Optimization of response surface methodology and in vitro antioxidant, antimicrobial activity of Phellodendron amurense callus tissue

Phellodendron amurense is the main plant source of berberine, and over exploitation has led to the depletion of wild resources. Therefore, tissue culture technology is being used to produce berberine and reduce the pressure on the utilization of wild resources. In this study, based on the seedling of P. amurense used as the material, the callus induction rate was taken as the index to optimize callus culture conditions by single factor experiments and response surface methodology. The optimal conditions of callus culture were determined: stem segment as explants, sucrose concentration 18 g/L, amount of nitrogen 1.0 N, combination of exogenous plant hormone 2, 4-D 2.0 mg /L + 6-BA 1.4 mg/L, under these conditions, the callus induction rate of P. amurense was about 97.06%+/- 8.69. Berberine was extracted from the callus that cultured under the optimal conditions and its content was6.14 +/- 1.12 mg/g (DW), which met the berberine content standard of not less than 0.6% standard of the Chinese Pharmacopoeia. In vitro antioxidant and antibacterial activities were tested for the extracts of the callus and traditional Chinese medicine (TCM) "GuanHuangbai". The results showed that the antioxidant activities of the two extracts were mainly related to the concentrations of berberine. The antioxidant activity of callus extracts (IC50: 0.2166 mg/ml +/- 0.0387) was slightly higher than that of Guanhuangbai extracts (IC50: 0.2169 mg/ml +/- 0.0392). The Guanhuangbai extracts of P. amurense exhibited much better antimicrobial activity than the callus extracts for gram-positive bacteria, but the similar potency for the gram-negative bacteria and fungi in the present study. The extracts from callus of P. amurense had better antimicrobial activity in the experiment.