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At least 199 records · Page 11Linked to original sources
PubMed1973

Use of the 295- to 300-nanometer circular dichroism through of ribonucleic acid to study helix winding: effect of acridine orange.

Acridine orange decreases the amplitude of the 295-nm circular dichroism (CD) trough of ribosomal ribonucleic acid (rRNA) where the trough has been related to coil character. Since acridine orange is known from earlier work to intercalate between base pairs of nucleic acids, causing an unwinding of the coil, and our studies show a decrease in the 295-nm CD trough, it appears that CD measurements may be used to observe relative unwinding of rRNA. Under similar solution conditions, melting temperatures with acridine orange indicate no significant change in the stabilization of rRNA structure by acridine orange. Hypochromicity studies show no increase in the percent base pairing in rRNA when 0.1 M tris(hydroxymethyl)aminomethane (pH 7.6) with 1.35 M KCl is used. These results indicate that CD changes in the amplitude of the 295-nm trough of rRNA are related to helix winding in rRNA.

Acridines↗
PubMed1994

Detection of borreliacidal antibody by using acridine orange and flow cytometry.

Borreliacidal antibody has been shown to be important for the serodiagnosis of Lyme disease and determination of immune status. Our results show that borreliacidal antibody can be rapidly and accurately detected by flow cytometry. Acridine orange was added to normal and immune sera containing Borrelia burgdorferi organisms in the presence and absence of complement prior to data acquisition by flow cytometry. The flow cytometric parameters of side scatter and detection of acridine orange fluorescence were used to determine events per minute (number of labeled spirochetes), percent shift in fluorescence (number of dead spirochetes), and mean channel fluorescence (intensity of fluorescence-labeled spirochetes) of acridine orange-labeled spirochetes. Borreliacidal antibody was detected as early as 4 h, with optimal detection 16 to 24 h after incubation of B. burgdorferi organisms with immune serum and complement. Our results also showed that complement was necessary for detection of borreliacidal antibody. Flow cytometry with acridine orange-labeled spirochetes provides a rapid means for detection of borreliacidal antibody.

Acridine Orange↗
PubMed1992

[Quenching of ethidium-DNA fluorescence by novel acridines with antitumor activities].

In order to elucidate the relationships between the antitumor activity and the molecular structure of novel acridine derivatives (1a-f, and 2a-e in Chart 1) the DNA-binding properties (intercalation) of the derivatives were examined by the quenching in fluorescence of an ethidium-DNA complex, which may be caused by the displacement of DNA-bound ethidium by a second DNA-binding ligand, acridines. The concentration (C50 value) of the acridine necessary to reduce the initial fluorescence of DNA-bound ethidium by 50% showed a good correlation with their antitumor activities. The fluorescence quenching of the acridines was examined using 4'-(9-acridinylamino)- methanesulfonanilide (amsacrine, AMSA) as a typical standard of the second DNA-bound ligand, and calf thymus DNA with an apparent site size of two base pairs.

Acridines↗
PubMed2003

Evaluation of acridine in Nafion as a fluorescence-lifetime-based pH sensor.

We report a novel fluorescence-lifetime-based pH sensing method that utilizes acridine incorporated into Nafion (AcNaf) as the fluorescent indicator. The AcNaf sensor is excited using a 380 nm light emitting diode (LED) and the fluorescence lifetimes are measured at 450 and 500 nm. The fluorescence behavior of acridine as a function of pH in aqueous phosphate buffers and incorporated into the Nafion membrane has been investigated. The results show that incorporating acridine into Nafion changes the apparent ground-state pKa from -5.45 to -9, while the apparent excited-state pKa* is only slightly changed (approximately 9.4 in 0.1 M phosphate buffer). The AcNaf film shows a good pH response with a change in average lifetime of approximately 19 ns (at an emission wavelength of 450 nm) over the pH 8 to 10 range. We also show that excited-state protonation does not occur in the AcNaf sensor film and that chloride quenching cannot occur because of the permselective nature of Nafion. We also discuss how the unique structure of Nafion affects the fluorescence behavior of acridine at various pH values and examine the impact of buffer concentration on apparent pKa and pH sensing ability.

