Determination of selenium content in aqueous extract of medicinal plants used as herbal supplement for cancer patients

The chemical constituents in medicinal plants (MPs), including elements, are partially responsible for their medicinal and nutritional properties as well as toxic effects. This research aimed to monitor selenium (Se) contents in aqueous extract of MPs used for treatment of cancer and different diseases. In present work the Se in MPs was extracted in aqueous media by microwave-assisted (ME) and conventional extraction (CE) methods. The total and residual Se in MPs were determined, prior to microwave-assisted acid digestion. The Se in aqueous extracts and digests were analysed by electrothermal atomic absorption spectrometry. The optimum extractable Se in MPs were obtained by ME and CE, required 2 and 40 min, respectively. Precision and accuracy of the methodologies were checked by standard addition method. The Se contents in aqueous extract of MPs were found in the range of 1.09–2.23 μg/g corresponding to 21–33% of total Se contents. The daily intake of Se from aqueous extract of MPs as recommended by herbalist (10 g of plant material) was found in the range of 20–40% of daily requirement.