In a previous study several Ayurvedic medicines with elevated arsenic and lead exceeded intake guidelines if ingested as recommended (Saper et al., 2008
), but nothing was known about their speciation and associated solubility. Thus the present study addressed these issues in samples that were specifically selected to represent the products in the previous study with the highest concentrations of arsenic and lead, in addition to several others that had detectable amounts of these elements, including some that have not been studied previously. The process used to produce several of the products, known as Rasa Shastra
, combines herbs with metals, minerals and gems, and is believed to produce medicines that are safe and therapeutic (Shastri, 1979
; Satpute, 2003
). Additionally, the processing of the minerals (shodhana
or ‘purification’) is claimed to eliminate their harmful effects, rendering them non-toxic (Kumar et al., 2006
). In the current study, sample 11 (Mahayograj Guggulu) contains a high concentration of lead, around 5% by weight (50,000 mg.kg−1
), which was likely added as naga bhasma
(lead ash) (Raza, 1975
are calcined or ashed minerals or gems; in chemical terms, the bhasma
process is mainly oxidative roasting. The lead species in the sample could not be detected by X-ray diffraction analysis, likely because only amorphous forms were present, but the lead form was nearly 100% bioaccessible in the final product. This suggests that the bhasma
process may actually increase the bioaccessibility of the lead starting material, most likely elemental lead, which is insoluble in water. Of note, Mahayograj Guggulu is the traditional Indian medicine most frequently associated with reported lead poisoning cases (Ernst, 2002
; Centers for Disease Control and Prevention, 2004
; Saper et al., 2008
In the present study we report a reasonably high concentration of arsenic (around 90 mg.kg−1
) in Mahayograj Guggulu (sample 11). This arsenic was likely introduced as part of a bhasma
, since arsenic minerals like orpiment and realgar are often incorporated into the bhasma
process (Thatte et al., 1993
). These minerals may also be contaminants of other metal starting materials. The arsenic speciation in this sample was primarily As(V)–O along with a solid As(III)–O compound and an As–S compound (likely remaining from added arsenic-sulfide mineral such as orpiment or realgar) (). The high proportion of oxidized (and likely soluble) species As(III)–O and As(V)–O (89%) resulting from a likely starting material of insoluble orpiment or realgar gives additional evidence that the bhasma
process changed the arsenic from a less soluble to a more soluble form. The speciation in starting materials and the end product naga bhasma
should be studied directly to further examine this point.
Differences in total arsenic and lead, as well as percent bioaccessibility of these two elements, were noted between results in the present study and those reported recently for a sample of Mahayograj Guggulu (total lead and lead bioaccessibility were lower in the previous study, and arsenic was not detected) (Jayawardene et al., 2010
). These differences probably reflect the heterogeneity of this sample from commercial sources, and the same heterogeneity probably exists for traditionally prepared preparations. Therefore, whether our findings with commercially prepared Mahayograj Guggulu are generalizable to such preparations requires further research.
Arsenic speciation was also determined in several other samples, chosen because their arsenic content is around or above 10 mg.kg−1 (). Most of these samples, including Yog-Raj (Yograj) Guggulu (samples 5, 36), Trifala Guggulu (sample 24), Mahasudarshan (sample 30), and Sugar Fight (sample 34) have not been classified as Rasa Shastra medicines, which means that they have no mineral ingredients. Consequently, the likeliest arsenic source is plant ingredients. The three other samples analyzed for arsenic speciation, Ayu-Hemoridi-Tone (sample 38), Shilajeet (sample 10) and Shilajit (sample 33), have been classified as Rasa Shastra medicines, indicating that they contain metals, minerals, or gems, although they are also derived from plant material (Shilajeet(jit) is made of “mineral pitch”, the dried exudate of the plant Asphaltum punjabinum from rock).