Acridines↗
PubMed1994

Differential inhibition of cyclic AMP-dependent protein kinase, myosin light chain kinase and protein kinase C by azaacridine and acridine derivatives.

A series of 72 acridine and azaacridine derivatives have been tested as inhibitors of Ca(2+)- and phospholipid-activated protein kinase C (PKC), the catalytic subunit of cyclic AMP-dependent protein kinase (cAK) and Ca(2+)-calmodulin-dependent myosin light chain kinase (MLCK). A series of monomethyl derivatives of N-(2-dimethylaminoethyl)-acridine-4-carboxamide that have anti-tumour activity are good inhibitors of MLCK (IC50 values ranging from 4-138 microM) but these same compounds are ineffective or relatively poor inhibitors of PKC or cAK. With only several exceptions, the effective azaacridine inhibitors of PKC and MLCK (IC50 values < 200 microM) have basic or neutral 4-substituents whereas the effective azaacridine inhibitors of cAK have either neutral or acidic 4-substituents. The four exceptions found to this generality are effective inhibitors of all three protein kinases with IC50 values of about 100 microM or less. With several exceptions azaacridine inhibitors of PKC are also inhibitors of MLCK but effective inhibitors of cAK are relatively poor inhibitors of MLCK and PKC and vice versa. 4-N-(2-dimethylaminoethyl)-6-azaacridone-4-carboxamide is a competitive inhibitor of MLCK with respect to both the peptide substrate and ATP. All other acridines and azaacridines examined are non-competitive inhibitors of both MLCK and cAK with respect to both ATP and peptide substrate. All azaacridine PKC inhibitors examined are competitive with respect to ATP and noncompetitive with respect to peptide substrate suggesting that binding of these inhibitors is at or near the enzyme active site. The inhibition of MLCK (but not cAK or PKC) by anti-tumour acridine carboxamides suggests a novel site of in vivo biological action and a useful criterion for the detection of potential antitumour compounds.

Acridines↗
PubMed1985

The metabolism of the carcinogen 7-methylbenz[c]acridine by hepatocytes isolated from untreated and induced rats.

The metabolic fate of the carcinogenic aza-aromatic hydrocarbon 7-methyl[7-(14)C]benz[c]acridine (14C-7MBAC) was studied in hepatocytes freshly isolated from untreated, phenobarbital-pretreated and 3-methylcholanthrene-pretreated rats. 14C-7MBAC (4-200 microM) was metabolized in a concentration-dependent manner; Michaelis-Menten kinetics were not followed. Using 100 microM 14C-7MBAC, the bulk of the ethyl acetate-extractable metabolites were found in the incubation medium; about 50% of the total metabolites were not extractable into ethyl acetate. The nature of the water-soluble metabolites was examined by enzyme hydrolysis of glucuronides and sulphates, and by glutathione-depletion experiments. Organo-extractable metabolites were examined by reverse-phase h.p.l.c. and quantified by co-chromatography with standards. pretreatment of the rats with mixed-function oxidase inducers, phenobarbital and 3-methylcholanthrene resulted in 2.85- and 5.70-fold increases, respectively, in total metabolism of 14C-7MBAC. Major metabolites for all three hepatocyte preparations co-chromatographed with 7-hydroxymethylbenz[c]acridine, trans-5,6-dihydro-5,6-dihydroxy-7-methylbenz[c]acridine and trans-8,9-dihydro-8,9-dihydroxy-7-methylbenz[c]acridine.

Acridines↗
PubMedDate not supplied

[Evaluation of direct microscopic examination, acridine orange staining and culture methods for studies of Trichomonas vaginalis in vaginal discharge specimens].

