IDTQ-Grupo Vinculado PLAPIQUI - CONICET, Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Av. Vélez Sarsfield 1611, Ciudad Universitaria, Córdoba, Argentina.
Ultrason Sonochem. 2014 Mar;21(2):478-84. doi: 10.1016/j.ultsonch.2013.08.023. Epub 2013 Sep 10.
This work reports a comparative study about extraction methods used to obtain anthraquinones (AQs) from stems and leaves of Heterophyllae pustulata Hook (Rubiáceae). One of the conventional procedures used to extract these metabolites from a vegetable matrix is by successive Soxhlet extractions with solvents of increasing polarity: starting with hexane to eliminate chlorophylls and fatty components, following by benzene and finally ethyl acetate. However, this technique shows a low extraction yield of total AQs, and consumes large quantities of solvent and time. Ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) have been investigated as alternative methods to extract these compounds, using the same sequence of solvents. It was found that UAE increases the extraction yield of total AQs and reduces the time and amount of solvent used. Nevertheless, the combination UAE with benzene, plus MAE with ethyl acetate at a constant power of 900 W showed the best results. A higher yield of total AQs was obtained in less time and using the same amount of solvent that UAE. The optimal conditions for this latter procedure were UAE with benzene at 50 °C during 60 min, followed by MAE at 900 W during 15 min using ethyl acetate as extraction solvent.
本工作报道了从 Heterophyllae pustulata Hook（Rubiaceae）茎和叶中提取蒽醌（AQs）的方法比较研究。从植物基质中提取这些代谢物的一种常规方法是用极性逐渐增加的溶剂进行连续索氏提取：先用正己烷去除叶绿素和脂肪成分，再用苯，最后用乙酸乙酯。然而，这种技术对总蒽醌的提取率较低，且需要消耗大量的溶剂和时间。超声辅助提取（UAE）和微波辅助提取（MAE）已被研究为提取这些化合物的替代方法，使用相同的溶剂序列。结果发现，UAE 提高了总蒽醌的提取率，同时减少了所用溶剂的时间和用量。然而，在 900 W 的恒定功率下，UAE 与苯结合，MAE 与乙酸乙酯结合的效果最好。在相同的溶剂用量和更短的时间内，该方法获得了更高的总蒽醌收率。对于后一种方法，最佳条件是在 50°C 下用苯进行 UAE 提取 60 分钟，然后在 900 W 下用乙酸乙酯进行 MAE 提取 15 分钟。
