Heavy Metals in Some Thai Traditional Drugs and Herbal Extracts

Abstract

Quantification of 4 heavy metals, namely lead, arsenic, cadmium and iron, in 14 herbal extracts, 12 of which being powdered and 2 oils, and 5 traditional preparations was investigated by using atomic absorption spectroscopy. Herbs used included Morinda citrfolia, Murdannia lorifomis, Androgrphis paniculata, Hibiscus sabdariffa, Terminalia bellirica, Zingiber officinale, Kaempferia parviflora, Streblus asper, Piper retrofractum, Piper nigrum, Terminalia chebula, Curcuma Longa and Hyptis suaveolens; 5 traditional preparations, were included in this study. Lead was not found in 4 of the herbal extracts and 4 of the traditional preparations. Arsenic and cadmium were found in all of the samples at various levels: 12 herbal extracts and 3 traditional preparations with a low level (>0 - < 0.2 ppm) of lead; 9 herbal extracts and 3 traditional preparations with a moderate level (>0.040 - < 0.030 ppm) of cadmium. Iron was found in 11 herbal extracts and 5 traditional preparations, of which 10 herbal extracts and 4 traditional preparations found with not more than 25 ppm. The highest level of lead, at 12.9 + 2.2 ppm, was found in water extracts of dried fruits of Morinda citrfolia. Murdannia lorifomis, extracted by pressing juices from fresh leaves without solvents, gave high levels of lead, cadmium and iron. Androgrphis paniculata extract from dried leaves also gave high levels of lead and cadmium. 4.29 + 0.05 ppm of lead was found in one of the traditional preparations but lower than the WHO minimum allowance level. It shows that some heavy metals were retained in these herbal extracts and traditional preparations. The extraction could be one of the factors involved. Control of toxic heavy metals in herbal extracts and/or traditional preparations is one of the vital indications for quality assurance.