Trichomonas vaginalis is the causative agent of human trichomoniasis which is a sexually transmitted disease mainly in women. The infection may be asymptomatic or symptomatic such as severe vaginitis and cervicitis. The aim of this study was to compare direct microscopic examination, acridine orange stained examination and culture in Modified Diamond medium, for the detection of T. vaginalis from the vaginal swab samples of 310 patients (age ranges: 17-45 years old) who were complaining from vaginal discharge. Of them 40 (12.9%) samples were found positive with culture, 20 (6.5%) were positive with direct microscopy and 19 (6.1%) were positive with acridine orange staining method. The positive results were obtained in 17 cases by each of the three methods, in 3 cases by direct microscopy and culture, in 2 cases by acridine orange staining and culture, and in 18 cases by culture only. T. vaginalis has been detected in 19.5% of 41 patients with itching, 15.7% of 190 patient with groin pain and 23.2% of 43 patients with cervical erosion, in addition to vaginal discharge, by at least one of the methods. In conditional evaluation, there were no statistically significant differences between T. vaginalis positivity with age groups and the contraceptive methods used. As a result, it was concluded that for the laboratory diagnosis of T. vaginalis, acridine orange staining technique does not have any superiority over direct microscopy. Although direct microscopy is a practical and economical method, it has low sensitivity, so all of the suspected samples which are found negative by this method, should be cultivated for a definite diagnosis.

Acridine Orange↗
PubMedDate not supplied

Relationship between resonance energy and carcinogenic activity of benz[c]acridines.

In order to investigate the correlation between the carcinogenic activity of benz[c]acridines and the electron density, the Huckel orbital method was used. Resonance energies, circuit resonance energies and bond currents of benz[c]acridines were calculated by Aihara's TRE theory. It was shown that these compounds had very stable aromatic characters with positive resonance energies and that the resonance energies per pi-electron values for the compounds with lack of the double bond corresponding to the K-region from the parent skeleton were more stable than those of their parent compounds. 7-Methyl-benz[c]acridine derivatives with the methyl groups at 7-, 7, 9-, 7, 10-, 7, 11-, 7, 9, 10-, or 7, 9, 11-positions except 5, 7-dimethylbenz[c]acridine had potent carcinogenic activity and significantly lower resonance energy per pi-electron.

Acridines↗
PubMed1979

The use of acridine orange for testing blood platelet integrity.

Two processes are involved in the accumulation of acridine orange in human blood platelets. One follows a diffusion like kinetics and is independent of the ATP level whereas the second one can be completely abolished by ATP depletion. The acridine orange incorporation rate seems to be a suitable parameter for testing platelet integrity. It reflects very sensitively the influence of the preparation method as well as of anticoagulating substances used on the stability of platelet suspensions. The rates of acridine orange incorporation and of aggregation were measured in platelet-rich plasma and in saline suspended platelets after gel filtration, respectively, over a period of 120 min storage. Both rates are influenced to a different degree by anticoagulating agents such as citrate, heparin and EDTA. When contact with anticoagulating agents during platelet preparation is avoided, platelets show a constant acridine orange incorporation and aggregation during storage and the smallest morphological alteration.

Acridine Orange↗
PubMed1979

Pharmacological studies on new oncostatic acridine derivatives. I. Acute and subchronic action.

Preclinical pharmacological studies of two acridine derivatives, dihydrochloride N10-oxide 1-nitro-9-/3-dimethylaminopropylamino/-acridine (C-666) and dihydrochloride 1-nitro-9-[(2-dimethylamino)-1-methylethylamino]-acridine (C-829) are reported. Both compounds are characterized by biological activity, poor absorption from the gastrointestinal tract and local irritant action. Quality differences in an effect of both investigated acridine derivatives on the central nervous system were noted. C-666 proved to be deprived of the effect typical of the central component compounds while C-829 demonstrated mostly sedative activity. Clear dissociation in the effect of these both compounds was seen in in vitro experiments on isolated smooth muscle organs. C-666 acted spasmolytically on the motory action of intestine muscles while C-829 acted spastically. Both preparations had clearly hipotensic influence which can be due to the vascular effect and to their affinity with the intramyocardium transmitting system. Neither a distinctive effect on reproductivity of animals nor the teratogenic action were observed in the functional experiments.

