Synthesis of new 2-naphthyl ethers and their protective activities against DNA damage induced by bleomycin-iron

Article abstract of DOI:10.1248/cpb.57.1348

The reaction of 2-naphthaloxyacetic acid with thiosemicarbazide in the presence of phosphoryl chloride, followed by treatment with phenacylbromides, led to the formation of imidazo[2,1-b][1,3,4]thiadiazoles 3a-c. 2-(Naphthalen-3-yloxy)acetohydrazide 4 on treatment with ethyl 2-(2-arylhydrazono)-3-oxobutanoates (5a-c), 2-methoxymethylene)malononitrile, or ethyl 2-cyano-3,3-bis(methylthio)acrylate led to the formation of substituted pyrazoles 6-8. The reaction of the hydrazide 4 with hydrazonoyl chlorides 9a-c and 1,2,4,5-benzene tetracarboxylic-1,2:4,5-dianhydride produced bis-diazo compounds 10a-c and dimide 11 respectively. All new compounds were tested for their protective activity against DNA damage induced by bleomycin-iron complex. Compound 2 showed the greatest protection against DNA damage, thus diminishing chromogen formation between the damaged DNA and thiobarbituric acid.

Full text of DOI:10.1248/cpb.57.1348

1348
Chem. Pharm. Bull. 57(12) 1348—1351 (2009)
Vol. 57, No. 12
Synthesis of New 2-Naphthyl Ethers and Their Protective Activities
against DNA Damage Induced by Bleomycin–Iron
c
Bakr F. ABDEL-WAHAB, ,a Abdel-Aziz S. EL-AHL,b and Farid A. BADRIA
*
b
a Applied Organic Chemistry Department, National Research Center; Dokki, Giza, Egypt: Chemistry Department, Umm
c
Al-Qura University, University College Makah; Kingdom of Saudi Arabia: and Pharmacognosy Department, Faculty of
Pharmacy, Mansoura University; Mansoura 35516, Egypt.
Received May 13, 2009; accepted August 20, 2009; published online September 17, 2009
The reaction of 2-naphthaloxyacetic acid with thiosemicarbazide in the presence of phosphoryl chloride, fol-
lowed by treatment with phenacylbromides, led to the formation of imidazo[2,1-b][1,3,4]thiadiazoles 3a—c. 2-
(Naphthalen-3-yloxy)acetohydrazide 4 on treatment with ethyl 2-(2-arylhydrazono)-3-oxobutanoates (5a—c), 2-
methoxymethylene)malononitrile, or ethyl 2-cyano-3,3-bis(methylthio)acrylate led to the formation of substituted
pyrazoles 6—8. The reaction of the hydrazide 4 with hydrazonoyl chlorides 9a—c and 1,2,4,5-benzene tetracar-
boxylic-1,2:4,5-dianhydride produced bis-diazo compounds 10a—c and dimide 11 respectively. All new com-
pounds were tested for their protective activity against DNA damage induced by bleomycin–iron complex. Com-
pound 2 showed the greatest protection against DNA damage, thus diminishing chromogen formation between
the damaged DNA and thiobarbituric acid.
Key words 2-naphthaloxyacetic acid; imidazo[2,1-b]-1,3,4-thiadiazole; pyrazole; hydrazonoyl chloride; 1,3,4-thiadiazole;
DNA·bleomycin–iron complex
Aryloxyacetic acids and their derivatives often possess onated as a singlet at d 5.28. The formation of the imidazo-
many important biological activities. Some of these com- thiadiazole 3 was indicated by the absence of the NH2 band
pounds are used as herbicides and plant-growth regula- in the IR spectrum and the appearance of an imidazole pro-
tors.1—5) Substituted pyrazoles and 1,3,4-thiadiazoles have ton (C5-H) around d 8.6 in the 1H-NMR spectrum.
