New pyrazolylpyrazoline derivatives as dual acting antimalarial-antileishamanial agents: synthesis, biological evaluation and molecular modelling simulations

Promising inhibitory activities of the parasite multiplication were obtained upon evaluation of in vivo antimalarial activities of new pyrazolylpyrazoline derivatives against Plasmodium berghei infected mice. Further evaluation of 5b and 6a against chloroquine-resistant strain (RKL9) of P. falciparum showed higher potency than chloroquine. In vitro antileishmanial activity testing against Leishmania aethiopica promastigote and amastigote forms indicated that 5b, 6a and 7b possessed promising activity compared to miltefosine and amphotericin B deoxycholate. Moreover, antileishmanial activity reversal of the active compounds via folic and folinic acids showed comparable results to the positive control trimethoprim, indicating an antifolate mechanism via targeting leishmanial DHFR and PTR1. The compounds were non-toxic at 125, 250 and 500 mg/kg. In addition, docking of the most active compound against putative malarial target Pf-DHFR-TS and leishmanial PTR1 rationalised the observed activities. Molecular dynamics simulations confirmed a stable and high potential binding of 7a against leishmanial PTR1.

Thin-layer chromatography/matrix-assisted laser desorption/ionisation mass spectrometry and matrix-assisted laser desorption/ionisation mass spectrometry imaging for the analysis of phospholipids in LS174T colorectal adenocarcinoma xenografts treated with the vascular disrupting agent DMXAA

RATIONALE

5,6-Dimethylxanthenone-4-acetic acid (DMXAA) is a low molecular weight drug of the flavonoid group, which has an anti-vascular effect in tumours causing endothelial cell apoptosis and activation of cytokines. Flavonoid-based compounds have been reported to lead to an upregulation in the expression of lysophosphatidylcholines (LPC)-type lipids in solid tumours. A study employing TLC/MALDI-MS and MALDI-MS imaging to examine LS174T colorectal adenocarcinoma xenografts following administration of DMXAA has been conducted into this effect.

METHODS

LS174T colorectal adenocarcinoma xenografts grown in male immune-deficient mice were treated with 27.5 mg/kg DMXAA. The control (before treatment) and 4 h and 24 h post-treatment tumours were excised and divided into two. MALDI-MS imaging experiments were carried out on 12 µm cryosections sections taken from one half of the tumours and from the other half the lipids were extracted and analysed by TLC/MALDI-MS. These experiments were carried out in triplicate.

RESULTS

Statistical analysis of the MALDI-MS imaging data set indicated an increased amount of LPC in the 24 h post-treated sample and a decreased amount of PC in the 24 h post-treated sample, compared with the 4 h post-treated sample and the control. These effects were confirmed by the TLC/MALDI-MS data. The lipid extracts were separated into six spots on the TLC plate. These were identified as arising from different lipids classes, i.e. LPC, sphingomyelins (SM), phosphatidylcholines (PC) and phosphatidylethanolamines (PE). The TLC/MALDI-MS data indicated that LPC were highly expressed in the 4 h and 24 h post-treated tumour samples compared with the control. Examination of the mass spectrometric images confirms this increase and demonstrates additionally that the increase in the signals arising from LPC appears to be localised primarily within the central areas of the xenograft.

CONCLUSIONS

An increase in expression of LPC lipids in solid tumours treated with DMXAA has been demonstrated and shown to be localised in the central area of the tumour.

Peri-parturient rise in faecal strongyle egg counts of different genotypes of sheep in North Sumatra, Indonesia

Faecal strongyle egg counts were monitored in peri-parturient ewes and dry ewes grazing in a rubber plantation in North Sumatra, Indonesia. A significant rise in faecal egg counts was observed during the post-parturient period. Haemonchus contortus was the dominant species in the faecal cultures of the lactating ewes. The intensity of the peri-parturient rise was affected by the genotype of the sheep, which were the local Sumatra and its F1 crosses with St. Croix, Barbados Blackbelly and Java Fat-tail. The peri-parturient rise in egg counts was highest in Sumatra and lowest in the Barbados Blackbelly x Sumatra cross. A significant effect of litter size on the peri-parturient rise was also demonstrated. These findings are discussed in relation to the epidemiology and control of gastrointestinal nematodes in the humid tropics.

Comparison of resistance of four genotypes of rams to experimental infection with Haemonchus contortus

Fifty-five rams aged about 18-24 months weighing 30-42 kg were used in this study. Ten rams of each of four genotypes, S (Sumatra), H1 (50% Sumatra-50% Virgin Island), B1 (50% Sumatra-50% Barbados Blackbelly), E1 (50% Sumatra-50% Java Fat-tail), were infected orally with a newly isolated strain of Haemonchus contortus. Each animal received 2000 infective larvae 3 times week-1 for 3 weeks, with a total of 18,000 larvae. Fifteen rams belonging to Sumatra and its crosses with Virgin Island were used as uninfected controls. Peak egg counts were observed on Day 35 for genotype B1 and on Day 42 for genotype H1 and S. In genotype E1 a slow but consistent increase in EPG continued until Day 49 when the experiments terminated. Overall faecal egg counts at all sampling dates were not statistically different between genotypes (P > 0.05). There was a large variation in the EPG of individual rams within a genotype. The overall average EPG (geometric means) of individual rams within a genotype ranged from 3 to 1028 for B1, 4 to 261 for E1, 7 to 3119 for H1 and 9 to 506 for S. The analysis of packed cell volume (PCV) for four genotypes and controls from all sampling times showed significant differences (P < 0.05). The overall mean PCV was highest in S (31.1) and lowest in H1 (28.4). The ranking of four genotypes for PCV was S > E1 > B1 > H1. The decrease of PCV during the course of infection was highly significant for all genotypes of infected rams (B1, E1, H1, S) (P < 0.01). PCV of the control group did not exhibit much change during the course of the experimental period. Weight gain of infected rams was lower than those of uninfected controls (P < 0.5) but there was no significant difference between the four genotypes of infected rams. Individual variation within genotype in susceptibility to infections was generally more important than between genotype differences. Two major conclusions of the present study are: (1) The imported breeds with higher body weight, namely the Barbados Blackbelly and Virgin Island, may be used in cross breeding to increase the body size of local Sumatra sheep. (2) Based on the faecal egg counts it is possible to identify the animals for use in selective breeding programmes for higher resistance to H. contortus.

Helminth infections of sheep in North Sumatra, Indonesia

Gastrointestinal tracts of 73 indigenous sheep were obtained from the Medan abattoir in North Sumatra, Indonesia, and examined for the presence of helminths. A total of 13 species of helminths, eight nematodes, one cestode and four trematodes were encountered. All sheep were infected by more than one species of nematodes. Trichostrongylus colubriformis, T. axei and Haemonchus contortus were the most common species. The intensity of the nematode infections was very high: the average burden was over 7500 worms. Trichostrongylus spp. accounted, on average, for 81.5% of the total nematode burden. No influence of age on total nematode burden could be shown. Eurytrema pancreaticum and Schistosoma spindale were found in 23.3% and 4.1% of the examined sheep, respectively. The results are discussed in relation to common management and helminth control systems.