Selective extraction of nuciferine from Nelumbo nucifera Gaertn. leaves via heat reflux method: process optimisation and efficiency evaluation.

This study evaluated alkaloid content in Nelumbo nucifera leaves at different maturity stages and optimised the heat reflux extraction process for nuciferine and total alkaloids. Alkaloid content reached a maximum at the 1-month-old stage. Nuciferine was the major alkaloid, accounting for more than 70% of the total alkaloid content. Initial optimisation using the one-factor-at-a-time approach determined extraction conditions of 96% ethanol, 60 °C, a liquid-to-solid ratio of 8:1, 60 min extraction time, and three extraction cycles, which yielded 3.36 ± 0.05 mg/g dry material of total alkaloids. Response surface methodology was then applied to further optimise the process by considering factor interactions. The optimal conditions were 87% ethanol, 70 °C, and a liquid-to-solid ratio of 8 mL/g. The experimental results achieved 3.19 mg/g nuciferine and 4.24 mg/g total two alkaloids, showing improved extraction efficiency compared with previous studies.