Cuneyt Cirak

Changes in the contents of main secondary metabolites in two Turkish Hypericum species during plant development.

Context: The genus Hypericum (Guttiferae) has received considerable scientific interest as a source of biologically active compounds. Objective: The study determined the morphogenetic and ontogenetic variation in the main bioactive compounds of two Hypericum species, namely, Hypericum aviculariifolium subsp. depilatum var. depilatum (Freyn and Bornm.) Robson var. depilatum and Hypericum orientale L. through HPLC analyses of whole plants as well as individual plant parts (stems, leaves, and reproductive tissues). Materials and methods: The plant materials were harvested at five phenological stages: vegetative, floral budding, full flowering, fresh fruiting, and mature fruiting; dried at room temperature, then assayed for chemical content. Results: In H. aviculariifolium, no kaempferol accumulation was observed and the highest level of hypericin, pseudohypericin, and quercitrin was reached at full flowering (0.71, 1.78, and 4.15u2009mg/g DW, respectively). Plants, harvested at floral budding produced the highest amount of rutin, hyperoside, and isoquercitrine (32.96, 2.42, 1.52u2009mg/g DW, respectively). H. orientale did not produce hypericin, pseudohypericin, or kaempferol. Rutin, hyperoside, and isoquercetine levels were the highest at floral development (1.76, 11.85, and 1.21u2009mg/g DW, respectively) and plants harvested at fresh fruiting produced the highest amount of quercitrine and quercetine (0.20 and 1.30u2009mg/g DW, respectively). Discussion: For the first time, the chemical composition of the Turkish species of Hypericum was monitored during the course of ontogenesis to determine the ontogenetic and morphogenetic changes in chemical content. Conclusions: Plant material should be harvested during flower ontogenesis for medicinal purposes in which the content of many bioactive substances tested reached their highest level.

Secondary metabolites of Hypericum orientale L. growing in Turkey: variation among populations and plant parts

The present study was conducted to determine the variation in the content of several plant chemicals, namely hyperforin, hypericin, pseudohypericin, chlorogenic acid, rutin, hyperoside, isoquercetine, kaempferol, quercitrine and quercetine among ten Hypericum orientale L. populations from Northern Turkey. The aerial parts representing a total of 30 individuals were collected at full flowering and dissected into floral, leaf and stem tissues. After dried at room temperature, the plant materials were assayed for chemical contents by HPLC. The populations varied significantly in chemical contents. Among different plant parts, the flowers were found to be the principle organ for hyperforin, hypericin, pseudohypericin and rutin accumulations while the rest of the chemicals were accumulated mainly in leaves in all growing localities. The chemical variation among the populations and plant parts is discussed as being possibly the result of different genetic, environmental and morphological factors.

Chemical composition of Hypericum species from the Taeniocarpium and Drosanthe sections

The presence of several phytochemicals, namely naphthodianthrones hypericin and pseudohypericin, phloroglucinol derivatives hyperforin and adhyperforin, the phenolic acids as chlorogenic acid, neochlorogenic acid, caffeic acid and 2,4-dihydroxybenzoic acid, the flavonols, hyperoside, isoquercitrin, quercitrin, quercetin, avicularin, rutin, and flavanols (+)-catechin and (−)-epicatechin, as well as biflavonoid amentoflavone was investigated in seven Turkish species of Hypericum from Taeniocarpium and Drosanthe sections. Plants were harvested at flowering, dried at room temperature, dissected into different tissues and assayed for chemical contents by HPLC. All chemicals were detected at various levels depending on species and plant parts. Despite the observed quantitative variation in the chemical content of plant material, it was found that phytochemical profiles of the species from the same section were very similar. The present data could be helpful in selecting the future targets for phytochemical and biological studies as well as enriching our current chemical knowledge about Hypericum species. Such kind of data could also be useful for elucidation of the chemotaxonomical relationships among the sections of Hypericum genus.