also attracted much attention due to their diverse biological
The hydrazide of 2-naphthaloxyacetic acid 4 has been
activities, such as DNA protective,6—8) antimicrobial,9,10) an- used in the production of several compounds with potent bio-
tibacterial,11) anesthetic,12) and anticonvulsant13) activities. logical activity.27,28) Incorporation of the hydrazide portion of
On the other hand, imidazo[2,1-b]-1,3,4-thiadiazole deriva- these compounds into a pyrazole ring led to a new class of
tives have been of interest to the medicinal chemists for pyrazole compounds.29—32) We report here the synthesis of
many years because of their anticancer,14) antitubercular,15) some new pyrazoles and discuss their protective activity
antibacterial,16) antifungal,17) anticonvulsant, analgesic,18) and against DNA damage induced by bleomycin–iron complex.
antisecretory19) activities. In continuation of our previ- Treatment of acid hydrazide 4 with equimolar quantities
ous work on the synthesis of biologically active hetero- of ethyl 2-(2-arylhydrazono)-3-oxobutanoates 5a—c, 2-
cycles,20—23) we report here the preparation of a new series of (methoxymethylene)malononitrile, and/or ethyl 2-cyano-3,3-
compounds with a 2-naphthaloxyacetyl moiety in addition to bis(methylthio)acrylate in absolute ethanol gave the pyra-
1,3,4-thiadiazoles, imidazo[2,1-b]-1,3,4-thiadiazoles, pyra- zoles 6—8 (Chart 2).
1
zoles, or imide with the objective of obtaining new biologi-
cally active compounds.
In the H-NMR spectra of 6a—c, a singlet proton at d
10.22 to 10.33 ppm attributed to enolic OH was observed.
The IR spectrum of compound 7 showed absorption bands in
Results and Discussion
In the previous work, imidazo[2,1-b]-1,3,4-thiadiazoles
were prepared by the reaction of 2-aminothiadiazoles with a-
bromoketones.24,25) Thus the 2-naphthaloxyacetic acid 1 re-
quired for the present study was synthesized by refluxing of
2-naphthol with chloroacetic acid in dry acetone containing
anhydrous potassium carbonate,26) which upon reaction with
thiosemicarbazide in the presence of phosphorusoxychloride
yielded 5-[(2-naphthaloxy)methyl]-1,3,4-thiadiazol-2-amine
2. The imidazo[2,1-b]-1,3,4-thiadiazoles 3a—c were ob-
tained by the condensation of 2 with appropriate phenacyl
bromides with refluxing in dry ethanol (Chart 1). The struc-
tures of compounds 2 and 3 were supported by spectral data
such as IR, NMR, mass, and elemental analysis.
In the IR spectrum of 1,3,4-thiadiazol-2-amine 2, broad
absorption bands around 3107 and 3264 cmꢀ1 indicates the
presence of an NH2 group in the compound, and its 1H-NMR
spectrum showed a singlet at d 7.82 due to the NH2 protons
Chart 1. Synthesis of 1,3,4-Thiadiazoles and Imidazo[2,1-b]-1,3,4-thiadi-
attached to the 1,3,4-thiadiazole ring. The proton of CH2 res- azoles
© 2009 Pharmaceutical Society of Japan
∗ To whom correspondence should be addressed. e-mail: Bakrfatehy@yahoo.com

December 2009
1349
Chart 2. Synthesis of Compounds 6—11
the region 2227, 3309 and 3235 cmꢀ1 characteristic of car-
bonitrile and amino groups, while the IR spectrum of com-
pound 8 showed absorption bands in the regions of 1749,
3324 and 3233 cmꢀ1 attributed to ester CꢁO and NH2
groups. In addition, bis-diazo compounds 10a—c were
formed by simple condensation of the hydrazide 4 with hy-
drazonoyl chlorides 9a—c in ethanol (Chart 2). The forma-
tion of bis-diazo compounds 10a—c was indicated by the ab-
sence of one carbonyl band in the IR spectra and the appear-
ance of two singlet NH protons around d 10.19 and 11.16 in
their 1H-NMR spectra.
