The objective of this study was to investigate the content of essential elements in medicinal plants in the Kingdom of Saudi Arabia (KSA). Five different medical plants (mahareeb
Medicinal plants are used by millions of people around the world. The usage of medicinal plants was mainly in primary healthcare by most of the users [[
Copper is found in various human transcription factors and enzymes and is considered as an important essential trace element. However, excessive intake of copper can lead to liver damage and Wilson’s disease. Wilson’s disease results from accumulation of free copper in the liver, brain, and kidney [[
Iron is well established as an essential element and is a component of haemoglobin and is present in several human enzymes. Iron is present in high levels in red blood cells and muscle tissue. High doses of iron can cause hepatotoxicity. Acute liver failure has been reported after an overdose of ferrous sulphate in a young adult [[
Manganese is an important element and is a constituent of metalloenzymes that oxidize cholesterol and fatty acids [[
Selenium is an antioxidant and is involved in the biosynthesis of thyroid hormones. Selenium plays an important role in the immune system and can help suppress the progression of HIV to AIDS [[
Zinc is an essential element, and cellular zinc promotes homeostatic control to avoid accumulation of surplus zinc. Exposure to excessive zinc results in copper deficiency and cell apoptosis. In addition, zinc deficiency has been linked to a suppressed immune response [[
Subramanian et al. [[
Different essential elements with levels (mg/kg), including Fe (54.2–231), Zn (4.7–19), Cu (3.2–10.5), and Mn (8.8–490), were previously determined in herbs and spices from Saudi Arabia [[
Essential elements including Fe, Zn, Mn, and Cu were determined in six medicinal plants (Zizyphus jujube, Eugenia jambolana, Coccinia indica, Citrus acida, Ocimum sanctum, and Trigonella foenumgraecum) from India. The concentrations (mg/kg) were in the following ranges: Fe 123–760, Zn 20.4–620, Mn 17.5–426, and Cu 0.4–35.5. The study concluded that these plants were rich in one or more of the investigated elements [[
The aim of this study was to assess the levels of essential elements in local medicinal plants from the KSA using ICP-MS. This study is necessary, because the studied plants are potential source of micronutrient elements such as Fe, Cu, Zn, Mn, and Se, which are considered as anti-oxidant elements as well. These medicinal plants could make a contribution to intake of essential elements based on their use to treat different diseases. The second purpose was also to calculate intake of each element per dose of each plant.
Toxic elements (Al, Pb, As, and Cd) were already determined in the five medicinal plants mahareeb (Cymbopogon schoenanthus), sheeh (Artemisia vulgaris), harjal (Cynanchum argel delile), nabipoot (Equisetum arvense), and cafmariam (Vitex agnus-castus). Therefore, all subsections related to sample collection and preparation, sample digestion, elemental measurements by using ICP-MS, chemicals reagents, and analytical method were the same as the previous study [[
The LODs were calculated after measuring 1% HNO
For quality control, continuing calibration verification (CCV) analysis was used for each run. The CCV was performed by testing 20 μg/L of a mixed standard of all measured elements after each set of five samples. A sample was spiked with mixed standards (20 μg/L) of analysed elements, and the recovery was calculated for each element.
Statistical analysis was performed on all plant samples using the two-sample t-test in Excel (paired-samples t-test). Differences were determined to be statistically significant if P<0.05 with 95% confidence level, among measured elements, and between washed and unwashed plants. SPSS version 22 was used, comparing means using one-way ANOVA, to investigate differences among the plant species for the individual elements with significance level of 0.05.
The LODs (μg/L) were as follows: Fe 0.34, Cu 0.03, Se 0.07, Zn 0.17, and Mn 0.04. The LOQs (μg/L) were as follows: Fe 1.12, Cu 0.08, Se 0.24, Zn 0.56, and Mn 0.12.
The average recoveries of the CCV for each element in one session after each set of five measurements were as follows: Fe 79.57%, Cu 91.57%, Se 88.20%, Zn 90.50%, and Mn 84.90%. The recoveries of the spiked sample with the five elements were as follows: Fe 125.08%, Cu 83.54%, Se 94.39%, Zn 92.82%, and Mn 99.27%.