Altitudinal changes in the content of bioactive substances in Hypericum orientale and Hypericum pallens

Altitudinal changes in the content of hypericin, pseudohypericin, hyperforin, adhyperforin, chlorogenic acid, neochlorogenic acid, caffeic acid, 2,4-Dihydroxybenzoic acid, amentoflavone, hyperoside, isoquercitrin, quercitrin, quercetin, avicularin, rutin, (+)-catechin and (−)-epicatechin among Hypericum orientale L. and Hypericum pallens Banks and Sol. populations from Northern Turkey were investigated for the first time. Thirty flowering individuals were collected from five different altitudes (400, 950, 1,150, 1,620 and 2,150xa0m) for H. pallens and six different altitudes (500, 1,150, 1,650, 2,100, 2,720 and 3,250xa0m) for H. orientale. The plant materials were dried at room temperature and subsequently assayed for chemical contents by HPLC. All chemicals were detected in both species at various levels depending on altitude of growing sites except for caffeic acid which was absent in H. pallens. It was found that plants from higher altitudes produced significantly higher amount of the bioactive compounds tested. The results were discussed as a possible protective response of plants to the different abiotic stress factors as high ultraviolet (UV)-B radiation and low temperature which were prevalent in higher altitudes.

Changes in the content of bioactive substances among Hypericum montbretii populations from Turkey

In the present study, we investigated the variation in the content of seventeen secondary metabolites among Hypericum montbretii Spach., Hypericaceae, populations from five different growing zones in Turkey for the first time.The plants were collected at full flowering, and after they were dried at room temperature, they were assayed for chemical contents by HPLC. Chemical constituents of plants varied significantly among populations except for 2,4-dihydroxybenzoic acid which was accumulated at similar levels. Plants from population - 1 yielded the highest amount of hypericin and pseudohypericin (1.27 and 2.97 mg/g, respectively) while hyperforin and adhyperforin accumulations were the highest in plants from population - 2 (6.64 and 1.24 mg/g, respectively). (+)-Catechin and (-)-epicatechin were accumulated at significantly higher levels by plants of population - 4 (1.54 and 4.35 mg/g, respectively). The highest accumulation level of the rest compounds namely, chlorogenic and neochlorogenic acids, amentoflavone, hyperoside, isoquercitrin, quercitrin, quercetin, avicularin and rutin was reached in plants from population-5 (2.64, 4.37, 2.35, 10.26, 3.52, 4.37, 1.55, 1.56 and 20.54 mg/g, respectively). The pronounced chemical diversity between populations is discussed to possibly be the result of different environmental, morphological and genetic factors.

Aromatic profiling of wild and rare species growing in Turkey: Hypericum aviculariifolium Jaub. and Spach subsp. depilatum (Freyn and Bornm.) Robson var. depilatum and Hypericum pruinatum Boiss. and Bal.

The volatile constituents of the rare species of Hypericum, namely Hypericum pruinatum (as one population) and Hypericum aviculariifolium subp. depilatum var. depilatum (endemic, as two populations namely ‘Gümüş’ and ‘Yeniköy’) growing wild in the mountainous parts of Northern Turkey were studied for the first time. The essential oils (EOs) were extracted by hydrodistillation of the air-dried aerial parts and analysed by GC-FID and GC-MS. A total of 56, 49 and 50 EO components representing 98.2%, 96.9% and 99.4% of the total composition were identified respectively from one population for H. pruinatum and two populations for Hypericum aviculariifolium subp. depilatum var. depilatum. GC-MS profiles showed significant compositional variations not only between the two Turkish species, but also between the two populations of the same species highlighting the importance of genetic factors affecting secondary metabolite profile.

Morphogenetic and phenological changes in phenolic content of Hypericum leptophyllum, an endemic Turkish species

The present study was conducted to determine the morphogenetic and phenologic variations in the content of the main bioactive compounds in Hypericum leptophyllum Hochst., an endemic species from Turkish flora. Wild plants were harvested at five phenological stages: vegetative, floral budding, full flowering, fresh fruiting, and mature fruiting, and assayed for chemical content by HPLC. Results indicated that H. leptophyllum did not accumulate hypericin, pseudohypericin, hyperforin, and adhyperforin. The phenolic content in whole plants increased generally during plant phenology and higher accumulation levels were observed at flowering. Among the reproductive organs, amentoflavone, quercetin, avicularin, and hyperoside contents were the highest in floral buds (2.09, 2.18, 0.55, and 2.62xa0mg g−1 dry mass (DM), respectively). Leaves harvested at the floral budding stage produced the highest content of chlorogenic acid, neochlorogenic acid, caffeic acid, and isoquercetin (53.32, 6.25, 0.03, and 1.91xa0mg g−1 DM,...

Phenological changes in the chemical content of wild and greenhouse-grown Hypericum pruinatum: flavonoids

* Correspondence: cuneytc@omu.edu.tr