A review on the extraction and separation of andrographolide from Andrographis paniculata: extraction selectivity, current challenges and strategies

Andrographolide is the main active ingredient of Andrographis paniculata (Burm.f.) Nees, known as "natural antibiotic". Here, for the purpose of discovering a more efficient, low-cost extraction and separation method, the research status of andrographolide was reviewed. At present, researches only take extraction rate as the only index to optimize extraction parameters, but ignores the importance of extraction selectivity. It is usually meaningless to blindly pursue the extraction rate without considering the difficulty and cost of subsequent separation. So, factors affecting extraction selectivity such as solvent choice, temperature and physicochemical effects caused by extraction technique itself, are first discussed. Different extraction techniques for andrographolide were discussed by comparing the selectivity, efficiency and cost of extraction. The separation procedures of andrographolide such as decolorization, impurity removal, crystallization, membrane separation, solid-phase extraction and partition chromatography and their challenges and possible strategies are also discussed. It is hoped that this review can provide guidance for researchers who are committed to advancing the field of andrographolide extraction and purification.