Ayflegül GÜVENÇ*°, Gülsen KEND‹R*, Ayfle EKEN**, Ahmet AYDIN**
Evaluation of Inorganic Compounds of Erica L. Species (Ericaceae) Native to Turkey
Summary
Türkiye’de Do¤al Olarak yetiflen Erica L. Türlerinin (Ericaceae) ‹norganik Bilefliklerinin Tayini
Özet
Evaluation of Inorganic Compounds of Erica L. Species (Ericaceae) Native to Turkey
Native Erica species are widely distributed along the coasts of Turkey and include E. arborea, E. manipuliflora, E. bocquetii and E. sicula subsp. libanotica. The plant materials and their water extracts were digested in Microwave Acid Digestion System.
The important minerals of these plants (Zn, Cu, Fe, Ca, Mg, Pb, Cd, Mo, Mn, As) were determined by Atomic Absorption Spectroscopy (AAS) with Graphite Furnace System. The concentrations of Cd, As and Pb in these four Erica species were determined to be lower than the permissible levels as stated by WHO (World Health Organization).
Key Words: Erica arborea, Erica manipuliflora, Erica bocquetii, Erica sicula subsp. libanotica, trace elements.
Received : 10.04.2009 Revised : 24.08.2009 Accepted : 15.09.2009
Do¤al Erica türleri Türkiye k›y›lar›nda yayg›n olarak yetiflir. Bu türler, E. arborea, E. manipuliflora, E. bocquetii ve E. sicula subsp. libanotica’d›r. Bitkilerin kendileri ve sulu ekstreleri Mikrodalga asit dijestiyon sisteminde parçaland›. Bu bitkilerin önemli mineralleri (Zn, Cu, Fe, Ca, Mg, Pb, Cd, Mo, Mn, As) atomik absorpsiyon spektrometresinde (AAS) alev ve grafit tüp atomizasyon teknikleri kullan›larak tayin edildi. Bu dört Erica türünün Cd, As ve Pb miktarlar› WHO (Dünya Sa¤l›k Örgütü) taraf›ndan izin verilen s›n›rlar›n alt›nda tespit edildi.
Anahtar Kelimeler: Erica arborea, Erica manipuliflora, Erica bocquetii, Erica sicula subsp. libanotica, Eser elementler.
* Ankara University, Faculty of Pharmacy, Department of Pharmaceutical Botany, Ankara, Turkey
** Gülhane Military Medical Academy, Department of Pharmaceutical Sciences, Department of Toxicology, Ankara, Turkey
° Corresponding author e-mail: [email protected]
INTRODUCTION
The genus Erica L. (Ericaceae) is represented by more than 700 species in the world. It is mainly found in South Africa, but also in the Mediterranean and Western Europe.
This genus is represented by four species which only one taxon is endemic in Turkey. E. arborea L. and E.
manipuliflora Salisb. are very common in all coasts of Turkey; E. bocquetti (Peflmen) P. F. Stevens is an endemic species, and E. sicula Guss. subsp. libanotica (C.& W.
Barbey) P. F. Stevens has a rare distribution in Southwest Anatolia (Fig. 1) (1). According to the International Union for the Conservation of Nature and Natural Resources (IUCN) Red Data Book, E. bocquetii and E. sicula are vulnerable in Turkey (2). These species are referred to as
“funda”, “püren” or “süpürge çal›s›” in Turkey (3).
Herbal teas prepared from the aerials parts of E. arborea
and E. manipuliflora have been used as diuretic and astringent and in the treatment of urinary infections in Turkey (3,4). Five percent infusion of E. arborea is taken as one glassful after meals as a weight-loss measure5.
Erica species contain many active compounds such as flavonoids, anthocyanidols, coumarins and triterpenic compounds (6-11). Cytotoxic, anticarcinogenic, antiulcer, and antimicrobial activities of some Erica species were reported (12-16). The metal content in the leaves and stem tissues of E. andevalensis was determined by Rodriguez et al.(17) and concentrations were found to be in normal ranges.
