Effects of major nutrients, growth regulators and inoculum size on enhanced growth and camptothecin production in adventitious root cultures of Ophiorrhiza mungos L.

Abstract

Adventitious root cultures of medicinal plants are a source of secondary metabolites of pharmaceutical importance. Ophiorrhiza mungos (Rubiaceae) contains a bioactive compound, camptothecin (CPT), which possess anticancer activity. Adventitious roots of O. mungos were induced on aseptic leaf explants and established isolated root cultures. Various culture parameters were studied and showed that 1/2th strength MS liquid media with 5.0 % (w/v) sucrose, 0.5mgL−1 IBA, 0.25mgL−1 1-Naphthaleneacetic acid (NAA) and 0.1mgL−1 Gibberellic Acid (GA3) and an inoculum size of 2gL−1 was ideal for enhanced biomass combined and CPT yield. The concentration of ammonium to nitrate at 20:40mM favoured root growth and 50:10mM favoured CPT accumulation. A significant increase in root growth was observed at 1.25mM phosphate and CPT accumulation was unaffected. Roots were grown in a modified nutrient medium (MS1) according to the results obtained with the individual culture parameters and obtained significantly high biomass and CPT production. CPT was estimated using high performance liquid chromatography (HPLC). The results revealed the effect of major nutrients, growth regulators and inoculum size on growth and CPT production. The study showed that adventitious root culture of O. mungos is a viable alternative culture method for CPT production and results are useful in the scaling up studies using suitable bioreactor systems for the large-scale production of CPT.