The treatment of the acid hydrazide 4 with 1,2,4,5-benzene
tetracarboxylic-1,2:4,5-dianhydride in refluxing glacial acetic
acid for 5 h afforded the dimide 11 (Chart 2). The IR spec-
trum of compound 11 showed three absorption bands in the
region of the 1786—1624 cmꢀ1 characteristic of carbonyl
groups, and in addition the mass spectrum of the dimide 11
Table 1. Results of the Bleomycin-Dependent DNA Damage Assay of
Synthesized Compounds
Sample (extract)
Absorbance (nm)
2
3a
3b
3c
6a
6b
6c
7
8
10a
10b
10c
11
0.0064
0.045
0.18
0.180
0.180
0.18
0.052
0.180
0.180
0.038
0.050
0.045
0.180
showed a peak corresponding to its molecular ion peak at m/z its protective activity against DNA damage induced by the
614. bleomycin–iron complex. The results in Table 1 show that
Bleomycin-Dependent DNA Damage The bleomycins compound 2 had the highest protection against DNA damage
are a family of glycopeptide antibiotics that are used rou- induced by the bleomycin–iron complex, thus diminishing
tinely as antitumor agents. The bleomycin assay has been chromogen formation between the damaged DNA and TBA.
adopted for assessing the prooxidant effects of food antioxi- Compounds 3a, 6c, 10a, 10b, and 10c showed weak to mod-
dants. The antitumor antibiotic bleomycin binds iron ions erate activity, while compounds 3b, 3c, 6a, 6b, 7, 8, and 11
and DNA. The bleomycin–iron complex degrades DNA that, exhibited slight activities.
upon heating with thiobarbituric acid (TBA), yields a pink
Structure–Activity Relationship From the shown re-
chromogen. Upon the addition of suitable reducing agents sults in Table 1 we conclude that the protective activity
antioxidants compete with DNA and diminish chromogen against DNA damage induced by the bleomycin–iron com-
formation.33)
plex requires the 2-(naphthalen-2-yloxy) methyl moiety and
All the newly synthesized compounds were examined for 1,3,4-thiadiazole. An unsubstituted phenyl ring exhibits bet-

1350
Vol. 57, No. 12
thalen-2-yloxy)ethanone (6a): Yield, 42%; mp 180—181 °C; IR (KBr)
n
3H, CH3), 5.09 (s, 2H, OCH2), 7.25—7.62 (m, 11H, Ar-H), 10.33 (s, 1H,
OH, D2O exchangeable), MS m/z (%): 386 (Mꢂ, 12), 144 (100). Anal. Calcd
for C22H18N4O3: C, 68.38; H, 4.70; N, 14.50. Found: C, 68.45; H, 4.81; N,
ter activity than the substituted derivatives as shown in 10a,
10b, and 10c.
max/cmꢀ1 1652 (CꢁO), 3455 (enolic OH); 1H-NMR (DMSO-d6) d: 2.41 (s,
Conclusion
A series of new 2-naphthyl ethers was prepared using sim- 14.67.
1-{4-[(2,4-Dichlorophenyl)diazenyl]-5-hydroxy-3-methyl-1H-pyrazol-1-
yl}-2-(naphthalen-2-yloxy)ethanone (6b): Yield, 53%; mp 195 °C; IR (KBr)
max/cmꢀ1 1662 (CꢁO), 3443 (enolic OH); 1H-NMR (DMSO-d6) d: 2.34 (s,
3H, CH3), 5.08 (s, 2H, OCH2), 7.19—7.41 (m, 9H, Ar-H), 10.32 (s, 1H, OH,
D2O exchangeable), MS m/z (%): 423 (Mꢂ, 12), 113 (100). Anal. Calcd for
C22H16Cl2N4O3: C, 58.04; H, 3.54; N, 12.31. Found: C, 58.23; H, 3.62; N,
12.43.
ple methods and their protective activities against DNA dam-
age induced by bleomycin–iron were evaluated. The 1,3,4-
thiadiazol-2-amine derivative 2 gave the greatest protection
against DNA damage, while the others showed moderate to
low activity.
