Synthesis and microbiological activity of some 4-butyl-2H-benzo[1,4]thiazin-3-one derivatives

Article abstract of DOI:10.1016/S0014-827X(01)01113-2

The synthesis and physicochemical properties of 4-butyl-2H-benzo[1,4]thiazin-3-one derivatives are described. These new compounds were synthesised by alkylation in 4-N position and acylation and/or alkylation of 6-NH₂ by phase transfer catalysis. Acid hydrolysis of 6-alkylacylamino group yielded 6-alkylamino-4-butyl-2H-benzo[1,4]thiazin-3-ones. The antimicrobial in vitro activity was determined on five compounds. Copyright

Full text of DOI:10.1016/S0014-827X(01)01113-2

www.elsevier.com/locate/farmac
Il Farmaco 56 (2001) 689–693
Synthesis and microbiological activity of some
4-butyl-2H-benzo[1,4]thiazin-3-one derivatives
V.L. de M. Guarda a,*, M. Perrissin b, F. Thomasson b, E.A. Ximenes c, S.L. Galdino c,
I.R. Pitta c, C. Luu-Duc b
a Escola de Farma´cia, Uni6ersidade Federal de Ouro Preto, CEP, 35400-000 Ouro Preto, MG, Brazil
b Laboratoire de Chimie-Parmacie, CNRS UPR 5077, Uni6ersite´ Joseph Fourier, Grenoble I, F-38706 La Tronche Cedex, France
c Departamento de Antibio´ticos, Uni6ersidade Federal de Pernambuco, CEP, 50670-901 Recife, PE, Brazil
Received 6 April 2000; accepted 30 March 2001
Abstract
The synthesis and physicochemical properties of 4-butyl-2H-benzo[1,4]thiazin-3-one derivatives are described. These new
compounds were synthesised by alkylation in 4-N position and acylation and/or alkylation of 6-NH2 by phase transfer catalysis.
Acid hydrolysis of 6-alkylacylamino group yielded 6-alkylamino-4-butyl-2H-benzo[1,4]thiazin-3-ones. The antimicrobial in vitro
activity was determined on five compounds. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Benzothiazines; Antimicrobial activity
1. Introduction
nitro-aniline (1) with sodium sulfide and sulfur [9] gave
2-amino-4-nitrobenzenethiol (sodium salt 2), which is
cyclised to 6-nitro-2H-benzo[1,4]thiazin-3-one (3) with
chloroacetic acid [1]. N-butylation with butyl bromide
in alkaline medium [10] afforded 4. The reduction of
the nitro group by SnCl2 in acidic medium [11] gave the
corresponding amine 5. N-acylation of the amino group
followed by phase transfer catalysed alkylation in basic
medium [12] led to N-alkylacyl (8–11). Acid hydrolysis
of 10 and 11 afforded 6-alkylamino-4-butyl-2H-
benzo[1,4]thiazin-3-ones 12 and 13 (Scheme 1).
A large number of 2H-benzo[1,4]thiazine derivatives
exhibit different pharmacological activities: antimicro-
bial, anticancerous, immunostimulating, aldose reduc-
tase inhibitor [1–5]. The alkylation of 4-N position of
2H-benzo[1,4]thiazines affords bactericidal and antifun-
gal derivatives [6,7].
The synthesis of 6-alkylacylamino-4-methyl-2H-
benzo[1,4]thiazin-3-ones has been previously reported
[8]. In the present paper, we describe the synthesis and
the physicochemical properties of 4-butyl-2H-
benzo[1,4]thiazin-3-one derivatives. The antimicrobial
activity of five of these compounds has been investi-
gated in vitro against cocci and bacilli.
3. Experimental
Melting points were determined with a capillary
Bu¨chi apparatus and are uncorrected. The purity of the
compounds is controlled by thin layer chromatography
on silica pre-coated plates Merck 60F254. The spots are
revealed under UV light or iodine vapour and the Rf
values are measured.
