Extraction optimisation of daphnoretin from root bark of Wikstroemia indica (L.) C.A. and its anti-tumour activity tests

The bark of Wikstroemia indica is rich in daphnoretin, which has strong antiviral and anti-tumour activities. In order to optimise the extraction conditions of daphnoretin from the bark of W. indica, various extraction parameters were chosen to identify their effects on daphnoretin extraction. Response surface methodology (RSM) was applied to obtain the optimal combination of these parameters. Results showed that the optimisation conditions for daphnoretin extraction were: ethanol concentration 67.44%, extraction time 49.44 min, temperature 60.19 °C and liquid–solid ratio 23.49:1. The maximum extraction of daphnoretin obtained experimentally was 2.18‰. The mathematical model developed was found to fit well with the experimental data. Further, four kinds of human cancer cell lines, HeLa, A549, CNE and HEp-2, were tested in vitro to explore the anti-tumour spectrum of daphnoretin. It was found for the first time that daphnoretin showed significant inhibition on the proliferation of CNE and HeLa cells.