Research Article
Hypericin in Some Hypericum Species from Turkey
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Cuneyt Cirak
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Kudret Kevseroglu
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Tevfik Ozen
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The species belonging to Hypericum genus have been used as traditional medicinal plants due to their wound-healing[1], bactericide[2], anti-inflammatory[3]. Diuretic and sedative properties[4] for last two hundred years. Today especially Hypericum perforatum, also known as St. Johns worth and native to relatively dry temperature zones of Europe and North America, is one of plants used in drug production industry the most intensively[5]. This plant contains a number of biologically active secondary metabolites belonging to at least ten different classes[6]. In the clinical studies, anti-tumour[7,8] and anti-cancer[9-11] properties of Hypericum perforatum were determined. Especially using of this unique plant as an antidepressant is very popular[12].
Now a days, there has been an increasing tendency in using of plant-originated raw matters in medicinal treatment due to some reasons such as synthetic products have some adverse effects on human health and are very expensive or plant-originated matters have multifunctional effects in contrast to synthetic products[13]. Today, about 25% of the drugs prescribed worldwide and 121 active compounds being in current use come from plant. Of the 252 drugs considered as basic and essential by the World Health Organization (WHO), 11% are exclusively of plant origin and a significant numbers are synthetic drugs obtained from natural precursors. It is estimated that 60% of anti-tumor and anti-infectious drugs already on the market or under clinical trial are of natural origin[14]. The vast majority of these cannot yet be synthesised economically and are still obtained from wild or cultivated plant[15].
Hypericin, a photoactive dianthone, has a great importance in economical and health care point of view[16] and is one of the plant-originated raw matters used in medicinal treatments. Total hypericin content of products has been used for standardisation purposes within the botanical industry[17]. Antidepressant effect of Hypericum extracts has been originated from their hypericin contents to a large extent. Recently it was reported that hypericin exhibit antiviral[18,19] properties. Therefore, it is suggested that Hypericum species containing hypericin have a potential in using of Acquired Immuno Deficiency Syndrome (AIDS) treatment[20]. Also, hypericin has a chemotaxonomically importance for the infrageneric classification of the genus Hypericum. That is why, it is the most important constituent Hypericums contain.
There are about 300 Hypericum living in mild temperature zone of the world but, limited number of them contain hypericin[21,22]. Turkey is an important center for Hypericum. There are 69 Hypericum species in Turkey, 24 of which are endemic[23]. In this study, to investigate the presence of hypericin in some Hypericum from Turkey was aimed.
Plant materials: Hypericum plants were collected between August and September, 2003 from five sites Northern Turkey: Rize, Trabzon, Amasya, Samsun and Kastamonu and identified by Dr. Hasan Korkmaz, Department of Biology, University of 19 Mayis, Samsun-Turkey. All plants were growing wild and no herbarium materials were used. Sampling was randomised from plant crowns that had at least three stems. The top 1/3 of the crown was harvested between 10:00 AM and 2:00 PM. Conditions on the day of collection were clear and sunny at all sites. Temperatures ranged from 24 to 35 °C. Samples were dissected into tissue parts and dried overnight (or until constant weight) at 65°C, the current temperature used by wildcrafters in USA for industry production[24].
Determination of hypericin content of samples: Dried and homogenised aerial parts of plants were extracted with chloroform in a sonicator to remove their chlorophyll contents until samples seen colourless and filtered. The dried powder was then extracted with methanol and the filtrate allowed to evaporate in a water bath. This was followed by an addition of chloroform and the mixture was shaken. The supernatants was then discarded and the solid phase, containing hypericin, was dissolved in methanol and filtered. The hypericin content was determined in methanol extracts by a spectrophotometer (Shimadzu UV 3000) at 590 nm[25]. Three determination were made from each sample and the mean value was calculated.
The 18 examined species represent about 5% of all taxa in the genus. The results from the quantification of hypericin was presented in Table 1 where the species were listed alphabetically.
Hypericin was observed in 12 species and was not detectable in the rest. There is so far no report related to secondary metabolites content of some Hypericum evaluated here, H. aviculariifolium subsp. depilatum (endemic), H. heterophyllum, H. hyssopifolium subsp. elongatum, H. nummularioides, H. orientale, H.pruinatum and H. venustum and in the present study, it is the first time we have reported the presence of hypericin in 4 species, H. aviculariifolium subsp. depilatum, H. nummularioides, H. pruinatum and H. venustum.
Table 1: | Presence of hypericin and its total content in some Hypericum spp. |
aEndemic; bMeans of three determinations |
The results are in accordance with those of Gerassim and Kitanov[26] reporting the presence of hypericin in H. bithynicum, H. linarioides, H. montanum, H. montbretii, H. origanifolium, H. perfoliatum, H. perforatum and absence of hypericin in H. androsaemum and H. bupleuroides. Similarly, hypericin was reported in H. hirsutum by Makovetskaya and Maksiutina[27] and wasnt reported in H.scabrum by Zevakova et al.[28].
The total content of hypericin in the investigated species varies widely from 0.003% in H. venustum to 0.303% in H. perforatum. The largest amount was found in the species of H. perforatum used for hypericin production worldwide commonly in botanical industry. Moderate quantities of this component was established in H. aviculariifolium subsp. depilatum, H. bithynicum and H. montbretii (0.108, 0.174 and 0.224%, respectively). The lowest quantities were observed in H. venustum and H. perfoliatum with 0.003 and 0.005%.
It should be noted that differences in the content of hypericin in some reinvestigated species were found when the results were compared to those of other authors. These distinctions are due to the different methods used and perhaps to geographical and ecological factors, population variability, using herbarium or fresh plant materials and the phases of plant collection. For examples, Gerassim and Kitanov[26] have found 0.056% hypericin in flowering plants of H. perfoliatum, whereas we observed only 0.005% of this component in the herb of the same plant, collected during the budding period.
Of all Hypericum, so far, only a few have been reported to contain hypericin[29] and although a large number of species have been phytochemically investigated from the other subfamilies of Guttiferae, hypericin has been established only in Hypericum species[26]. Thus, it may be concluded that the occurrence of hypericin in Hypericum species has an important pharmacological value for their medicinal evaluation and taxonomic value for infrageneric classification of the genus.