Inhibitor Report for: Cyclipostin

The progression of mycobacterial diseases requires the development of new therapeutics. This study evaluated the efficacy and selectivity of a panel of Cyclophostin and Cyclipostins analogues (CyCs) against various bacteria and mycobacteria. The activity 26 CyCs was first assayed by the agar plate method. Compounds exhibiting 50-100% growth inhibition were then selected to determine their minimum inhibitory concentrations (MICs) by the resazurin microtiter assay (REMA). The best drug candidate was further tested against clinical mycobacterial isolates and bacteria responsible for nosocomial infections, including 6 Gram-negative bacteria, 5 Gram-positive bacteria, 29 rapid-growing mycobacteria belonging to the Mycobacterium chelonae-abscessus clade and 3 slow-growing mycobacteria (Mycobacterium marinum, Mycobacterium bovis BCG and Mycobacterium tuberculosis). Among the 26 CyCs tested, 10 were active and their inhibitory activity was exclusively restricted to mycobacteria. The best candidate (CyC17) was further tested against 26 clinical strains and showed high selectivity for mycobacteria, with MICs (<2-40 microg/mL) comparable with those of most classical antimicrobials used to treat M. abscessus infections. Together, these results support the fact that such CyCs represent a new family of potent and selective inhibitors against mycobacteria. This is of particular interest for future chemotherapeutic developments against mycobacterial-associated infections, especially against M. abscessus, the most drug-resistant mycobacterial species.

Cyclipostins are bicyclic lipophilic phosphate natural products. We report here that synthesized individual diastereomers of cyclipostins P and R have nanomolar IC50s toward hormone sensitive lipase (HSL). The less potent diastereomers of these compounds have 10-fold weaker IC50s. The monocyclic phosphate analog of cyclipostin P is nearly as potent as the bicyclic natural product. Bicyclic phosphonate analogs of both cyclipostins exhibit IC50s similar to those of the weaker diastereomer phosphates (about 400nM). The monocyclic phosphonate analog of cyclipostin P has similar potency. A series of monocyclic phosphonate analogs in which a hydrophobic tail extends from the lactone side of the ring are considerably poorer inhibitors, with IC50s around 50muM. Finally cyclophostin, a related natural product inhibitor of acetylcholinesterase (AChE) that lacks the hydrocarbon tail of cyclipostins, is not active against HSL. These results indicate a critical SAR for these compounds, the hydrophobic tail. The smaller lactone ring is not critical to activity, a similarity shared with cyclophostin and AChE. The HSL kinetics of inhibition for the cyclipostin P trans diastereomer were examined in detail. The reaction is irreversible with a KI of 40nM and a rate constant for inactivation of 0.2min(-1). These results are similar to those observed for cyclophostin and AChE.

Hormone-sensitive lipase (HSL) is a key enzyme of lipid metabolism and its control is therefore a target in the treatment of diabetes mellitus. Cultures of the Streptomyces species DSM 13381 have been shown to potently inhibit HSL. Ten inhibitors of HSL, termed cyclipostins, have been isolated from the mycelium of this microorganism and a further nine related compounds detected. Their structures were characterized by 2-D NMR experiments and by mass spectrometry and were found to comprise neutral cyclic enol phosphate esters with an additional y-lactone ring. On account of their ester-bound fatty alcohol side chain, the cyclipostins have physicochemical properties similar to those of triglycerides. The outstanding characteristic of the cyclipostins is their strong anti-HSL activity, with IC50 values in the nanomolar range.

The progression of mycobacterial diseases requires the development of new therapeutics. This study evaluated the efficacy and selectivity of a panel of Cyclophostin and Cyclipostins analogues (CyCs) against various bacteria and mycobacteria. The activity 26 CyCs was first assayed by the agar plate method. Compounds exhibiting 50-100% growth inhibition were then selected to determine their minimum inhibitory concentrations (MICs) by the resazurin microtiter assay (REMA). The best drug candidate was further tested against clinical mycobacterial isolates and bacteria responsible for nosocomial infections, including 6 Gram-negative bacteria, 5 Gram-positive bacteria, 29 rapid-growing mycobacteria belonging to the Mycobacterium chelonae-abscessus clade and 3 slow-growing mycobacteria (Mycobacterium marinum, Mycobacterium bovis BCG and Mycobacterium tuberculosis). Among the 26 CyCs tested, 10 were active and their inhibitory activity was exclusively restricted to mycobacteria. The best candidate (CyC17) was further tested against 26 clinical strains and showed high selectivity for mycobacteria, with MICs (<2-40 microg/mL) comparable with those of most classical antimicrobials used to treat M. abscessus infections. Together, these results support the fact that such CyCs represent a new family of potent and selective inhibitors against mycobacteria. This is of particular interest for future chemotherapeutic developments against mycobacterial-associated infections, especially against M. abscessus, the most drug-resistant mycobacterial species.

Cyclipostins are bicyclic lipophilic phosphate natural products. We report here that synthesized individual diastereomers of cyclipostins P and R have nanomolar IC50s toward hormone sensitive lipase (HSL). The less potent diastereomers of these compounds have 10-fold weaker IC50s. The monocyclic phosphate analog of cyclipostin P is nearly as potent as the bicyclic natural product. Bicyclic phosphonate analogs of both cyclipostins exhibit IC50s similar to those of the weaker diastereomer phosphates (about 400nM). The monocyclic phosphonate analog of cyclipostin P has similar potency. A series of monocyclic phosphonate analogs in which a hydrophobic tail extends from the lactone side of the ring are considerably poorer inhibitors, with IC50s around 50muM. Finally cyclophostin, a related natural product inhibitor of acetylcholinesterase (AChE) that lacks the hydrocarbon tail of cyclipostins, is not active against HSL. These results indicate a critical SAR for these compounds, the hydrophobic tail. The smaller lactone ring is not critical to activity, a similarity shared with cyclophostin and AChE. The HSL kinetics of inhibition for the cyclipostin P trans diastereomer were examined in detail. The reaction is irreversible with a KI of 40nM and a rate constant for inactivation of 0.2min(-1). These results are similar to those observed for cyclophostin and AChE.

Cyclophostin, a structurally unique and potent naturally occurring acetyl cholinesterase (AChE) inhibitor, and its unnatural diastereomer were prepared in 6 steps and 15% overall yield from hydroxymethyl butyrolactone. The unnatural diastereomer of cyclophostin was converted into cyclipostin P, a potent naturally occurring hormone sensitive lipase (HSL) inhibitor, using a one pot dealkylation-alkylation process. The inhibition [IC(50)] of human AChE by cyclophostin and its diastereomer are reported, as well as constituent binding (K(I)) and reactivity (k(2)) constants.

Hormone-sensitive lipase (HSL) is a key enzyme of lipid metabolism and its control is therefore a target in the treatment of diabetes mellitus. Cultures of the Streptomyces species DSM 13381 have been shown to potently inhibit HSL. Ten inhibitors of HSL, termed cyclipostins, have been isolated from the mycelium of this microorganism and a further nine related compounds detected. Their structures were characterized by 2-D NMR experiments and by mass spectrometry and were found to comprise neutral cyclic enol phosphate esters with an additional y-lactone ring. On account of their ester-bound fatty alcohol side chain, the cyclipostins have physicochemical properties similar to those of triglycerides. The outstanding characteristic of the cyclipostins is their strong anti-HSL activity, with IC50 values in the nanomolar range.