8-Substituted 5-[(aminoalkyl)amino]-6H-v-triazolo[4,5,1-de]acridin-6-ones as potential antineoplastic agents. Synthesis and biological activity

A series of 8-substituted 5-[(aminoalkyl)amino]-6H-v-triazolo[4,5,1-de]acridin-6-ones (2), structurally related to the imidazoacridinones (1), was synthesized and tested for cytotoxic and antineoplastic activity. Preliminary biological results indicated that the 8-OH derivatives possess the highest antitumor activity. No relationship has been found between the nature of the C-8 substituent and antitumor activity.

High-performance liquid chromatographic method for the determination of polycyclic hydrocarbon metabolite distributions

Analytical separations and quantification of eight metabolites of benzo[a]pyrene, nine metabolites of 7-methylbenz[c]acridine and nine metabolites of dibenz[a,j]acridine have been carried out on two reversed-phase high-performance liquid chromatographic systems using 3- and 10-microns C8 packings. Quantitative results for the distributions of primary metabolites for the two systems closely agreed and showed that up to 70% savings in chromatographic time could be achieved with the 3 micron particle size columns.

Activities of new acridone alkaloid derivatives against Plasmodium yoelii in vitro

Forty-seven new acridone alkaloid derivatives (SA compounds) were tested for antimalarial activity in vitro. At a concentration of 1.0 microgram/ml, six of these inhibited 50% or more of the incorporation of [3H]hypoxanthine into Plasmodium yoelii in vitro. The four most potent compounds, SA 3757, SA 3548, SA 3761 and SA 3499, showed 50% inhibitory concentration (IC50) values of 0.023 microgram/ml, 0.03 microgram/ml, 0.053 microgram/ml and 0.15 microgram/ml, respectively. The chemotherapeutic indexes of these four acridones, based on the ratio of the 50% lethal concentration (LC50) values for cell growth of L1210 cells to the IC50 for inhibition of uptake of [3H]hypoxanthine into P. yoelii, were calculated to be equal to or more higher (greater than 870, 263, 189 and greater than 133, respectively) than chloroquine diphosphate (315) or pyrimethamine (87).

Solvolysis of the bay-region diol epoxides of 7-methylbenz[c]acridine in aqueous solution and effect of DNA

The hydrolysis of the bay-region syn- and anti-diol epoxides of 7-methylbenz[c]acridine (7MBAC) has been studied in aqueous solution. The rates of reaction have been measured at low ionic strength in the absence and presence of DNA, as a function of pH and temperature, by spectrophotometry and high-pressure liquid chromatography. The major products are the corresponding tetrols, but the syn diastereomer also undergoes rearrangement to a keto diol. The hydrolysis reaction is catalyzed by both acid and DNA and conforms to a mechanism in which a physical association complex is formed between diol epoxide and DNA, followed by two parallel pathways in which the diol epoxide either is hydrolyzed or becomes covalently bound to the DNA. The rate constants are significantly lower than the corresponding ones for the diol epoxides of benzo[a]pyrene. However, the extent of covalent binding of 7MBAC diol epoxides to DNA was found to be 12-30%, depending on the pH of reaction, values that are 2-3 times greater than for the benzo[a]pyrene diol epoxides reacted under the same conditions of low ionic strength. The very small changes (2 nm) in spectroscopic characteristics observed for the covalently bound adduct as compared to the free tetrol suggest that the binding occurs with little intercalation of the compound between the base pairs of DNA.

1H NMR study of the binding of bis(acridines) to d(AT)5.d(AT)5. 2. Dynamic aspects

Measurements of the 1H NMR spectra and relaxation rates were used to study the dynamic properties of 9-aminoacridine (9AA) and four bis(acridine) complexes with d(AT)5.d(AT)5. The behavior of the 9AA (monointercalator) and that of C8 (bisintercalator containing an eight-carbon atom linker chain) are entirely similar. For both compounds, the lifetime of the drug in a particular binding site is 2-3 ms at approximately 20 degrees C, and neither affects the A.T base pair opening rates. The complex with C10 (bisintercalator containing a 10-carbon atom linker chain) is slightly more stable than the C8 complex since its estimated binding site lifetime is 5-10 ms at 29 degrees C. Base pairs adjacent to the bound C10 are destabilized, relative to free d(AT)5.d(AT)5, but other base pairs in the C10 complex are little affected. Bis(acridine) pyrazole (BAPY) and bis(acridine) spermine (BAS) considerably stabilize those base pairs that are sandwiched between the two acridine chromophores, but in the BAS complex proton exchange from the two flanking base pairs appears to be accelerated, relative to free d(AT)5.d(AT)5. The lifetime of these drugs in specific binding sites is too long (>10 ms) to be manifested in increased line widths, at least up to 41 degrees C. An important conclusion from this study is that certain bisintercalators rapidly migrate along DNA, despite having large binding constants (K>10(6) M-1). For C8 and C10 complexes, migration rates are little different from those deduced for 9AA. The rigid linker chain in BAPY and the charge interactions in BAS retard migration of these two bisintercalators. These results provide new parameters that are useful in understanding the biochemical and biological properties of these and other bisintercalating drugs.

1H NMR study of the binding of Bis(acridines) to d(AT)5.d(AT)5. 1. Mode of binding

1H NMR has been used to investigate the mode of binding to d(AT)5.d(AT)5 of a series of bis(acridine) derivatives connected by different types of linker chains. The length and character (ionic, aliphatic, rigid, and flexible) of the linker chains are found to have a profound effect on the binding of these derivatives to the DNA. Bis(acridine) derivatives with linker chains shorter than 9 A monointercalate under the conditions used in the NMR study, whereas those bis(acridines) with chains of 9.8 A or longer bisintercalate. We find no evidence for the violation of the so-called neighbor exclusion principle. Although all of the bis(acridines) contain the same chromophores, their NMR spectra clearly demonstrate that they form complexes with d(AT)5.d(AT)5 which have different structures. This emphasizes the important effect that the linker chain has on the structure of the intercalation complex.

The determination of n-values for some acridines by controlled potential coulometric reduction

The reduction of some aminoacridines has been investigated by controlled potential coulometry. The number of electrons involved in the first reduction stage has been determined by a graphical treatment of the current-time values obtained using a divided electrolysis cell. With the exception of 5-aminoacridine the results confirm the values obtained indirectly by Kaye5.