n
1-{4-[(4-Fluorophenyl)diazenyl]-5-hydroxy-3-methyl-1H-pyrazol-1-yl}-
2-(naphthalen-2-yloxy)ethanone (6c): Yield, 53%; mp 196—197 °C; IR
Experimental
Chemistry All melting points were recorded on an Electrothermal IA
9000 series digital melting point apparatus. Elemental analytical data (in ac-
cord with the calculated values) were obtained from the microanalytical unit,
Cairo University, Giza, Egypt. The IR spectra (KBr) were recorded on a Shi-
1
(KBr) nmax/cmꢀ1 1635 (CꢁO), 3455 (enolic OH); H-NMR (DMSO-d6) d:
2.46 (s, 3H, CH3), 5.10 (s, 2H, OCH2), 7.15—7.83 (m, 10H, Ar-H), 10.22 (s,
1H, OH, D2O exchangeable), MS m/z (%): 402 (Mꢂꢀ2, 1.86), 144 (100).
Anal. Calcd for C22H17FN4O3: C, 65.34; H, 4.24; N, 13.85. Found: C, 65.45;
H, 4.33; N, 13.92.
1
madzu CVT-04 spectrophotometer. The H-NMR spectra were recorded at
270 MHz on a Varian EM-360 spectrometer using tetramethylsilane (TMS)
as an internal standard. Chemical shift (d) values are given in parts per mil-
lion. The mass spectra were recorded using a Varian MAT CH-5 spectro-
meter (70 eV). 2-(Naphthalen-7-yloxy)acetic acid 1,26) 2-(naphthalen-3-
yloxy)acetohydrazide 4,34,35) hydrazonoyl chlorides 9a—c36,37) were prepared
according to the procedures reported in literature.
5-Amino-1-[2-(naphthalen-3-yloxy)acetyl]-1H-pyrazole-4-carbonitrile
(7) To a solution of 4 (0.43 g, 2 mmol) in anhydrous ethanol (20 ml), 2-
(methoxymethylene)malononitrile (0.22 g, 2 mmol) was added and the reac-
tion mixture was refluxed for 4 h. The product which separated on cooling,
were collected by filtration and recrystallized from ethanol to give the com-
pound 7. Yield 61%; mp 248—249 °C; IR (KBr) nmax/cmꢀ1 1633 (CꢁO),
2227 (CN) 3309, 3235 (NH2); 1H-NMR (DMSO-d6) d: 4.89 (s, 2H, OCH2),
7.35—7.77 (m, 7H, Ar-H), 7.82 (s, 1H, pyrazole-H), 10.32 (s, 2H, NH2, D2O
exchangeable), MS m/z (%): 292 (Mꢂ, 100). Anal. Calcd for C16H12N4O2: C,
65.75; H, 4.14; N, 19.17. Found: C, 65.84; H, 4.27; N, 19.26.
Ethyl 5-Amino-3-(methylthio)-1-[2-(naphthalen-3-yloxy)acetyl]-1H-
pyrazole-4-carboxylate (8) A mixture of equimolar quantities of 4
(0.43 g, 2 mmol) ethyl 2-cyano-3,3-bis(methylthio)acrylate (0.43 g, 2 mmol)
was refluxed in dry ethanol for 6 h. The product, that separated on cooling,
was collected by filtration and recrystallized from ethanol to give the com-
pound 8. Yield, 58%; mp 170—172 °C; IR (KBr) nmax/cmꢀ1 1622, 1749
(2CꢁO), 3324, 3233 (NH2); 1H-NMR (DMSO-d6) d: 1.5 (t, 3H, CH3–ester),
2.43 (s, 3H, SCH3), 4.20 (q, 2H, CH2–ester), 5.23 (s, 2H, OCH2), 7.36—7.79
(m, 7H, Ar-H), 10.20 (s, 2H, NH2, D2O exchangeable), MS m/z (%): 385
(Mꢂ, 12), 144 (100). Anal. Calcd for C19H19N3O4S: C, 59.21; H, 4.97; N,
10.90; S, 8.32. Found: C, 59.35; H, 5.09; N, 10.98; S, 8.46.