The concentrations (μg/g) of the five measured elements in unwashed and washed plant samples are shown in Table 1. Triplicate measurements n=3 for each sample were carried out. In general, washed plants showed lower concentrations than unwashed plants for all elements measured. This indicates that washing removed essential elements from the plants. In some cases, the removal was as much as 80% of the original concentration in the unwashed sample. The reason for washing the plants was to investigate the impact of washing on the level of original concentrations of the essential elements. We can derive from these results that rigorous washing will remove high percentages of essential elements in plants in the filtrate. Therefore, the users who drink the filtrate can ingested the removed percentage, which can be source of the essential elements in such plants. The level of essential elements in filtrate can be calculated as a difference between unwashed and washed plants (Table 2). It is noteworthy that nabipoot showed high levels of Mn, Zn, and Cu in the washed sample, although contribution from water (deionized water) used for washing was negligible. Moreover, only harjal and cafmariam showed the same trend for Cu, and this could be caused by a contamination. However, other plants were not affected by such a trend.
Concentrations (μg/g) of the five essential elements measured in unwashed, washed, and infusion in the five medicinal plants (n=3; mean ± SD).
Elements Mahareeb Sheeh Harjal Nabipoot Cafmariam Unwashed plants (μg/g) Fe 1757.9 ± 2.8 193.4 ± 10.6 399.7 ± 6.7 859.8 ± 0.8 580.4 ± 9.0 Cu 21.8 ± 0.1 18.0 ± 0.1 20.6 ± 0.1 21.7 ± 0.0 11.3 ± 0.1 Zn 17.7 ± 0.2 32.7 ± 0.8 19.7 ± 0.3 17.1 ± 1.2 15.4 ± 0.3 Se 0.3 ± 0.0 0.1 ± 0.0 0.31 ± 0.0 0.92 ± 1.7 0.13 ± 0.0 Mn 121.5 ± 0.9 33.0 ± 0.8 143.7 ± 2.1 77.0 ± 1.6 23.6 ± 0.4 Washed plants (μg/g) Fe 614.3 ± 12.6 160.1 ± 4.3 248.2 ± 3.5 576.4 ± 5.7 237.3 ± 1.8 Cu 10.0 ± 0.1 17.49 ± 0.0 37.66 ± 0.1 24.0 ± 0.1 52.1 ± 0.2 Zn 14.4 ± 0.3 8.0 ± 0.1 12.8 ± 0.2 21.0 ± 0.2 5.0 ± 0.1 Se 0.1 ± 0.0 0.1 ± 0.0 0.2 ± 0.0 0.6 ± 0.0 0.1 ± 0.0 Mn 98.4 ± 0.1 28.4 ± 0.7 110.6 ± 1.5 94.8 ± 1.6 13.3 ± 0.2 Measured concentration (μg/g) in infusion of each medical plant after boiling with deionized water Fe 1.4 ± 0.0 2.3 ± 0.0 3.4 ± 0.1 2.3 ± 0.0 1.3 ± 0.4 Cu 0.6 ± 0.0 1.0 ± 0.0 0.7 ± 0.0 0.4 ± 0.0 0.4 ± 0.0 Zn 2.1 ± 0.1 4.3 ± 0.1 5.8 ± 0.1 4.7 ± 0.1 1.9 ± 0.0 Se 0.1 ± 0.0 0.1 ± 0.0 0.1 ± 0.0 0.4 ± 0.0 0.03 ± 0.0 Mn 14.8 ± 0.2 13.0 ± 0.3 16.7 ± 0.2 9.0 ± 0.3 1.6 ± 0.0
Calculated levels (mg) of essential elements measured in unwashed and washed plants, based on the commonly used quantity of each plant in one dose (g), and calculated dosage of exposure (μg) in infusion.
Elements Mahareeb Sheeh Harjal Nabipoot Cafmariam Unwashed plants (mg) Fe 5.86 0.72 2.95 3.09 2.52 Cu 0.073 0.081 0.152 0.078 0.049 Zn 0.059 0.147 0.146 0.061 0.067 Se 0.00083 0.00063 0.00229 0.0033 0.00056 Mn 0.405 0.149 1.061 0.276 0.102 Washed plants (mg) Fe 2.05 8.72 1.83 2.07 1.03 Cu 0.033 0.079 0.278 0.086 0.086 Zn 0.0478 0.0359 0.0945 0.0755 0.0215 Se 0.00017 0.0004 0.00163 0.00226 0.00035 Mn 0.3278 0.1275 0.8172 0.3401 0.0578 Calculated dosage of exposure (μg) in infusion of each medical plant after boiling with deionized water Fe 4.63 13.39 25.22 8.36 5.40 Cu 1.92 4.48 5.00 1.51 1.83 Zn 7.04 19.47 42.65 16.72 8.23 Se 0.22 0.57 0.68 1.55 0.14 Mn 49.17 58.24 123.15 32.33 6.72
Mahareeb (Cymbopogon) showed higher concentrations of the measured elements compared with the other plants. The levels of elements for all medicinal plants were as follows: Fe > Mn > Zn > Cu > Se. The increasing order of the plants based on the concentrations of each individual element as follows:
Thus, mahareeb has a tendency to the highest contents of elements, whereas cafmariam has a tendency to the lowest in most of the cases.
