Enhancement of anthraquinone production in Cassia tora root cultures using medium manipulation technique

Anthraquinone (AQ) such as aloe-emodin, chrysophanol, emodin and physcion are valued pharmacological active compounds found in Cassia tora. Root cultures of C. tora have been established in order to study on their AQ production. C. tora root cultures were established from root explants in Murashige & Skoog (MS) medium supplemented with 0.1 mg/L α-naphthaleneacetic acid (NAA) and 1.0 mg/L kinetin (Kn). In this study effects of basal media and plant growth regulators on growth and AQ production of C. tora root cultures were evaluated. Variety of basal media including Gamborg's B5 (B5), MS and Nitsch & Nitsch (NN) supplemented with 0.1 mg/L α-naphthaleneacetic acid (NAA) and 1.0 mg/L kinetin (Kn) were used. The 4 week-old root cultures were harvested. The biomasses were recorded and the harvested roots were subjected to HPLC quantitative analysis of AQ. Biomass of the root cultures reached the highest when cultured in B5 medium (0.44 ± 0.045 g DW/flask) while NN (0.25 ± 0.078 g DW/flask) and MS (0.19 ± 0.065 g DW/flask) were not appropriate for growth of the root cultures. AQ production in the root cultures from MS and B5 media were comparable (2.35 ± 0.142 mg/g DW and 2.31 ± 0.133 mg/g DW, respectively). Considering the growth and the AQ production, B5 was the most appropriate media for culturing C. tora root cultures. Optimal level of Kn and NAA in B5 medium were further investigated. Kn greatly influenced on AQ production in dose dependent manner whereas NAA affected on root morphology and biomass. Optimization of Kn and NAA concentrations revealed that B5 medium supplemented with 1.0 mg/L NAA and 2.0 mg/L Kn gave the highest content of AQ in the root cultures (3.59 ± 0.166 mg/g DW) which was 1.6-fold fold higher than the levels of the non-optimized group.