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Herpes simplex virus infections are the cause of significant morbidity, and currently used therapeutics are largely based on modified nucleoside analogs that inhibit viral DNA polymerase function. To target this disease in a new way, we have identified and optimized selective thiazolylphenyl-containing inhibitors of the herpes simplex virus (HSV) helicase-primase enzyme. The most potent compounds inhibited the helicase, the primase and the DNA-dependent ATPase activities of the enzyme with IC50 (50% inhibitory concentration) values less than 100 nM. Inhibition of the enzymatic activities was through stabilization of the interaction between the helicase-primase and DNA substrates, preventing the progression through helicase or primase catalytic cycles. Helicase-primase inhibitors also prevented viral replication as demonstrated in viral growth assays. One compound, BILS 179 BS, displayed an EC50 (effective concentration inhibiting viral growth by 50%) of 27 nM against viral growth with a selectivity index greater than 2,000. Antiviral activity was also demonstrated for multiple strains of HSV, including strains resistant to nucleoside-based therapies. Most importantly, BILS 179 BS was orally active against HSV infections in murine models of HSV-1 and HSV-2 disease and more effective than acyclovir when the treatment frequency per day was reduced or when initiation of treatment was delayed up to 65 hours after infection. These studies validate the use of helicase-primase inhibitors for the treatment of acute herpesvirus infections and provide new lead compounds for optimization and design of superior anti-HSV agents.

Molecular modeling analysis of the recently published X-ray crystal structure of nevirapine bound to wild type human immunodeficiency virus type 1 reverse transcriptase (WT-RT) indicated the presence of a lipophilic cavity proximal to the 4-position of the inhibitor. A series of 4-substituted derivatives of nevirapine were thus synthesized to assess structure-activity relationships (SARs) and to see if increased binding to this region might translate into greater activity against mutant RTs. The results show that compounds with an appropriately spaced aryl ring appended to the 4-position of the dipyridodiazepinone ring system show good activity against WT-RT. Furthermore certain derivatives appear to inhibit the Y181C mutant RT. Attempts to combine these results with the recent discovery that 2-substituents enhance activity against the Y181C mutant led to a few compounds with moderate activity against both enzymes. The SAR of these two positions, however, could not be combined in a simple fashion.

Dibenz[b,f][1,4]oxazepin-11(10H)-ones (III), pyrido[2,3-b][1,4]benzoxazepin-6(5H)-ones (IV), and pyrido[2,3-b]- [1,5]benzoxazepin-5(6H)-ones (V) were found to inhibit human immunodeficiency virus type 1 reverse transcriptase with IC50 values as low as 19 nM. A-ring substitution has a profound effect on activity, with appropriate substituents at the positions ortho and para to the lactam nitrogen providing dramatically enhanced potency. Substitution in the C-ring is generally neutral or detrimental to activity. Although a C-ring amino substituent at the position meta to the lactam carbonyl is generally beneficial to activity, it has essentially no effect when the A-ring is optimally substituted. Like the dipyridodiazepinone nevirapine, compounds III-V are specific for HIV-1 RT, exhibiting no inhibitory activity against HIV-2 RT or other virial reverse transcriptase enzymes.

Novel pyrido[2,3-b][1,4]benzodiazepinones (I), pyrido[2,3-b][1,5]benzodiazepinones (II), and dipyrido[3,2-b:2',3'-e][1,4]diazepinones (III) were found to inhibit human immunodeficiency virus type 1 (HIV-1) reverse transcriptase in vitro at concentrations as low as 35 nM. In all three series, small substituents (e.g., methyl, ethyl, acetyl) are preferred at the lactam nitrogen, whereas slightly larger alkyl moieties (e.g., ethyl, cyclopropyl) are favored at the other (N-11) diazepinone nitrogen. In general, lipophilic substituents are preferred on the A ring, whereas substitution on the C ring generally reduces potency relative to the corresponding compounds with no substituents on the aromatic rings. Maximum potency is achieved with methyl substitution at the position ortho to the lactam nitrogen atom; however, in this case an unsubstituted lactam nitrogen is preferred. Additional substituents on the A ring can be readily tolerated. The dipyridodiazepinone derivative 11-cyclopropyl-5,11-dihydro-4-methyl-6H-dipyrido[3,2-b:2',3'-e] [1,4]diazepin-6-one (96, nevirapine) is a potent (IC50 = 84 nM) and and selective non-nucleoside inhibitor of HIV-1 reverse transcriptase, and has been chosen for clinical evaluation.

