The small herb Phyllanthus amarus belings to the spurge family Euphorbiaceae. It is is an important plant of several traditional Asian medicines such as the Indian Ayurvedic system, the traditional Thai medicine or the chinese herbal medicine. It is used for a variety of problems with stomach, urogenital system, liver, kidney and spleen. Supposedly extracts from some Phylllanthus species contain biologically active compounds responsible for liver protection from any toxic substances which makes these plants and their extracts a well sought after commodity. However, there are about 1000 species with varying combinations of chemical constituents making it rather confusing. And it gets worse.
For example, Phyllanthus amarus that can be found throughout Thailand and is known in Thai under the vernacular name “Look Tai Bai” (ลูกใต้ใบ) meaning “seeds under leaf”. However, several other species of same genus share this name due morphological similarities, mostly the presence of seeds under the leaves. Therefore, plant material of Phyllanthus amarus picked by a layperson may result in the collection of additional undesired species and thereby causing the end product to be of inferior quality. The plant material is subsequently processed to powder form for capsules or tea rendering any morphological identification impossible.
A group of researchers from Thailand and Greece used two plastid loci (rbcL and trnL) to generate suitable primers for distinguishing Phyllanthus species by high resolution melting (HRM) analysis.
This method proved to be a very sensitive tool that can be used for rapid detection of contamination as low as 1% of other Phyllanthus species in P. amarus admixtures. All commercial products of P. amarus obtained from a local market in Thailand were found to contain pure raw materials of P. amarus without any substitution or contamination.
The group also found that the use of trnL DNA barcoding coupled with HRM analysis (more and more referred to as bar-HRM) proved to be the most effective method for differentiating Phyllanthus amarus from its congeners, which is especially useful for determining any unwanted plant ingredients in commercial medicinal products. The combination of DNA Barcoding and HRM also reduces cost and time (4 h) in comparison with standard sequence based DNA Barcoding.
For example, Phyllanthus amarus that can be found throughout Thailand and is known in Thai under the vernacular name “Look Tai Bai” (ลูกใต้ใบ) meaning “seeds under leaf”. However, several other species of same genus share this name due morphological similarities, mostly the presence of seeds under the leaves. Therefore, plant material of Phyllanthus amarus picked by a layperson may result in the collection of additional undesired species and thereby causing the end product to be of inferior quality. The plant material is subsequently processed to powder form for capsules or tea rendering any morphological identification impossible.
A group of researchers from Thailand and Greece used two plastid loci (rbcL and trnL) to generate suitable primers for distinguishing Phyllanthus species by high resolution melting (HRM) analysis.
This method proved to be a very sensitive tool that can be used for rapid detection of contamination as low as 1% of other Phyllanthus species in P. amarus admixtures. All commercial products of P. amarus obtained from a local market in Thailand were found to contain pure raw materials of P. amarus without any substitution or contamination.
The group also found that the use of trnL DNA barcoding coupled with HRM analysis (more and more referred to as bar-HRM) proved to be the most effective method for differentiating Phyllanthus amarus from its congeners, which is especially useful for determining any unwanted plant ingredients in commercial medicinal products. The combination of DNA Barcoding and HRM also reduces cost and time (4 h) in comparison with standard sequence based DNA Barcoding.
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