The first total synthesis of heteromine B, and an improved synthesis of heteromine A; natural products with antitumor activities

Efficient total syntheses of heteromines A and B (antitumor compounds previously isolated from the plant Heterostemma brownii Hayata) from commercially available 2-amino-6-chloropurine have been developed. The synthesis of heteromine A is considerably shorter than the previously reported synthesis, only requiring four steps, whereas the iodide salt of heteromine B was prepared in five steps. Heteromines A and B showed no significant antibacterial activity and therefore appear to be selective toward cancer cell lines.     

Synthesis and In Vitro Antitumor Evaluation of Some New Pyrimido[4,5‐b]quinoxaline 5,10‐Dioxide Derivatives

A new series of tricyclic pyrimidoquinoxaline derivatives were synthesized and evaluated as antitumor assays and compared with standard drug 5‐fluorouracil. These new pyrimidoquinoxaline derivatives were synthesized by the reaction with o‐aminonitrilequinoxaline derivative 3 with various reagents. One from which, the condensation of o‐aminonitrile with potassium cyanate in acetic acid was stated as a new procedure for building the pyrimidine ring incorporate to quinoxaline moiety. Further condensation of aminonitrile 3 with formamide or Vilsmeier reaction followed by transamination or carbon disulphide was applied as procedures for the pyrimidine ring syntheses. Compound 15 achieved significant in vitro antitumor activity, and compounds 9 and 14 have high activities.     

Streptonigrin and lavendamycin partial structures. Preparation of 7-amino-2-(2′-pyridyl)quinoline-5,8-quinone-6′-carboxylic acid: A probe for the minimum,potent pharmacophore of the naturally occurring antitumor-antibiotics

The preparation of 7-amino-2-(2′-pyridyl)quinoline-5,8-quinone-6′-carboxylic acid (4) constituting a potential minimum, potent pharmacophore of streptonigrin (1) and lavendamycin (2) , two structurally-related naturally-occurring antitumor-antibiotic, is detailed. In contrast to observations associated with streptonigrin and lavendamycin in which the C-6′ acid potentiates the antitumor, antimicrobial, and cytotoxic activity of the naturally-occurring, substituted 7-aminoquinoline-5,8-quinone AB ring systems, the C-6′ carboxylic acid of 4 diminishes the observed antimicrobial and cytotoxic properties of 7-amino-2-(2′-pyridyl)quinoline-5,8-quinone.     

Antimicrobial activity of 3-(substituted methyl)-2-phenyl-4H-l-benzothiopyran-4-ones

A series of 3-(substituted Methyl)-2-phenyl-4H-l-benzothiopyran-4-ones (thioflavones) and thioflavone 1,1-dioxides was prepared to test for antimicrobial activity and for antitumor activity. It was shown that an introduction of a substituted methyl group in the 3-position of thioflavone resulted in significant antimicrobial activity against Trichophytons. 3-(Acetoxymethyl)thioflavone shows the most antimicrobial potency in vitro against Trichophyton mentagrophytes. Most of the thioflavone 1,1-dioxides showed antimicrobial activity against fungi. Five of the 40 related compounds demonstrated weak antitumor activity against P-388 lymphocytic leukemia.     

Synthesis and Pharmacological Investigations of Novel Pyrazolyl and Hydrazonoyl Cyanide Benzimidazole Entities

Various novel benzimidazole entities linked to pyrazolyl and hydrazonoyl cyanide substrates carrying aryl and heteroaryl groups ( 8a – e to 10a – e ) were synthesized using new route syntheses and were focused on their pharmacological evaluation as one of the most important factors for the determination of the activity of these synthesized compounds. The obtained benzimidazoles' series were fully characterized and exhibited remarkable pharmacological activity upon in vitro screening for their antibacterial activity against strains of selected pathogenic Gram‐positive bacteria (Staphylococcus aureus) and Gram‐negative bacteria (Escherichia coli) comparing with Ampicillin and Kanamycin as standard antibacterial agents and against human liver cancer cell lines (HepG2) as antitumor agents as well.     

