Profile of Some Trace Elements in Selected Traditional Medicines used for Various Aliments in Ebonyi State, Nigeria

Background: Traditional medicines have been in use before conventional drugs in Nigeria and Ebonyi State in particular. The use has been on the increase of recent no matter the levels of education and exposure due to the efficacy. They are sometimes considered as dietary supplements once they are found to be rich in one or more elements. The knowledge on concentrations of these trace elements is important for determining the effectiveness of the plants in treating various ailments so as to understand their pharmacological actions. Aim of Study: This study was conducted to investigate the profile of certain trace elements having therapeutic properties related to various ailments as found in herbal medicines sold in Ebonyi State. Study volunteers and Methods: The herbal medications were found in various locations in Ebonyi State, Nigeria where they were displayed for sale. The mineral elements in 20 herbal medications under study such as metal ions copper, zinc and manganese were determined using atomic absorption spectrophotometer of the AA220FS Buck scientific model, air – acetylene flame at a flame temperature of 2600ºC and flame height of 6mm at varying wavelengths of each metal ions - Cu (324.8nm), Zn (213.9nm), and Mn (279.5nm). Results: The highest mean concentration of copper among the herbal medications studied was found in African Iba (5.64±4.19mg/L), followed by Restorative tonic (5.26±3.78mg/L). The least concentration of copper was found in Golden seed (0.38±0.54mg/L). For zinc, the highest concentration of zinc was found in Divine roots (101.64±3.73mg/L), followed by Zaram pile (96.68±5.59mg/L) and least in Deep roots (31.54±4.04mg/L). Manganese was found to be highest in Ukwara (17.61±5.39mg/L), followed by Golden seed (16.45±5.87mg/L) and least in Bitter Extra (1.43±0.42mg/L). Conclusions: It was observed that all the medications studied had zinc, manganese and copper. Trace elements were found to be present in all the herbal medications studied and in amounts sufficient to meet the required daily allowance (RDA). The average concentrations of Cu and Mn were below the tolerable upper intake levels while that of Zinc were seen above this level.


Introduction
Medicinal plants are widely used all over the world and, according to the World Health Organization (WHO), for many millions of people, traditional medicines, including herbal medicines, are the main source of health care and, sometimes, the only source of care [1]. Their demand is growing worldwide both in developing and industrialized countries, as a complementary way to treat and to prevent diseases [2][3][4]. Medicinal plants play an important role in traditional medicine and are widely consumed as home remedies [5]. Thus, it can safely be presumed that a major part of traditional therapy involves the use of plant extracts or their active principles [6]. The past decade has seen a significant increase in the use of herbal medicine due to their minimal side effects, availability and acceptability to the majority of the populace especially in third world countries. Consumption of these plants contributes to the intake of minerals, essential and non essential by the people including infants and the elderly [7]. Many metabolic disorders resulting in human ailments have experimentally been shown to be managed by traditionally used medicinal plants.
Among the factors attributing to the healing potential of these medicinal plants, are the trace elements present in them [8].
However, it is widely known that in higher concentration, trace elements in medicinal plants are responsible for their toxicity.
Besides being used for the treatment of diseases, these traditional medicinal medications are also used as dietary supplements once they are found to be rich in one or more elements (Table 1).
Elemental content in medicinal plants can vary in a wide range, depending on factors such as soil geochemical characteristics, atmospheric deposition and the ability of each plant species to selectively accumulate some of them [9,10]. The determination of major, minor and trace elements in medicinal plants and their impacts on human health are also of great importance due to the growth of environmental pollution that directly affects the plants and, therefore, their phytotherapics. Besides, being essential in the living system, the elements can be at the same time toxic, when at concentrations beyond those necessary for metabolic functions [11][12][13]. In the present study, elemental analysis of some selected traditional medicinal medication was carried out using atomic absorption spectroscopy.

Sample collection
Three samples were collected each for twenty (20) different herbal medications shown in Table 1 The sixty (60) herbal medications were made for in-vitro administration and were purchased from various locations in Ebonyi State. The samples in liquid formulation were contained in plastic or bottle containers and contained such information like herbal product name, manufacturers name and address, production and expiration dates, NAFDAC enlisting and batch numbers. All herbal medications studied were produced and processed in Nigeria. Parameters analyzed were zinc, copper and manganese.

Trace elements determination by AAS as described by Vogel [14]
The metal ions copper, zinc and manganese were determined using atomic absorption spectrophotometer of the AA220FS Buck

Sample preparation and digestion using wet digestion technique
The bottle or container containing the liquid sample was first shaken to obtain homogeneity. The digestor was then switched on and allowed to heat up to set temperature of 350 degree Celsius.
10ml of liquid sample was measured into a digestion tube whereas 20ml of nitric acid and sulphuric acid was added to the sample in the tube in the ratio 2:1. The tubes were then placed in the digestion block already at 350 degree Celsius and the digestion process allowed for 20min. The digest was then allowed to cool and later transferred into a measuring cylinder. This is followed by dilution of the digest with distilled water to a set volume of 25ml with the prepared digests taken to Atomic Absorption Spectrophotometer (AAS) for trace element determination.

Procedure for analysis
The proper hollow cathode lamp for the analysis was first chosen and the lamp was allowed to warm up for a minimum of 15 minutes. During this period, the instrument was aligned, and the monochromator was positioned at the correct wavelength.
The proper monochromator slit width was selected, and the The curve corrector was set to read out the proper concentration.
The samples were then aspirated and the concentrations determined directly from the readout system of the instrument.
The actual concentration of the element was then mathematically derived from the formula shown below:     Table 2 shows the mean level of mineral elements in herbal medications found in various locations in Ebonyi state, Nigeria. Table 3 shows the frequency and concentration data of the trace elements in the herbal medications. It was observed that all the medications studied had zinc, manganese and copper (100% incidence rate). The mean level of Cu in all samples was 3.57±0.12mg/L (Table 3) which is lower than its recommended tolerable upper intake levels (10mg/day) and consumption of the herbal medications will not pose an immediate health risk.

Discussion
The mean range of Cu is 2.20mg/L-8.60mg/L and the highest concentration of copper among the herbal medications studied was found in African Iba (5.64±4.19mg/L); this was followed by Restorative tonic (5.26±3.78mg/L). The least concentration of copper was found in Golden seed (0.38±0.54mg/L) (  [17,18]. The metals can be beneficial or harmful depending on their levels in the body. While copper forms parts of most body enzymes regulating various body metabolism like hemoglobin synthesis, energy production and many oxidation-reduction reactions., Zinc is required for normal growth, DNA synthesis and proper thyroid function. Utensils, polluted soil and fumigants used to preserve the herbal plant from destruction have been identified as sources of copper contamination [20].
Accidental contamination can occur during manufacture and when medicinal herbs are grown in polluted soil [19]. Copper toxicity may result in skin discoloration, vomiting and liver damage while zinc toxicity can result in deleterious effect on the immune system and reduced copper level in the body. Zinc deficiency can lead to growth retardation.

Conclusion
The present study revealed the three elements of Zn, Cu, and Mn were found in all the herbal medications. The average concentrations of Cu and Mn were below the tolerable upper intake levels while that of Zinc were seen above this level. The high Zn content observed in majority of the samples has the potential of posing health risks to consumers of these medications. Therefore, due to the high patronage of these herbal products by the populace, there is need for their constant monitoring by the development of routine programmes in order to safeguard their safety since unsupervised use could have cumulative effect, which in turn may lead to their toxicity.