6
Waisser and co-workers
Table 3. Antimycobacterial activity(logMIC)of compounds 18–34 and INH
(values calculated according to equations (1)–(3) are given in parentheses).
——————————————————————————————
log MIC
= –0.675(±0.240)σ – 0.293(±0.138)π –
0.057(±0.138) I + 1.680(±0.111)
M.tub.
(1)
(2)
(3)
R = 0.856; s = 0.234; F = 9.14; n = 14
Cmpds
log MIC (mmol/l)
M. tuberculosis
M. kansasii
M. avium
log MIC
= –0.352(±0.172)σ – 0.422(±0.103)π –
0.126(±0.104) I + 2.069(±0.080)
——————————————————————————————
M.kans..
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
INH
1.8 (1.7)
1.5 (1.6)
1.5 (1.2)
1.8 (1.9)
>1.2a (1.3)
0.9 (0.8)
0.9 (1.2)
1.2 (1.2)
>2.1a (2.3)
1.8 (1.6)
1.2 (1.1)
1.2 (1.1)
2.1 (1.8)
1.2 (1.2)
0.9 (0.8)
0.9 (1.2)
>1.8a (2.2)
0.6
2.1 (2.1)
1.8 (1.9)
>1.5a (1.5)
2.4 (2.2)
>1.2a (1.3)
1.2 (1.2)
1.5 (1.6)
1.8 (1.8)
>2.1a (2.4)
2.1 (1.9)
1.8 (1.8)
1.2 (1.4)
2.4a (2.5)
1.5 (1.1)
1.2 (1.1)
1.2 (1.5)
>1.8a (2.3)
2.7
2.1 (2.3)
2.1 (2.1)
>1.5a (1.8)
2.4 (2.4)
>1.2a (2.0)
1.8 (1.6)
1.8 (1.9)
2.1 (2.1)
>2.1a (2.6)
2.1 (2.1)
2.1 (1.9)
>1.5a (1.7)
2.4 (2.2)
1.8 (1.8)
1.2 (1.4)
1.8 (1.7)
>1.8a (2.4)
2.7
R = 0.927; s = 0.164; F = 16.32; n = 14
log MIC
= –0.288(±0.165)σ – 0.363(±0.104)π –
0.176(±0.095) I + 2.278(±0.076)
M.av..
R = 0.909; s = 0.159; F = 12.76; n = 14
From the above equations we conclude that the activity of
the compounds under study increases with increasing elec-
tron-withdrawing ability of the substituents on the phenyl
[1]
ring. Unlike the earlier study we found that the antimyco-
bacterial activity also increases with increasing hydrophobic-
ity of these substituents. The antimycobacterial activity of
6,8-dibromoderivatives correlates with the antimycobacterial
activity of 6,8-dichloroderivatives. The calculated values of
log MIC according to equations (1)–(3) are given in Table 3.
——————————————————————————————
a) MIC would be at a higher value due to the limited solubility of the
compound.
Acknowledgment
Table 4. Hammett constants σ and hydrophobic constants π of the substi-
tuents on the phenyl ring.
——————————————————————————————
This work was supported by grant 203/96/0262 of the Grant Agency of the
Czech Republic and grant 35/95 of the Grant Agency of the Charles Univer-
sity.
Substituent
σ
π
Substituent
σ
π
——————————————————————————————
H
0
0
4-CH3
4-N(CH3)2 –0.83
3-NO2
4-OCH3
–0.17
0.60
–0.08
0.05
Experimental Part
4-Br
3-Cl
4-Cl
3,4-Cl2
0.23
0.37
0.23
0.60
1.19
0.77
0.73
1.50
0.71
–0.27
Mp Kofler (uncorr.).– IR-spectra: a Nicolet Impact 400 spectrometer. KBr
pellets or solution in chloroform.– Elemental analyses: a Laboratorní
prístroje CHN analyzer, microanalysis data were within ±0.4% of the calcu-
lated values.
–0.03
——————————————————————————————
From ref.[6]
.
General Procedure for the Preparation of Salicylanilides
determined after incubation at 37 °C for 14 days (see Table 3). MIC was the
lowest concentration of an antimycobacterially active substance (see the
above concentrations), at which inhibition of mycobacteria growth occurred.
A suspension of 3,5-dihalogenosalicylic acid (0.02 mol) and the substi-
tuted aniline (0.02 mol) in chlorobenzene (100 ml) was heated under reflux
in the presence of PCl3 (0.01 mol) for 3 h. The reaction mixture was filtered
while hot, and the product allowed to crystallize upon cooling, which yielded
80–95% of the theoretical amount. The product was recrystallized from
ethanol–water (Table 1).
Calculation
All calculations were carried out using the Multireg H program (Klemera)
for Microsoft Excel. The values of the substituent constants (σ and π) were
taken from the literature[6], and are summarized in Table 4.
General Procedure for the Preparation of 3-Aryl-6,8-dihalogeno-2H-1,3-
benzoxazine-2,4(3H)-diones:
References
Ethyl chloroformate (48 mmol) was added dropwise to a stirred solution
of the salicylanilide (40 mmol) in dry pyridine (20 ml) at 0 °C. The mixture
was heated on a steam bath for 1 h, and subsequently poured into 5%
hydrochloric acid (140 ml). After standing for 12 hours, the product was
filtered off, suspended in 5% potassium hydroxide solution, filtered again,
and crystallized from ethanol (Table 2).
✩
Dedicated to Prof. Dr. Hans Dietrich Stachel, Munich, on the occasion
of his 70th birthday
[1] K. Waisser, J. Hladuvková, L. Kubicová, V. Klimešová, V. Buchta,
À. Odlerová, Sci. Pharm. 1996, 64, 701–705.
[2] K. Waisser, Folia Pharm. Univ. Carol. 1992, 16, 39–42.
Microbiological Assay
[3] H. Lemaire, C. H. Schramm, A. Cahn, J. Pharm. Sci. 1961, 50,
For the evaluation of antimycobacterial activity of the substances in vitro,
the followingstrainswereused: M. tuberculosis CNCTC My 331/88, M. kan-
sasii CNCTC My 235/80, M. avium CNCTC My 330/88, obtained from the
Czech National Collection of Type Cultures (CNCTC), National Institute of
Public Health, Prague. Antimycobacterial activity of the compounds against
these strains was determined in the Šula semisynthetic medium (SEVAC,
Prague).
The compounds were added to the medium in a dimethyl sulfoxide
solution. The following concentrations were used: 1000, 500, 250, 125, 62,
31, 16, 8, and 4 µmol/l. The minimum inhibitory concentrations were
831–837.
[4] I. S. Ioffe, M. Z. Zalmanovich, Zh. Obshch. Khim. 1959, 29, 2682–
2685.
[5] R. E. Stenseth, J.W. Baker, D.P. Roman, J. Med. Chem. 1963, 6,
212–213.
[6] M. Kuchar, V. Rejholec, VyuÁití kvantitativních vztahu mezi strukturou
a biologickou aktivitou, Academia, Praha 1987, pp. 51, 85.
Received: April 22, 1997 [FP210]
Arch. Pharm. Pharm. Med. Chem. 331, 3–6 (1998)