Herbal assessment: Metal stats

Chemometric medicine

 

A statistical analysis of the elemental content of 23 commercial herbal medicines reveals how effective chemometric tools can be in studying such products.

Radjassegarin Arumugam, Rengasamy Ragupathi Raja Kannan, Jayabalan Jayalakshmi, Karunamoorthy Manivannan, Gopalraj Karthikai Devi and Perumal Anantharaman of the Centre of Advanced Study in Marine Biology at Annamalai University, in Tamil Nadu, India, evaluated a range of common herbal remedies using multivariate analysis - specifically principal component analysis (PCA) and hierarchical cluster analysis (HCA) - to uncover any relationships that might exist between various metallic elements in these products.

They studied 13 elements: aluminium, cadmium, chromium, cobalt, copper, iron, lead, magnesium, manganese, nickel, potassium, sodium and zinc using values for the metals' concentration by dry weight in milligrams per kilogram of product. The traditional herbal remedies investigated included Eclipta prostrata (the false daisy used for catarrh in infants), the alkaloid-rich Adhatoda vasica (used to treat breathing problems), Phyllanthus amarus (commonly known as stonebreaker), Hybanthus enneaspermus (used for stomach and kidney problems), Cardiospermum halicacabum (the balloon plant used to treat diarrhoea), Acacia nilotica (gum arabic) and Denolix elata (poinciana used in treating arthritis). Others used to "treat" diabetes, jaundice, dental caries, tuberculosis, skin problems, constipation, ulcers, chicken pox, cholera, measles, dysentery, heart disease, high blood pressure, malaria and other diseases were also assessed.

The team points out that over the last few decades herbal medicine has become increasingly common regardless of whether or not any given remedy has demonstrable or proven efficacy against any specific disease or condition. Moreover, its use is very widespread in Asia and there are many species used by Ayurvedic and other "healers". Traditional healers in India for instance are thought to draw from some 2500 different plant species for their treatments. According to the World Health Organisation (WHO), some 3300 million people, mainly in developing nations use such traditional remedies exclusively and regularly.

The presence of toxic elements in food and medicinal plants may cause severe health problems including kidney failure, liver damage and other forms of chronic toxicity, the team says. It is therefore important to have straightforward methods of assessing their toxicity in terms of metal content as well as other factors.

"Chemometric techniques applied to the data of mineral and trace elements of chemical analysis in medicinal plants might provide an interesting and promising approach to classification of commercial brands and quality control in the pharmaceutical industry," the team says. They have now applied those tools to a range of herbal remedies.

Metal detector

"Interestingly," they say, "the toxic element cadmium was below detectable levels in all the samples and Cr, Pb and Ni were lower than the permissible limits as prescribed by WHO." The study demonstrates how PCA and HCA procedures can be used successfully, the next step is to apply them to the many other herbal products available and to determine which, if any, based on metal content represent a health risk rather than a remedy. The team has previously published a demonstration of the technique could be applied the analysis of seagrasses based on by ICP-OES data, team member Rengasamy Kannan told me.