Plants have been observed to contain elevated arsenic concentrations when harvested from areas that have naturally or anthropogenically elevated soil arsenic concentrations, e.g., (Koch et al., 2000
) and some plants used in Ayurvedic medicines have been shown to contain arsenic (Singh and Garg, 1997
). Roots especially are susceptible to contamination, e.g., (Aldrich et al., 2007
), and if these were included in the compounding of the medicines, they might have contributed to the arsenic content. The speciation of the arsenic in the samples indicates that an As–S compound is found in all samples except for Ayu-Hemoridi-Tone (sample 38) but the quality of the spectra was not sufficiently high to identify the As–S compound with certainty (, Red χ2
values). As(III)–S compounds are commonly found in fresh and live plant samples using mass spectrometric (Bluemlein et al., 2009
) and XAS methods (Pickering et al., 2000
; Smith et al., 2008
), although these compounds appear to be relatively unstable to processing steps like harvesting, drying and aging in air (Smith et al., 2008
; Bluemlein et al., 2009
). In some plants, however, As–S compounds have been observed to survive air-drying and grinding steps (Mir et al., 2007
). Similar mild preparation techniques were likely used for all the medicines (e.g., cleaning, drying and grinding plants, aqueous extractions at 60–70 °C of guggulu), as described for Yogaraga Guggulu (Simha et al., 2008
). In the absence of the knowledge of any mineral forms of arsenic added to the products that have not been classified as Rasa Shastra
medicines, we propose that it is possible that the As–S species in these samples are derived from plants. This may be a possibility for Shilajeet (jit) (samples 10, 33) as well, but the possibility of the As–S compound as a mineral form, scraped from rocks that may have contained arsenic minerals, cannot be discounted.
In five samples, Yog-Raj Guggulu (sample 5), Mahayograj Guggulu (sample 11), Trifala Guggulu (sample 24), Mahasudarshan (sample 30), and Shilajit (sample 33), the AsV
compound present had a white line position that was 1.0 eV higher than solid KH2
(). Arsenic white lines that are approximately 1.0 eV higher than arsenate have been seen previously in dried plant and insect residues (Mir et al., 2007
; Andrahennadi et al., 2009
) and the compound with this energy has been identified as an octahedrally coordinated As (V)–glycerol compound (Andrahennadi et al., 2009
). When the As (V)–glycerol was included in the fittings, the higher energy compounds in the present study were tentatively identified as the glycerol compound. The presence of this compound may be attributable to the dried plant residues in the medicines.
When the bioaccessibility results are compared with the speciation results, it appears that percent bioaccessibility increases with the proportion of pentavalent arsenic () (n=9, r=0.82, p<0.05). The correlation is even better when As(III)–O is summed with As(V)–O (n=9, r=0.93, p<0.05). At the same time, a negative correlation is observed between the bioaccessibility and the proportion of the As–S species suggesting that these may be the arsenic species that are not bioaccessible () (n=9, r=−0.93, p<0.05). Thus the appearance of oxidized As(III)–O and As(V)–O in these medicines, either introduced as an ingredient or resulting from processing, may make the arsenic more available for uptake into the human body, where toxic effects can be exerted. Since it is difficult with XANES to distinguish As(V)–O as a soluble species, such as the potassium arsenate (KH2AsO4) used as a standard in the present study, from insoluble species such as scorodite (FeAsO4 · 2H2O), we cannot state with certainty that the As(V)–O species found in these samples are indeed the forms dissolved in the bioaccessibility test; further research involving XANES testing of residues from the bioaccessibility test would be required. No organoarsenic species were detected in any samples, although they may be present at very low concentrations below the technique’s detection limit.
Fig. 3 Percent arsenic species vs. percent bioaccessibility for As(V)–O species (sum of species matching KH2AsO4 +As(V)–glycerol),
As(V)–O+As(III)–O, and □ As–S, based on samples (n=9) analyzed by XANES. (more ...)
The implications of using the studied medicines were determined by comparing estimated daily intakes with acceptable daily intakes. Of the fourteen medicines included in the present study that previously exceeded the ANSI standard for lead in Saper et al. (2008)
, only five exceed this standard in . Likewise, the three medicines that exceeded arsenic standards in Saper et al. (2008)
no longer exceed any standards in the present work. However, one sample (sample 38, Ayu-Hemoridi-Tone) exceeds the ANSI arsenic standard in , but was not included in the Saper et al. (2008)
evaluation because its arsenic concentration was not detectable by the XRF method used. Incorporating bioaccessibility into the intake calculations therefore resulted in a decrease in the number of samples exceeding standards, compared with results using total concentrations.