Optimized culture medium for the production of flavonoids from Orostachys cartilaginea VN Boriss. callus cultures

The optimal culture medium for the production of flavonoid compounds from Orostachys cartilaginea V.N. Boriss. calluses was studied. In callus cultures of O. cartilaginea, the flavonoid monomer content, in decreasing order was kaempferol-3-O-rutinoside (Kp-3-rut), quercetin 3-O-glucoside (Qc-3-glc), epicatechin gallate (Ecg), kaempferide (Ke), and quercetin (Qc). The results of the uniform design experiment indicated that the production of Qc, Ke, Qc-3-glc, Kp-3-rut, and total flavonoids were satisfactory in callus grown on full salt strength (1x) of Murashige and Skoog (MS) medium supplemented with 3.5 mg L-1 6-benzylaminopurine (BA) and 0.1 mg L-1 1-naphthalene acetic acid (NAA). By contrast, only Ecg was found in callus grown on 0.75x MS medium supplemented with 1.5 mg L-1 BA and 0.3 mg L-1 NAA. A phosphate concentration of 1.25 mM in the MS medium favored the production of Qc and Ke, whereas 0.75 mM phosphate was optimal for the production of Ecg, Qc-3-glc, Kp-3-rup, and total flavonoids. The NH4+/NO(3)(-)ratios of 30/30 mM in the MS medium promoted Ke, Ecg, Qc-3-glc, Kp-3-rup, and total flavonoid production. However, a NH4+/NO(3)(-)ratio of 20/40 mM enhanced Qc production. The effect of sucrose concentrations on the accumulation of different flavonoid monomers was comparatively more regular. The flavonoid content increased as the sucrose concentration increased from 20 to 40 g L-1, peaked at 40 g L-1, and decreased at concentrations greater than 40 g L-1. Therefore, 40 g L-1 sucrose was optimal for the production of the five flavonoid monomers and total flavonoids. The present findings demonstrate the possibility of producing flavonoid compounds from O. cartilaginea callus.