In vivo conversion of [4-14C]sitosterol and [22,23-3H]sitosterol to stigmasterol in barley seedlings

Six-day-old barley seedlings were allowed to take up [4-¹⁴C]sitosterol and [22, 23-³H]sitosterol for 2.5 hr and the incorporation into the sterol fractions was determined after 0, 6, 12 and 24 hr. Sitosterol was readily incorporated into every sterol class. The ³H/¹⁴C ratio in the free forms dropped when compared with the ³H/¹⁴C ratio of the administered sitosterol. In the free sterol, radioactive stigmasterol, showing a ³H/¹⁴C ratio half that of the sitosterol ³H/¹⁴C ratio, was isolated and its radiochemical purity established by dilution with carrier material and crystallization to constant specific activity.