Krystian Pluta

Anticancer activity of newly synthesized azaphenothiazines from NCI’s anticancer screening bank#

The activity of the newly synthesized azaphenothiazines: tricyclic 10-substituted dipyridothiazines 1-9, pentacyclic 6-substituted diquinothiazines 10-22 and hexacyclic diquinothiazinium salt 23 was tested on 55-60 in vitro cell lines. The cell lines included nine types of cancer: leukemia, non-small cell lung cancer, colon cancer, CNS cancer, melanoma, ovarian cancer, renal cancer, prostate cancer and breast cancer (National Cancer Institute, Bethesda, MD, USA). The features of the chemical substituent at the thiazine nitrogen atom confer the anticancer activity of diquinothiazines 10-23. Unexpectedly, the most active of the dipyridothiazines 1-9 was the unsubstituted compound 1 (the substituent is a hydrogen atom). The most cytotoxic compound was the half-mustard derivative 18. The GI(50) value of this compound was -7.06 (corresponding to 40 ng/ml) when tested on the melanoma cell line SK-MEL-5 and -6.0 - -6.62 using cell lines from various cancers including: leukemia (CCRF-CEM), the MOLT-4 cell line, colon cancer (HCT-116), central nervous system cancer (SNB-75 and SF-295), prostate cancer (PC-3), non-small cell lung cancer (NCI-H460 and HOP-92), ovarian cancer (IGROV1 and OVCAR-4) and breast cancer (MDA-MB-460). The ethylene group in the aminoalkylazaphenothiazines is as a good linker and is similar to the propylene and butylene linkers in aminoalkylphenothiazines. To our knowledge, this is the first demonstration of significant azaphenothiazine anticancer activity.

The immunosuppressive activities of newly synthesized azaphenothiazines in human and mouse models

In this study, we evaluated the activities of new types of azaphenothiazines in the following immunological assays: the proliferative response of human peripheral blood mononuclear cells induced by phytohemagglutin A or anti-CD3 antibodies; lipopolysaccharide-induced cytokine production by human PBMC; the secondary, humoral immune response in mice to sheep erythrocytes (in vitro); and delayed-type hypersensitivity in mice to ovalbumin (in vivo). In some tests, chlorpromazine served as a reference drug. The compounds exhibited differential inhibitory activities in the proliferation tests, with 10H-2,7-diazaphenothiazine (compound 1) and 6-(3-dimethylaminopropyl)diquinothiazine (compound 8) being most suppressive. Compound 1 was selected for further studies, and was found to be strongly suppressive in the humoral immune response even at low concentrations (1 μg/ml). Compound 1 also inhibited the delayed-type hypersensitivity lipopolysaccharide-induced production of tumor necrosis factor and interleukin-6 in cultures of human blood cells. As there were only two subjects in this study, the effects of these compounds on human blood cells need to be confirmed. In this paper, we also discuss the structure-activity relationships of selected compounds.

Synthesis of novel heteropentacenes containing nitrogen, sulfur and oxygen or selenium

Reactions of 2,2′-dichloro-3,3′-diquinolinyl sulfide with selected S-, O-, Se-, C- and N-nucleophiles proceeded as a hetero-ring closure to form six linear annelated pentacyclic heterocycles with a sulfur-containing central ring (1,4-dithiin, 1,4-thiazine, 1,4-thiaselenin, 1,4-oxathiin and thiopyran) in moderate to good yields. The X-ray study of selected heteropentacenes revealed that heteropentacenes, in contrast to homopentacene, are non-planar and folded along the central sulfur-heteroatom axis. The central six-membered ring is in a boat conformation.

RP TLC Determination of the Lipophilicity of New 10‐Substituted 2,7‐Diazaphenothiazines*

Abstract Experimental (R M0 and log P TLC) and calculated (log P calcd) lipophilicity parameters of eleven new bioactive 10‐substituted 2,7‐diazaphenothiazines 2–12 were determined by reversed‐phase thin‐layer chromatography on RP‐18 silica plates, with acetone‐aqueous TRIS (tris(hydroxymethyl)aminomethane) buffer as the mobile phase, and obtained by the calculation program miLogP. The parameter R M0 was converted into parameter log P TLC by use of a calibration curve obtained for five standards. The lipophilicity parameters were intercorrelated and discussed in the terms of structure-lipophilicity relationships. The parameter R M0 and specific hydrophobic surface area b were significantly intercorrelated showing three congeneric subclasses of 2,7‐diazaphenothiazines 2–12. The 2,7‐diazaphenothiazine system turned out to be less lipophilic than the classical phenothiazine one. *Part CIII in the series of Azinyl Sulfides.

Synthesis and selected immunological properties of 10-substituted 1,8-diazaphenothiazines

A new type of tricyclic azaphenothiazines—1,8-diazaphenothiazines—was obtained in the reaction of 2,3- and 3,4-disubstituted pyridines. The reaction ran as the Smiles rearrangement. The 1,8-diazaphenothiazine system was determined using NOE experiment and 2D NMR spectra (COSY, HSQC, HMBC). 10H-1,8-diazaphenothiazine was transformed into 10-derivatives with alkyl, aminoalkyl, amidoalkyl, sulfonamidoalkyl, and nitrogen half-mustard groups. The compounds were tested for their effects on phytohemagglutinin A-induced proliferative response of human peripheral blood mononuclear cells (PBMC) and lipopolysaccharide-induced tumor necrosis factor alpha production by human whole blood cultures. The compounds exhibited differential, dose-dependent inhibitory activities in these tests. All the compounds were low toxic against PBMC. The compounds showing the highest antiproliferative activity strongly inhibited the growth of leukemia L-1210 and colon cancer SW-948 cell lines, similarly as cisplatin, a reference drug.