Acridines↗
PubMed1978

[Elimination of penicillinase plasmids by the new acridine derivative, Dimer].

The possibility of eliminating the drug resistance determinants in penicillinase-producing staphylococci under the effect of an acridine "dimer", synthesized by French scientists was studied. Comparison of the eliminating activity of a number of acridine compounds, such as acrichin, acriflavine, proflavine and "dimer" showed that the new derivative of acridine as well as the other acridines used in the experiments induced elimination of the penicillinase plasmids when used in the sublethal concentrations.

Acridines↗
PubMedDate not supplied

Diverse biological activities displayed by phenothiazines, benzo[a]phenothiazines and benz[c]acridins (review).

This review summarizes our experiments which are investigating the relationship between the structure and activity of mainly phenothiazines, benzo[a]phenothiazines and benz[c]acridines. Phenothiazines had potent antiplasmid and antibacterial activities, but induced weak antimicrobial activity in vivo. Their antiplasmid activity seemed to be enhanced by Cl- or CF3- substitution at the 2C position of phenothiazines and modified by the side-chain length and hydrophobicity. Benzo[a]phenothiazines did not show any significant antiplasmid or antibacterial activity, but stimulated the differentiation of human myelogenous leukemic cell lines and natural killing activity of human peripheral blood mononuclear cells in vitro, and induced antimicrobial activity in vivo. Circuit current energy (CRE), circuit current (CC), bond current (BC), diatropic and paratropic properties of benzo[a]phenothiazines might be correlated with their biological activity. Benz[a]acridine showed both in vitro and in vivo antimicrobial activities, and carcinogenic activity for skin tumor. The carcinogenic benz[c]acridines showed out-of-phase in the L-region and their energy was accumulated in the K-region of the molecular orbitals. The results suggest the involvement of different molecular orbitals for the expression of various biological activities by phenothiazines, benzo[a]phenothiazines and benz[c]acridines.

Acridines↗
PubMed1979

Cytochemical specificity of acridine red towards RNA and depolymerised DNA.

The paper contains an account of the use of the basic dye, acridine red, of the xanthene group, for staining RNA and depolymerised DNA. The in situ absorption curve of nuclei stained with acridine red indicates a peak of maximum absorption at 560 nm, whereas in vitro absorption characteristics of an aqueous solution of the dye indicate the peak at 550nm. The possibility of using acridine red as a substitute for pyronin, when staining is required for RNA only or in methyl green-acridine red sequence for localising DNA and RNA has been discussed.

Acridines↗
PubMedDate not supplied

Radical productions and pi-spin density by UHF/PM3 method on benz[c]acridines and benzo[a]phenothiazines.

On the calculated pi-spin density (rho pi) of benz[c]acridines [1-12], benz[c]acridines [2,8-12] with alternately value of pi-spin density (rho pi) on angular ring, large negative pi-spin density at C-1 and C-3 positions and large positive pi-spin density at C-2 and C-4 positions indicates their carcinogenicity, except for 7-methylbenz[c]acridine [7]. Benz[c]acridines [1,3-6] which do not follow were not carcinogenic. Radical producing benzo[a]phenothiazines [13-16] and non-radical producing benzo[a]phenothiazines [17-19] gave calculated pi-spin density (rho pi) which was positive in radical producing benzo[a]phenothiazines [13-16] at N-12 position, and had the opposite pi-spin density in non-radical producing benzo[a]phenothiazines [17-19].

Acridines↗
PubMed2006

Tautomerism of acridin-9-amines substituted at the exocyclic nitrogen atom: spectroscopic investigations and theoretical studies.

