Fig 1.
Naturally occurring cytochalasins A-D and their percentage inhibition in the screening against T. cruzi and L. infantum corresponding to a compound concentration of 50 μM.
Table 1.
Trypanocidal and leishmanicidal activities of cytochalasins A–D against intracellular T. cruzi Tulahuen LacZ and L. infantum amastigotes and cytotoxicity for fibroblasts (HFF-1), human macrophages (THP-1) and hepatocytes (HepG2).
Fig 2.
Ratio of THP-1 cell infection by L. infantum promastigotes in the absence (negative control) or presence of cytochalasins A-D (20 to 2.5 μM, 2 h incubation).
A) After 2 hours of incubation, the cytochalasin was removed, and late-stage L. infantum promastigotes were added. B) Cytochalasins were not removed after incubation, and late-stage L. infantum promastigotes were added. Phagocytosis inhibition is expressed as a percentage of cells infected after counting 200 random cells. C) The toxicity of cytochalasins to promastigotes is expressed as the remaining living parasites after 24 h of incubation. **** p < 0.0001.
Fig 3.
Intermolecular interactions indicated as black dashed lines for cytochalasins A-D in the binding site for cytochalasin D in actin (cartoon and surface representations as grey, PDB ID: 3EKS).
A) Structure of cytochalasin A (light pink) highlighting intermolecular interactions of 7-hydroxy and backbone nitrogen of Ile136, N-H of the isoindolone ring with hydroxyl of Tyr143, carboxyl of the macrocycle lactone with backbone of Ala170; B) cytochalasin B (green) and the interaction of 7-hydroxy and backbone nitrogen of Ile136, N-H of the isoindolone ring with the backbone carbonyl of Gly168, carboxyl group of isoindolone ring with backbone of Ala170, C) cytochalasin C (yellow) interactions of 7-hydroxy and backbone nitrogen of Ile136, N-H of the isoindolone ring with hydroxyl of Tyr143, carboxyl of the macrocycle lactone with backbone of Ala170 and Gly168, carboxyl group of isoindolone ring and hydroxyl of macrocycle with backbone of Ala170, and D) cytochalasin D (blue) interacts similarly to cytochalasin C and there is an additional interaction of the macrocycle carbonyl with backbone of Ala170.
Table 2.
ADME properties of cytochalasins A–D determined in vitro and predicted in silico.
Fig 4.
Cytochalasins A-D (panels a-d) Bioavailability radar generated using the Swiss ADME web tool. The coloured area represents the optimal range for calculated properties, LIPO (-0.7 < LogP < 5), SIZE (150 g/mol < molecular mass < 500 g/mol), POLAR (20 Å2< TPSA < 130 Å2), INSOLU (0 < LogS < 6), INSATU (0.25 < fraction of Csp3 < 1), and FLEX (0 < nRotb < 9). All the compounds show good predicted oral bioavailability.