6-Substituted 9-fluoroquino[3,2-b]benzo[1,4]thiazines display strong antiproliferative and antitumor properties

6-Substituted 9-fluoroquino[3,2-b]benzo[1,4]thiazines - a new type of tetracyclic azaphenothiazines-were obtained from of 6H-9-fluoroquinobenzothiazine by the introduction of appropriate substituents to the thiazine nitrogen atom (alkyl, aminoalkyl, amidoalkyl, sulfonamidoalkyl and nitrogen half-mustard groups). The compounds displayed differential cytotoxic as well as antiproliferative actions against human peripheral blood mononuclear cells (PBMC) stimulated with phytohemagglutinin A (PHA). In addition, they suppressed lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNF-α) production by whole blood human cell cultures. Two compounds (4 and 15, with the propargyl and methanesulfonamidopropyl groups) were selected for further experiments because of lack of cytotoxicity and strong antiproliferative actions. Compound 4 showed strong suppressive actions on growth of L1210, SW948, A-431 and CX-1 tumor cell lines which were close to those of cisplatin, the reference drug (e.g. GI50 of 2.28 μg/mL vs. 1.86 μg/mL for L1210 cells). Further, the compound appeared to be equally effective as cyclosporine A (CsA) in the inhibition of human two-way mixed lymphocyte reaction (MLR). The compound did not significantly inhibit interleukin 2 (IL-2)-induced growth of CTLL-2 cell line. In addition, inhibition of prostaglandin (PG) synthesis by indomethacin or block of PG receptors did not interfere with the inhibitory effect of the compound on PHA-induced cell proliferation. Therefore, it is likely that the compound acts by inhibiting cell cycle as proposed for other phenothiazines. Further studies are required for the elucidation of the mechanism of action and therapeutic utility of these compounds in more advanced in vivo models.

SYNTHESIS AND PROPERTIES OF 14-SUBSTITUTED 1,4-THIAZINODIQUINOLINES

Abstract 4,4′-Dichloro-3,3′-diquinolinyl sulfide 1 reacted with aryl-, heteroaryl- and alkylamines in MEDG or phenol to 14-substituted thiazino[2,3-c;6,5-c′]diquinolines 2, Reaction with ammonia, ammonium carbonate or benzylamine led to unsubstituted thiazine 2a, Alkylation of thiazine 2a with alkyl halides gave 14-alkyl-I,4- thiazinodiquinolines 2b, 2c and 2f, The nature of the 14-substituent has a significant effect on 1H NMR and MS spectral properties.

X-ray structure of 6-phenyldiquino[3,2-b;5,6-b'] [1,4]thiazine

The title compound (C24H15N3S) is monoclinic, with a = 10.816(1), b = 8.193(1), c = 10.892(1), β = 104.20(1)° and space group P21. The molecule is folded with the central ring in a boat conformation. It can also be considered as folded around the C—C axis between the thiazine and pyridine rings. The butterfly folding angle between the two quinoline planes is 20.5(1)° and between the planes of the two halves of the thiazine ring is 30.6(1)°. The phenyl substituent is in an equatorial location with respect to the thiazine ring with the C—N···S angle of 163.0(2)°. The phenyl plane nearly bisects the pentacyclic ring system and is nearly perpendicular to the C(2), C(3), C(12), C(13) plane.

Synthesis and NMR Properties of Pentacyclic Heterocycles Containing Sulfur, Nitrogen And Oxygen Or Selenium

Abstract 4,4′-Dichloro-3,3′-diquinolinyl sulfide 3 underwent ring closure reactions with divalent nucleophiles to pentacyclic heterocycles: dithiin 4, thiopyran 5, thiazine 6, oxathiin 7 and thiaselenin 8 in good yield (76–100%). The chemical shift of the H-1 and H-13 protons in 1H NMR spectra is a result of the interaction between these atoms and the Z-atom.

Antioxidant Activity of Newly Synthesized 2,7-Diazaphenothiazines

A series of 19 derivatives of 2,7‐diazaphenothiazine was synthesized and evaluated for their antioxidant activity bearing in mind the structural similarity with “classical” phenothiazines several of which are considered powerful antioxidants. Among the new derivatives that inhibited in vitro Fe2+/ascorbate‐induced lipid peroxidation of rat liver microsomal membranes, several exhibited significant antioxidant activity with IC50 values in the range of 64–125 μM. Although N‐substitution led to a variable degree of antioxidant activity, the latter appears to correlate with the lipophilicity (expressed as clogP values) of the substituted derivatives. Reduced lipophilicity may also explain the relatively lower protection offered by these derivatives against lipid peroxidation when compared to their “classical” phenothiazine counterparts. Thus, modification of the phenothiazine structure by a substitution of two benzene rings with pyridine rings to form this new type of azaphenothiazines does not enhance antioxidant activity, although it retains it.