Schistosomiasis chemotherapy.

After malaria, schistosomiasis (or bilharzia) is the second most prevalent disease in Africa, and is occurring in over 70 countries in tropical and subtropical regions. It is estimated that 600 million people are at risk of infection, 200 million people are infected, and at least 200,000 deaths per year are associated with the disease. All schistosome species are transmitted through contact with fresh water that is infested with free-swimming forms of the parasite, which is known as cercariae and produced by snails. When located in the blood vessels of the host, larval and adult schistosomes digest red cells to acquire amino acids for growth and development. Vaccine candidates have been unsuccessful up to now. Against such devastating parasitic disease, the antischistosomal arsenal is currently limited to a single drug, praziquantel, which has been used for more than 35 years. Because the question of the reduction of the activity of praziquantel was raised recently, it is thus urgent to create new and safe antischistosomal drugs that should be combined with praziquantel to develop efficient bitherapies.

Design of small volume HX and triple-resonance probes for improved limits of detection in protein NMR experiments.

Three- and four-frequency nuclear magnetic-resonance probes have been designed for the study of small amounts of protein. Both "HX" (1H, X, and 2H channels) and "triple-resonance" (1H, 15N, 13C, and 2H) probes were implemented using a single transmit/receive coil and multiple-frequency impedance matching circuits. The coil used was a six-turn solenoid with an observe volume of 15 microl. A variable pitch design was used to improve the B1 homogeneity of the coil. Two-dimensional HSQC spectra of approximately 1mM single labeled 15N- and double labeled 15N/13C-proteins were acquired in experimental times of approximately 2h. Triple-resonance capability of the small-volume triple-resonance probe was demonstrated by acquiring three-dimensional HNCO spectra from the same protein samples. In addition to enabling very small quantities of protein to be used, the extremely short pulse widths (1H = 4, 15N = 4, and 13C = 2 micros) of this particular design result in low power decoupling and wide-bandwidth coverage, an important factor for the ever-higher operating frequencies used for protein NMR studies.

Stimulation of topoisomerase II-mediated DNA cleavage by an indazole analogue of lucanthone.

Lucanthone is an antitumour drug used as an adjuvant in radiation therapy. The drug intercalates into DNA and inhibits topoisomerase II. An indazole analogue of lucanthone (IA-5) was examined for its ability to modulate topoisomerase II-DNA cleavable complex formation in vitro. The drug contains a methylbenzothiopyranoindazole chromophore instead of the methyl-thioxanthenone nucleus of lucanthone. Using a radiolabelled linear plasmid DNA as a substrate, both lucanthone and the indazole analogue were shown to promote the cleavage of DNA by human topoisomerase II. Sequencing experiments with different restriction fragments indicated that the indazole drug promoted DNA cleavage primarily at sites having a C on the 3' side of the cleaved bond (-1 position). By contrast, in the same sequencing methodology lucanthone exerted a much weaker effect on topoisomerase II. The sequence selectivity of IA-5 is reminiscent of that of the anticancer drug mitoxantrone and its anthrapyrazole analogue losoxantrone, which is structurally close to IA-5. Binding to DNA and topoisomerase II inhibition are two distinct processes contributing separately to the cytotoxic activity of the indazole drug.

Studies on the mode of action of oxamniquine and related schistosomicidal drugs.

Adult Schistosoma mansoni were incubated for 1 hour in vitro with various drugs and then returned into the mesenteric veins of permissive animal hosts. Survival of schistosomes was assessed 3-4 weeks later by portal perfusion. Under these conditions, oxamniquine and hycanthone proved effective in killing S. mansoni, whereas UK-3883, lucanthone and lucanthone-4-desmethyl had no lethal activity. The same drugs which were schistosomicidal in vitro also persistently inhibited DNA, RNA, and protein synthesis in S. mansoni, whereas they were only transiently inhibitory against Schistosoma japonicum, against hycanthone-resistant S. mansoni and against immature worms. When drugs were administered in vivo to infected mice and the synthesis of macromolecules was assayed in vitro on worms obtained 1 or 3 days after treatment, not only oxamniquine and hycanthone, but also UK-3883 and lucanthone, proved effective in inhibiting the synthesis of macromolecules in sensitive--but not in resistant--S. mansoni. It is suggested that oxamniquine, like hycanthone, may exert its schistosomicidal activity by inhibiting nucleic acid synthesis in the parasite.

Aza analogues of lucanthone: synthesis and antitumor and bactericidal properties.

Three types of aza analogues of lucanthone were synthesized for evaluation as antitumor drugs. None of the compounds was found to have significant cytotoxic effects either on Friend tumor cells or on L1210 leukemia cells. However, one of the target compounds, 5,10-dihydro-10-oxo-1-[[3-(diethylamino)propyl]amino]-3-methylpyrido [4,3-b]quinoline, was shown to have noticeable antibiotic properties.