In the ground electronic state, the first two (1 and 2) of the compounds investigated--9-(methoxyamino)acridine (1), 9-hydrazinoacridine (2), N-(2-chloroethyl)acridin-9-amine (3) and N-(5-methylpyridin-2-yl)acridin-9-amine (4)--exist principally in the imino tautomeric form, while the other two (3 and 4) can coexist as amino and imino tautomers in solvents of various polarities and abilities to enter into specific interactions. These features of the molecules are reflected in the experimental absorption spectra and the predicted thermodynamic and spectral data. The predicted thermodynamic characteristics suggest that in the S1 state, the imino tautomers of 1, 2 and 4 and the amino tautomer of 3 are more stable than their tautomeric counterparts. However, the predicted rates of intersystem crossing suggest that the imino tautomers of 1-3 and the amino tautomer of 4 lose excitation energy very rapidly, so that only their counterpart tautomers in fact emit radiation. This explains why 1 and 2 do not fluoresce and why the amino form of 3 and the imino form of 4 are the emitters. 3 and 4 thus represent acridin-9-amines whose imino forms are preferred in the ground state, but whose respective amino and imino forms are preferred in the excited state. Because 3 and 4 are capable of tautomeric transformations in the ground and excited states, and also enter into specific interactions with solvents, these compounds could be potent spectral indicators or probes of environmental properties.

Aminacrine↗
PubMed2004

Negative ion photoelectron spectroscopy of acridine molecular anion and its monohydrate.

Negative ion photoelectron spectroscopy was employed to investigate the electronic structure of the acridine molecular anion and its monohydrated anion in the gas phase. Their adiabatic electron affinities were measured to be 0.896+/-0.010 and 1.18+/-0.05 eV, and the low-lying electronic excited states in both neutral acridine and in its monohydrate were revealed. The photoelectron spectra clearly exhibit the presence of low-lying singlet and triplet states having a (pi,pi*) configuration in an uncomplexed acridine molecule. Comparison of the photoelectron spectrum of acridine with that of anthracene shows that photodetachment processes into the excited states of (n,pi*) configuration have little intensity, implying a relatively large intramolecular structural relaxation in the (n,pi*) states.

Journal Article↗
PubMed2001

Acridine-a neglected antibacterial chromophore.

The use of acridines as antimicrobial agents was first proposed by Ehrlich and Benda in 1912, and the first clinical use of these agents occurred in 1917. Many compounds containing the acridine chromophore were synthesized and tested, and the aminoacridines found wide use, both as antibacterial agents and as antimalarials, during World War II. The emergence of the penicillins eclipsed the acridines in antisepsis due to the greater therapeutic efficacies of the former. However, with the current massive increases in drug-resistant bacterial infection, new acridine derivatives may be of use. In addition, the topical utilization of aminoacridines in conjunction with directed low-power light offers bactericidal action at much lower doses.

Aminoacridines↗
PubMed1989

Oligothymidylates covalently linked to an acridine derivative and with modified phosphodiester backbone: circular dichroism studies of their interactions with complementary sequences.

Oligothymidylates involving alternating alkyl phosphotriester-phosphodiester or methylphosphonate-phosphodiester backbones and covalently linked to an acridine derivative have been studied using circular dichroism. Two isomers with the same diastereoisomeric configuration for all the phosphotriesters (ethyl triester and neopentyl triester) or the methylphosphonate linkages were studied. These six compounds were compared to the parent oligonucleotide with unmodified phosphodiester bonds. Intramolecular interactions between the acridine and the bases of the oligonucleotides were revealed by the induced circular dichroism of the acridine dye. Binding to poly(rA) and poly(dA) induced large changes in the circular dichroism signal. All oligothymidylates formed double-stranded complexes with poly(rA). Substitution of phosphotriesters and methylphosphonates to phosphates allowed both double- and triple-stranded structures to be formed with with poly(dA). The double-stranded structures formed with poly(rA) and poly(dA) were characterized by different environments of the acridine dye. The circular dichroism spectra of the complexes with poly(dA) and the thermal stabilities of the complexes formed with both poly(rA) and poly(dA) were drastically dependent of the diastereoisomeric configuration of the phosphate modification. For the complexes formed with the pseudoequatorial stereoisomer the modification of the phosphate groups increased the stability of the complexes as compared with the oligothymidylate containing only phosphodiester linkages whereas it decreased it for pseudoaxial modifications.

Aminoacridines↗