Thiazolo[4,5-d]pyrimidines. Part I. synthesis and anti-human cytomegalovirus (HCMV) activity in vitro of certain alkyl derivatives

Alkyl derivatives of the thiazolo[4,5-d]pyrimidine congeners of guanine and uracil were prepared and assessed for in vitro activity against human cytomegalovirus (HCMV). The finding that the 3-pentyl 1b and 3-hexyl 1c derivatives of 5-aminothiazolo[4,5-d]pyrimidine-2,7(3H,6H)-dione (1e) had potent in vitro anti-HCMV activity prompted a broader study of alkyl derivatives in this ring system. A series of 3-alkyl derivatives of 1e , viz. 1f-w , were prepared by direct alkylation of the sodium salt of 1e and by subsequent modifications, 2a-d. For comparison with 1c , 5-amino-2-hexylaminothiazolo[4,5-d]pyrimidin-7(6H)-one (4) was prepared and studied. The 3-(2-alkenyl) derivatives of 1e were found to be the more active antiviral agents with the Z isomer of 5-amino-3-(2-penten-1-yl)thiazolo[4,5-d]pyrimidine-2,7(3H,6H)-dione (1f) having the better therapeutic index. Analogous 4-(2-alkenyl) derivatives of 2-aminothiazolo[4,5-d]pyrimidine-5,7(4H,6H)-dione 6a and 6b were also prepared but were found to have poor therapeutic indices. Single crystal X-ray diffraction analysis was used to unequivocally establish the structure of 1f.     

Novel Bleomycin Analogues: Synthesis,Antitumor Activity,and Interaction with DNA

The novel analogues 11 – 16 of bleomycin A₆ ( 3 ) were obtained by selective protection of the primary‐amine function of the β‐aminoalaninamide moiety of 3 by means of coordination with Cu^II ions, condensation with an aliphatic or aromatic acid R′COOH in the presence of dicyclohexylcarbodiimide, and demetalization (Scheme). The antitumor activity against HeLa and BGC‐823 in vitro, binding property with CT‐DNA, and cleavage potency towards pBR322 DNA were also studied (Tables 1–3). All the compounds 11 – 16 displayed significant antitumor activity, which was enhanced as the hydrophobicity of the C‐terminus substituent R′ increased, but decreased as the DNA‐binding affinity increased. There was a negative relationship between DNA‐cleavage potency and binding affinity to DNA in this series of compounds.     

Synthesis and biological activity of 23-hydroxybetulinic Acid C-28 ester derivatives as antitumor agent candidates

23-Hydroxybetulinic acid (1) served as the precursor for the synthesis of C-28 ester derivatives. The target compounds were evaluated in vitro for their antitumor activities against five cell lines (A549, BEL-7402, SF-763, B16 and HL-60). Among the obtained compounds, 6i had the most potent antitumor activity, with the IC₅₀ values of 8.35 μM in HL-60 cells and showed similar antitumor activity as cyclophosphamide in H22 liver tumor and as 5-fluorouracil in B16 melanoma in vivo.     

Design,Synthesis, and In Vitro Antileishmanial and Antitumor Activities of New Tetrahydroquinolines

A novel series of tetrahydroquinolines containing acetohydrazide, oxopyrazole, oxothioxodihydropyrazole, and thioxotriazole have been synthesized. Antileishmanial, antitumor, and cytotoxicity activities of synthesized compounds were evaluated in vitro. Antileishmanial activity of the most synthesized compounds showed tremendous activity towards Leishmania major. Most of the test compounds exhibited significant level of tumor inhibition. The tetrahydropyrano[2,3‐b]quinolin‐2‐one 6 and 4‐oxo‐4H‐pyrazol‐3‐yloxytetrahydroquinoline‐3‐carbonitrile derivatives 18 showed 100% tumor inhibition comparable with standard drug vincristine (100% tumor inhibition). Tetrahydroquinolines under investigation showed cytotoxicity with LD₅₀ values in the range 0.56–3.01 μg/mL compared with standard drug MS‐222 with LD₅₀ value of 4.30 μg/mL. The presence of a pyrazole ring markedly improved the activity profiles of tetrahydroquinoline. All newly synthesized compounds were characterized by IR, ¹H NMR, and MS.     

Ru(II)‐based antineoplastic: A “wingtip” N‐heterocyclic carbene facilitates access to a new class of organometallics that are cytotoxic to common cancer cell lines

The syntheses, structures, and chemotherapeutic activities of Ag(I)‐, Au(I)‐, and Ru(II)‐complexes ligated to a novel N‐heterocyclic carbene ligand, 2‐(4‐nitrophenyl)imidazo[1,5‐a]pyridin‐2‐ylidene ( 1 ), are described. The corresponding complexes, [Ag( 1 )₂][PF₆], [Au( 1 )₂][PF₆] ( 3 ), and [Ru( 1 )(p‐cymene)Cl][PF₆] ( 4 ), were prepared using convenient transmetallation chemistry and characterized using a range of spectroscopic and analytical techniques. X‐ray crystallography revealed that complexes 2 and 3 adopted linear structures whereas 4 exhibited a prototypical “piano‐stool”‐like geometry; the structural assignments were further supported by DFT calculations. A series of in vitro studies revealed that while the aforementioned Ag(I), Au(I) and Ru(II) complexes exhibited significant cytotoxicities against the human colon adenocarcinoma (HCT 116), lung cancer (A549), and breast cancer (MCF7) cell lines, the Ru derivative was most prominent.     

