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

•Adventitious roots were induced from Ophiorrhiza mungos aseptic leaf explants.•Established isolated root cultures of Ophiorrhiza mungos.•Culture parameters were optimized and proposed a modified nutrient medium (MS1).•A 16.65 fold increase in fresh growth index was obtained in the MS1 medium.•A 3.44 fold increase in CPT accumulation was achieved in the MS1 medium.

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, 0.5 mg L−1 IBA, 0.25 mg L−1 1-Naphthaleneacetic acid (NAA) and 0.1 mg L−1 Gibberellic Acid (GA3) and an inoculum size of 2 g L−1 was ideal for enhanced biomass combined and CPT yield. The concentration of ammonium to nitrate at 20:40 mM favoured root growth and 50:10 mM favoured CPT accumulation. A significant increase in root growth was observed at 1.25 mM 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.

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