Antitumoral activity of 1,2,4-oxadiazoles compounds isolated from the Neowerdermannia vorwerkii in liver and colon human cancer cells.

Two unknown 1,2,4-oxadiazoles (3-(pyridin-3-yl)-5-(thiophen-3-yl)-1,2,4-oxadiazole and 5-(3-hydroxyphenyl)-3-(pyridin-3-yl)-1,2,4-oxadiazole) and one known 1,2,4-oxadiazole (5-(3-methoxyphenyl)-3-(pyridin-3-yl)-1,2,4-oxadiazole) were isolated from tubers of Neowerdermannia vorwerkii, collected from the San Juan Huancollo, Ingavi province, La Paz, Bolivia. The chemical structures of these compounds were elucidated through NMR and HRMS spectroscopic analyses. All compounds showed apoptotic capacity against the SK-HEP-1 and Caco-2 tumour cells. 5-(3-methoxyphenyl)-3-(pyridin-3-yl)-1,2,4-oxadiazole and 5-(3-hydroxyphenyl)-3-(pyridin-3-yl)-1,2, 4-oxadiazole showed slight apoptotic capacities, with an IC50 between 17.46 ± 0.75 to 15.91 ± 0.62 μM and 39.29 ± 0.98 to 34.81 ± 0.70 μM, respectively. 3-(pyridin-3-yl)-5-(thiophen-3-yl)-1,2,4-oxadiazole showed a higher apoptotic capacity with an IC50 in the range of 0.98 ± 0.11 to 0.76 ± 0.03 μM, similar to that of the positive control (Dimethylenastron).