EFFECTS OF A NEW CLERODANE DITERPENOID ISOLATED FROM PROPOLIS ON CHEMICALLY-INDUCED SKIN TUMORS IN MICE

Propolis is a resinous material gathered by honey bees from the buds a nd bark of certain trees and plants and used inside their hives. Chara cteristic components of propolis are many kinds of flavonoid aglycones . The methanol extract of a Brazilian propolis was fractionated by HPL C, and a tumoricidal substance was isolated and characterized as a new clerodane diterpenoid (PMS-1) with a molecular formula of C20H32O3 (M W: 320). We investigated the effects of PMS-1 on skin tumorigenesis an d the development of skin tumors induced by 7,12-dimethylbenz(a)anthra cene application on mouse back skin. It was tentatively concluded that PMS-1 reduced the incidence of skin tumors by inhibition of DNA synth esis in a de novo pathway, and suppressed the growth of the tumors by decreasing DNA synthesis in a salvage pathway.