Based on comparison among the five plants, Fe contents in all plants showed significant difference (P<0.05) from each other. Mahareeb reported the highest value, and sheeh had the lowest level. From the statistical analysis for Cu levels among the five plants, mahareeb and nabipoot showed no significant difference (P>0.05), while the other three plants showed significant difference (P<0.05) among each other. Mahareeb reported the highest value, and cafmariam had the lowest level.
Based on the outcome of the statistical analysis among the five plants regarding the Mn content, there were significant differences (P<0.05) among all plants. Harjal reported the highest value for Mn, and cafmariam had the lowest level. Moreover, the statistical analysis regarding Zn levels in the five plants showed no significant difference (P>0.05) between mahareeb and nabipoot. However, the other three plants showed significant difference among each other. Sheeh reported the highest value, and cafmariam had the lowest level. The statistical analysis related to Se levels among the five plants showed significant difference (P<0.05) between mahareeb and nabipoot. No significant difference (P>0.05) was shown among the rest. Nabipoot had the highest value, and cafmariam had the lowest level. A significant difference (P<0.05) was observed in the levels of most measured elements between the washed and unwashed plants.
Washing removed a high percentage of Fe from all plants (33%–65%). High percentages of all elements in the range 19%–80% were removed from mahareeb by washing, compared with all other plants. Nabipoot showed the lowest percentage of elements removed by washing (0%–51%), compared with all other plants.
Based on personal communications with consumers and retailers, the quantity of each plant used in one dose is as follows: harjal 7.39 g, nabipoot 3.59 g, mahareeb 3.33 g, sheeh 4.49 g, and cafmariam 4.33 g. The quantity of each plant was calculated as an average of few small bunches. We calculated the quantities of each element contained in each dose of the medical plants in this study. The doses shown above for each plant were multiplied by the concentration of each measured element (Table 1), using the following equation: D (g) × C
Provisional maximum tolerable daily intake (PMTDI) of essential elements (Fe, Se, Zn, Mn, and Cu).
Number Element PMTDI Reference 1 Zinc (Zn) 1 mg/kg bw per day (70 mg/day∗) [21] 2 Copper (Cu) 0.5 mg/kg bw per day (35 mg/day∗) [21] 3 Selenium (Se) 70 μg/day for adults$ [7] 4 Manganese (Mn) 3 mg/day for adults$ [6] 5 Iron (Fe) 11 mg/day£ [8]
∗Calculated value based on PMTDI, equivalent to mg/day for a 70 kg person;
The investigated medicinal plants in this study are a source of the essential elements Fe, Cu, Zn, Se, and Mn. Essential elements are important for human health [[
Previous studies have been conducted to determine the levels of essential elements in medicinal plants. In Saudi Arabia, the element contents in various medicinal plants (different from this study) were already determined [[
The levels of trace elements, including Cu, Fe, Zn, Mn, and Se, have been determined in Chinese herbal medicines used for relieving heat [[
The results from a recent study [[
Another recent study [[
A study [[
From our previous study [[
We conclude from this study that medicinal plants are an important source of essential elements, such as Fe, Mn, Zn, Cu, and Se. Fe and Mn were the elements in the highest concentrations in all plants, with Se having the lowest concentration in all plants. In general, mahareeb contributed to higher levels of the essential elements compared with all other plants, while cafmariam reported the lowest levels of the essential elements. The washing process removed a percentage of the essential elements from all investigated plants. Infusion of all plants was measured, and calculated intake levels of essential elements per dose were below the recommended daily intake levels set by the WHO and EFSA.
The author declares that there are no conflicts of interest.
The author extends his appreciation to the Deanship of Scientific Research at King Khalid University for funding this work through the research group program under Grant no. R.G.P.1/7/38.
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By Eid I. Brima