Every day, it's likely that thousands of kratom products trade hands between suppliers, vendors, and consumers. But the contents of those kratom products aren't always verifiable. Most kratom is sold as a fine powder that varies in colour, so it's possible for non-kratom plant matter to enter the supply chain and go undetected by the naked eye.
But one group of Thai researchers attempted to take a closer look at the adulterated kratom issue. In a novel study, they developed a DNA analysis method that can efficiently identify kratom sample contents. They concluded that their method was "Simple, sensitive, and reliable." (Tungphatthong et al., 2020 pg 7)
According to the authors, the issue of adulterated kratom begins with suppliers. When demand exceeds supply, some farmers will substitute the kratom plant, mitragyna speciosa, with other plant species. (Tungphatthong et al., 2020 pg 3) And although these kratom substitutes may have "... similar or different morphological characters," the "... inadvertent substitution and adulteration can cause intoxication and even death" when consumed. (Tungphatthong et al., 2020 pg 3)
As a result, the authors stressed the importance of validating the identity of herbal products like kratom. But while many plant identification methods can be used to do so, not all are viable. Some, such as the PCR-RFLP method (polymerase chain reaction-restriction fragment length polymorphism), are time-consuming and not always reliable. (Tungphatthong et al., 2020 pg 3)
Thankfully, the authors surmised that another method, which combined DNA barcoding with Bar-HRM analysis, would be accurate. (Tungphatthong et al., 2020 pg 3) In the study that followed, they set out to create a Bar-HRM analysis method for kratom and test its efficacy.
To do so, the authors extracted DNA from each Mitragyna species (M. speciosa, M. diversifolia, M. hirsuta and M. rotundifolia) and their kratom product samples. All of their botanical materials — including the kratom products — were collected from Thailand. (Tungphatthong et al., 2020 pg 7)
Then, they designed four HRM "primer pairs" for the Mitragyna species to use for HRM analysis. They found that they could use the samples' varying "melting curve" profiles to differentiate Mitragyna speciosa from other Mitragyna species.
Using the melting curve profile as its analysis method, the team investigated the kratom samples. They found that five out of the six samples clustered with Mitragyna speciosa, indicating that those five were, indeed, comprised of kratom plant matter. However, the outlying sample clustered with Mitragyna diversifolia, showing that it contained plant matter from a non-kratom plant. (Tungphatthong et al., 2020 pg 6)
In closing, the authors concluded that the Bar-HRM analysis method was efficient for identifying kratom plant matter. They also said the method was "... suitable for routine analysis in the laboratory without the need for high expertise" (Tungphatthong et al., 2020 pg 6). This suggests that kratom vendors and even kratom consumers could use the method to verify the contents of kratom products themselves.
Readers should note that, as of this writing, the study hasn't been peer-reviewed. As a result, its findings should not be considered conclusive.