Pyridine-4(1)-one Alkaloids from as Antitrypanosomatid Agents.

Twelve new pyridine-4(1)-one derivatives, namely, 8-demethoxywaltherione F (), waltheriones R-V (, , , , and ), 1-methoxywaltherione O (), ()-15-hydroxywaltherione G (), (8)-8-hydroxywaltherione M (), (9,13)-2-hydroxymethylwaltherione C (), (9,10,13)-10-hydroxywaltherione C (), and ()-13-methoxywaltherione V (), as well as melovinone () and 5'-methoxywaltherione A () were isolated from the CHCl extract of the aerial parts of Their chemical structures were determined by means of a comprehensive analysis including H NMR, DEPTQ, HSQC, HMBC, H-H COSY, ROESY, and HRESIMS data. The absolute configurations were assigned via comparison of the experimental and calculated ECD data. In addition, the isolated constituents as well as the known waltheriones M-Q were evaluated for their in vitro antitrypanosomal activity. Compounds , , and as well as waltheriones M, P, and Q showed potent growth inhibition toward with IC values of 2.1, 0.8, 2.1, 1.3, 0.5, and 0.1 μM, respectively, and selectivity indices of >12, >33, >13, 5, 25, and 14. These findings further demonstrate that the waltheriones are a promising class of antichagasic compounds worthy of further investigations.