Naphthoflavone

Alkylphenols, ammonia, asbestos, chlorinated paraffins, 4-chloroaniline, cyanide, detergents, di- -butyl phthalate, polyaromatic hydrocarbons (PAHs e.g. anthracene, benzopyrene, methylcholanthrene, /i-naphthoflavone), nitrate, nitrite, petroleum oil, phenol, pentachlorophenol, 4-nitrophenol, dinitro-o-cresol, polychlorinated biphenyls (PCBs especially coplanar), polychlorinated dioxins, polybrominated naphthalenes, /i-sitosterol, sulfide, thiourea, urea, acid water, coal dust... 

The introduction of reversible redox indicators for the determination of arsenic(III) and antimony(III) has considerably simplified the procedure those at present available include 1-naphthoflavone, and p-ethoxychrysoidine. The addition of a little tartaric acid or potassium sodium tartrate is recommended when antimony(III) is titrated with bromate in the presence of the reversible... 

As an alternative, a reversible indicator may be employed, either (a) 1-naphthoflavone (0.5% solution in ethanol, which gives an orange-coloured solution at the end-point), or (b) p-ethoxychrysoidine (0.1% aqueous solution, colour change pink to pale yellow). Under these conditions, the measured 25 mL portion of the arsenic solution is treated with 10 mL of 10 per cent potassium bromide solution, 6 mL of concentrated hydrochloric acid, 10 mL of water and either 0.5 mL of indicator (a) or two drops of indicator (b). 

Details of some inducible P450 forms that play key roles in the metabolism of xenobiotics are shown in Table 2.4. P450s belonging to family lA are induced by various lipophilic planar compounds including PAHs, coplanar PCBs, TCDD and other dioxins, and beta naphthoflavone (Monod 1997). As noted earlier, such planar compounds are also substrates for P450 lA. In many cases, the compounds induce the enzymes that will catalyze their own metabolism. Exceptions are refractory compounds such as 2,3,7,8-TCDD, which is a powerful inducer for P450 lA but a poor substrate. 

Pesonen, M., Goksoyr, A., and Andersson, T. (1992). Expression of P450 lAl in a primary culture of rainbow trout microsomes exposed to B-naphthoflavone or 2,3,7,8-TCDD. Archives of Biochemistry and Biophysics 292, 228-233. 

Oikari, A. and B. Jimenez. 1992. Effects of hepatotoxicants on the induction of microsomal monooxygenase activity in sunfish liver by beta-naphthoflavone and benzo[a]pyrene. Ecotoxicol. Environ. Safety 23 89-102. 

Patriarca, C. et al., Popliteal lymph node response to procainamide and isoniazid. Role of beta-naphthoflavone, phenobarbitone and S9-mix pretreatment. Toxicol. Lett., 66, 21, 1993... 

Standard Method of S9 Fraction Preparation. The following describes the production of hepatic S9 mix from rats induced with a combination of phenobarbitone and jS-naphthoflavone, and is an adaptation of the method described by Gatehouse and Delow (1979). 

An obvious difference was also noted between control and induced skate hepaticdnicrosomal AHH activity in the presence of a-naphthoflavone (10 M). This compound, when added in vitro at this or higher concentrations, caused significant stimulation of AHH activity in control animals (about 3-fold) but inhibition (80%) was found in DBA-pretreated skates. Similar results were earlier reported for control and 3-methylcholanthrene-treated rats (23), where it appears that the response is due to differential effects of a-naphthoflavone on hepatic microsomal cytochrome P-450 (stimulated) and cytochrome P-448 (inhibited) (24). Our data suggests that there may be a novel form of cytochrome P-450 synthesized in skate liver in response to polycyclic hydrocarbon administration, even though there was no hypsochromic shift in the carbon monoxide difference spectrum of dithionite reduced hepatic microsomes from DBA-treated skates (relative to hepatic microsomes from control fish). 

One of our more interesting observations is illustrated in Table III. The administration of DBA to winter flounder increased hepatic microsomal AHH and 7-ethoxyresorufin deethylase activities as expected, and AHH activity was strongly inhibited in the DBA-treated flounder by 10" M a-naphthoflavone as we have previously reported for both little skate (4) and sheepshead (9). However, the presence of high AHH and 7-ethoxyresorufin deethylase activities in one control flounder, and the inhibition of AHH activity by a-naphthoflavone in this animal suggested that the hepatic microsomal MFO system of this fish was already induced. 

AHH Activity (FU/min/mg protein) Without a-Naphthoflavone With a-Naphtboflavone (10 M) 7-ERF Activity (pmol/min/mg protein)... 

On the other hand, the metabolism of benzo[a]pyrene, ethoxy-coumarin and ethoxyresorufin, which are preferentially oxidized by rodent cytochrome P -450, was greatly induced by the polyhalogenated biphenyls and 3-naphthoflavone. Despite large changes in... 

Figure 1. Effect of potential inducing agents on certain hepatic microsomal enzymes of the rainbow trout. Animals were infected intraperitoneally with either phenobarbital (65 mg/kg) 3-methylcholanthrene (20 mg/kg) 2,3-benzanthracene (10 mg/kg) or /3-naphthoflavone (100 mg/kg). The animals were sacrified and hepatic microsome prepared 48 hr after infection. Each bar is the mean SE (n = 3-5) ( ), induced activity (T) significantly different from control (C) activity...

Figure 3. Spectra of ethylisocyanide-ferrocytochrome P-450 complexes, rainbow trout. Conditions were as in Figure 2, except rainbow trout hepatic microsomes were used. (A) Microsomes from rainbow trout treated with (j-naphthoflavone (100 mg/kg sacrificed 4 days later). Protein concentration, 1.4 mg/mL total P-450 concentration, 0.48 fi.M. (B) Microsomes from control fish. Protein concentration, 0.93 mg/mL, total P-450 concentration, 0.22 /iM.

Figure 4. SDS-polyacrylamide gel electrophoresis of microsomes from variously pretreated rainbow trout (A), control microsomes, 90 fig protein/gel (B), /3-naphthoflavone-inauced microsomes, 90 fig protein/gel (C), Aroclor 1242-induced microsomes, 90 fig protein/gel.

The RDA reaction is also a typical process of flavones, naphthoflavones, and methoxynaphthoflavones. [115] In many cases it provides intact A- and B-ring fragments, and therefore, it is of high relevance for structure elucidation. The intensity ratio of A- to B-ring fragments was found to be strongly influenced by the substituent position, i.e., to be very sensitive to the charge distribution within the molecular ion. [116]... 

Guigugli, F.H. Kavka, J. Garibay, M.E. Santillan, R.L. Joseph-Nathan, P. Mass Spectral Studies of Naphthoflavones. Org. Mass Spectrom. 1987, 22, 479-485. 

WB shows CYP7A/induction in arachnoid, dura mater, choroid plexus, pineal gland, and pituitary of rat brain by //-naphthoflavone (Morse et al., 1998). 

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