Sterols: Isolation from a Blue-Green Alga

Abstract
A crystalline mixture of sterols was isolated from the filamentous blue-green alga Phormidium luridum. The mixture consisted of unsaturated 24-ethylcholesterols possessing Δ7-, Δ5,7-, and Δ5-bonds together with their Δ22-derivatives and a small amount of cholesterol. The major component was 24-ethyl-Δ7-cholestenol. Squalene and phytol were also evident.