DNA protective activity of triterpenoids isolated from medicinal mushroom Fomitopsis betulina

Abstract

Eleven 31-methylenlanostane triterpenoids, i.e., seven 21- and four 26-oic acids, as well as a lupane triterpenoid betulin, isolated from the fruiting bodies of the mushroom Fomitopsis betulina, were tested for in vitro protective effect on chromosome aberrations in peripheral human lymphocytes using cytochalasin-B blocked micronucleus (CBMN) assay. Most of the tested compounds showed a beneficial effect by reducing DNA damage of human lymphocytes more effectively than amifostine, a radioprotective agent, used as a positive control. All the tested compounds decreased MN frequency in the concentration dependent manner, with the concentration of 2.0 µg mL-1 being the most effective – with increase of the concentration the activity slightly decreases. The structure–activity relationship (SAR) studies indicated that the lanostanes containing a conjugated 7,9 (11)-diene system exhibit lower activity than Δ8-analogues. It was also demonstrated that the DNA protective activities within the Δ8-lanostane-26-oic acid group are affected by the substitution in position 3 pattern. In the Δ8 series the oxygenation at C-12 or 16 as well as 21- or 26-oic acid functionality proved beneficial for in vitro protective effect on chromosomal aberrations. Betulin exhibited the lowest protective activity, but it is still comparable to that of amifostine.