Biphenyl hydroxylation, activities

Golbeck JH, SA Albaugh, R Radmer (1983) Metabolism of biphenyl by Aspergillus toxicarius induction of hydroxylating activity and accumulation of water-soluble conjugates. J Bacteriol 156 49-57. 

The benzanthrone system is susceptible to both electrophilic and nucleophilic attack. The most reactive sites towards electrophiles are the 3- and 9-positions, which can be compared with the 4,4 -positions in biphenyl. The 9-position is somewhat deactivated by the carbonyl group, however. Thus, for example, monobromination takes place at the 3-position and further substitution gives 3,9-dibromobenzanthrone. Nitration and benzoylation similarly give rise to the 3-substituted product. The 3-position is in fact peri-hindered (compare naphthalene) so that sulphonation yields the 9-sulphonic acid. Electron withdrawal by the carbonyl group activates the 4- and 6-positions towards nucleophilic attack for example, hydroxylation occurs at these sites. 

The analogue in which carbon replaces oxygen in the enol ring should of course avoid the stability problem. The synthesis of this compound initially follows a scheme similar to that pioneered by the Corey group. Thus, acylation of the ester (7-2) with the anion from trimethyl phosphonate yields the activated phosphonate (7-3). Reaction of the yhde from that intermediate with the lactone (7-4) leads to a compound (7-5) that incorporates the lower side chain of natural prostaglandins. This is then taken on to lactone (7-6) by sequential reduction by means of zinc borohydride, removal of the biphenyl ester by saponification, and protection of the hydroxyl groups as tetrahydropyranyl ethers. 

Polybrominated Biphenyls. In air, the two processes that may result in significant degradation or transformation of PBBs are photooxidation by hydroxyl radicals and direct photolysis. The estimated half-life of pentachlorobiphenyl in air due to reaction with hydroxyl radicals is 41.6 83.2 days (Atkinson 1987a). Based on a structure-activity relationship for the estimation of half-lives for the gas-phase reactions of hydroxyl radicals with organic compounds (Atkinson 1987b), the estimated half-lives of hexabromobiphenyl and decabromobiphenyl due to reaction with OH radicals are 182 and 2,448 days, respectively. These half-lives are consistent with the half-life of pentachlorobiphenyl due to reaction with OH radicals. However, the half-lives of brominated biphenyls expected to be present in the particulate phase in the air may be even longer than the estimated half-lives due to gas phase reaction. Therefore, the Iransfonnation of the hexa- and other higher brominated PBBs in the atmosphere due to reaction with OH radicals may not be irrportant. 

George, J., Shylesh, S. and Singh, A. P. Vanadium-containing ordered mesoporous silicas Synthesis, characterization and catalytic activity in the hydroxylation of biphenyl, Appl. Catal., A, 2005, 290, 148-158. 

Some polychlorinated biphenyls, especially their non-planar para-hydroxylat-ed metabolites also possess estrogenic activity [126,135,140]. These metabolites have a higher estrogenic potency than their parent compounds. Some co-planar polychlorinated biphenyls (PCB 77 and PCB 126) have been shown in vivo to have estrogenic as well as antiestrogenic activities, probably solely through hydroxy metabolites (NIH shift to para). This reinforces the European view that EDCs can only be confirmed in intact animals. It is also known that some hydroxylated metabolites of polycyclic aromatic hydrocarbons (PAHs), e.g. 3,9-dihydroxybenzo[a]anthracene, show estrogenic activity [141 -143]. 

Figure 10 Theoretical (a) and practical (b) representation of QSARs. Panel b describes a QSAR for the methanotrophic oxidation (activity of methane monooxygenase) of 6>r /i6>(Ci2)-substituted biphenyls. The structural backbone was biphenyl, and the substituents considered included all halogens, methyl-, methoxy-, hydroxyl-, nitro-, and amino-moieties (Lindner et al, 2003). The molecular descriptors used in (b) are (charge on the ortho-csubon), (Taft s steric parameter), and log ow...

There is still considerable activity in the synthesis of Lythraceae alkaloids, although no new methods have emerged this year. Details have appeared of two independent syntheses of the biphenyl ether alkaloid decaline. - Arata s approach to the synthesis of decaline (35) cf. Vol. 5) has been applied to lagarine (36), using a benzyl group to protect the phenolic hydroxyl substituent. 4-Arylquinolizid-2-ones, cf. (34), are important synthetic intermediates, and their synthesis from isopelletierine and a variety of 2-bromobenzaldehyde derivatives has been studied. ... 

Connor K, Ramamootrhy K, Moore M, et al. 1997. Hydroxylated polychlorinated biphenyls (PCBs) as estrogens and antiestrogens Structure-activity relationships. Toxicol Appl Pharmacol 145 111-123. 

Moore M, Mustain M, Daniel K, et al. 1997. Antiestrogenic activity of hydroxylated polychlorinated biphenyl congeners identified in human serum. Toxicol Appl Pharmacol 142 160-168. 

Safe SH, Connor K, Raamamorthy K, et al. 1998. Estrogenic activity of hydroxylated polychlorinated biphenyls (PCBs) and their interactions. In Eisenbrand G, ed. Hormonally active agents in food Symposium. Weinheim, ERG Wiley-VCH, 200-207. 

One of the first SULTlAl inhibitors identified in the rat liver was 2, 6-dichloro-4-nitrophenol (DCNP) (Mulder and Scholtens, 1977). DCNP is a dead-end inhibitor, and exhibits low IC50 values toward SULTlAl and SULT 1 A3 (Seah and Wong, 1994). Hydroxylated polychlorinated biphenyls (HPCBs) are potent inhibitors of recombinant human SULTIEI. HPCBs exhibit low micromolar IC50 values toward thyroid hormones (Schuur et al., 1998). Several dietary chemicals such as quercetin, curcumin, and flavones are known to inhibit SULTs. Some commonly used drugs that inhibit SULTlAl and SULT1A3 activity include NSAIDs such as mefenamic acid, naproxen, and salicylic acid. 

Benzo(a)pyrene hydroxylase activities in hepatic and intestinal microsomes of fiber-fed rats are presented in Table VIII. There were no significant differences (0.05 level) among any of the purified fiber treatment groups in either liver or intestinal microsomes. Lab Chow-fed rats had the lowest liver microsomal benzo(a)pyrene hydroxylase (AHH) level. The indication of enhanced intestinal P-448-dependent hydroxylation of biphenyl in the pectin-fed rats (seen as elevated 3-hydroxybiphenyl formation in microsomes, Table Vl) was not supported by these preliminary data. 

Poly(biphenyl ether sulfone)s can be prepared, with carbonates or with the alkali metal hydroxides as activators. In the carbonate method, the poly(sulfone)s are prepared by the reaction of equimolar amounts of dihydroxy aromatic compounds and dihalodiaryl sulfones. Dihydroxy aromatic compounds are BP, 4,4 -dihydroxydiphenyl sulfone, hydroquinone, bisphenol A. Dihalodiaryl sulfones, are 4,4 -dichlorodiphenyl sulfone or 4,4 -difluorodiphenyl sulfone. 0.5 to about 1.0 mole of an alkali metal carbonate per mole of hydroxyl group is added. The condensation is conducted as azeotropic condensation, at a temperature of 210-300°C up to 15 hours. 

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