2. Chemistry
Several steps are necessary to synthesise 4-butyl-2H-
benzo[1,4]thiazin-3-ones. The treatment of 2-chloro-5-
IR spectra were recorded in KBr tablets (2%) or film
* Corresponding author.
E-mail addresses: vera@cpd.ufop.br (V.L. de M. Guarda),
1
with a Perkin–Elmer 1310 spectrophotometer. H and
13C NMR spectra were recorded with a Brucker AC
monique perrissin@ujf-grenoble.fr (M. Perrissin), pitta@elogica.
–
com.br (I.R. Pitta).
200 spectrometer in DMSO-d6. Chemical shifts (l) are
0014-827X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0014-827X(01)01113-2

690
V.L. de M. Guarda et al. / Il Farmaco 56 (2001) 689–693
expressed in ppm and coupling constants (J) in Hertz
(Hz). Electronic impact mass spectra (70 eV) were
measured with an R-1010C Delsi-Nermag spectrometer.
No elemental analysis was performed on the new com-
pounds but all mass spectra agree with their proposed
structure.
132.8 (C), 139.2 (C), 146.4 (C), 164.2 (CO). MS; m/z
(%): 266 (45.2), 219 (35.7), 210 (100), 195 (42), 181
(32.6), 149 (32.2), 135 (18.4).
3.2. 6-Amino-4-butyl-2H-benzo[1,4]thiazin-3-one (5)
The synthesis, physical and analytical properties of
compounds 2 and 3 have been previously described [8].
To a cold and stirred solution of 3.72 g (16 mmol) of
stannous chloride dihydrate in 4 ml of concentrated
HCl is added portionwise, over a 15 min period, 3.5
mmol of compound 4. The mixture is left under stirring
for 15 min in an ice-bath. Then the temperature is
gradually increased up to reflux, which is kept for 2 h.
After cooling, the precipitate is collected, washed with
water to eliminate excess of HCl and suspended in
water. A 20% hydroxide solution is added (pH 10) to
give the corresponding amine, which is collected by
filtration, washed with water and 10% NaOH and
recrystallised from water. Yield 64%. M.p. 63–65°C
(hydrochloride m.p. 218–220°C). TLC: (CHCl3/
CH3COCH3 9:1) Rf 0.71. IR (KBr): w 3460, 3370, 2980,
3.1. 4-Butyl-6-nitro-2H-benzo[1,4]thiazin-3-one (4)
A mixture of compound 3 (1.05 g, 5 mmol) and
potassium hydroxide (0.56 g, 10 mmol) in DMSO/etha-
nol (10:12.5 ml) is stirred at room temperature for 10
min before butyl bromide (10 mmol) was added drop-
wise. The mixture is heated at 50°C under stirring for
15 h. After cooling, the crude butyl product precipi-
tated when water or crushed ice is added. It is collected
and recrystallised from 95% ethanol. Yield 68%. M.p.
86–87°C. TLC: (C6H5CH3/CH3COOC2H5 6:4) Rf 0.79.
IR (KBr): w 2930, 2850, 1680, 1520, 1350, 745 cm−1. 1H
NMR (DMSO-d6): l 0.87 (t, 3H, CH3-4, J=7.2 Hz),
1.12–1.32 (m, 2H, CH2-4), 1.43–1.57 (m, 2H, CH2-4),
3.62 (s, 2H, CH2-2), 4.06 (t, 2H, CH2-4, J=7.2 Hz),
7.69 (d, 1H, aromatic H, J=8.5 Hz), 7.87 (dd, 1H,
aromatic H, J=8.5 and 2.2 Hz), 8.00 (d, 1H, aromatic
H, J=2.2 Hz). 13C NMR (DMSO-d6, BB decoupling
and DEPT): l 13.5 (CH3), 19.1 (CH2), 28.6 (CH2), 29.7
(CH2), 43.0 (CH2), 112.4 (CH), 117.5 (CH), 128.9 (CH),
1
2865, 1650 cm−1. H NMR (DMSO-d6): l 0.88 (t, 3H,
CH3-4, J=7.2 Hz), 1.18–1.37 (m, 2H, CH2-4), 1.44–
1.58 (m, 2H, CH2-4), 3.32 (s, 2H, CH2-2), 3.82 (t, 2H,
CH2-4, J=7.2 Hz), 5.22 (s, 2H, NH2), 6.28 (dd, 1H,
aromatic H, J=8.2 and 1.6 Hz), 6.54 (d, 1H, aromatic
H, J=1.6 Hz), 6.98 (d, 1H, aromatic H, J=8.2 Hz).
