Enhanced production of harringtonine and homoharringtonine in Cephalotaxus fortunei callus culture by periodic temperature oscillation

Total production of harringtonine, homoharringtonine and isoharringtonine in solid cultures of Cephalotaxus fortunei was 1.22 mg/l by periodic oscillation in temperature between 10 and 25°C every 12 h for 45 days. Production was enhanced 1.8 and 1.3-fold compared to the controls at constant temperatures of 10 or 25°C. For suspension cultures subjected to such an oscillation every 24 h for 30 days, total alkaloid production of 0.18 mg/l was achieved, a 2.0 and 1.1-fold improvement compared to the suspension culture controls, correspondingly.