Enhanced accumulation of triterpenoids and flavonoids in cell suspension cultures of Azadirachta indica (A. Juss.) with an extended stationary phase

Accumulation of three triterpenoids (azadirachtin-A, nimbin and salannin) and two flavonoids (quercetin and kaempferol) was analyzed in cell suspension cultures of Azadirachta indica A. Juss. By feeding cells with a sterile solution of sucrose, it was possible to sustain viability of cells in batch cultures without subculturing for 60 d. Such long-term cell suspension cultures exhibited an extended steady stationary phase which facilitated enhanced accumulation of azadirachtin-A, nimbin, salannin, quercetin and kaempferol. 40% of the cells were viable towards the end of 60 d of incubation. Maintaining cells for longer time under stationary phase facilitated transformation of cells from low productivity to high productivity. The cells in stationary phase could serve as a starting material for the selection of elite cell lines and for bioreactor cultures for large-scale production of these compounds.