Read this article to learn about the modern methods of herbal drugs extraction.
Plants are naturally gifted bio-factories for the synthesis of medicinal compounds, which have seen the discovery of new drugs with high therapeutic value.
Today when different chromatographic methods can provide high resolution of complex mixtures, with detection limits down to few Nano grams or below but still the whole advanced analytical process can be wasted if an unsuitable sample preparation or extraction method has been applied before the sample reaches the chromatograph.
With the herbal drug usage gaining worldwide recognition as evident from the 1994 WHO data, which says that 90% of the world’s population uses medicinal plant for curing and 81 % have no access to synthetic drugs, establishment of proper quality and safety becomes a challenging issue. In all research associated with natural product, extraction forms the key basic step.
Unfortunately, even though most of the research in medicinal plants starts with extraction, but still today not much attention has been paid to this crucial step. Extraction or sample preparation forms the crucial first step in the analysis of herbs, because it is necessary to extract the desired chemical components from the herbal materials for further separation and characterization.
Although many traditional sample preparation methods are still in use, the trends in recent years have been towards:
(a) The ability to use smaller initial sample sizes even for trace analyses,
(b) Greater specificity or greater selectivity in extraction,
(c) Increased potential for automation or for on-line methods, reducing manual operations,
(d) A more environmentally friendly approach (green chemistry) with less waste and the use of small volumes or no organic solvents.
The conventional extraction methods like Soxhlet, maceration and hydro distillation are error prone, tedious and often large volume of organic solvents are consumed in the extraction process. In addition, each extraction step adds to the risk of sample loss and contamination.
The acceptance of new techniques has been slow, despite the good performances of several novel methods, such as supercritical fluid extraction, pressurized liquid extraction, microwave and ultrasound assisted extraction.
These new methods are typically much faster and often more selective than conventional methods, and consume lesser volume of organic solvents. In general, they allow more efficient extraction of analytes and increases sample throughput, thus they are likely to play an important role in the overall effort of ensuring and providing high quality herbal products to consumers worldwide.
In this article recent developments and applications of modern extraction techniques for the extraction, clean up, and concentration of analytes from medicinal plants or herbal materials are reviewed.
These modern techniques include supercritical fluid extraction (SFE), microwave assisted extraction (MAE) and ultrasound assisted extraction (UAE). Emphasis is placed on brief description of the unique capabilities, working principle and current applications of each modern technique.