Ethidium activity

Sources of AOX include PhCs, their metabolites, chlorine-forming disinfectants, used in cleaning activities, and halogen-containing solvents, employed in laboratories, as well as other chemical substances like ethidium bromide [17]. AOX levels have been found to range from 150 to 7,760 pg in HWWs, in stark contrast to the 0.04-0.2 pg range measured in UWWs. 

Intercalation has been demonstrated with a number of other compounds having a polycyclic aromatic system and groups capable of forming hydrogen bonds. Among such compounds are the antibacterial 9-aminoacridine, the antimalarials mepacrine and chloroquine, the veterinary trypanocide ethidium (246), the thioxanthone lucanthone (247 R = Me) and its more active metabolite hycanthone (247 R = CH20H), which are used in the treatment of schistosomiasis, and the antineoplastic alkaloid ellipticine (248). A number of antibiotics, including the actinomycins, echinomycin and bleomycin, also intercalate. 

Figure 5.13 shows the structures of extrinsic fluors that have been of value in studying biochemical systems. ANS, dansyl chloride, and fluorescein are used for protein studies, whereas ethidium, proflavine, and various acridines are useful for nucleic acid characterization. Ethidium bromide has the unique characteristic of enhanced fluorescence when bound to double-stranded DNA but not to single-stranded DNA. Aminomethyl coumarin (AMC) is of value as a fluorogenic leaving group in measuring peptidase activity. 

Ethidium bromide is a common fluorescent stain for nucleic acids, ft is reported to have significant anti-tumor and anti-viral properties. However, its potential applications in human therapy are prevented, due to its mutagenic and carcinogenic activities in model organisms. 

Fluorescence-based indicator reactions can also be coupled to measurements of enzymatic activity. For example, very sensitive assays of endonuclease activity can be performed using as a substrate complexes of double stranded DNA containing intercalated ethidium bromide, which is strongly fluorescent. On cleaving or nicking the DNA, the intercalated ethidium is released into the solution causing a pronounced decrease in fluorescence intensity. 

The effects of amine-substituted ellipticine derivatives 88 and 105-111 on L1210 and the human colon tumor (HCT8) in vitro (Table III) indicate that these compounds are not more cytotoxic than ellipticine (1) (71). Furthermore, only a low order of activity was revealed in vivo against P388 for 110 and 111. The N-6 derivatives were inactive as antitumor agents. However, the DNA binding properties of all of these amine-substituted ellipticines were superior to 1, as determined by the ethidium displacement assay. 

The in vitro stability of the liposomes loaded with 1 and 2 were studied both in buffer and in 25% human serum.7,14 The stability was excellent as exemplified in Figure 4b by the leakage of WSP-1 and for comparison ethidium from actively loaded liposomes. 

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