13C NMR (DMSO-d6, BB decoupling and DEPT): l
13.6 (CH3), 19.3 (CH2), 29.0 (CH2), 31.5 (CH2), 43.2
(CH2), 103.7 (CH), 107.5 (C), 109.4 (CH), 128.5 (CH),
Scheme 1. Synthesis of 4-butyl-2H-benzo[1,4]thiazin-3-one derivatives.

V.L. de M. Guarda et al. / Il Farmaco 56 (2001) 689–693
691
139.8 (C), 148.5 (C), 165.0 (CO). MS; m/z (%): 236
(79.2), 193 (14.1), 180 (85.1), 165 (48.5), 151 (100), 135
(16.7), 77 (16.5).
ate, 7.0 g of sodium hydroxide and 0.16 g of
tetrabutylammonium bromide is refluxed under vigor-
ous stirring. The suitable alkyl halide (7.5 mmol) in
toluene (10 ml) is added dropwise. Stirring is continued
for 4 h at the refluxing temperature. After cooling, the
mixture is filtered and the filtrate added with water (50
ml); the organic phase is separated, washed with water,
dried over anhydrous magnesium sulfate and
evaporated.
We have carried out N-ethylation (ethyl iodide) and
N-butylation (butyl bromide) on the acetyl compounds
and N-butylation (butyl bromide) and N-octylation
(octyl bromide), on the benzoyl ones.
3.3. 6-Acetylamino-4-butyl-2H-benzo[1,4]thiazin-3-one
(6)
A mixture of 1.18 g (5 mmol) of compound 5 and 10
ml of acetic anhydride is refluxed for 10 min. The
excess of anhydride is hydrolysed by 10 ml of water and
the mixture is again refluxed for 5 min. The precipitate
is washed with water and recrystallised from 95% etha-
nol. Yield 87%. M.p. 103–105°C. TLC: (CHCl3/
CH3COCH3 9:1) Rf 0.78. IR (KBr): w 3310, 2940, 2860,
1
1680, 1645 (large) cm−1. H NMR (DMSO-d6): l 0.91
(t, 3H, CH3-4, J=7.1 Hz), 1.19–1.37 (m, 2H, CH2-4),
1.47–1.60 (m, 2H, CH2-4), 2.04 (s, 3H, COCH3), 3.43
(s, 2H, CH2-2), 3.86 (t, 2H, CH2-4, J=7.1 Hz), 7.20–
7.30 (m, 2H, aromatic H), 7.67 (s, 1H, aromatic H),
10.07 (s, 1H, NH-6). 13C NMR (DMSO-d6, BB decou-
pling and DEPT): l 13.5 (CH3), 19.3 (CH2), 24.0 (CH3),
28.9 (CH2), 30.7 (CH2), 43.4 (CH2), 108.5 (CH), 113.7
(CH), 116.4 (C), 128.1 (CH), 138.7 (C), 139.2 (C), 164.7
(CO), 168.4 (CO). MS; m/z (%): 278 (100), 222 (26.5),
207 (39.8), 193 (29.4), 180 (87.3), 165 (31.5), 151 (81.3),
135 (17.1), 43 (69.1).