Synthesis of Propanehydrazonoyl Chlorides (10a—c) A mixture of 4
(0.43 g, 2 mmol) and appropriate hydrazonoyl chloride 9a—c (2 mmol) in
30 ml absolute ethanol was refluxed for 4 h. The solid formed was filtered
off, dried, and crystallized from EtOH/DMF (2 : 1).
2-(2-(2-(Naphthalen-2-yloxy)acetyl)hydrazono)-Nꢃ-phenylpropanehydra-
zonoyl Chloride (10a): Yield, 77%; mp 220—221 °C; IR (KBr) nmax/cmꢀ1
1663 (CꢁO), 3321—3183 (2NH); 1H-NMR (DMSO-d6) d: 2.31 (s, 3H,
CH3), 5.22 (s, 2H, OCH2) 7.08—7.89 (m, 11H, Ar-H), 10.19, 11.16 (2s, 2H,
2NH, D2O exchangeable), MS m/z (%): 394 (Mꢂ, 1.1), 144 (100). Anal.
Calcd for C21H19ClN4O2: C, 63.88; H, 4.85; N, 14.19. Found: C, 63.97; H,
4.96; N, 14.27.
5-[(Naphthalen-3-yloxy)methyl]-1,3,4-thiadiazol-2-amine (2) 2-
(Naphthalen-7-yloxy)acetic acid (20.2 g, 0.1 mol) and thiosemicarbazide
(9.1 g, 0.1 mol) in phosphorous oxychloride (30 ml) were refluxed gently for
30 min. The solution was cooled and water (90 ml) was added carefully. The
separated solid was filtered, suspended in water, and basified with aqueous
potassium hydroxide. The solid was filtered, washed with water, dried, and
crystallized from a mixture of N,N-dimethylformamide (DMF) and ethanol
(9 : 1) to obtain a colorless solid in 80% yield with a melting point of 192—
193 °C.
IR (KBr) nmax/cmꢀ1 3107, 3264 (NH2); H-NMR (DMSO-d6) d: 5.28 (s,
1
2H, OCH2), 7.13—7.45 (m, 7H, Ar-H), 7.82 (s, 2H, NH2, D2O exchange-
able), MS m/z (%): 257 (Mꢂ, 36), 144 (100). Anal. Calcd for C13H11N3OS:
C, 60.68; H, 4.31; N, 16.33; S, 12.46. Found: C, 60.73; H, 4.51; N, 16.40; S,
12.59.
2-[(Naphthalen-2-yloxy)methyl]-6-arylimidazo[2,1-b][1,3,4]thiadia-
zole (3a—c) A mixture of equimolar quantities of the 1,3,4-thiadiazol-2-
amine 2 (2.57 g, 0.01 mol) and appropriately substituted bromoacetyl com-
pound (0.01 mol) was refluxed in dry ethanol for 24 h. The excess of solvent
distilled off, and the solid hydrobromide that separated was collected by fil-
tration, suspended in water, and neutralized by aqueous sodium carbonate
solution to yield the free bases (3a—c). They were filtered, washed with
water, dried, and recrystallized from ethanol.
2-[(Naphthalen-2-yloxy)methyl]-6-p-tolylimidazo[2,1-b][1,3,4]thiadia-
zole (3a): Yield, 54%; mp 198—200 °C; H-NMR (DMSO-d6) d: 2.32 (s,
3H, CH3), 5.66 (s, 2H, OCH2), 7.23—7.55 (m, 11H, Ar-H), 8.60 (s, 1H, C5-
H, imidazole), MS m/z (%): 371 (Mꢂ, 83), 228 (100). Anal. Calcd for
C22H17N3OS: C, 71.14; H, 4.61; N, 11.31; S, 8.63. Found: C, 71.33; H, 4.88;
N, 11.43; S, 8.75.
