Proflavine Dyes

Proflavin, also known as preflavin and diaminoacridine, is a criflavin derivative that has a bactericidal effect on many Gram-positive bacteria. It has been used as a topical preservative in the form of dihydrochloride and hemisulfate, and has previously been used as a preservative for urine. It is also known that flavones have mutagenic effects on DNA by inserting between nucleic acid base pairs. It differs from most other mutagenic components in that it causes base pair deletions or base pair insertions rather than substitutions. In the presence of light, proflavonoids can induce double-strand breaks in DNA. Lutein is strongly absorbed in the blue region at 445 nm (in water at pH 7) with a molar extinction coefficient of c. 40,000. Preflavin belongs to acridine derivatives.

Figure 1. Chemical structure of en:proflavine.( Image created by Karol Langner)

Introductions about acridine

Acridine is an organic compound and a nitrogen heterocyclic ring, and its molecular formula is C13H9N. Acridine is a substituted derivative of the parent ring. This is a planar molecule that is structurally related to anthracene and one of the central CH groups is replaced by nitrogen. Like related molecules, pyridine and quinoline, apyridine is weakly basic, which is an almost colorless solid. Commercial pyridine has no commercial application, but atidine dyes were once popular. It crystallizes in the needle.

Figure 2. Acridine chemical structure.

Applications

At one time acridine dyes were commercially significant, but they are now uncommon because they are not lightfast. Acridine dyes are prepared by condensation of 1,3-diaminobenzene derivatives. Illustrative is the reaction of 2,4-diaminotoluene with acetaldehyde:

Figure 3. Synthesis of C.I. Basic Yellow 9, an acridine dye.

9-phenylacridine is the parent base of Chssaniline or 3,6-diamino-9-phenylacridine. It is the main component of the dye phosphine (not to be confused with phosphine gas). This dye is a by-product of making rosaniline. O-xylylenediamine forms a red salt, which dyes silk and wool to pale yellow. The salt solution is characterized by its fine yellow-green fluorescence. O. Fischer and G. Koerner synthesized phthalamide by condensing o-nitrobenzaldehyde and aniline, and reduced the resulting o-nitro-p-diaminotriphenylmethane to the corresponding o-amino compound. Oxidation to phthalamide. An isomer of acetophenone, benzoflavone, is also a dye made by K. Oehler from m-phenylenediamine and benzaldehyde. These materials condense to form tetraaminotriphenylmethane, which will lose ammonia when heated with acid, and generate 3,6-diamino-9,10-dihydrophenylacridine, which can be obtained by oxidation. It is a yellow powder that dissolves in hot water.

Reference:

1. Maier W.; et al. Synthesis of 1,3-dihydroxy-N-methylacridone and its conversion to rutacridone by cell-free extracts of Ruta-graveolens cell cultures. Phytochemistry. 1993, 32 (3): 691–698.