The dipyridodiazepinone human immunodeficiency virus type 1 (HIV-1)-specific reverse transcriptase (RT) inhibitor BI-RG-587 was tested for its ability to inhibit HIV-1 replication in both acutely and chronically infected cell lines. The ability of BI-RG-587 to inhibit steps in the virus replicative cycle other than reverse transcription was also assessed. BI-RG-587 was found to be a potent inhibitor of HIV-1 replication in acutely infected cells (50% inhibitory concentration [IC50] = 37.2 nM), and the sensitivity and kinetics of that inhibition was similar to the known RT inhibitor zidovudine (AZT). Even at 100x IC50, BI-RG-587 had no effect on gp120/CD4 interaction, syncytia formation, or envelope glycoprotein processing. In addition, no inhibition of viral replication or protein production was noted in a chronically infected cell line that produces viral products in an RT-independent manner. Finally, no inhibition of acute HIV-2 replication was noted, even with very high (2500x IC50 for HIV-1) concentrations of BI-RG-587. These results demonstrate that BI-RG-587 is a potent inhibitor of HIV-1 replication and that this inhibition occurs at the point of reverse transcription.

Nevirapine, a dipyridodiazepinone, is a highly specific inhibitor of HIV-1 reverse transcriptase (RT) which exhibits an IC50 = 84nM in enzyme assays and IC50 = 40nM against HIV-1 replication in cell culture. This nonnucleoside inhibitor acts noncompetitively with respect to nucleoside triphosphates, template and primer suggesting that nevirapine does not bind to the active site of RT. Studies employing an azido analogue of nevirapine as a photoaffinity probe indicated that one molecule of inhibitor is sufficient to inactivate one molecule of heterodimeric enzyme and demonstrated that only the p66 subunit of p66/p51 heterodimeric RT is covalently labeled by this probe. When subjected to trypic mapping, Tyr 181 and Tyr 188 were labeled with probe and consequently these aromatic residues are apparently near or actually within the RT binding site for nevirapine. The extent to which Tyr 181 and Tyr 188 participate/contribute to nevirapine binding was determined by making amino acid substitutions at these positions using the corresponding residues from HIV-2 RT which is not sensitive to nevirapine. A change at either position dramatically decreased the enzymes' sensitivity to nevirapine, as well as to TIBO derivative and Merck L-693,593, indicating that both Tyr 181 and 188 are crucial for inhibitor-enzyme interaction. Cell culture selection in the continued presence of nevirapine results in the appearance of resistant HIV-1, Tyr 181 to Cys, raising the concern that combination drug therapy will be required in the clinic.

A series of dipyridodiazepinones have been shown to be potent inhibitors of human immunodeficiency virus-1 (HIV-1) reverse transcriptase (RT). One compound, BI-RG-587, had a Ki of 200 nanomolar for inhibition of HIV-1 RT that was noncompetitive with respect to deoxyguanosine triphosphate. BI-RG-587 was specific for HIV-1 RT, having no effect on feline and simian RT or any mammalian DNA polymerases. BI-RG-587 inhibited HIV-1 replication in vitro as demonstrated by in situ hybridization, inhibition of protein p24 production, and the lack of syncytia formation in cultured human T cell lines and freshly isolated human peripheral blood lymphocytes. Cytotoxicity studies of BI-RG-587 on human cells showed a high therapeutic index (greater than 8000) in culture.

The structures of the title compounds I, II and III have been determined by X-ray crystallography. All three compounds, including the 8β-t-butyl isomer II(axial t-butyl), exist in double chair forms. Compound II is deformed by an outward tilt as well as a substantial twist (16.2°) of the t-butyl group away from the staggered conformation. A slightly lesser twist of 13.7° is found in the equatorial t-butyl isomer I. Outward bending of the axial N-methyl group also occurs in compound III.

A series of N-(4-substituted-thiazolyl)oxamic acid derivatives were synthesized and tested for antiallergy activity in the rat PCA model. These compounds were conveniently prepared by treatment of the appropriate acetophenone with thiourea and iodine or by reaction of the chloroacetylbenzene with thiourea to give the corresponding aminothiazoles; subsequent condensation with ethyloxalyl chloride gave the thiazolyloxamates. Many of the analogues showed a 50% inhibition at less than 2 mg/kg po or less than 0.4 mg/kg iv and were significantly more potent than disodium cromoglycate, which in the rat PCA model is orally inactive and gives a 50% inhibition at 1.2 mg/kg iv. Hydrolysis of the oxamates generally resulted in enhanced activities, while substitution of the phenyl ring with a variety of substituents (e.g., 4-F, 4-OEt, and 4-NHCOCH3) did not significantly enhance the activity of the unsubstituted phenyl derivative. One of the ethanolamine salts, N-[4-(1,4-benzodioxan-6-yl)-2-thiazolyl]oxamic acid ethanolamine salt (61, PRH-836-EA), has been selected for further pharmacological evaluation.

