Apicoplast acetyl Co-A carboxylase of the human malaria parasite is not targeted by cyclohexanedione herbicides.

Malaria parasites retain a relict plastid (apicoplast) from a photosynthetic ancestor. The apicoplast is a useful drug target but the specificity of compounds believed to target apicoplast fatty acid biosynthesis has become uncertain, as this pathway is not essential in blood stages of the parasite. Herbicides that inhibit the plastid acetyl Coenzyme A (Co-A) carboxylase of plants also kill Plasmodium falciparum in vitro, but their mode of action remains undefined.

Dimeric cyclohexane-1,3-dione oximes inhibit wheat acetyl-CoA carboxylase and show anti-malarial activity.

A series of dimeric 1,3-cyclohexanedione oxime ethers were synthesized and found to have significant antiplasmodial activity with IC(50)'s in the range 3-12 microM. The most active dimer was tested in the Plasmodium berghei mouse model of malaria and at a dose of 48 mg/kg gave a 45% reduction in parasitaemia. Several commercial herbicides, all known to be inhibitors of maize acetyl-CoA carboxylase, were also tested for antimalarial activity, but were essentially inactive with the exception of butroxydim which gave an IC(50) of 10 microM.

New substructure filters for removal of pan assay interference compounds (PAINS) from screening libraries and for their exclusion in bioassays.

This report describes a number of substructural features which can help to identify compounds that appear as frequent hitters (promiscuous compounds) in many biochemical high throughput screens. The compounds identified by such substructural features are not recognized by filters commonly used to identify reactive compounds. Even though these substructural features were identified using only one assay detection technology, such compounds have been reported to be active from many different assays.

Trypanothione reductase high-throughput screening campaign identifies novel classes of inhibitors with antiparasitic activity.

High-throughput screening of 100,000 lead-like compounds led to the identification of nine novel chemical classes of trypanothione reductase (TR) inhibitors worthy of further investigation. Hits from five of these chemical classes have been developed further through different combinations of preliminary structure-activity relationship rate probing and assessment of antiparasitic activity, cytotoxicity, and chemical and in vitro metabolic properties. This has led to the identification of novel TR inhibitor chemotypes that are drug-like and display antiparasitic activity.

Total synthesis of the potent anticancer Aglaia metabolites (-)-silvestrol and (-)-episilvestrol and the active analogue (-)-4'-desmethoxyepisilvestrol.

Total synthesis of the anticancer 1,4-dioxane containing natural products silvestrol (1) and episilvestrol (2) is described by an approach based on the proposed biosynthesis of these novel compounds. The key steps included an oxidative rearrangement of the protected d-glucose derivative 11 to afford the 1,4-dioxane 12, which could be elaborated to the coupling partner 5 and a photochemical [3 + 2]-cycloadditon between the 3-hydroxyflavone 27 and methyl cinnamate followed by base-induced alpha-ketol rearrangement and reduction to give the cyclopentabenzofuran core 33. The core (-)-6 and 1,4-dioxane fragment 5 were united by a highly stereoselective Mitsunobu coupling with the modified azodicarboxylate DMEAD to afford the axial coupled product 36.

Discovery of 2-iminobenzimidazoles as a new class of trypanothione reductase inhibitor by high-throughput screening.

A high-throughput screening campaign of a library of 100,000 lead-like compounds identified 2-iminobenzimidazoles as a novel class of trypanothione reductase inhibitors. These 2-iminobenzimidazoles display potent trypanocidal activity against Trypanosoma brucei rhodesiense, do not inhibit closely related human glutathione reductase and have low cytotoxicity against mammalian cells.

Formal total synthesis of salicylihalamides A and B.

An efficient synthesis of the macrolactone 3 of the salicylihalamides in 10 linear steps from alkene 6 is described. The key steps involved a Stille coupling between the chiral stannane 5 and benzyl bromide 4, which produced alkene 15 in good yield, and subsequent base-induced macrolactonization then gave compound 3. Macrolactone 3 was then converted into the known salicylihalamide A intermediate 18 in a three-step sequence.