Calcium and Magnesium Contents in Three Hypericum L. Species from Turkey

Introduction

It is important to report the quality values of medicinal plants. ¹ Hypericum L. that has 400 species in the world and 96 species in Turkey has grown in Europe, Asia, North Africa, and America. ^{2 –4} Hypericum species have antidepressant, analgesic, spazmolytic, anti-inflammatory, antiviral, and wound healing effects. ^5,6 As well as the counted effects, in Turkey, Hypericum species are used for its antiseptic, antihelmentic, antibacterial, and hepatoprotective effects. ^7,8 Although clinical trials give contradictory results, nowadays methanolic extracts of moderate forms are used as an alternative to classic antidepressants, with a favorable side effect profile. ^5,9,10

Magnesium (Mg) is an essential element for the nervous system. The citrate salt of Mg called as the antistress mineral is used to calm nerves and promote sleep and proper digestion. ¹¹ Mg deficiency increases sensitivity of physiological damage produced by stress. Psychological stress affects the intracellular Mg level. Mg concentration increases in extracellular space, urinary excretion is increased, and Mg in body is diminished. ¹²

Ion concentration is very important for living organisms. In living cells, calcium (Ca) ions are usually kept outside the cells and Mg ions are kept inside the cells. Several studies have shown that stress increases the level of Ca inside cells and accordingly the internal Mg:Ca ratio in the cells changes. ¹³ The changes in this ratio is so important. Although these two elements are similar in chemistry, biologically their functions and reactions are totally different. They act in the body as opposite to each other. Such as Ca excites nerves and Mg calms them down; Ca contracts muscles and Mg relaxes them. ¹³

A similar effect is seen in wound healing. People who consume Mg at low levels have been exposed to emotional stress-related heart disease. ^{13 –17} Depression is one of the major symptoms of Mg deficiency in the body. ^{18 –20}

The purpose of this study is to investigate Mg and Ca levels of three Hypericum species grown in Turkey. These data can help us to discuss the relationship between the antistress properties and Mg-Ca contents of the plants which are collected from western region of Turkey.

Materials and Methods

Results and Discussion

The validation parameters were analyzed for validity of the method that was used for the Ca and Mg content analyses of Hypericum sp. ²⁷

Linearity is one of the parameters for validation of the method. A 1000 mg L⁻¹ standard stock solution of Ca and Mg is used for the calibration curves of the analyses. The appropriate dilutions are done to obtain 0.2 to 1 mg L⁻¹ concentration range. Five different concentrations of the standard were prepared in this range for three times. Equation of the curve, correlation coefficient (r), and standard errors of the curve were found by y = 0.2409X + 0.0022, y = 0.0351X – 0.001 and r ²  = 0.9995, r ²  = 0.9951 for Mg and Ca, respectively, after regression analysis in 99% levels. ^{27 –29}

The concentration of 0.6 mg L⁻¹ Ca and Mg standard solutions are analyzed five times each to calculate the precision of the method. The relative standard deviation values of the study were less than 1%. SRM 1572 obtained from NIST is used for calculating accuracy of the method. The SRM has 5.800 ± 0.300 μg g⁻¹ Mg and 31.5 ± 1.0 μg g⁻¹ Ca. The dry weight of Mg and Ca in SRM 1572 is found as found 5.613 ± 0.537 and 29.6 ± 1.4 μg g⁻¹ respectively by the method in our study.

Mg and Ca concentrations, Ca:Mg ratio, and Mg:Ca ratio found in Hypericum species considered are shown in Table 1. Highest Ca and Mg levels were measured in H. perforatum. Mg levels in all species were significantly (P < .01) higher than Ca levels, especially in H. perforatum. The highest Ca:Mg ratio was found in H. triquetrifolium and the highest Mg:Ca ratio was found in H. empetrifolium.

We aimed to investigate the Mg and Ca contents in three Hypericum species distributed in the western part of Turkey. ⁷ Hypericum species have been ethnomedically used in different parts of Turkey. ⁷ There are not many articles on the topic of trace element contents of ethnomedically used plants.

Gomez et al. worked on metal content of H. perforatum in pharmaceutical derivates and herbal medicines. ^30,31 In pharmaceutical derivates, they found Ca and Mg levels in the range of 89–5210 and 34.5–75,476 μg mL⁻¹, respectively. The high Mg content is remarkable in these studies and these also support our results. In our study, both Mg and Ca concentrations were determined in three Hypericum species and both trace element levels were higher in H. perforatum.

In our previous studies, we demonstrated the relaxing effect of methanolic extract of H. triquetrifolium on smooth muscles and its antinociceptive activity for the first time. ^8,32

Hypericin, the component used to standardize extracts, showed antidepressant-like properties in the forced swimming test in rats. ³³ However, there is no evidence of the in vivo relevance of this effect. The involvement of hyperforin in the antidepressant effect of the extracts is more consistently documented. Pure hyperforin has antidepressant properties in animal models of depression and the potencies of different extracts closely correlate with their hyperforin content. ^{5,34 –37}

In conclusion, Mg is essential for proper functioning of the nervous system and is known as an antistress mineral. It is used to calm nerves and promote sleep and proper digestion. ^11,38 We proposed that the high concentration of Mg in Hypericum species could affect the sedative activity of the plant. The Mg content of the Hypericum species could have an additive effect of the antidepressant properties of the seconder metabolites of the species.

H. empetrifolium appears to have a higher Mg:Ca ratio, which would then make this species a better agent than the other two tested, assuming that all the Mg present can be delivered. These results can be considered indicative of a good antidepressant capacity and especially H. empetrifolium would be a promising plant source.