Comparative Anti-Brucellosis Activity of Some Trypaflavine Derivatives
Abstract Generated abstract
This study examines whether chemical modification of trypaflavine can produce derivatives with useful activity against brucella organisms, particularly through protection of amino groups by azo, acetyl, benzoyl, or benzylidene substituents. The authors synthesized a series of trypaflavine derivatives, characterized them analytically, and compared their activity against caprine and bovine brucella strains in vitro, with selected compounds tested in guinea pigs with chronic experimental brucellosis. Most derivatives showed lower in vitro activity than trypaflavine, although toluidine azo derivatives and some arsenic or mercury complexes were relatively more active within the series. Two compounds produced a protective effect in infected guinea pigs and were less toxic than trypaflavine, suggesting that amino group protection may reduce direct in vitro activity while improving therapeutic behavior in vivo.
Full Text
Comparative Antibrucellar Activity of Certain Trypaflavine Derivatives
L. P. Kulev, A. G. Pechenkin
Recently, chemotherapy has advanced the task of broadly investigating acridine derivatives in order to discover valuable medicinal agents among them [1].
Among compounds of this series, numerous derivatives of trypaflavine deserve attention, including azo-sulfanilamide derivatives and some others, patented as active chemotherapeutic preparations [2].
Taking into account the high bactericidal action of trypaflavine against brucella organisms [3], we set ourselves the goal of obtaining some of its azo derivatives and testing them for antibrucellar activity. In doing so, it was borne in mind that azo derivatives in the organism may first be reduced to hydrazo compounds, and then to free amines [4], i.e., the decomposition of trypaflavine azo derivatives will be accompanied by the formation of physiologically active substances, primarily trypaflavine itself. It was also intended to test in animals the antibrucellar activity of other trypaflavine derivatives with groups readily split off upon hydrolysis, for example acyl groups.
Thus, the same principle of preliminary protection of amino groups was taken as the basis for our studies—a principle that had proved successful in the investigation of complex compounds of trypaflavine1.
All microbiological and pharmacological tests of the synthesized preparations were carried out at the Novosibirsk Scientific-Research Veterinary Experimental Station by K. F. Lamikhov and S. S. Nazarov.
The synthesis of trypaflavine derivatives was carried out by ordinary methods.
The list of synthesized compounds, the results of analysis, and also certain properties and their activity against various strains of brucella of the caprine and bovine types are given in Table 1.
In in vitro experiments, diacetyl-, dibenzoyl-, and dibenzylidene derivatives of trypaflavine (Nos. 1, 4, 9 in Table 1) showed a bacteriostatic effect at dilutions up to 1:50,000.
Azo derivatives not containing an acridine nucleus—for example, the product of coupling diazotized osarsol with beta-naphthol or the product of coupling ortho-oxyquinoline with phenyldiazonium—showed absolutely no activity against brucella.
The most active in the series of trypaflavine azo derivatives proved to be the products of its coupling with toluidines, especially with the meta isomer (No. 18). It was established that replacement of the benzene ring by a naphthalene or quinoline ring sharply reduces the activity of the preparations (Nos. 16, 17, 42, 43). A decrease in antimicrobial activity is also observed when an azo group is introduced into the position adjacent to the amino group (Nos. 48, 56). If, however, the methyl or sulfamide group in these compounds is replaced by an arseno group, their activity increases noticeably (No. 45). It increases—
Here:
\[ R_1 = \text{3,6-diamino-10-methylacridinium chloride residue} \]
\[ R_2 = \text{3,6-diamino-10-methylacridinium chloride residue} \]
\[ R_3 = \text{3,6-diamino-10-methylacridinium chloride residue} \]
Table 1
| No. in order | Preparation No. | Formula | m.p., °C | Solubility in water | Yield, % | Analysis: found, % | Analysis: calculated, % | Activity of preparation, thousand |
|---|---|---|---|---|---|---|---|---|
| 1 | 1 | \(\mathrm{Ph{-}CO{-}R_3{-}CO{-}Ph}\) | 240–42 | difficult | 69 | nitrogen — 8.96 | nitrogen — 8.98 | 50 |
| 2 | 4 | \(\mathrm{Ph{-}CH_2{-}R_3{-}CH_2{-}Ph}\) | 105 | moderate | 70 | nitrogen — 9.58 | nitrogen — 9.57 | 50 |
| 3 | 9 | \(\mathrm{CH_3CO{-}R_3{-}COCH_3}\) | 240 | good | 82 | nitrogen — 12.18 | nitrogen — 12.22 | 25 |
| 4 | 18 | \(\mathrm{R_1{-}N{=}N{-}C_6H_3(CH_3){-}NH_2}\) | decomp. 245 | — | 45 | nitrogen — 18.49 | nitrogen — 18.58 | 50–400 |
| 5 | 19 | \(\mathrm{R_1{-}N{=}N{-}C_6H_3(CH_3)(NH_2)}\) | decomp. 240 | — | 43 | nitrogen — 18.43 | nitrogen — 18.58 | 50–200 |
| 6 | 20 | \(\mathrm{R_1{-}N{=}N{-}C_6H_3(NH_2)(CH_3)}\) | decomp. 180 | moderate | 43 | nitrogen — 18.50 | nitrogen — 18.58 | 50–200 |
| 7 | 16 | \(\mathrm{R_1{-}N{=}N{-}C_{10}H_5{-}NH_2}\) | 262–265 | good | 37 | nitrogen — 16.88 | nitrogen — 16.92 | 50 |
