Biomechanical but not timed performance asymmetries persist between limbs 9 months after ACL reconstruction during planned and unplanned change of direction

© 2018 Elsevier Ltd Whilst anterior cruciate ligament injury commonly occurs during change of direction (CoD) tasks, there is little research on how athletes execute CoD after anterior cruciate ligament reconstruction (ACLR). The aims of this study were to determine between-limb and between-test differences in performance (time) and joint kinematics and kinetics during planned and unplanned CoD. One hundred and fifty-six male subjects carried out 90° maximal effort, planned and unplanned CoD tests in a 3D motion capture laboratory 9 months after ACLR. Statistical parametric mapping (2 × 2 ANOVA; limb × test) was used to identify differences in CoD time and biomechanical measures between limbs and between tests. There was no interaction effect but a main effect for limb and task. There was no between-limb difference in the time to complete both CoD tests. Between-limb differences were found for internal knee valgus moment, knee internal rotation and flexion angle, knee extension and external rotation moment and ankle external rotation moment with lower values on the ACLR side (effect size 0.72–0.5). Between test differences were found with less contralateral pelvis rotation, distance from centre of mass to the ankle in frontal plane, posterior ground reaction force and greater hip abduction during the unplanned CoD (effect size 0.75–0.5). Findings demonstrated that kinematic and kinetic differences between limbs are evident during both CoD tests 9 months after surgery, despite no statistical differences in performance time. Biomechanical differences between tests were found in variables, which have previously been associated with ACL injury mechanism during unplanned CoD

Antimitotic herbicides bind to an unidentifed site on malarial parasite tubulin and block development of liver-stage Plasmodium parasites.

Malarial parasites are exquisitely susceptible to a number of microtubule inhibitors but most of these compounds also affect human microtubules. Herbicides of the dinitroaniline and phosphorothioamidate classes however affect some plant and protozoal cells but not mammalian ones. We have previously shown that these herbicides block schizogony in erythrocytic parasites of the most lethal human malaria, Plasmodium falciparum, disrupt their mitotic spindles, and bind selectively to parasite tubulin. Here we show for the first time that the antimitotic herbicides also block the development of malarial parasites in the liver stage. Structure-based design of novel antimalarial agents binding to tubulin at the herbicide site, which presumably exists on (some) parasite and plant tubulins but not mammalian ones, can therefore constitute an important transmission blocking approach. The nature of this binding site is controversial, with three overlapping but non-identical locations on ?-tubulin proposed in the literature. We tested the validity of the three sites by (i) using site-directed mutagenesis to introduce six amino acid changes designed to occlude them, (ii) producing the resulting tubulins recombinantly in Escherichia coli and (iii) measuring the affinity of the herbicides amiprophosmethyl and oryzalin for these proteins in comparison with wild-type tubulins by fluorescence quenching. The changes had little or no effect, with dissociation constants (Kd) no more than 1.3-fold (amiprophosmethyl) or 1.6-fold (oryzalin) higher than wild-type. We conclude that the herbicides impair Plasmodium liver stage as well as blood stage development but that the location of their binding site on malarial parasite tubulin remains to be proven

Synthesis and evaluation of phenoxyoxazaphospholidine, phenoxyoxazaphosphinane, and benzodioxaphosphininamine sulfides and related compounds as potential anti-malarial agents

A series of phenoxyoxazaphospholidine, phenoxyoxazaphosphinane and benzodioxaphosphininamine sulfides and related cyclic organophosphorus compounds based on the lead anti-tubulin herbicides amiprophos methyl and butamifos were synthesised and evaluated for anti-malarial activity. Of these compounds, while none of the phenoxyoxazaphospholidines, phenoxyoxazaphosphinanes or benzodioxaphosphininamine sulphides were more potent than APM, phosphorothioamidate 30, a dual compound also bearing an aminoquinoline motif, showed promising activity against Plasmodium falciparum (IC50 0.038 ?M) and warrants further study

Synthesis and evaluation of phosphoramidate and phosphorothioamidate ana- logues of amiprophos methyl as potential antimalarial agents Synthesis and evaluation of phosphoramidate and phosphorothioamidate analogues of amiprophos methyl as potential antimal