3.6. 6-Acetylethylamino-4-butyl-2H-benzo[1,4]thiazin-
3-one (8)
Yield 57%. M.p. 91–93°C. TLC: (C6H5CH3/
CH3COOC2H5 6:4) Rf 0.38. IR (KBr): w 2945, 2855,
1655 (large) cm−1. 1H NMR (DMSO-d6): l 0.83 (t, 3H,
CH3-4, J=7.1 Hz), 0.99 (t, 3H, CH3-6, J=7.1 Hz),
1.13–1.31 (m, 2H, CH2-4,), 1.35–1.50 (m, 2H, CH2-4),
1.76 (s, 3H, COCH3), 3.51 (s, 2H, CH2-2), 3.63 (q, 2H,
CH2-6, J=7.1 Hz), 4.02 (t, 2H, CH2-4, J=7.1 Hz),
6.96 (dd, 1H, aromatic H, J=7.9 and 1.8 Hz), 7.27 (d,
1H, aromatic H, J=1.8 Hz), 7.45 (d, 1H, aromatic H,
J=7.9 Hz). 13C NMR (DMSO-d6, BB decoupling and
DEPT): l 12.9 (CH3), 13.6 (CH3), 19.1 (CH2), 22.5
(CH3), 28.8 (CH2), 30.3 (CH2), 42.3 (CH2), 42.8 (CH2),
118.5 (CH), 122.6 (CH), 122.9 (C), 128.8 (CH), 139.4
(C), 141.5 (C), 164.5 (CO), 168.4 (CO). MS; m/z (%):
306 (89.7), 264 (16), 249 (21.1), 193 (36.4), 179 (26.6),
84 (22.6), 70 (100), 43 (51.7).
3.4. 6-Benzoylamino-4-butyl-2H-benzo[1,4]thiazin-
3-one (7)
To a suspension of 1.18 g (5 mmol) of compound 5
in 20 ml of 5% NaOH, 2 ml of benzoyl chloride were
added dropwise. The mixture is vigorously stirred for
10 min. The precipitate is separated, washed with water
and recrystallised from 95% ethanol. Yield 82%. M.p.
139–140°C. TLC: (C6H5CH3/CH3COOC2H5 6:4) Rf
0.64. IR (KBr): w 3320, 2960, 2865, 1670, 1640 cm−1
.
1H NMR (DMSO-d6): l 0.89 (t, 3H, CH3-4, J=7.2
Hz), 1.21–1.39 (m, 2H, CH2-4), 1.50–1.65 (m, 2H,
CH2-4), 3.46 (s, 2H, CH2-2), 3.92 (t, 2H, CH2-4, J=7.2
Hz), 7.35 (d, 1H, aromatic H, J=8.4 Hz), 7.48–7.62
(m, 4H, aromatic H), 7.82 (d, 1H, aromatic H, J=1.7
Hz), 7.94 (dd, 2H, aromatic H, J=7.9 and 1.7 Hz),
10.31 (s, 1H). 13C NMR (DMSO-d6, BB decoupling and
DEPT): l 13.6 (CH3), 19.3 (CH2), 29.0 (CH2), 30.7
(CH2), 43.4 (CH2), 109.8 (CH), 115.0 (CH), 117.4 (C),
127.6 (2CH), 128.1 (CH), 128.3 (2CH), 131.6 (CH),
134.7 (C), 138.5 (C), 139.1 (C), 164.7 (CO), 165.6 (CO).
MS; m/z (%): 340 (46.3), 284 (12.9), 235 (8.1), 151 (8.4),
105 (100), 77 (75), 51 (10.3).
3.7. 6-Acetybutylamino-4-butyl-2H-benzo[1,4]thiazin-
3-one (9)
Yield 36%. M.p. 117–118°C. TLC: (CHCl3/C2H5OH
9:1) Rf 0.87. IR (KBr): w 2930, 2860, 1650 (large) cm−1
.
