Study on the optimal extraction conditions of anthocyanin from the fruit of Solanum nigrum L.

Objective:The best solvent to extract anthocyanins from Solanum nigrum L. fruits and the optimal extraction condition were obtained.Methods:14 kinds of solvents were chosen to extract. The correlation between yield of total phenols, flavonoids, anthocyanins and antioxidant activity was analyzed. Based on the single-factor test analysis, the full factorial design, steepest ascent design and central composite design for response surface analysis were applied.Results:60% ethanol was the best solvent to extract anthocyanins from Solanum nigrum L. fruits.The content of total phenols, flavonoids and anthocyanins from 60% ethanol extract was ( 1.99 ± 0.03) mg /g, ( 1.02 ±0.01) mg /g, ( 0.82 ±0.02) mg /g, respectively.The ABTS·+and ·OH scavenging activity was up to 88.18% ± 0.59%, 82.45% ± 0.59%, respectively. The ferric reducing antioxidant capacity of the extracts was ( 5.45 ± 0.06) mmol /L equivalent to FeSO 4. The correlation between yield and antioxidant activity:total phenols > flavonoids > anthocyanin. The best extraction technology of anthocyanins from Solanum nigrum L. was as follows:pH1.0, temperature 29℃, time 85.5min and liquid-solid ratio 1∶25. On this extraction condition, the content of Solanum nigrum L.anthocyanins was ( 0.86 ± 0.05) mg /g.Conclusion:The obtained model was credible and could be used for extraction of anthocyanins from Solanum nigrum L.fruits.