Antiparasitic activity of C-geranyl flavonoids from Mimulus bigelovii.

Bioactivity-directed fractionation of the MeOH fraction of the extract of Mimulus bigelovii by means of an axenic Leishmania amastigote assay and chromatographic techniques resulted in the isolation of four C-geranyl flavanones, diplacone (1), 3'-O-methyldiplacone (2), 4'-O-methyldiplacone (3), 3'-O-methyldiplacol (4), together with a geranylated flavone, cannflavin A (5). These compounds were separated from M. bigelovii for the first time.

Structure-activity relationship investigations of leishmanicidal N-benzylcytisine derivatives.

In vitro leishmanicidal activity of 16 N-benzylcytisine derivatives has been evaluated using Leishmania donovani axenic amastigotes. In general, halogen (bromo-, chloro-) derivatives appeared to be more toxic against parasites than their parent compounds. Quantum-chemical calculations helped to recognize certain patterns in the structure of frontier orbitals related to bioactivity of compounds.

Antikinetoplastid activity of 3-aryl-5-thiocyanatomethyl-1,2,4-oxadiazoles.

A series of 5-thiocyanatomethyl- and 5-alkyl-3-aryl-1,2,4-oxadiazoles were synthesized and evaluated for their activity against kinetoplastid parasites. Formation of the oxadiazole ring was accomplished through the reaction of benzamidoximes with acyl chlorides, while the thiocyanate group was inserted by reacting the appropriate 5-halomethyl oxadiazole with ammonium thiocyanate. The thiocyanate-containing compounds possessed low micromolar activity against Leishmania donovani and Trypanosoma brucei, while the 5-alkyl oxadiazoles were less active against these parasites.