Streptonigrin and related compounds III. Synthesis and microbiological activity of destrioxyphenylstreptonigrin and analogues

Synthesis of three tricyclic analogues of streptonigrin, based on the 2-(2′-pyridyl)quinoline-5,8-dione system and with the characteristic substitution pattern of rings A and C of streptonigrin is described. The C-ring precursor, in the form of a substituted 2-acetylpyridine was condensed with either 3-hydroxy-5-methoxy-2-nitrobenzaldehyde or 3-hydroxy-4-methoxy-2-nitrobenzaldehyde, followed by reductive cyclization and oxidation to the corresponding quinones 12 and 29 . The 7-amino substitution was introduced in 12 via bromination and azidation. The 6-amino substitution was introduced through direct reaction of 29 with sodium azide. Destrioxyphenylstreptonigrin 2 was twice as active and the 6-amino-7-inethoxy analogue 4 was as active as streptonigrin in a microbiological assay. A 4′-bromo analogue of 2 was 60% as active as streptonigrin.     

Streptonigrin and related compounds IV. Precursors for the a-ring

The synthesis of streptonigrin or its tricyclic (ABC) analogues by the Friedlander condensation requires a 2-nitrobenzaldehyde with all the necessary functionalities. A number of alternative syntheses are examined. It is shown that oxidation of 8-amino-5,6-dimethoxy-2,2-pyridylquinoline leads to 8-amino-2,2-pyridylqunoline-5,6-dione instead of 6-methoxy-2,2-pyridylquinoline-5,8-dione. The synthesis of two useful precursors: 4-bromo-3-hydroxy-5,6-dimethoxy-2-nitrobenzaldehyde and 4-bromo-3-hydroxy-5-methoxy-2-nitrobenzaldehyde is described.     

Synthesis and cytotoxic activity of certain new arylazothiazole containing compounds

2‐Amino‐5‐arylazo‐4‐(2‐chlorophenyl)thiazoles ( 2a‐e ) were prepared by the coupling of aryldiazonium chlorides with 2‐amino‐4‐(2‐chlorophenyl) thiazole ( 1 ). The thioureas 3a‐e were obtained by condensing the arylazothiazoles 2a‐c with the appropriate isothiocyanates. Reaction of 2d with aromatic aldehydes afforded the chalcone analogues 4a‐c . The pyridone derivatives 5a,b were synthesized by reacting the ketone 2d with different aromatic aldehydes, ethyl cyanoacetate and ammonium acetate. On the other hand, 5b was also prepared by cyclizing 4c with ethyl cyanoacetate and ammonium acetate. Furthermore, 6‐chloroimidazo[2,l‐b]‐thiazole 7 was obtained from the acid derivative 6b by treatment with POC1₃. While, the imidazo[2,l‐b]‐thiazolones 9a‐d were produced by the cyclization of the chloroacetyl derivatives 8a‐d with DMAP/pyri‐dine. Representative examples of the prepared compounds were tested for in vitro antitumor activity against two human tumor cell lines. Some compounds showed activity against brain tumor cell lines.     

Synthesis and in vitro evaluation of some new pyrimidines and related condensed ring systems as potential anticancer agents

Several new pyrimidines 6–11, 18–20 , furo-, thieno-, and pyrrolo[2,3-d]pyrimidines 3, 8, 12 , triazolo-[4,3-a]pyrimidines 14, 15, 16 and tetrazolo[1,5-a]pyrimidine 17 were prepared from the known intermediate 5-(2-hydroxyethyl)-6-methyl-2-thiouracil ( 2 ). Compound 7 (4-chloro-5-(2-chloroethyl)-2-methylthio-6-methyl-pyrimidine) exhibited weak antitumor activity in vitro.     

