DNA barcodes reveal adulteration in traditional medicines

Many of the drugs did not have Phyllanthus used to treat hepatitis as claimed.  

Traditional medicines in the large unorganised market contain spurious plant extracts and, sometimes, heavy metals that pose serious risks to health, an exhaustive genetics-based study has revealed.

The set of studies shows that traditional medicinal markets are replete with unrelated plant materials that substitute for endangered or rare ones, while the final product, in some instances, contains heavy metals, particularly lead.

In a review published in the journal Drug Safety earlier this year, scientists from Bengaluru, working with their counterparts in Canada, have called for a herbal trade authentication system to address “concerns over widespread adulteration.”

Tracing the genes

Among the researchers is G. Ravikanth from Ashoka Trust for Research in Ecology and the Environment (ATREE), who stumbled upon significant adulteration of herbal products. In 2008, while attempting to trace the genetic history of Phyllanthus (Leaf flower), his team was surprised to see claims of the plant being used in abundance in herbal medicines, despite its relative rarity. Taking samples from 12 wholesale markets across south India (such as Bengaluru, Kollam, Madurai and Thiruvananthapuram), their DNA analysis showed that nearly 25% of samples were not Phyllanthus amarus (used to treat hepatitis), but a mixture of other species which did not contain the curative elements of phyllanthin and hypophyllanthin.

Taking off from this, they focussed their attention on species adulteration and developed DNA barcodes — short genetic sequences, much like a supermarket barcode, which becomes an identifying mark — for 150 species commonly used in traditional medicine.

“The process was long. We collected samples from across the country, certified them through taxonomists, analysed the DNA and found two or three genes that were consistent. These codes can provide undeniable proof of adulteration, which molecular analysis cannot,” said Dr. Ravikanth.

The team set about comparing raw herbal products marketed with the ‘barcodes’ of the actual species.

Between 2010 and 2016, five published studies or reviews detailed the scale of the adulteration.

Ashoka bark, which is used to cure many ailments including leucorrhea, uterine disorders, and as an anti-inflammatory, anti-bacterial drug — whose harvesting is highly regulated under forest laws — was found to have an astounding 90% adulteration by seven other species, including papaya or drumstick bark in Tamil Nadu and Sal trees in Central India.

“Bark and roots, which are powdered before sale, are the most adulterated, while for fruits such as Garcinia indica [kokum], adulteration is rarer,” said the researcher.

Subsequent analysis of market samples from across the country showed the widespread adulteration of other species: Seena — used in the treatment of a wide range of conditions, from constipation to arthritis — was adulterated between 8% to as much as 50%; Sida species, used for analgesic or anti-bacterial properties, was 80% adulterated.

The recently published review lists more than 30 medicinal varieties where adulteration has been studied. “In some cases, collectors cannot differentiate between similar plants, which may not have therapeutic effects. But, for endangered plants or those found in the wild which make up a significant part of Ayurvedic products, the demand is so high that the products are intentionally adulterated,” said Dr. Ravikanth.

Concern mounts

In their review and in a project proposal to the Department of Biotechnology, researchers have suggested a policy framework which includes setting up of laboratories that use DNA-based tools and a quality assurance certification for raw products in herbal markets. Unlike chemical drugs which are certified at the product stage, for traditional medicine, the certification needs to happen in markets where it is in raw form.

The concern is echoed by practitioners of traditional and alternative medicine too. “Quality, even in some big brand products, is definitely not there. And as consumption increases, relying on trust of the practitioner will not be enough. Without systemic quality control, there will be a negative impact on the perception of Ayurveda,” says V. Rajendra, Chairman of Ayurveda Board of Studies, Rajiv Gandhi University of Health Sciences, Karnataka.

N.A. Magadum, president of AYUSH Federation in Karnataka wants a system of penalties for traders and manufacturers.

Impact unclear

While the effects of the phenomenon on humans is yet to be assessed, what is becoming clear is that lead found in a few traditional medicines is causing harm. The National Referral Centre for Lead Projects in India (NRCLPI) at St. Johns Hospital in Bengaluru — which coordinates with more than 30 national centres — says the second highest cause of lead poisoning among their patients, who complain of nausea, weakness, loss of appetite, headaches, was through the intake of traditional medicines. The majority of patients are, however, from the lead battery sector.

Thuppil Venkatesh, Director of the Centre and “Lead Man of India”, says that five years ago, barely two patients a year turned up with high levels of lead in their blood, but the figure now is as high as 30 a month, due to traditional medicines.

Since 2014, the centre has detected more than 100 herbal products with lead ranging from 90 parts per million (ppm) to 7,000 ppm. A 2008 study co-authored by Dr. Venkatesh estimated that lead, mercury and arsenic could be present in up to 20% of traditional medicinal products.

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Printable version | Jun 17, 2021 12:37:37 PM |

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