Higher efficiency of thymine-adenine clamp-modified single-stranded oligonucleotides in targeted nucleotide sequence correction is not correlated with lower intracellular degradation.

Specific single-stranded oligonucleotides can induce targeted nucleotide sequence correction in eukaryotic genes in vitro and in vivo. Our model for investigating the reasons for the low correction rates achieved by this method is the correction of a point mutation in the hypoxanthine-guanine phosphoribosyltransferase gene (hprt) in the cell line V79-151. Using single-stranded phosphorothioate-modified oligonucleotides, the correction rates of this hprt mutation were low but always reproducible. One reason for low exchange rates may be fast intracellular degradation of the oligonucleotides. Therefore we compared the exchange rates of different 3' and 5' end-modified oligonucleotides with their degradation rates. Thymine-adenine (TA) repeat (clamp)-modified oligonucleotides showed higher correction rates than those with a guanine-cytosine (GC) clamp and 5' clamps induced higher correction rates than clamps at the 3' end. Experiments on the stability of the most effective 5'-TA and 3'-TA clamp-modified oligonucleotide indicated rapid cleavage and the occurrence of shortened oligonucleotides in the presence of cytoplasmic and nuclear extracts. The phosphorothioate-modified oligonucleotides were more stable, but their correction rates were lower. We suggest that there is no direct correlation between the biological stability of the full-length oligonucleotides and the exchange rates achieved.

[Methylated 2-aryl-1,4-naphtoquinone derivatives with diminished antioxidative activity]. / Methylierte 2-Aryl-1,4-naphthochinonderivate, 5-Lipoxygenase-Inhibitorenmit reduzierter antioxidativer Aktivität.Untersuchungen an 1,4-Naphthochinonen, 28. Mitt.

Methylated 2-aryl-1,4-naphtoquinone derivatives with diminished antioxidative activity 2-(3,5-Di-tert-butyl-4-hydroxyphenyl)-3-hydroxy-1,4-naphthoquinone (1) is a selective 5-lipoxygenase (5-LOX) inhibitor possessing high antioxidative activity (AOA). In order to study the question if this activity corresponds to the mechanism of the 5-LOX inhibition (redox type 5-LOX inhibitor) the analogues 57-66 and their 3-methoxy derivatives 47-56 of the reference compound 1 were synthezised. These compounds are mono- and dimethylated within the benzoid molecular moiety which were tested for their 5-LOX inhibiting activity using human granulocytes and for their AOA by a chemiluminometric method. The synthesis of the test compounds runs in the following manner: Diels-Alder reaction of 1,4-benzoquinone (2) with the buta-1,3-dienes 3-8, bromination of the 1,4-naphthoquinones 9-14, arylation with 2,6-di-tert-butylphenol and substitution of bromine of the aryl-bromonaphthoquinones 33-46 by methoxy and hydroxy functions. A key step is the cc separation of the regioisomeric mixtures 25/26-31/32. The most potent 5-LOX inhibitors (IC50 = 1-3 microM) possess methylfunctions in 5-/8-position and show markedly diminished AOA compared with 1. 5-LOX inhibition and AOA in this class of compounds hence are not positively correlated.

[Partially hydrogenated aryl-1,2/1,4-anthraquinone derivatives, 5-lipoxygenase inhibitors with arotinoid structure]. / Partiell hydrierte Aryl-1,2/1,4-anthrachinon-Derivate, 5-Lipoxygenase-Inhibitoren mit Arotinoid-Struktur.

The combination of 5-LOX inhibition and retinoid activity in one molecule could be an interesting pharmacological tool to influence psoriasis. Thus we synthesized compounds with arotinoid structure by anellation of the 5-LOX inhibitors 1 and 2 with 1,1,4,4-tetramethylcyclohexane. A key step was the CuCl-MeCN-O2 oxidation of tetrahydroanthracenol 13 to the corresponding 1,2-anthraquinone 14 which could be converted to the analogous 2-hydroxy-1,4-anthraquinone 19 by Thiele-Winter reaction followed by oxidation. The halogenated quinones 9 and 21 were arylated with 2,6-di-tertbutylphenol and demethylated or hydrolyzed to the target compounds 3 and 4 which were tested in comparison with the non-anellated 5-LOX inhibitors 1 and 2 for LOX inhibition in activated human granulocytes and for antioxidative activity by the method of Popov with the chemiluminometer Photochem. The results are discussed in relation to the corresponding logP values. The 1,2-quinones 1 and 3 are more potent 5-LOX inhibitors than their 1,4-analogues 2 and 4, the tetrahydroanthraquinon derivatives 3 and 4 are less potent than the naphthoquinones 1 and 2. All compounds are devoid of any activity in cell differentiation as compared to retinoic acid as indicated by the NBT test with HL-60 leukemia cells.

[2-(3-Halogen-4-hydroxyphenyl)-1,4-napthoquinone derivatives from 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-analogs, potent 5-lipoxygenase inhibitors. 27. 1,4-Naphthoquinones]. / 2-(3-Halogen-4-hydroxyphenyl)-1,4-naphthochinon-Derivate aus 2-(3,5-Di-tert-butyl-4-hydroxyphenyl)-Analoga, potente 5-Lipoxygenase-Inhibitoren. Untersuchungen an 1,4-Naphthochinonen, 27. Mitt.

A new simple and fast method for the synthesis of halogenated hydroxyphenyl naphthoquinones as potential 5-lipoxygenase (LOX) inhibitors is presented. While the aryl naphthoquinone 1, a potent 5-LOX inhibitor, with AlCl3 is debutylated to 2a and 2b, the oxidized cyclohexadienylidene derivative 3 reacts comparably by concomitant halogenation to 4a and with AlBr3 to 4b, respectively. As products of a side reaction of 6 with TiCl4 and BBr3 the tetracyclic benzo[b]naphthol[2,1-d]furan derivatives 8a and 8b are isolated. Selected compounds are investigated for 5-lipoxygenase inhibiting and antioxidative properties. There is a clear-cut correlation of both qualities in those compounds with a 3-OH function and with two, one or without any tert-butyl group at the phenyl moiety. In contrast the quinone 6 (3-Cl) and the dibenzofuran 8a are powerful 5-LOX inhibitors with only low antioxidative activity.