The World Health Organization (WHO) survey indicated that about 70-80 % of the world’s population rely on non-
conventional medicine, mainly of herbal sources, in their primary healthcare (18). In recent years, many researchers have focused on some inorganic compound concentrations in the environment considered as the factors indispensable for the proper functions of living organisms19,20. These compounds are contained in enzymes and activate them, thereby influencing in an essential way biochemical processes in cells (20). However, many medicinal plants can have a toxic effect, particularly if they contain toxic elements such as lead (Pb), cadmium (Cd) and arsenic (As). There are no standards for medicinal raw plant materials, which establish a permissible level of inorganic compounds in such materials. WHO mentions the maximum permissible levels in raw plant material (plants used in therapeutics or food) as 1.0 mg/kg for As, 0.3 mg/kg for Cd and 10 mg/kg for Pb (20,21). We thus planned to observe both important minerals and toxic elements that could impact human health.
The aim of the present study was to study the mineral composition of native Erica species in Turkey using the Atomic Absorption Spectroscopy (AAS) with Graphite Furnace System. For this purpose, calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), molybdenum (Mo), zinc (Zn), As, Cd, and Pb were investigated in raw plant materials and aqueous extracts of four Erica species.
EXPERIMENTAL
Plant Material
Plant materials were collected in the flowering season from various locations in Turkey. During the collection of materials, aerial parts were taken for all species. Plant materials were dried at room temperature. Voucher
specimens are deposited in the AEF (Ankara University Faculty of Pharmacy Herbarium) in Turkey. Locations of the investigated plant samples are given in Table 1.
Extraction
Aqueous extracts were prepared from aerial parts of Erica species because these drugs are used in infusion form in traditional medicine in Turkey. For each species, 20 g powdered aerial parts were extracted by refluxing with distilled water (100 ml) for 30 minutes (min) followed by filtration. The resulting extracts were then freeze-dried.
Analysis of Inorganic Compounds
0.5 g raw plant materials and lyophilized products for mineral analysis were subjected to acid digestion with HNO3 65% (Merck) and H2O2 30% (Merck) mixture in microwave digestion unit (Milestone, MLS 1200 Mega) and analyzed using a Varian 30/40 model atomic absorption spectrophotometer. As, Pb, Cd, Mn, and Mo levels were determined by electrothermal atomization techniques (Graphite Furnace System) (Varian, GTA-96). Cu, Fe, Ca, Mg and Zn levels were determined by Flame Atomic Absorption System (Varian, PSC-56). Atomic absorption parameters in this study are given in Tables 2 and 3.
Validation parameters of the atomic absorption spectrometric analysis are given in Table 4.
RESULTS and DISCUSSION
In this study, two macroelements (Ca, Mg), three toxic elements (As, Cd, Pb) and five microelements (Cu, Fe, Table 1. Locations of the studied Erica species
SPECIES LOCATIONS
E. arborea L. A3 Bolu: Akçakoca, Alt›nçay village,
Çengel river around, 300 m, 14.viii.2003, G. Kendir ( AEF 23010! )
E. manipuliflora Salisb. C6 Hatay: Dörtyol, Topaktafl Y., Sar› su around, rocky slopes, North-west, 1100 m, 7.ix.2003, G. Kendir ( AEF 23013! )
E. sicula Guss. C3 Antalya: Between Antalya-Kemer,
Beldibi, Göynük river, in walley, rocky slopes, 42 m, 10.v.2003, R. S. Göktürk
& G. Kendir ( AEF 23009! ) E.bocquetii (Peflmen ) P. F. Stevens C2 Antalya: Elmal›, Ç›¤l›kara, Tekke
village , Topbafl place, clearings Cedrus libani forest, calcareus rocks, 1750 m, 19.vii.20003, A. and U. Güvenç & R. S.
Göktürk ( AEF 23016! )
Figure 1 : Distribution of Erica species in Turkey. ♥ E. arborea, ♣ E.
manipuliflora, ß E. bocquetii, ♦ E. sicula subsp. libanotica.