1H NMR (DMSO-d6): l 0.83 (t, 6H, CH3-4, J=7.1
Hz), 1.16–1.45 (m, 8H, 4CH2), 1.79 (s, 3H, COCH3),
3.51 (s, 2H, CH2-2), 3.61 (t, 2H, CH2-6, J=7.1 Hz),
4.03 (t, 2H, CH2-4, J=7.1 Hz), 6.96 (dd, 1H, aromatic
H, J=8.1 and 1.8 Hz), 7.27 (d, 1H, aromatic H,
J=1.8 Hz), 7.45 (d, 1H, aromatic H, J=8.1 Hz). 13C
NMR (DMSO-d6, BB decoupling and DEPT): l 13.6
(CH3), 13.7 (CH3), 19.0 (CH2), 19.4 (CH2), 22.5 (CH3),
28.8 (CH2), 29.4 (CH2), 30.4 (CH2), 42.3 (CH2), 47.6
(CH2), 118.3 (CH), 122.5 (CH), 122.8 (C), 128.8 (CH),
139.4 (C), 141.7 (C), 164.5 (CO), 168.6 (CO). MS; m/z
(%): 334 (49.4), 291 (11.6), 249 (46.2), 193 (26.9), 163
(25.3), 151 (28.6), 135 (12.8), 98 (36.8), 43 (100).
3.5. Alkylation of the amino group by phase transfer
catalysis [12]
A mixture of 5 mmol of acylated compounds dis-
solved in toluene (100 ml), 1.4 g of potassium carbon-

692
V.L. de M. Guarda et al. / Il Farmaco 56 (2001) 689–693
3.8. 6-Benzoylbutylamino-4-butyl-2H-benzo[1,4]-
thiazin-3-one (10)
3.11. 4-Butyl-6-butylamino-2H-benzo[1,4]thiazin-3-one
(12)
Yield 41%. M.p. 110–113°C. TLC: (C6H5CH3/
CH3COOC2H5 6:4) Rf 0.69. IR (KBr): w 2930, 2860,
Yield 60%. M.p. 73–74°C. TLC: (C6H5CH3/
CH3COOC2H5 8:2) Rf 0.59. IR (KBr): w 3360, 2940,
1
1
1660, 1630 cm−1. H NMR (DMSO-d6): l 0.77 (t, 3H,
2860, 1665 cm−1. H NMR (DMSO-d6): l 0.88 (t, 3H,
CH3-6, J=6.1 Hz), 0.86 (t, 3H, CH3-4, J=7.1 Hz),
0.97–1.11 (m, 4H, 2CH2), 1.20–1.39 (m, 2H, CH2),
1.41–1.57 (m, 2H, CH2), 3.40 (s, 2H, CH2-2), 3.73–3.85
(m, 4H, 2CH2), 6.90 (dd, 1H, aromatic H, J=8.2 and
1.7 Hz), 7.00 (d, 1H, aromatic H, J=1.7 Hz), 7.20–
7.32 (m, 6H, aromatic H). 13C NMR (DMSO-d6, BB
decoupling and DEPT): l 13.5 (CH3), 13.6 (CH3), 19.0
(CH2), 19.5 (CH2), 28.4 (CH2), 29.2 (CH2), 30.4 (CH2),
42.3 (CH2), 49.0 (CH2), 118.7 (CH), 121.7 (C), 122.1
(CH), 127.7 (2CH), 128.0 (2CH), 128.5 (CH), 129.3
(CH), 136.5 (C), 138.8 (C), 142.0 (C), 164.3 (CO), 169.1
(CO). MS; m/z (%): 396 (19.4), 291 (8.4), 249 (6.3), 177
(9.9), 160 (38.1), 105 (100), 77 (50.1).
