Optimization of fermentation conditions and purification of cordycepin from Cordyceps militaris

The fermentation medium and conditions for the production of cordycepin were optimized in static culture using single-factor experiments, Placket-Burman design, a central composite design, and response surface methodology. Among seven variables including temperature, pH, and the concentrations of glucose, tryptone, yeast extract, KH₂PO₄, and MgSO₄ · 7H₂O, temperature and the concentrations of yeast extract and tryptone were found to be the important factors that significantly affected cordycepin production. The optimized medium consisted of yeast extract 9.00 g/L and tryptone 17.10 g/L, while the optimized culture conditions consisted of seed age 3 days, with an inoculum size of 10% and incubation temperature of 27.1°C. A maximum cordycepin yield of 7.35 g/L was achieved in a 5-L fermenter under the optimized conditions. Next, cordycepin was partially purified and determined. The resulting product showed 90.54% high-performance liquid chromatography (HPLC)-ultraviolet (UV) purity. Therefore, cordycepin was applied to a cell viability assay on SH-SY5Y cells and RM-1 cells. Cordycepin can inhibit the proliferation of RM-1 cells with IC₅₀ of 133 µmol/L, but it has no inhibitory effect on SH-SY5Y cells. Supplemental materials are available for this article.