Elemental Composition of Motherwort Tinctures Prepared by Various Extraction Methods

INTRODUCTION. Herbal extraction products are commonly used in medical practice. Elemental impurities is one of their key quality indicators. Process technology is among the factors influencing the final product’s composition. Transfer specifics of elements, including heavy metals and As, from the initial plant material into extraction-based dosage are poorly highlighted.

AIM. This study aimed to assess the extraction of elemental impurities from medicinal plant materials into tinctures extracted by different methods.

MATERIALS AND METHODS. The study object was motherwort herb used for the industrial production of tinctures (manufacturer — OAO Flora Kavkaza). Tinctures were prepared under laboratory conditions using fractional maceration, ultrasound-assisted extraction, and vortex extraction. The elemental composition of the initial plant material and the obtained tinctures were analysed by inductively coupled plasma mass spectrometry (ICP-MS) using Agilent ICP-MS 7900.

RESULTS. Thirteen elements (V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Sr, Cd, Tl, Pb) were identified in the motherwort herb and its tinctures; Hg was not detected. Elemental concentrations in the initial raw material ranged from 0.007 to 121.098 mg/kg, whereas the toxic elements (Pb, Cd, As) complied with compendial requirements. In the tinctures, the heavy metals did not exceed 1.25 mg/kg; Zn, Cu, and Mn were present in higher concentrations, while Tl and Cd were found in minimal amounts. Potential intake of elements within the studied extracts was assessed, as well as their medical safety. The transfer rates of heavy metals and arsenic from the raw material into the obtained tinctures were calculated; for most elements, they did not exceed 46%. It was established that Zn was extracted into all test tinctures in the highest quantities, while Cd was transferred in the smallest amounts. When using fractional maceration, Zn, Ni, Cu, and Tl entered the tinctures in the highest quantities; vortex extraction resulted in the highest transfer of V, Cr, Co, and Sr. Ultrasound-assisted extraction resulted in the lowest amount of heavy metal impurities entering the solution.

CONCLUSIONS. The patterns of elemental transfer into hydroalcoholic extracts with different extraction methods were studied using motherwort tinctures as an example. It was established that fractional maceration and vortex extraction yields tinctures with a higher content of essential elements, whereas the use of ultrasound-assisted extraction results in minimum concentrations of toxic heavy metal impurities (Pb, Cd) and As.

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