AY-9944 inhibition of sterol biosynthesis inChlorella emersonii

WhenChlorella emersonii, a green alga, was cultured in the presence of 20 ppm AY-9944, a number of sterols accumulated which appear to be intermediates of sterol biosynthesis in this organism. The sterols isolated include 14α-methyl-ergost-8-en-3β-ol, 14α-methyl 24S-stigmast-8-en-3β-ol, 14α-methyl ergosta-8,24(28)-dien-3β-ol and 4α, 14α-dimethyl 24S-stigmast-8-en-3β-ol. Smaller quantities of several other sterols were found in addition to the normally occurring Δ⁷, chondrillasterol and Δ⁷. Control cultures were found to contain, in addition to the normally occurring sterols, smaller quantities of most of the sterols isolated from AY-9944 inhibited cultures. AY-9944 is a specific inhibitor of Δ⁷ in cholesterol biosynthesis in animals. However, sinceC. emersonii terminates sterol biosynthesis one step prior to the Δ⁷ step, AY-9944 apparently inhibits sterol biosynthesis prior to this step in this organism. The accumulation of 14α-methyl sterols in treated cultures suggests that AY-9944 is an effective inhibitor of the 14α-methyl removal inC. emersonii. Scientific Article No. A1865, Contribution No. 4775 of the Maryland Agricultural Experiment Station.