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Extraction as a pharmaceutically used term can be defined as the technique used for
the separation of therapeutically desired active constituent(s) and elimination of unwanted
insoluble material by treatment with selective solvents (South-East Asian (SEA) Regional Workshop
on Extraction Technologies for Medicinal and Aromatic Plants, 2006). Extraction mainly
involves the release of complex plant constituents and solubilization of secondary metabolites
from the matrix, followed by separation of soluble target compounds from the crude extract
through selective use of solvents (Yrjönen, 2004).
The various procedures that can be used for the extraction of medicinal plants
include: Maceration, infusion, percolation, decoction, Soxhlet extraction, counter current
extraction, aqueous-alcoholic extraction by fermentation, sonication, supercritical fluid extraction,
thermal desorption, phytonic extraction, steam distillation and enfleurage method. The head
space trapping technique, Microwave Assisted Extraction (MAE), solid phase
microextraction, protoplast extraction technique, microdistillation and molecular distillation are some of
the newer methods of extraction (Armstrong, 1999 and SEA Regional Workshop on
Extraction Technologies for Medicinal and Aromatic Plants, 2006). |