6-(4-Bromophenyl)-2-[(naphthalen-2-yloxy)methyl]imidazo[2,1-b]-
[1,3,4]thiadiazole (3b) Yield, 61%; mp 196—197 °C; H-NMR (DMSO-d6)
d: 5.67 (s, 2H, OCH2), 7.26—7.57 (m, 11H, Ar-H), 8.61 (s, 1H, C5-H, imi-
dazole), MS m/z (%): 437 (Mꢂꢂ1, 76), 436 (Mꢂ, 78) 293 (100). Anal. Calcd
for C21H14BrN3OS: C, 57.81; H, 3.23; N, 9.63; S, 7.35. Found: C, 57.93; H,
3.43; N, 9.71; S, 7.55.
1
Nꢃ-(2,4-Dichlorophenyl)-2-{2-[2-(naphthalen-2-yloxy)acetyl]hydrazono}-
propanehydrazonoyl Chloride (10b): Yield, 75%; mp 239—241 °C; IR
(KBr) nmax/cmꢀ1 1673 (CꢁO), 3316—3192 (2NH); 1H-NMR (DMSO-d6) d:
2.32 (s, 3H, CH3), 5.21 (s, 2H, OCH2) 7.15—7.83 (m, 10H, Ar-H), 10.12,
11.14 (2s, 2H, 2NH, D2O exchangeable), MS m/z (%): 462 (Mꢂ, 0.9), 144
(100). Anal. Calcd for C21H17Cl3N4O2: C, 54.39; H, 3.69; N, 12.08. Found:
C, 54.47; H, 3.76; N, 12.17.
1
Nꢃ-(4-Fluorophenyl)-2-{2-[2-(naphthalen-2-yloxy)acetyl]hydrazono}-
6-(Benzofuran-2-yl)-2-[(naphthalen-2-yloxy)methyl]imidazo[2,1-b]-
[1,3,4]thiadiazole (3c) Yield, 38%; mp 219—220 °C; H-NMR (DMSO-d6)
d: 5.72 (s, 2H, OCH2), 7.18 (s, 1H, benzofuran-H), 7.29—7.89 (m, 11H, Ar-
H), 8.73 (s, 1H, C5-H, imidazole), MS m/z (%): 397 (Mꢂ, 0.5), 144 (100).
Anal. Calcd for C23H15N3O2S: C, 69.50; H, 3.80; N, 10.57; S, 8.07. Found:
C, 69.53; H, 3.97; N, 10.66; S, 8.18.
1
propanehydrazonoyl Chloride (10c): Yield, 63%; mp 218—219 °C; IR (KBr)
1
n
max/cmꢀ1 1672 (CꢁO), 3311—3196 (2NH); H-NMR (DMSO-d6) d: 2.29
(s, 3H, CH3), 5.38 (s, 2H, OCH2) 7.24—7.89 (m, 10H, Ar-H), 10.20,
11.32(2s, 2H, 2NH, D2O exchangeable), MS m/z (%): 412 (Mꢂ, 1.8), 144
(100). Anal. Calcd for C21H18ClFN4O2: C, 61.09; H, 4.39; N, 13.57. Found:
C, 61.16; H, 4.56; N, 13.68.
Synthesis of pyrazoles 6a—c To a solution of 2-(naphthalen-7-yloxy)-
N,Nꢀ-[1,3,5,7-Tetraoxopyrrolo[3,4-f ]isoindole-2,6(1H,3H,5H,7H)-
diyl]bis[2-(naphthalen-2-yloxy)acetamide] (11) A mixture of 4 (0.43 g,
2 mmol) and 1,2,4,5-benzene tetracarboxylic-1,2:4,5-dianhydride (1.2 g,
2 mmol) in glacial acetic acid (25 ml) was refluxed for 5 h. The solid formed
was filtered off, washed with 95% ethanol, and crystallized from
AcOH : H2O to give 11. Yield, 77%; mp ꢄ300 °C; IR (KBr) nmax/cmꢀ1
1786—1624 (6CꢁO); 1H-NMR (DMSO-d6) d: 5.08 (s, 4H, 2OCH2) 7.35—
7.89 (m, 16H, Ar-H), 11.12 (2s, 2H, 2NH, D2O exchangeable), MS m/z (%):
acetohydrazide
4 (0.43 g, 2 mmol) in ethanol (20 ml), ethyl 2-(2-
(subs.phenyl)hydrazono)-3-oxobutanoates 5a—c (2 mmol), and a few drops
of glacial acetic acid were added. The reaction mixture was refluxed for 5 h,
and then the reaction mixture was evaporated to half its volume and kept at
room temperature overnight. The solid that separated was filtered off,
washed with cold ethanol, dried, and recrystallized from ethanol to give a
yellow powder of compounds 6a—c.
