Creating a Test to Detect High-Methyl Eugenol in Purple Tulsi

Jenn Hoskins
24th March, 2024

Creating a Test to Detect High-Methyl Eugenol in Purple Tulsi

Image Source: Natural Science News, 2024

Key Findings

  • Study at SRM Institute found high levels of a toxic substance in purple Tulsi, a medicinal plant
  • Researchers developed a new test to tell apart safe green Tulsi from potentially harmful purple Tulsi
  • Testing revealed 80% of Tulsi products in the market were the riskier purple variety
In the realm of traditional medicine, the authenticity of herbal products is a matter of significant concern. Medicinal plants like Tulsi, also known as Holy Basil (Ocimum tenuiflorum L.), are widely used for their health benefits. However, recent research by the SRM Institute of Science and Technology[1] has uncovered a critical issue: the presence of potentially harmful substances in certain Tulsi varieties. This study not only identifies the problem but also provides a solution to ensure the safety of Tulsi products. Tulsi is known for its therapeutic properties, including stress relief and immune system support. There are two main subtypes of O. tenuiflorum: green Tulsi and purple Tulsi. Both are valued for their medicinal properties, but they are not identical. Purple Tulsi has been found to contain higher levels of methyl eugenol (ME), a substance that, in significant quantities, can be moderately toxic and potentially carcinogenic. This raises concerns about the safety of Tulsi products, especially since distinguishing between the two subtypes is not straightforward. To address this, researchers developed a new method called allele-specific PCR (AS-PCR), which can differentiate between green and purple Tulsi. The method hinges on detecting genetic differences—specifically, single nucleotide polymorphisms (SNPs) and insertions/deletions (InDels) in the plant's chloroplast DNA. By focusing on a particular SNP in the ycf1 gene, scientists created primers to amplify distinct DNA fragments unique to each subtype. The green Tulsi produced a 521 base pair (bp) fragment, while the purple Tulsi yielded a 291 bp fragment. The AS-PCR method was rigorously tested on samples from both Tulsi subtypes and validated through Sanger sequencing, a method for determining the precise sequence of DNA. The technique proved to be accurate and reliable. When applied to 30 market-sourced Tulsi powder samples, the results were somewhat concerning: 80% were identified as purple Tulsi, only 3.5% as green Tulsi, 10% a mix of both, and 2 samples (6.5%) were not O. tenuiflorum at all but a different species, O. gratissimum. These findings are significant as they highlight a prevalent issue in the herbal product market: adulteration and misidentification. Previous studies[2][3][4][5] have underscored the widespread nature of this problem, revealing that many herbal products contain ingredients not listed on their labels, which can range from harmless fillers to potentially hazardous or ineffective substitutes. The implications are far-reaching, affecting not only consumer health but also the credibility of traditional medicine practices. The research by the SRM Institute of Science and Technology builds upon these earlier studies by offering a practical tool for the authentication of Tulsi. By implementing the AS-PCR method, producers and regulatory bodies can ensure that consumers receive the correct subtype of Tulsi, thereby mitigating the risks associated with ME. This method also sets a precedent for the development of similar authentication techniques for other medicinal plants, which could greatly enhance the reliability and safety of herbal products. In conclusion, the study presents a novel and effective approach to distinguishing between subtypes of Tulsi, addressing a critical safety concern in herbal medicine. Its application could lead to improved market surveillance and quality control, ensuring that the benefits of Tulsi can be enjoyed without the risk of exposure to unwanted toxic substances. This advancement in herbal pharmacovigilance represents a significant step forward in protecting consumer health and maintaining the integrity of traditional medicinal practices.

HerbsBiotechPlant Science


Main Study

1) Development of an allele-specific PCR (AS-PCR) method for identifying high-methyl eugenol-containing purple Tulsi (Ocimum tenuiflorum L.) in market samples.

Published 23rd March, 2024

Related Studies

2) Authentication of the market samples of Ashwagandha by DNA barcoding reveals that powders are significantly more adulterated than roots.

3) Product authenticity versus globalisation-The Tulsi case.

4) Identification of species adulteration in traded medicinal plant raw drugs using DNA barcoding.

5) Estimating Herbal Product Authentication and Adulteration in India Using a Vouchered, DNA-Based Biological Reference Material Library.

Journal: Drug safety, Issue: Vol 39, Issue 12, Dec 2016

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