In this article, the antioxidant activity of some alkaloids lipid peroxidation (LPO) in rat liver mitochondria has been studied. It has been established that diterpenoid alkaloids: 1-О-benzoylnapelline, napelline and songorine have a protective effect on mitochondria, reducing the damaging effect of Fe2+/ascorbate and the release of malondialdehyde (MDA) into the secondary products of peroxidation. The effect of alkaloids napelline, 1-O-benzoylnapelline and songorine on the processes of MDA formation in rat liver mitochondria in vitro has been studied.Where in at 200 мM concentrations, 1-О-benzoylnapelline inhibited the formation of MDA by 95 %, and the alkaloids napelline and songorine at this concentration inhibited the formation of MDA by 54 and 44 %. From the data obtained, it can be shown that 1-О-benzoylnapelline strongly inhibits the formation of MDA compared to songorine and napelline.