1-[5-Hydroxy-3-methyl-4-(phenyldiazenyl)-1H-pyrazol-1-yl]-2-(naph-

December 2009
1351
614 (Mꢂ, 19), 144 (100). Anal. Calcd for C34H22N4O8: C, 66.45; H, 3.61; N,
9.12. Found: C, 66.56; H, 3.76; N, 9.28.
17) Andotra C. S., Langer T. C., Kotha A., J. Indian Chem. Soc., 74, 125—
127 (1997).
Bleomycin-Dependent DNA Damage Assay33,38,39) To the reaction
mixtures in a final volume of 1.0 ml, the following reagents at the final con-
centrations stated were added: DNA (0.2 mg/ml), bleomycin (0.05 mg/ml),
FeCl3 (0.025 mM), magnesium chloride (5 mM), KH2PO4–KOH buffer pH 7.0
(30 mM), and ascorbic acid (0.24 mM) or the test fractions diluted in MeOH
to give a concentration of (0.1 mg/ml). The reaction mixtures were incubated
in a water-bath at 37 °C for 1 h. At the end of the incubation period, 0.1 ml of
ethylenediaminetetraacetic acid (EDTA) (0.1 M) was added to stop the reac-
tion (the iron–EDTA complex is unreactive in the bleomycin assay). DNA
damage was assessed by adding 1 ml 1% (w/v) thiobarbituric acid (TBA)
and 1 ml of 25% (v/v) hydrochloric acid (HCl) followed by heating in a
water-bath maintained at 80 °C for 15 min. The chromogen formed was ex-
tracted into butan-l-ol, and the absorbance was measured at 532 nm.
18) Khazi I. A. M., Mahajanshetti C. S., Gadad A. K., Tarnalli A. D.,
Sultanpur C. M., Arzneim.-Forsch./Drug. Res., 46, 949—952 (1996).
19) Andreani A., Leonia A., Locatelli A., Morigi R., Rambaldi M., Simon
W. A., Senn-Bilfinger J., Arzneim.-Forsch./Drug. Res., 50, 550—553
(2000).
20) Abdel-Wahab B. F., Mohamed S. F., Amr A. E., Abdalla M. M.,
Monatsh Chem., 139, 1083—1090 (2008).
21) Amer F. A., Hammouda M., El-Ahl A.-A. S., Abdel-Wahab B. F., J.
Heterocycl. Chem., 45, 1549—1569 (2008).
22) Abdalla M. M., Abdel-Wahab B. F., Amr A. E., Monatsh Chem., 140,
129—137 (2009).
23) Amr A. E., Sabrry N. M., Abdalla M. M., Abdel-Wahab B. F., Eur. J.
Med. Chem., 44, 725—735 (2009).
24) Jadhav V. B., Kulkarni M. V., Rasal V. P., Biradar S. S., Vinay M. D.,
Eur. J. Med. Chem., 43, 1721—1729 (2008).
References
25) Abdel-Wahab B. F., Farghaly M., Badria F. A., Pharm. Chem. J.
(2009), accepted.
1) Shi Y. N., Lu Y. C., Fang J. X., Hua Y. L., Chem. J. Univ. (Chinese),
16, 1710—1713 (1995).
26) Yar M. S., Siddiqui A. A., Ali M. A., J. Chinese Chem. Soc., 54, 5—8
(2007).
