Bioassay-guided fractionation of the EtOAc crude extract from Sicilian almond hulls, a waste materialfrom
Prunus dulcis crop, allowed identification of 10 constituents, isolated as pure compounds (
1-
5,
7, and
10) or unseparable mixtures (
5 +
6 and
8 +
9). All compounds were subjected to spectroscopicanalysis and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide bioassay on MCF-7 humanbreast cancer cells. In addition to the main components oleanolic (
1), ursolic (
2), and betulinic (
3)acids, the 2-hydroxy analogues alphitolic (
4), corosolic (
5), and maslinic (
6) acids, as well as therelated aldehydes, namely, betulinic (
7), oleanolic (
8), and ursolic (
9), were identified. From a morepolar fraction, the
![](/images/gifchars/beta2.gif)
-sitosterol 3-
O-glucoside (
10) was also identified. A sample of commerciallyavailable betulin (
11) was also included in bioassays as further support to a structure-activityrelationship study. Betulinic acid showed antiproliferative activity toward MCF-7 cells (GI
50 = 0.27
![](/images/entities/mgr.gif)
M), higher than the anticancer drug 5-fluorouracil.Keywords: Almond hulls;
Prunus dulcis sin.
amygdalus; terpenoids; antiproliferative; MCF-7 cells;structure-activity relationship study