Department of Pharmaceutical Botany, Faculty of Pharmacy, Mahidol University, Bangkok, Thailand.
Department of Chemical Engineering, Faculty of Engineering, Mahidol University, Nakhon Pathom, Thailand.
Sci Rep. 2021 Nov 11;11(1):22026. doi: 10.1038/s41598-021-01602-x.
Centella asiatica (L.) Urban extracts are widely used as food, drugs and cosmetics, and the main active compounds are glycosides (madecassoside and asiaticoside) and aglycones (madecassic acid and asiatic acid). Green extraction is an interesting concept that can produce safe and high-quality extracts that use less solvent, time and energy with the environmental friendly. This study investigated the optimum conditions for extracting a triterpenoid glycoside-enriched C. asiatica extract using microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE). Central composite design and response surface methodology (RSM) were used for the experimental design and data analysis. Four-month-old C. asiatica tetraploid plants were selected as the elite raw material containing high amount of triterpenoid glycosides for the extraction experiments, and the triterpenoid content was determined by a validated HPLC method. The results demonstrated that the RSM models and equations were reliable and could predict the optimal conditions to enhance C. asiatica extract yield, glycoside and aglycone amounts. The percent of ethanol was the major factor that had a significant effect on C. asiatica yield and glycoside and aglycone content during MAE and UAE. The maximum triterpenoids content in extract; 7.332 ± 0.386% w/w madecassoside and 4.560 ± 0.153% w/w asiaticoside 0.357 ± 0.013% w/w madecassic acid and 0.209 ± 0.025% w/w asiatic acid were obtained by MAE with 80% ethanol at 100 watts for 7.5 min, whereas the optimal conditions for highest total triterpenoids extraction from dry plant was UAE with 80% ethanol, temperature 48 °C, 50 min enhanced 2.262 ± 0.046% w/w madecassoside, 1.325 ± 0.062% w/w asiaticoside, 0.082 ± 0.009% w/w madecassic acid and 0.052 ± 0.007% w/w asiatic acid as secondary outcome. Moreover, it was found that MAE and UAE consumed energy 59 and 54%, respectively, lower than that of the conventional method, maceration, in term of kilowatt-hour per gram of total triterpenoids. These optimized green conditions could be recommended for C. asiatica extraction for triterpenoid glycoside-enriched extracts production for the pharmaceutical or cosmeceutical industries and triterpenoids quantitative analysis in raw materials.
积雪草（L.）Urban 提取物被广泛用作食品、药品和化妆品，主要活性化合物为糖苷（积雪草苷和羟基积雪草苷）和苷元（积雪草酸和羟基积雪草酸）。绿色提取是一个有趣的概念，可以使用更少的溶剂、时间和能源，同时对环境友好，生产安全和高质量的提取物。本研究采用微波辅助提取（MAE）和超声辅助提取（UAE），探讨了提取富含三萜糖苷的积雪草提取物的最佳条件。中心复合设计和响应面法（RSM）用于实验设计和数据分析。选择四个月大的四倍体积雪草植物作为含有高含量三萜糖苷的优质原料进行提取实验，并采用验证后的 HPLC 方法测定三萜含量。结果表明，RSM 模型和方程是可靠的，可以预测提高积雪草提取物产率、糖苷和苷元含量的最佳条件。乙醇的百分比是 MAE 和 UAE 过程中对积雪草产率、糖苷和苷元含量有显著影响的主要因素。通过 MAE 用 80%乙醇在 100 瓦下提取 7.5 分钟，可获得提取物中三萜含量最高，分别为 7.332±0.386%w/w 积雪草苷和 4.560±0.153%w/w 羟基积雪草苷、0.357±0.013%w/w 积雪草酸和 0.209±0.025%w/w 羟基积雪草酸；而从干植物中提取总三萜的最佳条件是 UAE 用 80%乙醇，温度 48°C，时间 50 分钟，可分别提高 2.262±0.046%w/w 积雪草苷、1.325±0.062%w/w 羟基积雪草苷、0.082±0.009%w/w 积雪草酸和 0.052±0.007%w/w 羟基积雪草酸，作为次要结果。此外，与常规方法（浸渍法）相比，MAE 和 UAE 分别消耗 59%和 54%的能量，每克总三萜的千瓦小时数更低。这些优化的绿色条件可推荐用于积雪草的提取，以生产富含三萜糖苷的提取物，用于制药或化妆品行业，以及原材料中三萜类化合物的定量分析。