2) Kitagawa M., Yamamoto K., Katakura S., Kanno H., Yamada K.,
Chem. Pharm. Bull., 39, 2681—2690 (1991).
27) Palaska E., Sahin G., Kelicen P., Durlu N. T., Altinok G., Farmaco, 57,
101—107 (2002).
28) Sahin G., Palaska E., Ekizoglu M., Ozalp M., Farmaco, 57, 539—542
(2002).
3) Baker B. R., Hurlbut J. A., J. Med. Chem., 12, 677—680 (1969).
4) Jain P. K., Srirastara S. K., J. Indian Chem. Soc., 69, 402—409 (1992).
5) Li Y. J., Dai Y. J., Chen J. C., Chem. J. Chin. Univ. (Chinese), 9, 584—
591 (1988).
29) Yar M. S., Siddiqui A. A., Ali M. A., Bioorg. Med. Chem. Lett., 16,
4571—4574 (2006).
30) Holla B. S., Udupa K. V., Indian J. Chem., 29B, 887—889 (1990).
31) Holla B. S., Udupa K. V., Sridhar K. R., Bull. Chem. Soc. Jpn., 62,
3409—3411 (1989).
6) Vasquez H., Strobel H., Int. J. Oncol., 18, 553—557 (2001).
7) Nichols K. D., Kirby G. M., Biochem. Pharm., 75, 538—551 (2008).
8) Poorrajab F., Ardestani S. K., Foroumadi A., Emami S., Kariminia A.,
Behrouzi-Fardmoghadam M., Shafiee A., Exp. Parasitol., 121, 323—
330 (2009).
32) Hallur M. S., Sangapure S. S., Asian J. Chem., 11, 845—849 (1999).
33) Gutteridge J., Rowley D., Halliwell B., Biochem. J., 199, 263—265
(1981).
34) Mullican M. D., Wilson M. W., Connor D. T., Kostlan C. R., Schrier D.
J., Dyer R. D., J. Med. Chem., 36, 1090—1099 (1993).
35) Husain M. I., Kumar A., Srivastava R. C., Curr. Sci., 55, 644—646
(1986).
9) Abdel-Wahab B. F., Abdel-Aziz H. A., Ahmed E. M., Arch. Pharm.,
341, 734—739 (2008).
10) Abdel-Aziz H. A., Abdel-Wahab B. F., El-Sharief M. A. M. Sh.,
Abdulla M. M., Monatsh. Chem., 140, 431—437 (2009).
11) Mandour A. H., Fawzy N. M., El-Shihi T. H., El-Bazza Z. E., Pak. J.
Sci. Ind. Res., 38, 402—405 (1995); Chem. Abstr., 127, 135773
(1997).
36) Nedime E., Hamit O., Fak E., J. Fac. Pharmacy Istanbul Univ., 17, 1—
24 (1981).
12) Mazzone G., Pignatello R., Mazzone S., Panico A., Pennisi G.,
Farmaco, 48, 1207—1224 (1993).
37) Dieckmann W., Platz O., Chem. Ber., 38, 2989—2992 (1905).
38) Badria F. A., Ameen M., Akl M., Z. Naturforsch., 62c, 656—660
(2007).
39) El-Gazzar A., Gaafar A. M., Youssef M. M., Abu-Hashem A., Badria,
F. A., Phosphorus, Sulfur, Silicon, Rel. Elem., 182, 2009—2037
(2007).
13) Chufan E. E., Pedregosa J. C., Badini O. N., Bruno-Blanch L.,
Farmaco, 54, 838—841 (1999).
14) Terzioglu N., Gürsoy A., Eur. J. Med. Chem., 38, 781—786 (2003).
15) Kolavi G., Hegde V., Khan I., Gadad P., Bioorg. Med. Chem., 14,
3069—3080 (2006).
16) Gadad A. K., Mahajanshetti C. S., Nimbalkar S., Raichurkar A., Eur.
J. Med. Chem., 35, 853—857 (2000).