INSERT GRAPHICAL ABSTRACT HERE A series of phosphoramidate and phosphorothioamidate compounds based on the lead antitubulin herbicidal agents amiprophos methyl (APM) and butamifos were synthesised and evaluated for antimalarial activity. Of these compounds, phosphorothioamidates were more active than their oxo congeners and the nature of both aryl and amido substituents influenced the desired activity. The most active compound was 46, O-ethyl-O-(2-methyl-4-nitrophenyl)-N-cyclopentyl phosphorothioamidate, which was more effective than the lead compound. Keywords: phosphoramidate; phosphorothioamidate, antimalarial, tubulin, Plasmodium falciparum. Malaria is a devastating parasitic disease caused by apicomplexan species of the genus Plasmodium, notably the most virulent species P. falciparum, and is responsible for about 800,000 deaths per annum, many of these in children and pregnant women, and most of these in Africa. 1 Most current therapies for malaria target the blood stage in the life cycle of the Plasmodium parasite. 7 Typical antitubulin agents such as taxanes and Vinca alkaloids, while potent against Plasmodium, are non-selective. In contrast, herbicidal agents of the dinitroaniline class such as trifluralin 1 have shown activity against P. falciparum with minimal cytotoxicity. 9 Electron microscopic autoradiography showed radioactive trifluralin associated with microtubule fragments. 11 Trifluralin has poor aqueous solubility, with a reported clogP of 5.322, 12 and as well as affecting its pharmacokinetics this may cause it to accumulate in membranous compartments of the parasite and its host erythrocyte, away from its site of action in the cell. 14 Despite these drawbacks, many dinitroanilines have been synthesised and tested against both apicomplexan and kinetoplastid parasites. Of the many derivatives evaluated, some of the more interesting compounds with activity against apicomplexans are shown in INSERT FIGURE 1 HERE Armson has reported IC 50 values for trifluralin and the sulfonamide dinitroaniline oryzalin 2 against Cryptosporidium of 750 and 800nM, respectively. 15 Oryzalin and its analogues have also been investigated for activity against Toxoplasma gondii. While oryzalin itself had an IC 50 value of 0.25µM, benzenediamine 3 had an IC 50 value of 36nM. 16 Regioisomeric dinitroanilines exhibited interesting activity against several parasites, with 4 and 5 the most potent, both with an IC 50 value of 0.44µM against P. falciparum. 17 Phosphorothioamidate herbicides, typified by APM 6 and butamifos 7 18 Molecular modelling studies have shown that the electrostatic surfaces of the phosphorothioamidates are very similar to those of the dinitroanilines, with the electronegative domains of the ortho nitro (-phenyl) group and the phosphorothio group matching both the shape and spacing of the equivalent regions of the dinitroanilines. Original syntheses for pesticidal phosphorothioamidates involve sequential substitution of a pentavalent phosphorus species. One available approach is the reaction of an anhydrous alkali metal phenolate and an alkali metal monohydric alkoxide with an N-substituted dichlorothiophosphoramide in an excess of the alcohol used to prepare the alkoxide. INSERT SCHEME 1 HERE Having varied the phenolic substituents in phosphoramidates 8-23, we then wished to investigate the effect of varying the nature of the amide functionality, by introduction of primary, secondary and tertiary nitrogen species, and also branched and cyclic systems. These compounds, 25-49, were synthesised using analogous methodology to that used in Scheme 1, and the resultant phosphoro(thio)amidates are shown in 13 C and 31 P NMR spectroscopy and mass spectrometry analysis, while the purity of the compounds was assessed by elemental analysis. Synthetic procedures, spectral data and testing methodology are provided in the Supplementary section. INSERT TABLES 1 AND 2 HERE Known SAR for herbicidal activity 24 predicts that deactivating aromatic substituents such as a nitro group may enhance activity. With regard to antimalarial activity, 26 Variation of the amido functionality on the nitrogen however had an obvious effect on activity. Within the amido homologues 25-30, this effect was not as dramatic as within the para-trifluoro series 32-44, as increasing the chain length and branching did improve activity up to C5, as evidenced by the IC 50 values of compounds 36 and 38, at 4.5 and 8.6µM respectively. This indicated that pentyl or cyclopentylamino substituents were optimal, as further enhancing the lipophilic nature of the side chain resulted in reduced activity, as shown by the n-heptyl compound 40. Analysis of the predicted clogP values as shown in The present study has allowed us to conclude that an electron-withdrawing group on the phenolic ring may enhance activity within the phosphoroamidate series, particularly in the para-position. Additional aromatic alkyl substitution may enhance activity, although it does not appear to be crucial. For most compounds tested, phosphorothioamidates were more active than their oxo congeners. Within these, an alkylamido C5 residue seems to be optimal. Of all compounds prepared, 36 and 46 are most worthy of further investigation. Acknowledgments We acknowledge Enterprise Ireland (PC/2005/070) for financial support

Identification of Plasmepsin Inhibitors as Selective Antimalarial Agents using Ligand Based Drug Design

We describe the application of Ligand Based Virtual Screening technologies towards the discovery of novel Plasmepsin (PM) inhibitors, a family of malarial parasitic aspartyl proteases. Pharmacophore queries were used to screen vendor libraries in search of active and selective compounds. The virtual hits were biologically assessed for activity and selectivity using whole cell Plasmodium falciparum parasites and on target in PM II, PM IV and the closely related human homologue, Cathepsin D assays. Here we report the virtual screening highlights, structures of the hits and their demonstrated biological activity

Identification of plasmepsin inhibitors as selective anti-malarial agents using ligand based drug design

We describe the application of ligand based virtual screening technologies towards the discovery of novel plasmepsin (PM) inhibitors, a family of malarial parasitic aspartyl proteases. Pharmacophore queries were used to screen vendor libraries in search of active and selective compounds. The virtual hits were biologically assessed for activity and selectivity using whole cell Plasmodium falciparum parasites and on target in PM II, PM IV and the closely related human homologue, Cathepsin D assays. Here we report the virtual screening highlights, structures of the hits and their demonstrated biological activity

Identification of plasmepsin inhibitors as selective anti-malarial agents using ligand based drug design

We describe the application of ligand based virtual screening technologies towards the discovery of novel plasmepsin (PM) inhibitors, a family of malarial parasitic aspartyl proteases. Pharmacophore queries were used to screen vendor libraries in search of active and selective compounds. The virtual hits were biologically assessed for activity and selectivity using whole cell Plasmodium falciparum parasites and on target in PM II, PM IV and the closely related human homologue, Cathepsin D assays. Here we report the virtual screening highlights, structures of the hits and their demonstrated biological activity