CH3-4, J=7.0 Hz), 0.90 (t, 3H, CH3-6, J=6.9 Hz),
1.22–1.37 (m, 4H, 2CH2), 1.44–1.57 (m, 4H, 2CH2),
2.98 (dt, 2H, CH2-6), 3.32 (s, 2H, CH2-2), 3.86 (t, 2H,
CH2-4, J=7.2 Hz), 5.73 (t, 1H, NH-6, J=4.8 Hz),
6.27 (dd, 1H, aromatic H, J=8.1 and 1.9 Hz), 6.47 (d,
1H, aromatic H, J=1.9 Hz), 7.03 (d, 1H, aromatic H,
J=8.1 Hz). The NH proton at 5.73 ppm was confi-
rmed by the irradiation of the double triplet at 2.98
ppm of 6-NCH2. 13C NMR (DMSO-d6, BB decoupling
and DEPT): l 13.6 (CH3), 13.7 (CH3), 19.3 (CH2), 19.7
(CH2), 29.1 (CH2), 30.7 (CH2), 31.5 (CH2), 42.4 (CH2),
43.1 (CH2), 101.7 (CH), 107.1 (CH), 107.3 (C), 128.5
(CH), 139.8 (C), 148.7 (C), 165.1 (CO). MS; m/z (%):
292 (100), 249 (90.2), 207 (21.1), 193 (56.2), 177 (16.7),
163 (51.9), 151 (26.5), 41 (33.9).
3.9. 6-Benzoyloctylamino-4-butyl-2H-benzo[1,4]-
thiazin-3-one (11): liquid compound
3.12. 4-Butyl-6-octylamino-2H-benzo[1,4]thiazin-3-one
(13)
Yield 83%. TLC: (C6H5CH3/CH3COOC2H5 8:2) Rf
Yield 33%. M.p. 69–71°C. TLC: (C6H5CH3/
CH3COOC2H5 6:4) Rf 0.71. IR (KBr): w 3320, 2900,
0.50. IR (KBr): w 2930, 2860, 1670, 1640 cm−1 1H
.
1
NMR (DMSO-d6): l 0.83 (t, 3H, CH3-4, J=6.1 Hz),
0.77 (t, 3H, CH3-6, J=5.9 Hz), 1.05–1.08 (m, 4H,
2CH2), 1.22 (large s, 10H, 5CH2), 1.45–1.55 (m, 2H,
CH2-4), 3.40 (s, 2H, CH2-2), 3.75–3.80 (m, 4H, CH2-4),
6.90 (dd, 1H, aromatic H, J=8.2 and 1.9 Hz), 6.99 (d,
1H, aromatic H, J=1.9 Hz), 7.20–7.32 (m, 6H, aro-
matic H). 13C NMR (DMSO-d6, BB decoupling and
DEPT): l 13.5 (CH3), 13.9 (CH3), 19.0 (CH2), 22.0
(CH2), 26.2–28.6 (5CH2), 30.4 (CH2), 31.1 (CH2), 42.3
(CH2), 49.2 (CH2), 118.6 (CH), 121.7 (C), 122.1 (CH),
127.7 (2CH), 128.0 (2CH), 128.5 (CH), 129.3 (CH),
136.5 (C), 138.5 (C), 142.0 (C), 164.3 (CO), 169.1 (CO).
MS; m/z (%): 452 (0.6), 347 (8.5), 249 (13.1), 177 (12.8),
105 (100), 77 (48.7), 43 (13.3), 41 (19.3).
2840, 1660 cm−1. H NMR (DMSO-d6): l 0.81–0.91
(m, 6H, 2CH3), 1.22–1.37 (m, 12H, 6CH2), 1.47–1.54
(m, 4H, 2CH2), 2.97 (dt, 2H, CH2-6, J=6.6 Hz), 3.31
(s, 2H, CH2-2), 3.86 (t, 2H, CH2-4, J=7 Hz), 5.72 (t,
1H, NH-6), 6.26 (dd, 1H, aromatic H, J=8.4 and 2.1
Hz), 6.46 (d, 1H, aromatic H, J=2.1 Hz), 7.03 (d, 1H,
aromatic H, J=8.4 Hz). 13C NMR (DMSO-d6, BB
decoupling and DEPT): l 13.6 (CH3), 13.8 (CH3), 19.3
(CH2), 22.0 (CH2), 26.6–29.1 (5CH2), 31.2 (CH2), 31.6
(CH2), 42.7 (CH2), 43.1 (CH2), 101.5 (CH), 107.2 (CH,
C), 128.5 (CH), 139.8 (C), 148.7 (C), 165.1 (CO). MS;
m/z (%): 348 (68.9), 249 (100), 193 (39.2), 177 (12.7),
163 (27.9), 151 (25.8), 43 (26.8), 41 (24.3).