Mn, Mo, Zn) were determined in the aerial parts of these species and their aqueous extracts. Element concentration results of the Erica species as determined from the raw materials and their lyophilized extracts are shown in Tables 5 and 6, respectively.
The Food and Nutrition Board of the U.S. National Academy of Sciences has recommended 1.5-3.0 mg estimated value as a safe and adequate daily intake of Cu for adults (22).
In the four plants and their infusions, Cu ranged between 1.63-5.76 µg/g. 5.76 µg/g Cu can provide a maximum 0.2%
of the daily Cu requirement. Fe is an essential element due
to its function in many diverse processes in plants and human health. Fe content of the Erica species and their water extracts ranged between 36.73-57.06 and 39.3-142.6 µg/g, respectively. 142.6 µg/g Fe can provide a maximum 1% of the daily Fe requirement. Zn was observed in the whole material in the range of 7.50-32.2 µg/g. 32.2 µg/g Zn can provide a maximum 0.2% of the daily requirement for Zn. In this study, the highest concentrations of Cu, Fe and Zn were determined in the raw plant materials of E.
manipuliflora and their infusions.
While the highest Mn concentration was determined in the raw materials of E. manipuliflora and in infusions of E.
arborea, the lowest Mn concentration was observed in E.
sicula subsp. libanotica.
The lowest Mo concentration was determined in the raw materials and water extract of E. arborea, whereas the highest concentration was observed in the raw plant material of E. manipuliflora and in the water extract of E. sicula subsp. libanotica.
The concentration of macroelements Ca and Mg in the raw plant materials of Erica species were determined in the ranges of 2317-11287 µg/g for Ca and 1096-3105 µg/g for Mg. Their water extracts were observed in the range of 6930-12248 µg/g (10-fold of daily need for Ca) and 4114- 6507µg/g (2% of daily need for Mg), respectively. The highest Ca was determined in E. sicula subsp. libanotica and E. bocquetii, and the highest Mg was observed in E.
sicula subsp. libanotica and E. manipuliflora. In a previous work, Penuelas et al.(23) (2001) reported the lowest concentrations of Ca and the highest concentrations of Fe Table 2. Graphite furnace atomic absorption system
Elements Wavelength (nm) Ash temperature (˚C) Atomization temperature (˚C)
As 193.7 800 2300
Pb 217.0 400 2000
Cd 228.8 300 1800
Mn 279.5 800 2400
Mo 313.3 1200 2650
Table 3. Flame atomic absorption system
Elements Wavelength (nm) Gas mixture
Cu 327.4 Air - acetylene
Fe 372.0 Air -acetylene
Ca 422.7 Nitrous oxide - acetylene
Mg 285.2 Air - acetylene
Zn 213.9 Air - acetylene
Table 4. Validation parameters of atomic absorption spectrometric analysis
Cu 0.18 µg/ml
98 Fe 0.19 µg/ml
97 Mn 0.011 ng/ml 94
Mo 0.98 ng/ml
93 Ca 0.097 µg/ml 98
Mg 0.018 µg/ml 98
Zn 0.048 µg/ml 97
Pb 0.99 ng/ml
91 Cd 0.051 ng/ml 92
As 2.35 ng/ml
91 Detection Limit
% Recovery
Elements Validation
Parameters
Table 5. Content of elements in raw materials of Erica species
Erica arborea (n=5) 4.70 ± 0.95 49.02 ± 7.51 23.56 ± 5.49 0.43 ± 0.095 2317 ± 185 1937 ± 176 12.20 ± 1.31
0.66 ± 0.09 0.04 ± 0.006 0.41 ± 0.045
E. bocquetii (n=5) 1.63 ± 0.02 42.58 ± 7.12 15.39 ± 4.89 1.01 ± 0.12 8457 ± 285 1096 ± 98 9.20 ± 1.45 0.49 ± 0.08 0.04 ± 0.004 0.28 ± 0.031
E. manipuliflora (n=5) 4.17 ± 0.86 57.06 ± 10.50
31.67 ± 8.26 3.07 ± 0.45 4036 ± 175 2024 ± 138 15.20 ± 2.21 0.96 ± 0.07 0.07 ± 0.003 0.37 ± 0.041