| 8 | 17 | \(\mathrm{R_1{-}N{=}N{-}C_{10}H_5{-}NH_2}\) | 245–248 | — | 34 | nitrogen — 16.80 | nitrogen — 16.92 | 50 |
| 9 | 43 | \(\mathrm{R_1{-}N{=}N{-}C_{10}H_5(N){-}OH}\) | decomp. 300 | — | 73 | nitrogen — 15.93 | nitrogen — 15.98 | 25 |
| 10 | 48 | \(\mathrm{R_2{-}N{=}N{-}C_6H_4{-}CH_3}\) | 255–257 | — | 36 | nitrogen — 18.52 | nitrogen — 18.58 | 50 |
| 11 | 56 | \(\mathrm{R_2{-}N{=}N{-}C_6H_4{-}SO_2NH_2\cdot HCl}\) | 262–265 | moderate | 83 | nitrogen — 17.67 sulfur — 6.72 chlorine — 14.68 |
nitrogen — 17.56 sulfur — 6.69 chlorine — 14.89 |
25 |
| 12 | 45 | \(\mathrm{R_2{-}N{=}N{-}C_6H_4{-}As(=O)(OH)(ONa)}\) | decomp. 220 | good | 85 | nitrogen — 14.43 arsenic — 15.52 |
nitrogen — 14.37 arsenic — 15.41 |
100 |
| 13 | 55 | \(\left[\mathrm{R_2N{=}N{-}C_6H_4{-}As(=O)(OH)(ONa)}\right]\cdot \mathrm{KHgI_3}\) | decomp. 200 | good | 76 | mercury — 18.05 arsenic — 6.65 |
mercury — 17.77 arsenic — 6.63 |
200 |
| 14 | 68 | \(\left[\mathrm{R_2N{=}N{-}C_6H_4{-}CH_3}\right]\cdot \mathrm{KHgI_3}\) | 180 | moderate | 78 | mercury — 19.98 | mercury — 20.10 | 100 |
is even greater if, together with the introduction of an arsenic group, mercury–iodide potassium is complexly attached (No. 55).
It should be noted that the azo derivatives of trypaflavine in which it occurs as the azo component (preparation No. 18) give a complex compound with mercury–iodide potassium. However, with potassium iodide or with silver iodide potassium this azo derivative does not form complexes, which is apparently explained by closure of a six-membered ring by means of a hydrogen bond, as a result of which the complex-forming ability of the amino group with metal salts is weakened:
\[ \mathrm{ \begin{array}{c} \text{acridine residue with } H_2N\text{ substituent} {-}N{=}N{-}C_6H_4{-}CH_3,\\ \text{with an intramolecular } N{-}H\cdots N \text{ hydrogen bond and } CH_3Cl \text{ at the acridinium nitrogen.} \end{array} } \]
Mercury salts, which are stronger complexing agents, are probably able to break the hydrogen bond and to coordinate in a complex manner with the nitrogen of the amino group. It is possible that the formation of a hydrogen bond in azo derivatives of this type also explains the sharp decrease in their antimicrobial activity outside the organism as compared with trypaflavine itself (Table 1, Nos. 45, 48, 56).
From the results of microbiological tests outside the organism it is evident that none of the preparations synthesized by us showed any appreciable increase in activity compared with trypaflavine, whose maximal antibrucellar action in our experiments appeared at a dilution of 1:500,000. On the contrary, in the overwhelming majority of cases a sharp decrease in this activity was observed, which agrees with the considerations expressed by us concerning the inactivation of trypaflavine inside the organism by unprotected amino groups.
Some of the compounds obtained by us (18, 56 in the table) were tested on guinea pigs with the chronic form of experimental brucellosis. In this case a clearly expressed protective effect was obtained, characterized by a sharp reduction in the recoverability of brucellae from the internal organs of the treated animals, and also by a considerable reduction in the pathomorphological changes of these organs.
The fact deserves attention that treatment of experimental brucellosis in guinea pigs with preparations Nos. 18 and 56 gave a definite positive result, whereas treatment with free trypaflavine, acrichine, synthomycin, and biomycin in parallel groups of guinea pigs infected with the same strains of brucellae gave no effect whatsoever.
It should also be noted that preparations Nos. 18 and 56 exhibited considerably lower toxicity (by a factor of 5–10) than trypaflavine itself.
Conclusions
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Certain azo-, acetyl-, benzoyl-, and benzylidene derivatives of trypaflavine have been synthesized; their analysis and microbiological tests have been carried out.
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It has been shown that protection of the amino groups of trypaflavine reduces its antibrucellar activity in experiments outside the organism and accounts for a definite protective effect in the treatment of experimental chronic brucellosis in guinea pigs.
LITERATURE
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Grigorovskii A. M. Uspekhi khimii, 21, 615, 1952.
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C. A. 1949, 43, 2738 E; U.S. patent 2,309,118, Jan. 26, 1949. C. A. 1949, 43, 8105 a; U.S. patent 2,476,925, July 19, 1949.
C. A. 1948, 42, 5621 E; British patent 577,200, May 8, 1946.
C. A. 1922, 16, 18359; U.S. patent 1,408,974, May 7.
C. A. 1935, 29, 15869;
C. A. 1934, 28, 48408. -
Zarodovskii P. F. Brucellosis. Medgiz, 1953.
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Jenkins G., Hartung W. Chemistry of organic medicinal preparations. Izd. Inostr. Lit., 461–465, 1949.
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L. P. Kulev, A. G. Pechenkin, “Complex Compounds of Trypaflavine and Their Antibrucellar Activity,” the article is included in this collection. ↩