Analogues of hycanthone and lucanthone as antitumor agents.

Hycanthone analogues (5 and 6) containing 7-substituted hydroxyl groups were prepared and evaluated as antitumor agents. These compounds were significantly more active than the corresponding unsubstituted derivatives. The 7-hydroxylated 4-(hydroxymethyl)-9H-xanthen-9-ones, 11 and 12, were also active antitumor agents. However, the 7-hydroxy-9H-xanthen-9-one counterparts of the 7-hydroxylucanthones were totally devoid of antitumor activity. Results obtained thus far are consistent with the hypothesis that 4-hydroxymethyl substituents in the 9H-xanthen-9-one and 9H-thioxanthen-9-one series are required for antitumor activity.

Ring-hydroxylated analogues of lucanthone as antitumor agents.

A series of ring-alkoxylated and ring-hydroxylated analogues of lucanthone was prepared and tested for antitumor activity. The most biologically interesting members of this group were the 7-hydroxylucanthone derivatives, 50 and 51, which gave T/C values in the NCI P-388 antitumor screen of 188 and 265, respectively. The apparent association constants and delta Tm values for a number of analogue-DNA complexes were determined to ascertain whether there was any quantitative correlation with biological activity. The most that can be said is that intercalation may be a necessary but far from sufficient condition for antitumor activity.

Nitro and amino derivatives of lucanthone as antitumor agents.

A group of nitro and amino derivatives of lucanthone was prepared and tested for antitumor activity. Reaction of 1-chloro-4-methyl-7-nitrothioxanthenone and N,N-diethylethylenediamine gave the 7-amino analogue (11) directly, accompanied by 7-amino-1-chloro-4-methylthioxanthenone. The antitumor activity of 11 was inferior to that of lucanthone and 7-hydroxylucanthone. The most active compound in the series was the nitro compound 1. In the P-388 lymphocytic leukemia screen it showed a T/C = 178 at 200 mg/kg.

Mutagenicity of hycanthone in Drosophila: additional results and a comparison with some analogs.

The data reported in this paper extend earlier results on the effects of hycanthone in Drosophila. The main findings are the following. (1) A refined brood-pattern analysis of hycanthone-induced sex-linked recessive lethals confirmed the specific sensitivity of mid- and late spermatids. Injection of young males 0--20 h old) did not cause a shift in the brood pattern, but tended to produce higher rates of recessive lethals than injection of 4-day-old males, although the difference was not significant. (2) An autosomal recessive lethal test (chromosome 2) similarly showed a low sensitivity of premeiotic stages. (3) Feeding of hycanthone was much less effective than injection. This difference was not observed for the methyl analog lucanthone. From the observation that hycanthone- and lucanthone-induced mutations exhibited different germ-cell-stage sensitivity patterns, it was concluded that lucanthone does not (at least not exclusively) act via metabolic activation to hycanthone. (4) After injection, the hycanthone analogs IA-3-N-oxide and IA-4-N-oxide were marginally mutagenic. (5) It was shown previously that hycanthone was ineffective in producing breakage events, in Drosophila. In this report, hycanthone is shown to be weakly active in inducing ring-X chromosome loss. This emphasizes the relative sensitivity of the ring-X-loss test, in comparison with the tests that detect translocations or dominant lethals.

Genetic analysis of adenine-3 mutants induced by hycanthone, lucanthone and their indazole analogs in Neurospora crassa.

Ad-3 mutants induced by hycanthone, lucanthone and their indazole analogs, IA-3, IA-4 and IA-5 were studied to characterize the genetic alterations produced by these agents in Neurospora crassa. The results of genetic analysis indicate that, in marked contrast to past experiments with chemical mutagens on heterokaryon 12, all of these antischistosomal agents induce a very high frequency of multilocus deletions.

Stereospecific sulfur oxidation of 7-methylthioxanthone-2-carboxylic acid by Calonectria decora.

Thin-layer chromatography was used to determine the ability of three microorganisms capable of sulfur oxygenation, including Aspergillus niger, Streptomyces armentosus subsp. armentosus, and Calonectria decora, to oxidize 7-methylthioxanthone-2-carboxylic acid to the corresponding sulfoxide in growing cultures. In addition, optical rotary dispersion, circular dichroism, and nuclear magnetic resonance analysis in the presence of chiral shift reagent were used variously to access reaction stereoselectivity, absolute configuration, and optical purity of isolated products. The data indicated that C. decora produced the sulfoxide in high yield (69%) and optical purity (97%), most probably in the S-configuration.