This report will provide an assessment of the progress that has been made in the design of immune regulatory agents and will draw attention to those areas that are considered to offer the greatest promise. We will begin with a brief outline of the matrix of cellular events that are associated with the immune response. Compounds that have been reported to alter these events are discussed in the context of the segment of this matrix wherein their primary activity is observed. Emphasis is placed on the diverse structural groups encountered and the opportunities for innovation in synthesis and the analysis of structure-activity relationships. Substances that have demonstrated clinical potential are highlighted

8β- t -Butyl- trans -decahydroquinoline picrate crystallizes a double chair with an axial t -butyl group. Except for a 16.2° torsion of the t -butyl group way from the staggered conformation, the molecule displays only minor conformation deformations.

From S. namaquense L. Bolus, we have isolated the known base tortuosamine (7) and two new alkaloids, 3′methoxy-4′-O-methyljoubertiamine (6) and (–)-mesembrane (2) the structures of which have been established by spectroscopic and X-ray methods. Previous suggestions concerning the absolute configuration of alkaloids of the 3a-aryl-cis-octahydroindole ring system are confirmed by an X-ray analysis of (–)-mesembrane hydrochloride monohydrate which crystallizes in the monoclinic system, space group P21, with a= 14.50(1), b= 8.02(1), c= 7.57(1)A, β= 93.4(1)°, Z= 2. The crystal structure was solved by direct methods and refined by least-squares calculations to R 0.055 over 1 158 reflections from diffractometer measurements. The absolute configuration was established by the anomalous dispersion effect. The c.d. spectrum of (–)-mesembrine, considered as an axial β-aminoketone, is shown to exhibit normal octant behaviour.

The 13C NMR spectra of 62 oxanes (tetrahydropyrans) with and without methyl substituents at various ring positions, some of them bearing in addition (or instead) ethyl, vinyl, ethynyl, carbomethoxy and methylol substituents at C-2, have been recorded, and the 294 resulting chemical shifts have been correlated by multiple linear regression analysis. Axial and equatorial α-, β-, γ-, δ-, gem- and vic-parameters for shifts caused by methyl groups at all ring positions, and similar parameters for Et,—CHCH2,—CCH, CO2Me and CH2OH groups at C-2, are reported. Standard deviations of the parameters are, in most cases, within 0.3 ppm and the agreement of calculated and experimental shifts is excellent. This is probably the largest parameter set of this type extant. 13C NMR spectra of a number of additional substituted tetrahydropyrans, and of 3,6-dihydro-2H-pyrans and 3,4-dihydro-2H-pyrans, are tabulated and discussed.

This report will provide an assessment of the progress that has been made in the design of immune regulatory agents and will draw attention to those areas that are considered to offer the greatest promise. We will begin with a brief outline of the matrix of cellular events that are associated with the immune response. Compounds that have been reported to alter these events are discussed in the context of the segment of this matrix wherein their primary activity is observed. Emphasis is placed on the diverse structural groups encountered and the opportunities for innovation in synthesis and the analysis of structure-activity relationships. Substances that have demonstrated clinical potential are highlighted

The structures of the title compounds I, II and III have been determined by X-ray crystallography. All three compounds, including the 8β-t-butyl isomer II(axial t-butyl), exist in double chair forms. Compound II is deformed by an outward tilt as well as a substantial twist (16.2°) of the t-butyl group away from the staggered conformation. A slightly lesser twist of 13.7° is found in the equatorial t-butyl isomer I. Outward bending of the axial N-methyl group also occurs in compound III.

Crystals of the title complex are tetragonal, space group P4/n, with a= 12.590(7), c= 7.840(5)A, and Z= 2. The crystal structure has been solved by the heavy-atom method and refined by full-matrix least-squares calculations to R 0.059 over 860 statistically signrfrcant reflections from diffractometer measurements (Cu-Kα radiation). The square-pyramidal [CrCl4O]– anion has crystallographic 4mm(C4v) symmetry with Cr–O 1.519(12) and Cr–Cl 2.240(3)A, and O–Cr–Cl 104.5(1)°. The [AsPh4]+ cation has crystallographic (S4) symmetry [As–C 1.906(6)A C–As–C 105.3(3) and 111.5(3)°]. E.s r. spectroscopy has been used to estimate the equilibrium constants for the reaction [CrCl4O]–+ L [graphic omitted] [CrCl4OL]n– in CH2Cl2solution {n= 1 when L = PPh3O (K= 3 ± 2), P(NMe2)3O (K= 463 ± 130), thf (K < 1), or py (K= 160); n= 2 when L = Cl–(K= 43 ± 10 with [AsPh4]Cl and 250 ± 33 dm3 mol–1 with [NEt4]Cl)}.