4. Biological activity
3.10. Hydrolysis of benzoyl compounds
The calculation of minimal inhibitory concentration
(MIC) was performed in vitro against six microorgan-
isms (cocci, Gram-positive and Gram-negative bacilli):
Micrococcus fla6us — DAUFPE 323, Bacillus cereus
— DAUFPE 11, Salmonella enteritidis — DAUFPE
415, come from the collection of the Department of
Antibiotics of the Federal University of Pernambuco;
Staphylococus aureus, Escherichia coli and Proteus 6ul-
garis are wild strains isolated from contaminated food.
The Mueller–Hinton agar has been used as a
medium of reference for antimicrobial activity tests [13].
Inocula were prepared from 18 h-old subcultures at
A suspension of benzoyl compound (2 mmol) in 5 ml
of 70% sulfuric acid is refluxed at 147–150°C for 30
min. After cooling, 6 ml of water is added and the
mixture poured into 20 ml of ice water. The precipitate
is extracted twice by 20 ml of chloroform. Ammonium
hydroxide (28% solution, 10 ml) is added to the organic
phase, which is washed with water, dried over magne-
sium sulfate and vacuum evaporated. The crude
product is treated with petroleum ether and ethyl ace-
tate and then recrystallised from methanol.

V.L. de M. Guarda et al. / Il Farmaco 56 (2001) 689–693
693
Table 1
Antimicrobial activity of investigated compounds (MIC in mg/ml)
Acknowledgements
The authors thank the Conselho Nacional de
Microorganism
Compounds
Desenvolvimento Cientifico e Tecno-logico (CNPq),
Brazil and the International Cooperation Agreement
4
6
7
9
12
Ciprofloxacin
(CAPES/COFECUB) for their support.
a
a
a
M. fla6us
S. aureus
B. cereus
S. enteriditis
E. coli
2
64
32
64
0.25
a
a
a
4
2
8
2
4
a
a
a
a
a
a
a
a
a
4
a
64
16
References
a
a
a
16
a
P. 6ulgaris
64
[1] G. Grandolini, V. Ambrogi, C. Rossi, M.C. Tiralti, L. Tutto-
bello, Synthesis, antibacterial and antifugal activities of some
new derivatives of benzothiazole, 1,4-benzothiazine and 1,5-ben-
zothiazepine, Eur. J. Med. Chem. — Chim. Ther. 21 (1986)
455–460.
a ]128 mg/ml.
37°C in this broth. The turbidity of culture suspension
was adjusted to obtain 0.5 on the Mac Farland scale,
i.e. 108 UFC/ml. The solutions of each drug were
prepared at the concentration of 1280 mg/ml in a mix-
ture of DMSO/Tween 80/distilled water (1:1:8) and
then in distilled water from mother solutions. Serial
dilutions were made with sterile distilled water accord-
ing to a geometric progression of ratio 2, such as the
concentrations of Petri plates which were in the range
of 128–0.5 mg/ml. In the same way, it was verified that
DMSO, at the 1/10 dilution, was completely inactive on
the tested microorganisms.
Plates of Petri are prepared by mixing one part of
each dilution of drug with nine parts of the Mueller–
Hinton agar medium. Each plate, including a drug-free
control plate, is inoculated by streak using a calibrated
loop (0.05 ml). The plates are examined for the pres-
ence or absence of growth after 18 h of incubation at
37°C. The MIC is considered to be the lowest drug
concentration for which there is no microbial growth
[14]. Ciprofloxacin was used as the reference antibiotic.
