitrophenyl phosphate (189), phenolphthalein monophosphate (140), or thymolphthalein monophosphate (141) where the phenol released can be determined spectrophoto-metrically [only the Bodansky method (13) uses a Pi determination]. A number of fluorogenic substrates have been used for phosphatase studies, e.g., jS-naphthyl phosphate (30, 148), 4-methylumbelliferyl phosphate (143), and 3-O-methylfluorescein phosphate (144) The main advantage here is the much greater sensitivity of fluorescence as compared with spectrophotometric assays as little as 1 pmole of 4-methyl-umbelliferone can be detected in continuous assay. 

Anhydro-(7-oxy-4-methylcumarin-8-diazonium-hydroxide), called in Beil 8-Diazo 4-methyl-umbelliferon and in Ref 2 fi-Methylumbelli-feron e 3-diazoanhydrid,... 

Methyl-umbelliferone (low), scopoletin (low), 1-hydroxypyrene Rifampin, 3-methylchloranthrene... 

CHLORO-4-METHYL-UMBELLIFERONE BIS(2-CHLOROETHYL)PHOSPHATE seeDFH600... 

DDT can be determined in microgram amounts by its inhibition of carbonic anhydrase (69). Several of the chlorinated insecticides as well as the carbamate insecticide, Sevin, are potent lipase inhibitors. As little as 0.1-1 /Ag/ml of Sevin, aldrin, heptachlor, lindane, 10 / g/ml of DDT, and 2,4-d can be determined fluorimetrically with 2-3% precision by the lipase inhibition when 4-methyl umbelliferone heptanoate is used as substrate (70). The lipase inhibition procedure for DDT determination is much easier to carry out than the carbonic anhydrase assay which involves monitoring gaseous COo production. 

BIOTRANSFORMATIONS OF 4-METHYL UMBELLIFERONE DERIVATIVES - FUNGAL MEDIATED O-DEALKYLATIONS. 

Thus the limited range of preparative examples illustrate that enzyme/microorgrmism catalyzed dealkylation is a topic in its infancy emd further work is necessary to delineate mechanism and the scope of the reaction. Consequently, in the present study five derivatives of 4-methyl umbelliferone (7-hydroxy, 4- methyl coumarin) namely, 7-o-methyl, 7-o-ethyl, 7-o-butyl, 7-o-benzyl and 7-o-acetyl, were chosen for the study of biotransformation with Asperigillus niger. 

These considerations lead to a general discussion of exciplex lasers. This is a well-established laser scheme for dye lasers where charge-taransfer complexes of excited molecules form the upper lasing state. Examples are the dyes 4-methyl-umbelliferone or N-methylacridin 92h... 

H60 A13-50680 0,0-Bis(2-chloroethyl) 0-(3-chloro-4-methyl-7-coumarinyl) phosphate BRN 1271357 3-Chloro-4-methyl-umbelliferone bis(2-chloroethyl)phos-phate 3-Chloro-7-hydroxy-4-methylcoumarin bis(2-chlo-roethyl)phosphate 3-Chloro-7-hydroxy-4-methyl-2H-1 -benzopyran-2-one bis(chloroethyl)phosphate ... 

Lubbers and Opitz [109] followed the changes in fluorescence of a solution of 4-methyl umbelliferone in 1 pM hydrogencarbonate buffer as a function of CO2 partial pressure. The indicator solution was covered with a 6-pm PTFE membrane and the ratio of fluorescence intensity at 445 nm measured under excitation at 318 and 357 nm was related to pressure. 

The commercially available fluorogenic substrate that has been described in detail in the literature for assay of beta-glucuronidase activity is 4-methyl umbelliferyl glucuronide (MUG). This compound is not fluorescent until cleaved by beta-glucuronide to release 4-methyl umbelliferone (7-hydroxy-4-methyl coumarin). The product is fluorescent only when the hydroxyl group is ionized. The pKa of this hydroxyl is around 8, and maximal fluorescence will only be obtained if the product is in solution at a pH greater than the pKa fluorescence is relatively low at the neutral pH of the living cell. 

---