Exceptionally high in vitro antitumor activity of substituted triphenyltin benzoates including salicylates against a human mammary tumor,MCF-7, and a colon carcinoma,WiDr

Nine new substituted triphenyltin benzoates of the type Ar₃Sn? OOC? C₆H₂XYZ [X = Y = H, Z = 2-OCH₃ and 4-F; X = H, Y = 3-F, Z = 5-F; X = H, Y = 2-OH, Z = 5-Cl, 5-NH₂, 5-OCH₃ and 5-SO₃H; X = 2-OH, Y = 3-CH(CH₃)₂ and Z = 5-CH(CH₃)₂] were prepared and possess considerable in vitro antitumor activity against two human tumor cell lines (MCF-7, a mammary tumor, and WiDr, a colon carcinoma) comparable with that of mitomycin C.     

Novel Quinazoline Derivatives Bearing a Sulfapyridine Moiety as Anticancer and Radiosensitizing Agents

Quinazoline derivatives posses many types of biological activities and have recently been reported to show substantial antitumor activity in vitro and/or in vivo. There is a variety of mechanisms for their anticancer activity. The present work reports the possible utility of methyl anthranilate in the synthesis of some new quinazoline derivatives, bearing a substituted sulfonamide moiety. All the newly synthesized compounds were evaluated for their in vitro anticancer activity against human liver cancer cell line, using doxorubicin as a reference drug. In addition, the most active compounds 14 and 15 were selected and evaluated for their ability to enhance the cell killing effect of γ‐radiation.     

Synthesis of Novel 4β-(1, 2, 3-Triazol-1-yl) Podophyllotoxins as Potential Antitumor Drugs

The synthesis, characterization and in vitro antitumor activity of two novel podophyllotoxins, 4β-(5-methyl-1, 2, 3-triazol-1-y1)podophyllotoxin (5) and 4β-(5-phenyl-1, 2, 3-triazol-1-y1)podophyllotoxin (6), are described.     

Synthesis,Structure and in vitro Antitumor Activity of a Multinuclear Diorganotin(IV) Complex [(n‐Bu)4Sn2{2,5‐F2C6H3C(O)NHO}2{2,5‐F2C6H3C(NO)O}]2

A new multinuclear dibutyltin(IV) complex [(n‐Bu)₄Sn₂{2,5‐F₂C₆H₃C(?O)NHO}₂{2,5‐F₂C₆H₃C(?NO)O}]₂ 1 , was synthesized and structurally characterized by melting point measurement, elemental analysis, FT‐IR, ¹H, ¹³C, ¹¹⁹Sn NMR spectroscopies, and X‐ray diffraction analysis. The complex exhibited in vitro antitumor activity against a murine sarcoma carcinoma cell line (S‐180), which was higher than that of 5‐fluorouracil (5‐Fu), currently used clinically as an antitumor agent.     

Design and Synthesis of Novel C4‐Linked Substituted 2H‐Chromen‐2‐one‐hypoxanthine Hybrids as Potential Antimicrobial Agents: An Approach to Molecular Docking Studies

We present here design and synthesis of very efficient, high‐yielded and simple approach of a series of C₄‐linked coumarin–hypoxanthine pharmacophores 1 ( a–j ) with moderate to excellent in vitro antimicrobial activity. According to earlier studies, potential modification at C₄‐position of coumarin ring provided excellent bioactive molecules. All the titled compounds were characterized by spectroscopic and elemental analyses. Titled compounds have been developed via systematic tuning of coumarin ring substitutions, which are prepared from the well‐known Pechmann condensation reaction. The addition of a pendent nucleobase in hypoxanthine group improved the in vitro antimicrobial activity. Computational studies were also mimicking the potent biomolecules. A good pharmacokinetic profile is suggested by theoretical calculation of absorption, distribution, metabolism, and excretion properties. Therefore, synthesis of these titled compounds provided an insight towards better antimicrobial agents.     

New potential antitumor quinazolinones derived from dynamic 2-undecyl benzoxazinone: Synthesis and cytotoxic evaluation

Since the quinazoline and its derivatives have been considered as a novel class of cancer chemotherapeutic agents that show promising activity against different tumors, a new series of 6-iodo-2-undecylquinazolin-4(3H)-ones were prepared via reaction of 6-iodo-2-undecyl-4H-benzoxazin-4-one with nitrogen nucleophiles, namely, primary amines, 4-amino antipyrine, hydrazine hydrate, diamines, ethanol amine, and/or hydrazide derivatives and screened for their antitumor activity in vitro against a panel of three human tumor cell lines namely; hepatocellular carcinoma (liver) HepG2, colon cancer HCT-116, and mammary gland breast MCF-7. Compounds 14, 16, and 18 showed remarkable broad spectrum antitumor activity. All compounds were fully characterized by means of IR, MS, and ¹H-NMR spectra.