Two labdane type diterpenes, labd-13(E)-ene,-8 alpha ,15-diol (1) and labd-
13(E)-ene,-8 alpha ,15-yl acetate (2) were isolated from the hexane extract
of Cistus creticus subsp. eriocephalus (Viv.) Greuter & Burdet leaves, whi
le (+)-19-acetoxy-cis-clerodan-3-en-15-oic acid (3) was isolated from the h
exane extract of Cistus monspeliensis L. leaves. The compounds were examine
d for their in vitro cytostatic and cytotoxic activity against nine human l
eukemic cell lines, three of which exhibited a multidrug resistant phenotyp
e. They were also evaluated for their anti-inflammatory activity in vivo on
the back of hairless mice. The cytostatic and cytotoxic activity of the te
sted diterpenes followed the order 1 >2 >3. Topical application of the dite
rpenes on barrier disrupted skin did not seem to have a significant contrib
ution to the repair rate of the skin barrier.