Novel and selective inactivators of Triosephosphate isomerase with anti-trematode activity

International audienceTrematode infections such as schistosomiasis and fascioliasis cause signifcant morbidity in an estimated 250 million people worldwide and the associated agricultural losses are estimated at more than US$ 6 billion per year. Current chemotherapy is limited. Triosephosphate isomerase (TIM), an enzyme of the glycolytic pathway, has emerged as a useful drug target in many parasites, including Fasciola hepatica TIM (FhTIM). We identifed 21 novel compounds that selectively inhibit this enzyme. Using microscale thermophoresis we explored the interaction between target and compounds and identifed a potent interaction between the sulfonyl-1,2,4-thiadiazole (compound 187) and FhTIM,which showed an IC50 of 5µM and a Kd of 66nM. In only 4hours, this compound killed the juvenile form of F. hepatica with an IC50 of 3µM, better than the reference drug triclabendazole (TCZ). Interestingly, we discovered in vitro inhibition of FhTIM by TCZ, with an IC50 of 7µM suggesting a previously uncharacterized role of FhTIM in the mechanism of action of this drug. Compound 187 was also active against various developmental stages of Schistosoma mansoni. The low toxicity in vitro in diferent cell types and lack of acute toxicity in mice was demonstrated for this compound, as was demonstrated the efcacy of 187 in vivo in F. hepatica infected mice. Finally, we obtained the frst crystal structure ofFhTIM at 1.9Å resolution which allows us using docking to suggest a mechanism of interaction between compound 187 and TIM. In conclusion, we describe a promising drug candidate to control neglected trematode infections in human and animal health

The clinical and molecular spectrum of galactosemia in patients from the Cape Town region of South Africa

BACKGROUND: The objective of this study was to document the clinical, laboratory and genetic features of galactosemia in patients from the Cape Town metropolitan region. METHODS: Diagnoses were based on thin layer chromatography for galactosuria/galactosemia and assays of erythrocyte galactose-1-phosphate uridyltransferase (GALT) and galactokinase activities. Patients were screened for the common S135L and Q188R transferase gene mutations, using PCR-based assays. Screening for the S135L mutation in black newborns was used to estimate the carrier rate for galactosemia in black South Africans. RESULTS: A positive diagnosis of galactosemia was made in 17 patients between the years 1980 to 2001. All had very low or absent galactose-1-phosphate uridyltransferase (GALT) activity, and normal galactokinase levels. The mean age at diagnosis was 5.1 months (range 4 days to 6.5 months). A review of 9 patients showed that hepatomegaly (9/9), and splenomegaly, failure to thrive, developmental delay, bilateral cataracts (6/9) were the most frequent features at diagnosis. Six had conjugated hyperbilirubinemia. Four experienced invasive E. coli infection before diagnosis. Ten patients were submitted to DNA analysis. All 4 black patients and 2 of mixed extraction were homozygous for the S135L allele, while all 3 white patients were homozygous for the Q188R allele. The remaining patient of mixed extraction was heterozygous for the Q188R allele. The estimated carrier frequency of the S135L mutation in 725 healthy black newborns was 1/60. CONCLUSIONS: In the absence of newborn screening the delay in diagnosis is most often unacceptably long. Also, carrier frequency data predict a galactosemia incidence of approximately 1/14 400 for black newborns in the Cape Metropole, which is much higher than the current detection rate. It is thus likely that many patients go undetected