Eleven 2,5-diphenyloxazole derivatives
(1–11), together with six known isoflavonoid
derivatives, were
isolated from the roots of Oxytropis lanata. The
2,5-diphenyloxazole (1) obtained proved to be identical
to a standard sample used as a scintillator and liquid laser dye.
The other oxazole derivatives isolated were found to have one to four
hydroxy and/or O-methyl groups in their phenyl rings.
Seven of the oxazole derivatives obtained are new (3–9). The inhibitory activity of the isolated compounds was
evaluated against Trypanosoma congolense, the causative
agent of African trypanosomosis in animals. Oxazoles with di- and
trihydroxy groups showed trypanocidal activity, and 2-(2′,3′-dihydroxyphenyl)-5-(2″-hydroxyphenyl)oxazole
(4) exhibited the most potent inhibitory activity (IC50 1.0 μM).