E. sicula subsp.
libanotica (n=5) 3.19 ± 0.89 36.73 ± 8.26 12.14 ± 2.18 1.23 ± 0.29 11287 ± 368 3105 ± 216 7.50 ± 1.18 0.63 ± 0.07 0.06 ± 0.004 0.48 ± 0.034 Element
(µg/g)
Cu Fe Mn Mo Ca Mg Zn Pb Cd As
Raw plant materials
Table 6. Content of elements in aqueous lyophilized extracts of Erica species
Erica arborea (n=5) 2.54 ± 0.65 135.8 ± 19.8 63.43 ± 11.13 0.67 ± 0.10 9620 ± 125 4114 ± 125 26.30 ± 4.23 0.19 ± 0.021 0.02 ± 0.001 0.44 ± 0.046 Element
(µg/g)
Cu Fe Mn Mo Ca Mg
Zn Pb Cd As
Lyophilized materials E. bocquetii
(n=5) 3.81 ± 0.88 76.1 ± 11.4 46.65 ± 9.45 1.39 ± 0.23 6930 ± 110 4252 ± 135 27.50 ± 5.23 0.52 ± 0.026 0.05 ± 0.001 0.80 ± 0.015
E. manipuliflora (n=5) 5.76 ± 0.95 142.6 ± 18.56
39.62 ± 8.82 1.44 ± 0.21 7115 ± 133 6507 ± 198 32.20 ± 6.58 1.03 ± 0.046 0.02 ± 0.001 0.10 ± 0.010
E. sicula subsp.
libanotica (n=5) 4.36 ± 0.75
39.3 ± 6.8 35.73 ± 8.56
2.14 ± 0.35 12248 ± 215
4882 ± 146 23.60 ± 5.51 0.75 ± 0.038 0.07 ± 0.002 0.29 ± 0.021
and Mn in E. arborea. Our results are in accordance with that study.
Concentrations of As (0.10-0.80 µg/g), Cd (0.02-0.07 µg/g) and Pb (0.19-1.03 µg/g) were determined in all these materials. These results were lower than WHO’s reported maximum permissible levels in raw plant materials for As, Cd and Pb (as 1.0, 0.3 and 10 mg/kg, respectively) (20,21.) CONCLUSION
Medicinal plants have been used for years to cure a multitude of diseases (18,19.) It is well known that some elements, based on their concentration, can play different roles in plant life and human health (19.) Furthermore, the content of essential elements in plants is conditional, being affected by the geochemical characteristics of a soil and by the ability of plants to selectively accumulate some trace elements. Medicinal plants should be picked in the areas without any contamination sources (20.) However, raw medicinal plant materials can be collected from everywhere in developing countries. Collected plant materials should be frequently controlled for toxic elements to guarantee safety of the medicinal plants.
The aim of our study was to contribute to the available information about mineral composition of the four species of Erica L. both growing and being used as herbal tea in Turkey. Complete procedures, sample preparation and measurements were validated. According to our results, all species have a low amount of toxic elements such as Pb, As and Cd. This result is in accordance with a previous study (17.) However, E. bocquetii is an endemic species, and this species was classified as “vulnerable (VU)” by Ekim et al. (2) (2000) in Turkey. Thus, only E. manipuliflora was found to be suitable as an herbal tea because the mineral concentrations in this species are within normal ranges for daily mineral supplementation. E. bocquetii is a beautiful plant; therefore, we can recommend it for culturing and landscape. According to our results, E.
arborea is not suitable as an herbal tea, because it has been indicated as having the lowest mineral element contents.
This is the first investigation regarding the mineral composition of the Erica species in Turkey. Results of this current work will form a basis for the future studies in this
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