The antimicrobial activity of investigated compounds is
shown in Table 1.
[2] R.R. Gupta, P.K. Dev, M.L. Sharma, C.M. Rajoria, A. Gupta,
M. Nyati, Anticancer activities of 2,3-dihydro-1,4-benzothiazi-
nes, and of their 4-(N-alkylamides) and 4-(N-alkyl N-nitro-
soamides), Anticancer Drugs 4 (1993) 589–592.
[3] D.K. Todorov, M.V. Ilarionova, R.R. Gupta, J. Molna, N.
Motohashi, In vitro–in vivo studies of benzothiazines against
lymphocytic leukemia P 388 cells, Heterocycl. Commun. 1 (1995)
153–155.
[4] L. Del Corona, G. Signorelli, A. Pinzetta, G. Coppi, Synthesis
and immunostimulating activity of new 1,4-benzothiazine deriva-
tives, Eur. J. Med. Chem. 27 (1992) 419–423.
[5] H. Tawada, Y. Sugiyama, H. Ikeda, Y. Yamamoto, K. Meguro,
Studies on antidiabetic agents. IX. A new aldose reductase
inhibitor, AD-5467, and related 1,4-benzoxazine and benzothi-
azine derivatives: synthesis and biological activity, Chem. Pharm.
Bull. 38 (1990) 1238–1245.
[6] M. Zimmermann, Aminoalkyl-2H-4H-1,4-benzothiazin-3-ones.
US patent 2,824,102, Chem. Abstr. 52 (1958) (1958) 12932c.
[7] H.S. Lowrie, 4-Amino-alkanoyl-2,3-dihydro-1,4-benzothiazines.
US patent 2,947,744 (1960), Chem. Abstr. 55 (1961) 583c.
[8] V.L. de M. Guarda, M. Perrissin, F. Thomasson, E.A. Ximenes,
S.L. Galdino, I.R. Pitta, C. Luu-Duc, Synthesis and microbio-
logical activity of some 2H-1,4-benzothiazin-3-one derivatives,
Heterocycl. Commun. 6 (2000) 49–54.
[9] K Fries, M. Vorbrodt, G. Siebert, Untersuchungen in der reihe
des phenylen-diazosulfides, Ann. 454 (1927) 121–324.
[10] L. Ngadi, A.M. Galy, J.P. Galy, J. Barbe, A. Cremieux, J.
Chevalier, Some new 1-nitro acridine derivatives as antimicrobial
agents, Eur. J. Med. Chem. 25 (1990) 67–70.
[11] V. Cecchetti, S. Dominici, A. Fravolini, F. Schiaffella, Synthesis
and antibacterial evaluation of 1,4-thiazinoquinoline-carboxylic
acids, Eur. J. Med. Chem. 19 (1984) 29–35.
[12] A. Koziara, S. Zawadzki, A. Zwierzak, Phase-transfer-catalysed
N-alkylation of N-substituted carboxamides, Synthesis 7 (1979)
527–529.
5. Results
Some new 2H-benzo[1,4]thiazin-3-one derivatives
have been synthesised and characterised by their physi-
cal and analytical properties. The fragments observed
by electronic impact mass spectrometry are in agree-
ment with the proposed structures.
[13] R. Cleeland, E. Grunberg, Laboratory evaluation of new antibi-
otics in vitro and in experimental animal infection, in: U. Lorian
(Ed.), Antibiotics in Laboratory Medicine, Williams and
Wilkins, Baltimore, 1986, pp. 825–876.
[14] P. Courvalin, F. Goldstein, A. Philippon, J. Sirot, L’antibi-
ogramme, MPC/Vigot, Bruxelles, 1985, pp. 191–195.
Five compounds were evaluated as potential antimi-
crobial agents against six microorganisms. Their activ-
ity is inferior to that of ciprofloxacin, the reference
.
antibiotic.