Abstract
Buddlejol
(
1
), a new sterol, has been isolated from the ethyl acetate soluble fraction of the antispasmodic plant
Buddleja asiatica
along with stigmasterol (
2
), lignoceric acid (
3)
, taraxerol (
4
) and α-amyrin (
5
), respectively. The structure of
Buddlejol
(1)
was established as
(24S)
-
stigmast
-
5,22
-
diene
-
7β
-
ethoxy
-
3β
-
ol
by spectral analysis and comparison with closely related structures.
Buddlejol
revealed to be a competitive inhibitor of chymotrypsin with the Ki value of 10.60 µM as indicated by Lineweaver–Burk and Dixon plots and their re-plots against its chymotrypsin inhibition assay, while the other compounds showed less inhibitory potential. The bioassay-guided isolation was stimulated by the preliminary cytotoxic screening of various fractions of
B. asiatica
.